INDAHNYA WANITA
Di ambil dari milis tetangga (alumni SMANSA Serang)
Adakah diantara kita yang tidak puas diciptakan menjadi seorang wanita? Ingin menuntut hak yang sama dengan Pria karena merasa derajatnya dibawah Pria ?Hanya orang kafir dan kaum materialislah yang berpikiran seperti itu,tidak percaya bahwa Allah SWT sang Pencipta telah menetapkan aturanyang begitu sempurnanya. Dalam Islam kedudukan wanita sederajat dengan pria namun karena takdir(akal dan perasaan) yang diberikan berbeda, maka tugas, kewajiban dantanggung jawabnya pun berbeda.Seorang Wanita harus patuh dan taat kepada suami sebagai kepala rumahtangga, namun sebaliknya Seorang suami pun harus patuh dan taat kepadasang Ibu yang dulu mengandung dan membesarkannya.sebaik-baik perhiasan dunia adalah wanita sholehah.Dan "perkara yang pertama kali ditanyakan kepada seorang wanita padahari kiamat nanti, adalah mengenai sholat lima waktu dan ketaatannyaterhadap suami."(HR.Ibnu Hibban dari Abu Hurairah)Ada 10 wasiat Rasulullah kepada putrinya Fathimah binti Rasulillah.Wasiat ini merupakan mutiara yang termahal nilainya bila kemudiandimiliki olehsetiap istri sholehah. Wasiat tsb adalah:
1. Kepada wanita yang membuat tepung untuk suami dan anak-anaknya,Allah pasti akan menetapkan kebaikan baginya dari setiap biji gandum,melebur kejelekan, dan meningkatkan derajat wanita itu.
2. Kepada wanita yang berkeringat ketika menumbuk tepung untuk suami dan anak-anaknya,niscaya Allah menjadikan dirinya dengan neraka tujuh tabir pemisah.
3. Tiadalah seorang yang meminyaki rambut anak-anaknya lalu menyisirnya dan mencuci pakaiannya,Allah akan menetapkan pahala baginya seperti pahala memberi makan seribu orang yang Kelaparan dan memberi pakaianseribu orang yang telanjang.
4. Tiadalah wanita yang menahan kebutuhan tetangganya, Allah akan menahannya dari minum telaga kautsar pada hari kiamat nanti.
5. Yang lebih utama dari seluruh keutamaan di atas adalah keridhoaan suami terhadap istri.Andaikata suamimu tidak ridho kepadamu, maka aku tidak akanmendoakanmu. Ketahuilah wahai Fathimah, kemarahan suami adalahkemurkaan Allah.
6. Apabila wanita mengandung, maka malaikat memohonkan ampunan baginya,dan Allah menetapkan baginya setiap hari seribu kebaikan serta meleburseribu kejelekan.Ketika wanita merasa sakit akan melahirkan, Allah menetapkan pahala baginya sama dengan pahala para pejuang di jalan Allah.Jika dia melahirkan kandungannya, maka bersihlah dosa-dosanya seperti ketika dia dilahirkan dari kandungan ibunya.Bila meninggal ketika melahirkan, maka dia tidak akan membawa dosasedikitpun. Didalam kubur akan mendapat pertamanan indah yang merupakanbagian dari taman sorga.Dan Allah memberikan pahala kepadanya sama dengan pahala seribu orangyang melaksanakan ibadah haji dan umrah, dan seribu malaikat memohonkanampunan baginya hingga hari kiamat.
7. Tiadalah wanita yang melayani suami selama sehari semalam denganrasa senang serta ikhlas, Allah mengampuni dosa-dosanya sertamemakaikan pakaian padanya di hari kiamat berupa pakaian yang serbahijau, dan menetapkan baginya setiap rambut pada tubuhnya seribukebaikan.Dan Allah memberikan kepadanya pahala seratus kali beribadah haji dan umrah.
8. Tiadalah wanita yang tersenyum di hadapan suami, Allah memandangnya dengan pandangan penuh kasih.
9. Tiadalah wanita yang membentangkan alas tidur untuk suami denganrasa senang hati, para malaikat yang memanggil dari langit menyeruwanita itu agar menyaksikan pahala amalnya, dan Allah mengampunidosa-dosanya yang telah lalu dan yang akan datang.
10. Tiadalah wanita yang meminyaki kepala suami dan menyisirnya,meminyaki jenggot dan memotong kumisnya, serta memotong kukunya,melainkan Allah memberi minuman arak yang dikemas indah kepadanya yangdidatangkan dari sungai2 sorga.Allah mempermudah sakaratul-maut baginya, serta kuburnya menjadi bagian dari taman sorga.Dan Allah menetapkan baginya bebas dari siksa neraka serta dapat melintasi shirathal-mustaqim dengan selamat.
Begitu indahnya menjadi wanita, dengan kelembutan dan kasihnya dapat merubah duniaJadilah diri-dirimu wanita sholehah, agar negeri menjadi indah, karena dirimu adalah tiang negeri iniSubhanallah……betapa Allah swt. telah mengagungkan seorang wanita yang telah diciptakanNYA, jauh lebih besar Dibanding apa yang mereka duga.Masihkah ada diantara kita yang tidak puas diciptakan menjadi seorang wanita ?
Sabtu, 27 September 2008
Minggu, 14 September 2008
cahaya tampak lampu dioda dari WBGS dengan logam tanah jarang sebagai doping
VISIBLE LIGHT EMITTING DEVICE FORMED FROM WIDE BAND GAP SEMICONDUCTOR DOPED WITH A RARE EARTH ELEMENT
source : http://www.wipo.int/
Visible Light Emitting Device Formed From Wide Band Gap Semiconauctor Doped With a Rare Earth Element Background of the invention Light emitting diodes (LED) and related light emitting devices are used in a vast number of applications. These can be used in most light emitting devices from simple panel lights to complex displays and lasers.
Currently LEDs are used in the automotive industry, consumer instrumentation electronics, and many military applications. Different compound are used to produce different wavelengths of light. For example. aluminum gallium arsenide is used for red LEDs, gallium aluminum phosphide for green, and GaN for blue. Light emitting materials formed from three different materials are often difficult to produce. Utilizing different LEDs together inherently requires allowing for different performance characteristics such as current and voltage requirements.
Wide band gap semiconductors (WBGS) doped with light emitting elements such as rare earth elements (RE) and other elements with partially filled inner shells are particularly attractive for L-Ds because the emission efficiency appears to increase with band gap value, thus allowing room temperature operation without the need to introduce impurities. Wide band gap generaily refers to a band gap of 2 eV or greater. Electroluminescence has been reported from several WBGS hosts including Er-doped gallium arsenide, gallium phosphide, GaN, ZnSe and SiC. Er-doped semiconductor light emitting diodes have been shown to emit in the infrared at about 1.5 microns. The infrared emission corresponds to transmissions between the lowest excited state (41, =2) and the ground state (41, 5, 2) of the erbium atoms. The first Er-doped semiconductor light emitting diodes emitted IR light only at very low temperatures. However, recent advancements have permitted IR light emission at near room temperature. Although IR emitting Er-doped GaN has a great deal of utility in the communications industry, it previously has not been useful in a light emitting diode requiring visible emission.
Summary of the Invention The present invention is premised on the reaiization that wide band gap semiconductor substrates doped with elements with partially filled inner shells such as rare earth elements and transition metals can be formed and will emit in the visible and ultraviolet spectrum at a wide range of temperatures. The wide band gap semiconductor material are group III-V and IV materials including diamond, GaN, AIN, InN, BN and alloys thereof. These are doped with elements such as cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, turbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium or other elements with partially filled inner shells.
By proper formation of the wide band gap semiconductor material and proper introduction of the rare earth element, a light emitting diode can be formed which emits in the visible spectrum.
By selection of the appropriate dopant material, one can select the appropriate color. For example, in GaN, erbium will produce green whereas thulium will produce blue and praseodymium will produce red.
The objects and advantages of the present invention will be further appreciated in the light of the following detailed description and drawing inwhich: Brief Description of the Drap* The Figure is a graph depicting the PL spectrum of Pr-implanted GaN films treated under different annealing conditions.
Detailed Description In order to form a light emitting devices according to the present invention, a wide band gap semiconductor material is formed on a substrate and doped with an effective amount of a rare earth element.
The substrate itself can be any commonly used substrate such as silicon, silica, sapphire, metals, ceramics and insulators.
The WBGS is either a group III-V material or a group IV material such as diamond. In particular the WBGS material can include III-V semiconductors such as GaN, InN, AIN, BN as well as alloys of these.
Any production method which forms crystalline semiconductors can be used. Suitable techniques indure molecular beam epitaxy (MBE), metal- organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PCVD), hydride vapor phase epitaxy (HVPE) and PECD. The desired thickness of a WBGS material will be formed on the substrate. For emission purposes the thickness of the WBGS is not critical. For practical reasons the thickness of the WBGS layer will be from about. 2 to about 5 microns, with around 1 to 2 microns being preferred.
For the rare earth or transition metal to be strongly optically active in the wide band gap semiconductor, group III deficient growth conditioners should be utilized. This should permit the rare earth element to sit in an optically active site which promotes the higher energy or visible light emission.
The dopant material is one which has a partially filled inner shell with transition levels that can result in visible or U. V. emission. The dopant material can be a transition metal such as chromium or a rare earth element preferably from the lanthanide series and can be any of cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, turbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium. Typically RE dopants include thulium for a blue display, praseodymium for a red display, and erbium for a green display. These can be added to the WBGS by either in situ methods or by ion implantation. Generally the concentration can be relativeiy high, from less than about 0.1% up to about 10 atomic percent. The dopant concentration can be increased until the emission stops. Generally, the preferred concentration will be about. 1 to about 10 atomic percent.
Further a full-color display can be created by utilizing three overlapping WBGS layers such as GaN each layer doped with different light emitting rare earth elements. Separate wiring could be used for each layer and each layer could be separated by transparent insulating layers.
An array of side by side light emitting diodes could also be used to provide a full color display. A combination of dopants in the same WBGS can also be employed.
It may be desirable to anneal the WBGS. This tends to increase emission up to a point. Generally the WBGS is annealed in an argon or other inert environment at a temperature 800-1200° C for 1-5 hours.
More preferably the temperature will be from 850-1050° C, most preferably about 950° C.
The invention will be further appreciated in light of the following detailed example.
Example 1.
An erbium-doped GaN Schottky contact LED emitting visible light was formed by growing an erbium-doped GaN film in a Riber MBE-32 system on a two inch pSi substrate. Solid sources are employed to supply the galiium (7 N purity) and erbium (3 N) fluxes while an SVTA rf plasma source is used to generate atomic nitrogen. In this application, a GaN buffer layer was first deposited for 10 minutes at a temperature of 600°C followed by GaN growth at a temperature of 750"C. The growth conditions were as follows: nitrogen flow rate 1.5 sccm at a plasma power of 400 Watts, gallium cell temperature of 922 °C (corresponding to a beam pressure of 8.2 x 10 7 torr) and erbium cell temperature of 1100°C. The resulting GaN growth rate was about 0.8 microns/hour, and the erbium concentration was about 1021/cri. GaN films with a thickness of 2.5 microns were utilized.
To fabricate Schottky diodes on the GaN: erbium films, a semitransparent aluminum layer was deposited by sputtering. The aluminum film was patterned into a series of ring structures of varying areas utiiizing a lift-off process. The aluminum rings serve as individual Schottky contacts while a large continuous aluminum surface was used as a common ground electrode. Electro luminescence characterization at ultraviolet and visible wavelengths was performed with a 0.3 m Acton research spectrometer fitted with a photo multiplier tube detector. All measurements were conducted at room temperature using dc applied bias voltage and current.
Applying reverse bias current to the order of 1 milliamp to a GaN: erbium Schottky LED, results in green emission visible with the naked eye under normal ambient lighting conditions. The emission spectrum consists of two strong and narrow lines at 537 and 558 nm which provides the green emission color. The two green lines have been identified as erbium transmissions from a 2H1"2 and 4S3, 2 levels to the 41, 5, 2 ground state. Photo luminescence characterization of the same GaN erbium films grown on silicon performed with a helium cadmium laser excitation source at a wavelength of 325 nanometers, corresponding to an energy greater than a GaN band gap, also produce green emissions from the same two transitions. Minor EL peaks were observed at 413 and at 666/672 nanometers.
The device had a threshold voltage for forward conduction of about 8.5 volts. At a forward voltage of 20 volts, a current flow of 350 milliamps is obtained. Under reverse bias of 20 volts, a current of about 30 microamps is measured. The capacitance voltage characteristic of the diode has a voltage intercept of about 11.5 volts and an effective GaN carrier concentration of approximately 10'2/cm3. The high diode forward resistence obtained in the current voltage characteristics of about 34 kilo- Ohms is probably due to the high resistivity of the GaN layer. The Schottky barrier height calculated from the capacitance voltage characteristics is approximately 9 volts, which was consistent with the threshold voltage. This large voltage probably indicates the presence of an insulating layer on the aluminum-GaN interface.
A linear relationship is maintained between the optical output and the bias current over a wide range of values. At current values smaller than 200 milliamps, the relationship is linear.
Example 2.
Er-doped GaN films are formed in a Riber MBE-32 system on c- axis sapphire substrates. Solid sources were employed to supply the Ga (7 N purity), AI (6 N), and Er (3 N) fluxes, while an SVTA Corp. rf plasma source was used to generate atomic nitrogen. The substrate was initially nitrided at 750 for 30 min at 400 W rf power with a N2 flow rate of 1.5 sccm, corresponding to a chamber pressure of mid-10-5Torr. An AIN buffer layer was grown at 550°C for 10 minutes with an AI beam pressure of 2.3 x 10 8 Torr (cell temperature of 970c C). Growth of the Er-doped GaN proceeded at 750°C for 3 hours with a constant Ga beam pressure of 8.2 x 10-7 Torr (cell temperature of 922°C). The Er cell temperature was varied from 950 to 1100CC. The resulting GaN film thickness was nominally 2.4um giving a growth rate of 0.8 am/h, as measured by scanning electron microscopy (SEM) and transmission optical spectroscopy. Photoluminescence (PL) characterization was performed with two excitation sources: (a) above the GaN band gap-HeCd laser at 325 nm (4-8 mW on the sample); (b) below the GaN band gap-Ar laser at 488 nm (25-30 mW). The PL signal was analyzed by a 0.3 m Acton Research spectrometer outfitted with a photomultiplier for ultraviolet (UV)- visible wavelengths (350-600 nm) and an InGaAs detector for infrared (1.5 um) measurements. The PL signal of the Er-doped GaN samples was obtained over the 88-400 K temperature range. Above band gap excitation (He-Cd laser) resulted in light green emission form the Er- doped GaN films, visible with the naked eye.
Two major emission multiplets are observed in the green wavelength region with the strongest lines at 537 and 558 nm. A broad emission region is also present, peaking in the light blue at 480 nm. The yellow band typically observed at-540-550 nm in GaN PL is absent.
Example 3.
Pr-doped GaN films were grown in a Riber MBE-32 system on 2" inch (50 mm) p-Si (111) substrates. Solid sources were employed to supply the Ga and Pr fluxes, while an SVTA rf-plasma source was used to generate atomic nitrogen. The growth of GaN: Pr followed the procedure previously discerned for GaN: Er. Substrate growth temperature was kept constant at 750° C and the Pr cell temperature was 1200° C. We estimate, based on our work with GaN: Er, that this cell temperature results in a Pr concentration in the range of 1018-102°/cm3.
PL characterization was performed with He-Cd and Ar laser excitation sources at wavelengths of 325 and 488 nm, respectively. The PL and EL signals were characterized with a 0.3-m Acton Research spectrometer outfitted with a photomultiplier tube (PMT) detector for UV-visible wavelengths and an InGaAs detector for IR. To measure EL characteristics, contacts were formed by sputtering a transparent and conducting indium-tin-oxide (ITO) layer onto the GaN: Pr structure.
He-Cd PL excitation (as 325 nm) resulted in an intense, deep red emission from the Pr-doped GaN, visible with the naked eye. The room temperature PL at visible wavelengths is shown in Fig. 1 for a 1.5 pm thick GaN film grown on Si. The spectrum indicates a very strong emission line in the red region at 650 nm, with a weak secondary peak at 668 nm.
Example 4.
Praseodymium implantation was performed in a MicroBeam 150 FiB system utilizing a Pr-Pt liquid alloy ion source (LAIS). The Pr-Pt alloy was prepared by mixing praseodymium and platinum at an atomic percent ratio of 87 : 13. This produces an eutectic alloy with a melting point of 718° C. Mass spectrum analysis showed that a Pr2+ target current of-200 pA was produced, representing 75% of the total target current. A Pt+ target current of-50 pA was also observed.
The Pr2+ beam was accelerated to high voltage and implantation was carried out at room temperature on GaN films grown by MBE, HVPE, and metalorganic chemical vapor deposition (MOCVD). After FIB implantation, the samples were annealed under different conditions. PL measurements were performed at room temperature by pumping the samples with a CW He-Cd laser at 325 nm. The He-Cd laser was focused on the sample surface, where the laser power and beam diameter were 12mW and 2001um, respectively. The PL signal was collecte by a lock-in amplifier and characterized with a 0.3-m Acton Research spectrometer outfitted with a photomultiplier tube (PMT) detector for UV-visible wavelengths and an InGaAs detector cooled to 0° C for IR. A grating of 1200 grooves/mm with a resolution of 1.67nm/mm was used for UV-visible wavelengths.
The Figure shows the annealing effect on PL intensity for a Pr- implanted GaN film grown on sapphire by MBE. The implanted pattern is a 136pmxl36pm square. The implantation was performed using a 300keV Pr2+ beam with a target current of 200pA. The pixel exposure time was 1.14ms and the pixei size was 0.265umx0. 265um. This results in a dose of-1 x10'S atoms/cm2. Simulation of these implantation conditions using TRIM'959 calculates a projected range of-60 nm and a peak concentration of-1.7x102° atoms/cm3. The sample was first annealed at 950° C for one hour in flowing argon. After this first anneal, the 650nm peak became discernible. The sample was subsequently annealed at 950° C for another two hours, leading to an increase in the peak intensity at 650nm. The third anneal was carried out at 1050° C for one hour resulting in the PL intensity at 650nm increasing by a factor of 4. In spite of the small implanted pattern size (136pmxl36pm), the emitted red light intensity was strong enough to be easily seen with the naked eye. Anneaiing for a fourth and final time at 1050° C resulted in a reduced PL intensity. This suggests that a one-step annealing at 1050° C is adequate to optically activate the Pr"ions implanted in the GaN film.
Similar PL spectra were observed from Pr-doped sulfide glasses.
Example 5.
A GaN region was also patterned by Pr FIB implantation. The implantation was performed using a 290keV Pr2+ beam for a dose of -4.7x10'4 atoms/cm2. After FIB implantation, the sample was annealed at 1050°C for one hour in Ar. Under UV excitation from the He-Cd laser, the implanted region emits red light, while unimplanted surrounding area shows the yellow band emission of GaN.
Exampie 6.
Pr implantation was also performed on GaN films grown by HVPE and MOCVD. Regions consisting of 141, umx141, um squares were implanted on both samples with a dose of 1X1015 atomsicm2 and a beam energy of 290keV. Both samples as well as a Pr-implanted MBE sample (dose = 4.7x10" atoms/cm2) show strong red emission at 650nm, which corresponds to the 3Po 3F2 transition of Pr3+. All three samples show similar band edge emission at around 365nm.
Example 7.
Pr-implanted GaN film grown by MBE on sapphire was formed.
After FIB implantation with a dose of 4.7x10'4 Pr/cm2 the sample was annealed at 1050°C for one hour in Ar. The Pr concentration of the in-situ doped GaN film is estimated to be at the range of 10'8-102° atoms/cm3.
In general, the PL intensity of the in-situ Pr-doped GaN sample is stronger (-5x) than that in the FIB-imptanted sample, which is expected from the much larger Pr-doped volume which is excited in the former case. For the samples. the full width at half maximum (FWHM) of the 648 and 650nm lines are-1.2nm, which corresponds to 3.6meV.
Thus the present invention can be utilized to produce light emitting devices from wide band gap semiconductor material utilizing rare earth dopants. The particular wavelength of emission is certainly characteristic of the added component. Further, it is possible to combine the rare earth implants to develop unique light emitting devices. Thus the present invention lends itself to a wide variety of different light emitting devices, extending from the infrared range down through the ultraviolet range.
source : http://www.wipo.int/
Visible Light Emitting Device Formed From Wide Band Gap Semiconauctor Doped With a Rare Earth Element Background of the invention Light emitting diodes (LED) and related light emitting devices are used in a vast number of applications. These can be used in most light emitting devices from simple panel lights to complex displays and lasers.
Currently LEDs are used in the automotive industry, consumer instrumentation electronics, and many military applications. Different compound are used to produce different wavelengths of light. For example. aluminum gallium arsenide is used for red LEDs, gallium aluminum phosphide for green, and GaN for blue. Light emitting materials formed from three different materials are often difficult to produce. Utilizing different LEDs together inherently requires allowing for different performance characteristics such as current and voltage requirements.
Wide band gap semiconductors (WBGS) doped with light emitting elements such as rare earth elements (RE) and other elements with partially filled inner shells are particularly attractive for L-Ds because the emission efficiency appears to increase with band gap value, thus allowing room temperature operation without the need to introduce impurities. Wide band gap generaily refers to a band gap of 2 eV or greater. Electroluminescence has been reported from several WBGS hosts including Er-doped gallium arsenide, gallium phosphide, GaN, ZnSe and SiC. Er-doped semiconductor light emitting diodes have been shown to emit in the infrared at about 1.5 microns. The infrared emission corresponds to transmissions between the lowest excited state (41, =2) and the ground state (41, 5, 2) of the erbium atoms. The first Er-doped semiconductor light emitting diodes emitted IR light only at very low temperatures. However, recent advancements have permitted IR light emission at near room temperature. Although IR emitting Er-doped GaN has a great deal of utility in the communications industry, it previously has not been useful in a light emitting diode requiring visible emission.
Summary of the Invention The present invention is premised on the reaiization that wide band gap semiconductor substrates doped with elements with partially filled inner shells such as rare earth elements and transition metals can be formed and will emit in the visible and ultraviolet spectrum at a wide range of temperatures. The wide band gap semiconductor material are group III-V and IV materials including diamond, GaN, AIN, InN, BN and alloys thereof. These are doped with elements such as cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, turbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium or other elements with partially filled inner shells.
By proper formation of the wide band gap semiconductor material and proper introduction of the rare earth element, a light emitting diode can be formed which emits in the visible spectrum.
By selection of the appropriate dopant material, one can select the appropriate color. For example, in GaN, erbium will produce green whereas thulium will produce blue and praseodymium will produce red.
The objects and advantages of the present invention will be further appreciated in the light of the following detailed description and drawing inwhich: Brief Description of the Drap* The Figure is a graph depicting the PL spectrum of Pr-implanted GaN films treated under different annealing conditions.
Detailed Description In order to form a light emitting devices according to the present invention, a wide band gap semiconductor material is formed on a substrate and doped with an effective amount of a rare earth element.
The substrate itself can be any commonly used substrate such as silicon, silica, sapphire, metals, ceramics and insulators.
The WBGS is either a group III-V material or a group IV material such as diamond. In particular the WBGS material can include III-V semiconductors such as GaN, InN, AIN, BN as well as alloys of these.
Any production method which forms crystalline semiconductors can be used. Suitable techniques indure molecular beam epitaxy (MBE), metal- organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PCVD), hydride vapor phase epitaxy (HVPE) and PECD. The desired thickness of a WBGS material will be formed on the substrate. For emission purposes the thickness of the WBGS is not critical. For practical reasons the thickness of the WBGS layer will be from about. 2 to about 5 microns, with around 1 to 2 microns being preferred.
For the rare earth or transition metal to be strongly optically active in the wide band gap semiconductor, group III deficient growth conditioners should be utilized. This should permit the rare earth element to sit in an optically active site which promotes the higher energy or visible light emission.
The dopant material is one which has a partially filled inner shell with transition levels that can result in visible or U. V. emission. The dopant material can be a transition metal such as chromium or a rare earth element preferably from the lanthanide series and can be any of cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, turbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium. Typically RE dopants include thulium for a blue display, praseodymium for a red display, and erbium for a green display. These can be added to the WBGS by either in situ methods or by ion implantation. Generally the concentration can be relativeiy high, from less than about 0.1% up to about 10 atomic percent. The dopant concentration can be increased until the emission stops. Generally, the preferred concentration will be about. 1 to about 10 atomic percent.
Further a full-color display can be created by utilizing three overlapping WBGS layers such as GaN each layer doped with different light emitting rare earth elements. Separate wiring could be used for each layer and each layer could be separated by transparent insulating layers.
An array of side by side light emitting diodes could also be used to provide a full color display. A combination of dopants in the same WBGS can also be employed.
It may be desirable to anneal the WBGS. This tends to increase emission up to a point. Generally the WBGS is annealed in an argon or other inert environment at a temperature 800-1200° C for 1-5 hours.
More preferably the temperature will be from 850-1050° C, most preferably about 950° C.
The invention will be further appreciated in light of the following detailed example.
Example 1.
An erbium-doped GaN Schottky contact LED emitting visible light was formed by growing an erbium-doped GaN film in a Riber MBE-32 system on a two inch pSi substrate. Solid sources are employed to supply the galiium (7 N purity) and erbium (3 N) fluxes while an SVTA rf plasma source is used to generate atomic nitrogen. In this application, a GaN buffer layer was first deposited for 10 minutes at a temperature of 600°C followed by GaN growth at a temperature of 750"C. The growth conditions were as follows: nitrogen flow rate 1.5 sccm at a plasma power of 400 Watts, gallium cell temperature of 922 °C (corresponding to a beam pressure of 8.2 x 10 7 torr) and erbium cell temperature of 1100°C. The resulting GaN growth rate was about 0.8 microns/hour, and the erbium concentration was about 1021/cri. GaN films with a thickness of 2.5 microns were utilized.
To fabricate Schottky diodes on the GaN: erbium films, a semitransparent aluminum layer was deposited by sputtering. The aluminum film was patterned into a series of ring structures of varying areas utiiizing a lift-off process. The aluminum rings serve as individual Schottky contacts while a large continuous aluminum surface was used as a common ground electrode. Electro luminescence characterization at ultraviolet and visible wavelengths was performed with a 0.3 m Acton research spectrometer fitted with a photo multiplier tube detector. All measurements were conducted at room temperature using dc applied bias voltage and current.
Applying reverse bias current to the order of 1 milliamp to a GaN: erbium Schottky LED, results in green emission visible with the naked eye under normal ambient lighting conditions. The emission spectrum consists of two strong and narrow lines at 537 and 558 nm which provides the green emission color. The two green lines have been identified as erbium transmissions from a 2H1"2 and 4S3, 2 levels to the 41, 5, 2 ground state. Photo luminescence characterization of the same GaN erbium films grown on silicon performed with a helium cadmium laser excitation source at a wavelength of 325 nanometers, corresponding to an energy greater than a GaN band gap, also produce green emissions from the same two transitions. Minor EL peaks were observed at 413 and at 666/672 nanometers.
The device had a threshold voltage for forward conduction of about 8.5 volts. At a forward voltage of 20 volts, a current flow of 350 milliamps is obtained. Under reverse bias of 20 volts, a current of about 30 microamps is measured. The capacitance voltage characteristic of the diode has a voltage intercept of about 11.5 volts and an effective GaN carrier concentration of approximately 10'2/cm3. The high diode forward resistence obtained in the current voltage characteristics of about 34 kilo- Ohms is probably due to the high resistivity of the GaN layer. The Schottky barrier height calculated from the capacitance voltage characteristics is approximately 9 volts, which was consistent with the threshold voltage. This large voltage probably indicates the presence of an insulating layer on the aluminum-GaN interface.
A linear relationship is maintained between the optical output and the bias current over a wide range of values. At current values smaller than 200 milliamps, the relationship is linear.
Example 2.
Er-doped GaN films are formed in a Riber MBE-32 system on c- axis sapphire substrates. Solid sources were employed to supply the Ga (7 N purity), AI (6 N), and Er (3 N) fluxes, while an SVTA Corp. rf plasma source was used to generate atomic nitrogen. The substrate was initially nitrided at 750 for 30 min at 400 W rf power with a N2 flow rate of 1.5 sccm, corresponding to a chamber pressure of mid-10-5Torr. An AIN buffer layer was grown at 550°C for 10 minutes with an AI beam pressure of 2.3 x 10 8 Torr (cell temperature of 970c C). Growth of the Er-doped GaN proceeded at 750°C for 3 hours with a constant Ga beam pressure of 8.2 x 10-7 Torr (cell temperature of 922°C). The Er cell temperature was varied from 950 to 1100CC. The resulting GaN film thickness was nominally 2.4um giving a growth rate of 0.8 am/h, as measured by scanning electron microscopy (SEM) and transmission optical spectroscopy. Photoluminescence (PL) characterization was performed with two excitation sources: (a) above the GaN band gap-HeCd laser at 325 nm (4-8 mW on the sample); (b) below the GaN band gap-Ar laser at 488 nm (25-30 mW). The PL signal was analyzed by a 0.3 m Acton Research spectrometer outfitted with a photomultiplier for ultraviolet (UV)- visible wavelengths (350-600 nm) and an InGaAs detector for infrared (1.5 um) measurements. The PL signal of the Er-doped GaN samples was obtained over the 88-400 K temperature range. Above band gap excitation (He-Cd laser) resulted in light green emission form the Er- doped GaN films, visible with the naked eye.
Two major emission multiplets are observed in the green wavelength region with the strongest lines at 537 and 558 nm. A broad emission region is also present, peaking in the light blue at 480 nm. The yellow band typically observed at-540-550 nm in GaN PL is absent.
Example 3.
Pr-doped GaN films were grown in a Riber MBE-32 system on 2" inch (50 mm) p-Si (111) substrates. Solid sources were employed to supply the Ga and Pr fluxes, while an SVTA rf-plasma source was used to generate atomic nitrogen. The growth of GaN: Pr followed the procedure previously discerned for GaN: Er. Substrate growth temperature was kept constant at 750° C and the Pr cell temperature was 1200° C. We estimate, based on our work with GaN: Er, that this cell temperature results in a Pr concentration in the range of 1018-102°/cm3.
PL characterization was performed with He-Cd and Ar laser excitation sources at wavelengths of 325 and 488 nm, respectively. The PL and EL signals were characterized with a 0.3-m Acton Research spectrometer outfitted with a photomultiplier tube (PMT) detector for UV-visible wavelengths and an InGaAs detector for IR. To measure EL characteristics, contacts were formed by sputtering a transparent and conducting indium-tin-oxide (ITO) layer onto the GaN: Pr structure.
He-Cd PL excitation (as 325 nm) resulted in an intense, deep red emission from the Pr-doped GaN, visible with the naked eye. The room temperature PL at visible wavelengths is shown in Fig. 1 for a 1.5 pm thick GaN film grown on Si. The spectrum indicates a very strong emission line in the red region at 650 nm, with a weak secondary peak at 668 nm.
Example 4.
Praseodymium implantation was performed in a MicroBeam 150 FiB system utilizing a Pr-Pt liquid alloy ion source (LAIS). The Pr-Pt alloy was prepared by mixing praseodymium and platinum at an atomic percent ratio of 87 : 13. This produces an eutectic alloy with a melting point of 718° C. Mass spectrum analysis showed that a Pr2+ target current of-200 pA was produced, representing 75% of the total target current. A Pt+ target current of-50 pA was also observed.
The Pr2+ beam was accelerated to high voltage and implantation was carried out at room temperature on GaN films grown by MBE, HVPE, and metalorganic chemical vapor deposition (MOCVD). After FIB implantation, the samples were annealed under different conditions. PL measurements were performed at room temperature by pumping the samples with a CW He-Cd laser at 325 nm. The He-Cd laser was focused on the sample surface, where the laser power and beam diameter were 12mW and 2001um, respectively. The PL signal was collecte by a lock-in amplifier and characterized with a 0.3-m Acton Research spectrometer outfitted with a photomultiplier tube (PMT) detector for UV-visible wavelengths and an InGaAs detector cooled to 0° C for IR. A grating of 1200 grooves/mm with a resolution of 1.67nm/mm was used for UV-visible wavelengths.
The Figure shows the annealing effect on PL intensity for a Pr- implanted GaN film grown on sapphire by MBE. The implanted pattern is a 136pmxl36pm square. The implantation was performed using a 300keV Pr2+ beam with a target current of 200pA. The pixel exposure time was 1.14ms and the pixei size was 0.265umx0. 265um. This results in a dose of-1 x10'S atoms/cm2. Simulation of these implantation conditions using TRIM'959 calculates a projected range of-60 nm and a peak concentration of-1.7x102° atoms/cm3. The sample was first annealed at 950° C for one hour in flowing argon. After this first anneal, the 650nm peak became discernible. The sample was subsequently annealed at 950° C for another two hours, leading to an increase in the peak intensity at 650nm. The third anneal was carried out at 1050° C for one hour resulting in the PL intensity at 650nm increasing by a factor of 4. In spite of the small implanted pattern size (136pmxl36pm), the emitted red light intensity was strong enough to be easily seen with the naked eye. Anneaiing for a fourth and final time at 1050° C resulted in a reduced PL intensity. This suggests that a one-step annealing at 1050° C is adequate to optically activate the Pr"ions implanted in the GaN film.
Similar PL spectra were observed from Pr-doped sulfide glasses.
Example 5.
A GaN region was also patterned by Pr FIB implantation. The implantation was performed using a 290keV Pr2+ beam for a dose of -4.7x10'4 atoms/cm2. After FIB implantation, the sample was annealed at 1050°C for one hour in Ar. Under UV excitation from the He-Cd laser, the implanted region emits red light, while unimplanted surrounding area shows the yellow band emission of GaN.
Exampie 6.
Pr implantation was also performed on GaN films grown by HVPE and MOCVD. Regions consisting of 141, umx141, um squares were implanted on both samples with a dose of 1X1015 atomsicm2 and a beam energy of 290keV. Both samples as well as a Pr-implanted MBE sample (dose = 4.7x10" atoms/cm2) show strong red emission at 650nm, which corresponds to the 3Po 3F2 transition of Pr3+. All three samples show similar band edge emission at around 365nm.
Example 7.
Pr-implanted GaN film grown by MBE on sapphire was formed.
After FIB implantation with a dose of 4.7x10'4 Pr/cm2 the sample was annealed at 1050°C for one hour in Ar. The Pr concentration of the in-situ doped GaN film is estimated to be at the range of 10'8-102° atoms/cm3.
In general, the PL intensity of the in-situ Pr-doped GaN sample is stronger (-5x) than that in the FIB-imptanted sample, which is expected from the much larger Pr-doped volume which is excited in the former case. For the samples. the full width at half maximum (FWHM) of the 648 and 650nm lines are-1.2nm, which corresponds to 3.6meV.
Thus the present invention can be utilized to produce light emitting devices from wide band gap semiconductor material utilizing rare earth dopants. The particular wavelength of emission is certainly characteristic of the added component. Further, it is possible to combine the rare earth implants to develop unique light emitting devices. Thus the present invention lends itself to a wide variety of different light emitting devices, extending from the infrared range down through the ultraviolet range.
Jumat, 12 September 2008
LED Green Power Technology
Why Indonesia doesnt care with semiconductor technology? while Nuclear technology still debatable and controversial let us think about green power technology based on it.
Why LED's?
LED's (Light emitting diodes) have begun to light the future with their capabilities of reducing power consumption by 80% over conventional lighting. Their "light" span is a minimum of 10 years for commercial usage, and a minimum of 25 years for residential applications. Besides eliminating the environmental hazards of mercury in fluorescents, LED's quietly illuminate with the closest look of natural daylight.
About LED Technology
Light emitting diodes (LEDs) were first developed in the1960s, but only in the past decade have LEDs had sufficient intensity for use in more than a handful of lighting applications (Stringfellow and Craford 1997), and specifiers are confronted with an increasing number of lighting products that incorporate LEDs for certain applications. Primarily, these applications have taken advantage of the characteristics of LEDs that have made them most suitable for indication, not illumination (Bierman 1998).
What determines the color of an LED?
The material used in the semiconducting element of an LED determines its color. The two main types of LEDs presently used for lighting systems are aluminum gallium indium phosphide (AlGaInP, sometimes rearranged as AlInGaP) alloys for red, orange and yellow LEDs; and indium gallium nitride (InGaN) alloys for green, blue and white LEDs. Slight changes in the composition of these alloys changes the color of the emitted light.
What are the electrical characteristics of LED's?
Individual LEDs are low voltage devices. Single indicator LEDs require 2 to 4 volts of direct current, with current in the range from 1 to 50 milliamperes. An illumination-grade LED containing a single semiconducting element requires the same voltage, but operating currents are much higher, typically several hundred milliamperes. A device containing multiple elements connected in series will require higher voltage corresponding to the larger number of individual elements in the device. LEDs require a specific electrical polarity. Applying voltage in reverse polarity can destroy them. Manufacturers provide specifications about the maximum reverse voltages acceptable for LED devices; 5 volts is a typical maximum rating.
Why is heat sinking important for LEDs?
It is common to refer to LEDs as "cool" sources in terms of temperature. This is because the spectral output of LEDs for lighting does not contain infrared radiation, unlike incandescent lamps that produce a large amount of infrared (of course, some LEDs for manufacturing purposes are designed to produce infrared energy, but these are not considered in this publication). LEDs are also often considered "cool" because they generate light through a mechanism other than thermal excitation of a substance, such as the tungsten filament in an incandescent lamp. Although LED lighting systems do not produce significant amounts of radiated heat, LEDs still generate heat within the junction, which must be dissipated by convection and conduction. Extracting heat from the device using heat sinks and by operating LEDs in lower ambient temperatures enables higher light output and longer life of the device.The need to ensure heat sinking with LED systems is also important to consider when these systems are installed in applications. There must be sufficient means to conduct the heat away from the system, or ventilation to cool heated surfaces by convection. Locating an LED lighting system in an insulated and relatively small space will likely result in rapidly increased junction temperature and suboptimal performance.
source : http://www.ledgreenpower.com/
Why LED's?
LED's (Light emitting diodes) have begun to light the future with their capabilities of reducing power consumption by 80% over conventional lighting. Their "light" span is a minimum of 10 years for commercial usage, and a minimum of 25 years for residential applications. Besides eliminating the environmental hazards of mercury in fluorescents, LED's quietly illuminate with the closest look of natural daylight.
About LED Technology
Light emitting diodes (LEDs) were first developed in the1960s, but only in the past decade have LEDs had sufficient intensity for use in more than a handful of lighting applications (Stringfellow and Craford 1997), and specifiers are confronted with an increasing number of lighting products that incorporate LEDs for certain applications. Primarily, these applications have taken advantage of the characteristics of LEDs that have made them most suitable for indication, not illumination (Bierman 1998).
What determines the color of an LED?
The material used in the semiconducting element of an LED determines its color. The two main types of LEDs presently used for lighting systems are aluminum gallium indium phosphide (AlGaInP, sometimes rearranged as AlInGaP) alloys for red, orange and yellow LEDs; and indium gallium nitride (InGaN) alloys for green, blue and white LEDs. Slight changes in the composition of these alloys changes the color of the emitted light.
What are the electrical characteristics of LED's?
Individual LEDs are low voltage devices. Single indicator LEDs require 2 to 4 volts of direct current, with current in the range from 1 to 50 milliamperes. An illumination-grade LED containing a single semiconducting element requires the same voltage, but operating currents are much higher, typically several hundred milliamperes. A device containing multiple elements connected in series will require higher voltage corresponding to the larger number of individual elements in the device. LEDs require a specific electrical polarity. Applying voltage in reverse polarity can destroy them. Manufacturers provide specifications about the maximum reverse voltages acceptable for LED devices; 5 volts is a typical maximum rating.
Why is heat sinking important for LEDs?
It is common to refer to LEDs as "cool" sources in terms of temperature. This is because the spectral output of LEDs for lighting does not contain infrared radiation, unlike incandescent lamps that produce a large amount of infrared (of course, some LEDs for manufacturing purposes are designed to produce infrared energy, but these are not considered in this publication). LEDs are also often considered "cool" because they generate light through a mechanism other than thermal excitation of a substance, such as the tungsten filament in an incandescent lamp. Although LED lighting systems do not produce significant amounts of radiated heat, LEDs still generate heat within the junction, which must be dissipated by convection and conduction. Extracting heat from the device using heat sinks and by operating LEDs in lower ambient temperatures enables higher light output and longer life of the device.The need to ensure heat sinking with LED systems is also important to consider when these systems are installed in applications. There must be sufficient means to conduct the heat away from the system, or ventilation to cool heated surfaces by convection. Locating an LED lighting system in an insulated and relatively small space will likely result in rapidly increased junction temperature and suboptimal performance.
source : http://www.ledgreenpower.com/
Rabu, 03 September 2008
Biografi matematikawan muda Indonesia
Artikel di bawah ini saya ambil dari MILIS Fisika Indonesia. Saya letakan di blog ini agar kita selalu bisa belajar dari pengalaman orang lain dan bisa menggali yang terbaik dari orang lain untuk mengimprove diri kita. Sukses buat Mas Hadi Susanto ;-)
Sekedar informasi :
Hadi Susanto adalah matematikawan Indonesia alumni dari ITB dan melanjutkan studi Doktoral bidang Matematik di University of Twente. Sejak januari 2008 menjadi staf pengajar di University of Nottingham, Inggris.
Hadi Susanto> > KEBANGKITAN NASIONAL HARUS DILAKUKAN SETIAP HARI> > > > > >
Tak banyak yang mengenal nama ini: Hadi Susanto.
Ia tak beredar di> tanah air sejak awal milenium baru, hampir sepertiga dari umurnya yang> baru 29 tahun. Apalagi untuk mendengar reputasinya sebagai salah> seorang matematikawan muda yang sedang memahatkan nama di jajaran> legenda pakar matematika dunia. > > > > Bahkan para pembaca novel superlaris Ayat-Ayat Cinta karya> Habiburrahman El-Shirazy pun tak akan menduga bahwa Hadi Susanto yang> menulis kata pengantar menarik di novel itu adalah Hadi Susanto yang> di umur 27 tahun meraih gelar doktor matematika dari Universiteit> Twente, Belanda, dan kini mengajar di Nottingham, Inggris. > > > > Lahir di sebuah desa kecil di kabupaten Lumajang, Jawa Timur, Hadi> mencecap pendidikan di SDN Kunir Lor 1, SMPN Kunir, dan SMAN 2> Lumajang. Saat di bangku SD, ia selalu terpilih sebagai wakil sekolah> dalam lomba cerdas cermat di tingkat kabupaten. Tapi begitu bertanding> nilainya hampir selalu nol. Saya selalu grogi melihat anak dari> sekolah lain yang selalu tampak keren dan bergaya, katanya.> > > > Kini dunia berbalik. Banyak yang grogi melihat prestasi mahasiswa> terbaik ITB tahun 2000 yang juga aktif berkiprah di dunia sastra. It> is impossible to be a mathematician without being a poet in soul> ungkapnya mengutip Sofia Vasilyevna Kovalevskaya (1850-1891),> matematikawan- cum-penyair Rusia perumus teorema Cauchy-Kovalevsky.> > Saat dikontak harian ini sebagai calon tamu berkaitan dengan Hari> Kebangkitan Nasional, awalnya Hadi menolak. Saya membaca wawancara> Koran Tempo dengan Pak Anies Baswedan (rektor Universitas Paramadina> red) lewat kiriman e-mail seorang teman. Saya tak sebanding dengan Pak> Anies untuk menjadi Tamu, katanya dengan suara lembut di ujung saluran> telepon internasional. > > > > Akhirnya, Kamis (15 Mei) lalu, calon ayah yang sedang menunggu> kelahiran anak pertamanya pada Juli depan ini bersedia juga> diwawancarai wartawan Tempo Akmal Nasery Basral, setelah> berkorespondensi lewat surat elektronik dalam beberapa kesempatan> sebelumnya. > > > > Mengapa menurut matematikawan muda yang 26 karya ilmiahnya sudah> muncul di sejumlah jurnal internasional itu kebangkitan nasional tak> akan terjadi jika hanya muncul dari perayaan yang timbul setahun> sekali? Petikannya:> > > > > > Anda menyelesaikan kuliah dalam tiga tahun dan terpilih sebagai> Mahasiswa Terbaik ITB tahun 2000. Bagaimana ceritanya?> > Sebetulnya masa kuliah saya hampir 4 tahun. Yang kuliah saja memang> 3 tahun, tapi memasuki tahun keempat saya mendapat kesempatan> mengunjungi Belanda selama 8 bulan untuk mengerjakan TA (tugas akhir> red) di Universiteit Twente (UT). Begitu diwisuda, saya diumumkan> terpilih sebagai penerima Ganesa Prize, Mahasiswa Berprestasi Utama> ITB, dengan hadiah mengunjungi Belanda lagi selama 3 bulan. Oleh UT> saya ditawari melanjutkan kuliah di sana. Maka mulai Agustus 2001 saya> mengambil program kombinasi Msc/PhD untuk periode 4 tahun. > > > > Tapi selesai PhD Anda tidak kembali ke Indonesia. Mengapa?> > Selesai dari Twente saya melanjutkan studi postdoctoral di> Massachussetts, Amerika Serikat. Saya mendapat visiting assistant> professorship selama tiga tahun di University of Massachussetts> (UMass), Amherst. Kewajiban saya mengajar dua kelas per semester> selain tugas melakukan riset. Menjelang selesai di UMass, saya> kirimkan sejumlah aplikasi ke universitas di Amerika Serikat dan> Eropa. Akhirnya sejak Januari 2008 saya menjadi dosen di University of> Nottingham, Inggris. Mengapa saya tidak segera kembali ke Indonesia,> karena saya ingin memperdalam dulu bidang ini. Apalagi sekarang istri> saya sudah di sini. Juli mendatang, insya Allah anak pertama kami lahir.> > > > > > Anda terlihat begitu mudah meniti karir. Berpindah-pindah dari> Belanda, Amerika Serikat, Inggris, sebagai doktor matematika padahal> usia Anda belum lagi 30 tahun. Apakah semua ini memang semudah yang> terlihat?> > Tidak. Dua tahun pertama saya kuliah di ITB, kondisi saya sulit> sekali. Saya tak bisa hidup hanya dari beasiswa, harus kerja juga.> Uang kerja dan beasiswa yang saya dapatkan dibagi tiga: untuk> kebutuhan saya di Bandung, keperluan orang tua di Lumajang, dan biaya> kuliah adik. Tiap Sabtu-Minggu saya keliling hotel dan gedung resepsi> di Bandung bermodal pakaian rapi. Tanpa tahu siapa yang punya hajat,> saya masuk saja ke pesta orang-orang kaya, yang penting bisa makan.> Pernah juga setelah libur lebaran, ketika kembali ke Bandung saya tak> punya cukup uang untuk membeli karcis kereta ekonomi. Akhirnya saya> naik kereta barang, duduk di lantai gerbong bersama sekitar 100-an> orang. Perjalanan sekitar 12 jam itu berlangsung malam hari, dan tanpa> lampu di gerbong saya. Gelap sekali. Mungkin kalau dituliskan bisa> jadi Laskar Pelangi (judul novel karya Andrea Hirata red) versi Orang> Jawa. (tertawa kecil). Itu beberapa contoh besar, kalau penderitaan> lainnya banyak sekali.> > > > > > Bagaimana Anda melewati masa-masa sulit itu untuk bersinar di ITB?> > Berkat dukungan dan doa banyak orang. Ketika Dosen Kuliah Agama> Islam saya, Ustad Asep Zaenal Ausof akan berangkat umroh, saya datangi> dia dan minta didoakan khusus. Saat itu kehidupan saya sedang di bawah> sekali. Usaha orang tua saya yang berjualan kain dan baju di pasar> bangkrut total. Kami terjebak rentenir, sehingga harus jual sawah, dan> akhirnya satu-satunya rumah yang kami punya persis menjelang saya> lulus SMA. Begitu lulus SMA, saya sudah memutuskan untuk tidak kuliah.> Tapi keluarga saya, terutama ibu, tidak setuju. Saya harus terus> kuliah. Alhamdulillah saya lulus UMPTN dan diterima di ITB. Tapi untuk> membayar uang masuk yang beberapa ratus ribu saja kami tak mampu,> akhirnya saya putuskan lagi untuk tidak mendaftar. Tapi ibu saya> berjuang terus sampai detik terakhir. Akhirnya ketika saya bisa> berangkat ke Bandung, dalam hati saya cuma ada satu tekad untuk> berhasil dan membahagiakan keluarga.> > > > > > Apa yang menyebabkan Anda begitu tertarik untuk mendalami matematika?> > Sejak SD saya suka mengamati bagaimana angka-angka bisa dimainkan> dengan operasi-operasi yang saling berhubungan. Di SMP saya mulai> menyadari bahwa dasar dari fenomena alam di sekitar kita bisa> dirumuskan melalui matematika. Ketika sesuatu sudah dituliskan ke> dalam persamaan dan rumus, sesuatu itu menjadi berada di tangan kita> yang bisa kita main-mainkan. Tapi pencerahan saya yang sebenarnya> terjadi di ITB ketika mengikuti ceramah agama yang disampaikan dosen> astronomi Pak Mudji Raharto. Beliau salah seorang astronom yang sampai> saat ini selalu menjadi rujukan dalam penentuan awal dan akhir bulan> Ramadhan. Ada satu bagian dari ceramahnya yang membuat saya terpana> bahwa alam semesta ini juga bisa dirumuskan dalam formulasi> matematika. Saat itu saya berkata dalam hati, Tuhan pasti ahli> matematika! Sejak itu pula saya melihat dunia ini seperti tersusun> dari angka-angka. Mungkin seperti film The Matrix.> > > > Tetapi mengapa bagi sebagian besar siswa Indonesia, matematika jauh> dari pengalaman yang menyenangkan seperti yang Anda alami?> > Matematika menjadi sesuatu yang menakutkan bagi mayoritas siswa> Indonesia karena pesan dari matematika itu sering tidak sampai. Jika> kita belajar matematika sebagai sebuah hapalan, maka matematika> menjadi tidak seksi lagi. Mempelajarinya menjadi sesuatu yang> memberatkan. Tapi jika kita tahu bahwa yang dipelajari itu adalah, dan> tidak lebih dari, PERUMUMAN dari masalah sehari-hari yang sudah kita> kenal, maka matematika akan menjadi sangat menyenangkan. Di Indonesia> ada beberapa matematikawan yang menguasai betul bagaimana membuat> matematika menjadi menarik, misalnya almarhum Profesor Andi Hakim> Nasution yang dulu rutin mengisi kolom di harian Republika dan> almarhum Profesor Ahmad Arifin dari ITB.> > > > Anda dikenal juga punya minat yang besar dalam sastra. Misalnya> dengan menulis kata pengantar novel Ayat-Ayat Cinta karya> Habiburrahman El-Shirazy yang kini merupakan film terlaris di tanah> air dari jumlah penonton. Puisi-puisi Anda muncul di banyak antologi> bersama. Bagaimana relasi antara matematika dan sastra ini berkelindan> dalam kehidupan Anda?> > Sebetulnya saya kenal Ustad Abik (nama panggilan Habiburrahman> El-Shirazy red) lewat internet. Saya waktu itu di Belanda, beliau di> Mesir. Kami bertemu di pesantrenvirtual. com. Dari situ sering> berdiskusi sastra. Menurut saya hubungan matematika dengan sastra> sangat dekat. Untuk bisa menikmati keindahan matematika, tidak hanya> diperlukan logika, tapi juga perasaan, seperti halnya seni. Einstein> mengatakan, "Pure mathematics is, in its way, the poetry of logical> ideas." > > > > > > Jadi seorang matematikawan pada dasarnya seorang penyair?> > Kurang lebih. Dan itu bukan cuma pendapat Einstein. Sofia> Kovalevskaya, wanita pertama yang mendapat pendidikan formal PhD di> Eropa yang terkenal dengan teorema Cauchy-Kovalevsky, juga seorang> penyair. Dia bilang, It is impossible to be a mathematician without> being a poet in soul. Karl Weierstrass, peletak dasar analisis> matematika modern yang juga mentor Sofia, membenarkan ungkapan> muridnya dan menambahkan, "It is true that a mathematician who is not> also something of a poet will never be a perfect mathematician. "> Kalau kita percaya dengan ucapan Wierstrass ini, maka saya paling> tidak penggemar sastra, karena belum bisa disebut sastrawan (tertawa).> > > > Contoh-contoh yang Anda sebut itu dalam konteks apresiasi, bukan?> Bagaimana dalam konteks kreasi atau penciptaan karya sastra?> > Saya kira contohnya juga banyak. Bahkan Hadiah Nobel di bidang> sastra pun ada matematikawan yang memenangkannya. Tahun 1904, Hadiah> Nobel untuk sastra diberikan kepada dramawan dan matematikawan spanyol> José Echegaray. Tahun 1950, Nobel sastra juga diberikan kepada> seorang matematikawan, Bertrand Russell. Dua orang ini disebut> matematikawan karena mereka memang profesor matematika. Saya mendengar> rumor bahwa pada 1999 seorang matematikawan, associate professor di> University of New Mexico, Gallup, juga sempat dinominasikan sebagai> kandidat penerima hadiah Nobel sastra.> > > > Apakah relasi yang akrab antara matematika dan sastra itu juga> terlihat di dunia Islam?> > Ada, misalnya Omar Khayyam yang terkenal dengan Rubaiyyat-nya itu.> Selain sebagai penyair, Omar Khayyam juga terkenal sebagai ahli> matematika geometri yang mengkoreksi postulat Euclid. Dan saya kira> tema-tema seperti ini harus sering diperbincangkan.> > > > Mengapa?> > Saya lihat dunia anak muda di Indonesia terlalu banyak dijejali> dengan tayangan infotainment, seakan-akan menjadi artis adalah> satu-satunya jalan yang harus ditempuh agar bisa sukses dan terkenal.> Ditambah dengan program-program pencari bakat yang menawarkan> ketenaran instan yang tanpa disadari sering kali menipu. Padahal dunia> sains juga menawarkan gaya selebritisnya sendiri. Misalnya setelah> buku Sylvia Nasar A Beautiful Mind terbit, publik jadi mengidolakan> matematikawan John Nash Jr. (A Beautiful Mind sudah difilmkan dengan> judul sama, dibintangi oleh aktor Russell Crowe sebagai John Nash Jr.> -- red). Bahan-bahan seperti ini cukup banyak. Saya sendiri> terinspirasi untuk menulis polemik antara Sylvia Nasar dengan Prof.> Shing-Tung Yau, salah seorang jenius matematika saat ini yang juga> aktif menulis puisi-puisi Cina. Konflik mereka sangat menarik di dunia> matematika, tak kalah hebohnya dengan kisruh Maia-Dhani di televisi> Indonesia (tertawa).> > > > Seperti apa sih kalau selebritis matematika berseteru?> > Konflik mereka dimulai ketika Nasar menulis artikel di The New> Yorker yang menuduh Shing-Tung Yau hendak mencuri kredit atas usaha> Grigori Perelman yang berhasil memecahkan satu dari Millenium Prize> Problems, yang untuk satu solusi dari masing-masing problem berhadiah> 1 juta dolar. Dari sini cerita yang menggemparkan dunia> permatematikaan internasional ini bergulir. Kisah ini menurut saya> menarik untuk dibaca anak-anak muda di Indonesia, selain buku-buku> matematika populer yang ditulis oleh mendiang Prof. Hans Wospakrik.> Intinya agar generasi muda kita tahu bahwa pengertian idola dan> selebritis itu bukan hanya dari kalangan artis.> > > > Jadi Anda mengharapkan ada semacam kebangkitan nasional, dari> generasi muda khususnya, dalam memaknai masa depan?> > Ketika kuliah di Bandung, saya melihat kebangkitan nasional itu> hanya motto belaka bagi kawan-kawan yang berasal dari kalangan berada.> Dan tidak mungkin perubahan besar yang diharapkan dari kebangkitan> nasional itu akan muncul jika hanya dihasilkan oleh kesadaran yang> muncul setahun sekali. Menurut saya kebangkitan nasional harus> dilakukan setiap hari, yaitu bangkit untuk bisa bermanfaat bagi orang> banyak minimal orang-orang yang bisa saya jangkau dengan kedua tangan> saya, dengan membuat mereka bermanfaat pula bagi orang-orang di> sekitar mereka. Dengan saling menularkan kebangkitan seperti ini saya> kira arti kebangkitan nasional itu baru menemukan maknanya. > > > > > > Bagaimana Anda melihat perkembangan dunia matematika di Indonesia> sekarang?> > Profesor Achmad Arifin pernah bilang, Matematikawan, khususnya> aljabar, Indonesia masih berada pada taraf memahami pekerjaan orang> lain, belum pada tahap mengembangkan. Saya kira pendapat ini benar.> Lihatlah bagaimana guru besar yang seharusnya menjadi ujung tombak dan> tolok ukur kualitas penelitian justru seringkali minim kontribusinya> di jurnal-jurnal internasional. Namun sebagai orang yang sejak lulus> S1 sampai saat ini belum pernah tinggal di Indonesia, saya merasa> tidak punya hak lebih untuk memberikan saran. Mesti begitu saya tahu> pasti ada banyak dosen dan periset di Indonesia yang terus memegang> idealismenya. Mereka orang-orang yang sangat militan di tengah segala> keterbatasan dalam melakukan penelitian. Pemerintah dan media massa> harus membantu mereka.> > > > Ada kisah-kisah yang lucu sebagai dosen matematika di luar negeri?> > Aksen bahasa Inggris di Nottingham ini kan berbeda dengan di> Massachussetts, jadi saya harus beradaptasi lagi ketika mengajar. Nah,> kadang-kadang begitu ada mahasiswa saya yang bertanya, saya masih> belum menangkap inti pertanyaannya, jadi saya bilang, coba ulangi> lagi? Eh, mereka bilang nggak jadi. Mungkin mereka pikir dosennya ini> ngetes apakah apakah mereka yakin dengan pertanyaan sendiri atau tidak> (tertawa)
Sekedar informasi :
Hadi Susanto adalah matematikawan Indonesia alumni dari ITB dan melanjutkan studi Doktoral bidang Matematik di University of Twente. Sejak januari 2008 menjadi staf pengajar di University of Nottingham, Inggris.
Hadi Susanto> > KEBANGKITAN NASIONAL HARUS DILAKUKAN SETIAP HARI> > > > > >
Tak banyak yang mengenal nama ini: Hadi Susanto.
Ia tak beredar di> tanah air sejak awal milenium baru, hampir sepertiga dari umurnya yang> baru 29 tahun. Apalagi untuk mendengar reputasinya sebagai salah> seorang matematikawan muda yang sedang memahatkan nama di jajaran> legenda pakar matematika dunia. > > > > Bahkan para pembaca novel superlaris Ayat-Ayat Cinta karya> Habiburrahman El-Shirazy pun tak akan menduga bahwa Hadi Susanto yang> menulis kata pengantar menarik di novel itu adalah Hadi Susanto yang> di umur 27 tahun meraih gelar doktor matematika dari Universiteit> Twente, Belanda, dan kini mengajar di Nottingham, Inggris. > > > > Lahir di sebuah desa kecil di kabupaten Lumajang, Jawa Timur, Hadi> mencecap pendidikan di SDN Kunir Lor 1, SMPN Kunir, dan SMAN 2> Lumajang. Saat di bangku SD, ia selalu terpilih sebagai wakil sekolah> dalam lomba cerdas cermat di tingkat kabupaten. Tapi begitu bertanding> nilainya hampir selalu nol. Saya selalu grogi melihat anak dari> sekolah lain yang selalu tampak keren dan bergaya, katanya.> > > > Kini dunia berbalik. Banyak yang grogi melihat prestasi mahasiswa> terbaik ITB tahun 2000 yang juga aktif berkiprah di dunia sastra. It> is impossible to be a mathematician without being a poet in soul> ungkapnya mengutip Sofia Vasilyevna Kovalevskaya (1850-1891),> matematikawan- cum-penyair Rusia perumus teorema Cauchy-Kovalevsky.> > Saat dikontak harian ini sebagai calon tamu berkaitan dengan Hari> Kebangkitan Nasional, awalnya Hadi menolak. Saya membaca wawancara> Koran Tempo dengan Pak Anies Baswedan (rektor Universitas Paramadina> red) lewat kiriman e-mail seorang teman. Saya tak sebanding dengan Pak> Anies untuk menjadi Tamu, katanya dengan suara lembut di ujung saluran> telepon internasional. > > > > Akhirnya, Kamis (15 Mei) lalu, calon ayah yang sedang menunggu> kelahiran anak pertamanya pada Juli depan ini bersedia juga> diwawancarai wartawan Tempo Akmal Nasery Basral, setelah> berkorespondensi lewat surat elektronik dalam beberapa kesempatan> sebelumnya. > > > > Mengapa menurut matematikawan muda yang 26 karya ilmiahnya sudah> muncul di sejumlah jurnal internasional itu kebangkitan nasional tak> akan terjadi jika hanya muncul dari perayaan yang timbul setahun> sekali? Petikannya:> > > > > > Anda menyelesaikan kuliah dalam tiga tahun dan terpilih sebagai> Mahasiswa Terbaik ITB tahun 2000. Bagaimana ceritanya?> > Sebetulnya masa kuliah saya hampir 4 tahun. Yang kuliah saja memang> 3 tahun, tapi memasuki tahun keempat saya mendapat kesempatan> mengunjungi Belanda selama 8 bulan untuk mengerjakan TA (tugas akhir> red) di Universiteit Twente (UT). Begitu diwisuda, saya diumumkan> terpilih sebagai penerima Ganesa Prize, Mahasiswa Berprestasi Utama> ITB, dengan hadiah mengunjungi Belanda lagi selama 3 bulan. Oleh UT> saya ditawari melanjutkan kuliah di sana. Maka mulai Agustus 2001 saya> mengambil program kombinasi Msc/PhD untuk periode 4 tahun. > > > > Tapi selesai PhD Anda tidak kembali ke Indonesia. Mengapa?> > Selesai dari Twente saya melanjutkan studi postdoctoral di> Massachussetts, Amerika Serikat. Saya mendapat visiting assistant> professorship selama tiga tahun di University of Massachussetts> (UMass), Amherst. Kewajiban saya mengajar dua kelas per semester> selain tugas melakukan riset. Menjelang selesai di UMass, saya> kirimkan sejumlah aplikasi ke universitas di Amerika Serikat dan> Eropa. Akhirnya sejak Januari 2008 saya menjadi dosen di University of> Nottingham, Inggris. Mengapa saya tidak segera kembali ke Indonesia,> karena saya ingin memperdalam dulu bidang ini. Apalagi sekarang istri> saya sudah di sini. Juli mendatang, insya Allah anak pertama kami lahir.> > > > > > Anda terlihat begitu mudah meniti karir. Berpindah-pindah dari> Belanda, Amerika Serikat, Inggris, sebagai doktor matematika padahal> usia Anda belum lagi 30 tahun. Apakah semua ini memang semudah yang> terlihat?> > Tidak. Dua tahun pertama saya kuliah di ITB, kondisi saya sulit> sekali. Saya tak bisa hidup hanya dari beasiswa, harus kerja juga.> Uang kerja dan beasiswa yang saya dapatkan dibagi tiga: untuk> kebutuhan saya di Bandung, keperluan orang tua di Lumajang, dan biaya> kuliah adik. Tiap Sabtu-Minggu saya keliling hotel dan gedung resepsi> di Bandung bermodal pakaian rapi. Tanpa tahu siapa yang punya hajat,> saya masuk saja ke pesta orang-orang kaya, yang penting bisa makan.> Pernah juga setelah libur lebaran, ketika kembali ke Bandung saya tak> punya cukup uang untuk membeli karcis kereta ekonomi. Akhirnya saya> naik kereta barang, duduk di lantai gerbong bersama sekitar 100-an> orang. Perjalanan sekitar 12 jam itu berlangsung malam hari, dan tanpa> lampu di gerbong saya. Gelap sekali. Mungkin kalau dituliskan bisa> jadi Laskar Pelangi (judul novel karya Andrea Hirata red) versi Orang> Jawa. (tertawa kecil). Itu beberapa contoh besar, kalau penderitaan> lainnya banyak sekali.> > > > > > Bagaimana Anda melewati masa-masa sulit itu untuk bersinar di ITB?> > Berkat dukungan dan doa banyak orang. Ketika Dosen Kuliah Agama> Islam saya, Ustad Asep Zaenal Ausof akan berangkat umroh, saya datangi> dia dan minta didoakan khusus. Saat itu kehidupan saya sedang di bawah> sekali. Usaha orang tua saya yang berjualan kain dan baju di pasar> bangkrut total. Kami terjebak rentenir, sehingga harus jual sawah, dan> akhirnya satu-satunya rumah yang kami punya persis menjelang saya> lulus SMA. Begitu lulus SMA, saya sudah memutuskan untuk tidak kuliah.> Tapi keluarga saya, terutama ibu, tidak setuju. Saya harus terus> kuliah. Alhamdulillah saya lulus UMPTN dan diterima di ITB. Tapi untuk> membayar uang masuk yang beberapa ratus ribu saja kami tak mampu,> akhirnya saya putuskan lagi untuk tidak mendaftar. Tapi ibu saya> berjuang terus sampai detik terakhir. Akhirnya ketika saya bisa> berangkat ke Bandung, dalam hati saya cuma ada satu tekad untuk> berhasil dan membahagiakan keluarga.> > > > > > Apa yang menyebabkan Anda begitu tertarik untuk mendalami matematika?> > Sejak SD saya suka mengamati bagaimana angka-angka bisa dimainkan> dengan operasi-operasi yang saling berhubungan. Di SMP saya mulai> menyadari bahwa dasar dari fenomena alam di sekitar kita bisa> dirumuskan melalui matematika. Ketika sesuatu sudah dituliskan ke> dalam persamaan dan rumus, sesuatu itu menjadi berada di tangan kita> yang bisa kita main-mainkan. Tapi pencerahan saya yang sebenarnya> terjadi di ITB ketika mengikuti ceramah agama yang disampaikan dosen> astronomi Pak Mudji Raharto. Beliau salah seorang astronom yang sampai> saat ini selalu menjadi rujukan dalam penentuan awal dan akhir bulan> Ramadhan. Ada satu bagian dari ceramahnya yang membuat saya terpana> bahwa alam semesta ini juga bisa dirumuskan dalam formulasi> matematika. Saat itu saya berkata dalam hati, Tuhan pasti ahli> matematika! Sejak itu pula saya melihat dunia ini seperti tersusun> dari angka-angka. Mungkin seperti film The Matrix.> > > > Tetapi mengapa bagi sebagian besar siswa Indonesia, matematika jauh> dari pengalaman yang menyenangkan seperti yang Anda alami?> > Matematika menjadi sesuatu yang menakutkan bagi mayoritas siswa> Indonesia karena pesan dari matematika itu sering tidak sampai. Jika> kita belajar matematika sebagai sebuah hapalan, maka matematika> menjadi tidak seksi lagi. Mempelajarinya menjadi sesuatu yang> memberatkan. Tapi jika kita tahu bahwa yang dipelajari itu adalah, dan> tidak lebih dari, PERUMUMAN dari masalah sehari-hari yang sudah kita> kenal, maka matematika akan menjadi sangat menyenangkan. Di Indonesia> ada beberapa matematikawan yang menguasai betul bagaimana membuat> matematika menjadi menarik, misalnya almarhum Profesor Andi Hakim> Nasution yang dulu rutin mengisi kolom di harian Republika dan> almarhum Profesor Ahmad Arifin dari ITB.> > > > Anda dikenal juga punya minat yang besar dalam sastra. Misalnya> dengan menulis kata pengantar novel Ayat-Ayat Cinta karya> Habiburrahman El-Shirazy yang kini merupakan film terlaris di tanah> air dari jumlah penonton. Puisi-puisi Anda muncul di banyak antologi> bersama. Bagaimana relasi antara matematika dan sastra ini berkelindan> dalam kehidupan Anda?> > Sebetulnya saya kenal Ustad Abik (nama panggilan Habiburrahman> El-Shirazy red) lewat internet. Saya waktu itu di Belanda, beliau di> Mesir. Kami bertemu di pesantrenvirtual. com. Dari situ sering> berdiskusi sastra. Menurut saya hubungan matematika dengan sastra> sangat dekat. Untuk bisa menikmati keindahan matematika, tidak hanya> diperlukan logika, tapi juga perasaan, seperti halnya seni. Einstein> mengatakan, "Pure mathematics is, in its way, the poetry of logical> ideas." > > > > > > Jadi seorang matematikawan pada dasarnya seorang penyair?> > Kurang lebih. Dan itu bukan cuma pendapat Einstein. Sofia> Kovalevskaya, wanita pertama yang mendapat pendidikan formal PhD di> Eropa yang terkenal dengan teorema Cauchy-Kovalevsky, juga seorang> penyair. Dia bilang, It is impossible to be a mathematician without> being a poet in soul. Karl Weierstrass, peletak dasar analisis> matematika modern yang juga mentor Sofia, membenarkan ungkapan> muridnya dan menambahkan, "It is true that a mathematician who is not> also something of a poet will never be a perfect mathematician. "> Kalau kita percaya dengan ucapan Wierstrass ini, maka saya paling> tidak penggemar sastra, karena belum bisa disebut sastrawan (tertawa).> > > > Contoh-contoh yang Anda sebut itu dalam konteks apresiasi, bukan?> Bagaimana dalam konteks kreasi atau penciptaan karya sastra?> > Saya kira contohnya juga banyak. Bahkan Hadiah Nobel di bidang> sastra pun ada matematikawan yang memenangkannya. Tahun 1904, Hadiah> Nobel untuk sastra diberikan kepada dramawan dan matematikawan spanyol> José Echegaray. Tahun 1950, Nobel sastra juga diberikan kepada> seorang matematikawan, Bertrand Russell. Dua orang ini disebut> matematikawan karena mereka memang profesor matematika. Saya mendengar> rumor bahwa pada 1999 seorang matematikawan, associate professor di> University of New Mexico, Gallup, juga sempat dinominasikan sebagai> kandidat penerima hadiah Nobel sastra.> > > > Apakah relasi yang akrab antara matematika dan sastra itu juga> terlihat di dunia Islam?> > Ada, misalnya Omar Khayyam yang terkenal dengan Rubaiyyat-nya itu.> Selain sebagai penyair, Omar Khayyam juga terkenal sebagai ahli> matematika geometri yang mengkoreksi postulat Euclid. Dan saya kira> tema-tema seperti ini harus sering diperbincangkan.> > > > Mengapa?> > Saya lihat dunia anak muda di Indonesia terlalu banyak dijejali> dengan tayangan infotainment, seakan-akan menjadi artis adalah> satu-satunya jalan yang harus ditempuh agar bisa sukses dan terkenal.> Ditambah dengan program-program pencari bakat yang menawarkan> ketenaran instan yang tanpa disadari sering kali menipu. Padahal dunia> sains juga menawarkan gaya selebritisnya sendiri. Misalnya setelah> buku Sylvia Nasar A Beautiful Mind terbit, publik jadi mengidolakan> matematikawan John Nash Jr. (A Beautiful Mind sudah difilmkan dengan> judul sama, dibintangi oleh aktor Russell Crowe sebagai John Nash Jr.> -- red). Bahan-bahan seperti ini cukup banyak. Saya sendiri> terinspirasi untuk menulis polemik antara Sylvia Nasar dengan Prof.> Shing-Tung Yau, salah seorang jenius matematika saat ini yang juga> aktif menulis puisi-puisi Cina. Konflik mereka sangat menarik di dunia> matematika, tak kalah hebohnya dengan kisruh Maia-Dhani di televisi> Indonesia (tertawa).> > > > Seperti apa sih kalau selebritis matematika berseteru?> > Konflik mereka dimulai ketika Nasar menulis artikel di The New> Yorker yang menuduh Shing-Tung Yau hendak mencuri kredit atas usaha> Grigori Perelman yang berhasil memecahkan satu dari Millenium Prize> Problems, yang untuk satu solusi dari masing-masing problem berhadiah> 1 juta dolar. Dari sini cerita yang menggemparkan dunia> permatematikaan internasional ini bergulir. Kisah ini menurut saya> menarik untuk dibaca anak-anak muda di Indonesia, selain buku-buku> matematika populer yang ditulis oleh mendiang Prof. Hans Wospakrik.> Intinya agar generasi muda kita tahu bahwa pengertian idola dan> selebritis itu bukan hanya dari kalangan artis.> > > > Jadi Anda mengharapkan ada semacam kebangkitan nasional, dari> generasi muda khususnya, dalam memaknai masa depan?> > Ketika kuliah di Bandung, saya melihat kebangkitan nasional itu> hanya motto belaka bagi kawan-kawan yang berasal dari kalangan berada.> Dan tidak mungkin perubahan besar yang diharapkan dari kebangkitan> nasional itu akan muncul jika hanya dihasilkan oleh kesadaran yang> muncul setahun sekali. Menurut saya kebangkitan nasional harus> dilakukan setiap hari, yaitu bangkit untuk bisa bermanfaat bagi orang> banyak minimal orang-orang yang bisa saya jangkau dengan kedua tangan> saya, dengan membuat mereka bermanfaat pula bagi orang-orang di> sekitar mereka. Dengan saling menularkan kebangkitan seperti ini saya> kira arti kebangkitan nasional itu baru menemukan maknanya. > > > > > > Bagaimana Anda melihat perkembangan dunia matematika di Indonesia> sekarang?> > Profesor Achmad Arifin pernah bilang, Matematikawan, khususnya> aljabar, Indonesia masih berada pada taraf memahami pekerjaan orang> lain, belum pada tahap mengembangkan. Saya kira pendapat ini benar.> Lihatlah bagaimana guru besar yang seharusnya menjadi ujung tombak dan> tolok ukur kualitas penelitian justru seringkali minim kontribusinya> di jurnal-jurnal internasional. Namun sebagai orang yang sejak lulus> S1 sampai saat ini belum pernah tinggal di Indonesia, saya merasa> tidak punya hak lebih untuk memberikan saran. Mesti begitu saya tahu> pasti ada banyak dosen dan periset di Indonesia yang terus memegang> idealismenya. Mereka orang-orang yang sangat militan di tengah segala> keterbatasan dalam melakukan penelitian. Pemerintah dan media massa> harus membantu mereka.> > > > Ada kisah-kisah yang lucu sebagai dosen matematika di luar negeri?> > Aksen bahasa Inggris di Nottingham ini kan berbeda dengan di> Massachussetts, jadi saya harus beradaptasi lagi ketika mengajar. Nah,> kadang-kadang begitu ada mahasiswa saya yang bertanya, saya masih> belum menangkap inti pertanyaannya, jadi saya bilang, coba ulangi> lagi? Eh, mereka bilang nggak jadi. Mungkin mereka pikir dosennya ini> ngetes apakah apakah mereka yakin dengan pertanyaan sendiri atau tidak> (tertawa)
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