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1.  Quasi-homoepitaxial GaN-based blue light emitting diode on thick GaN templateQuasi-homoepitaxial GaN-based blue light emitting diode on thick GaN templateQuasi-homoepitaxial GaN-based blue light emitting diode on thick GaN templateQuasi-homoepitaxial GaN-based blue light emitting diode on thick GaN template  
   李俊泽  陶岳彬  陈志忠  姜显哲  付星星  姜爽  焦倩倩  于彤军  张国义《中国物理 B》,2014年第1期
   The high power GaN-based blue light emitting diode (LED) on an 80%tm-thick GaN template is proposed and even realized by several technical methods like metal organic chemical vapor deposition (MOCVD), hydride vapor-phase epi- taxial (HVPE), and laser lift-off (LLO). Its advantages are demonstrated from material quality and chip processing. It is investigated by high resolution X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), Rutherford back-scattering (RBS), photoluminescence, current-voltage and light output-current measurements. The width of (0002) reflection in XRD rocking curve, which reaches 173" for the thick GaN template LED, is less than that for the conventional one, which reaches 258". The HRTEM images show that the multiple quantum wells (MQWs) in 80%tm- thick GaN template LED have a generally higher crystal quality. The light output at 350 mA from the thick GaN template LED is doubled compared to traditional LEDs and the forward bias is also substantially reduced. The high performance of 80-~m-thick GaN template LED depends on the high crystal quality. However, although the intensity of MQWs emission in PL spectra is doubled, both the wavelength and the width of the emission from thick GaN template LED are increased. This is due to the strain relaxation on the surface of 80%tin-thick GaN template, which changes the strain in InGaN QWs and leads to InGaN phase separation.    

2.  Quasi-homoepitaxial GaN-based blue light emitting diode on thick GaN template  
   李俊泽  陶岳彬  陈志忠  姜显哲  付星星  姜爽  焦倩倩  于彤军  张国义《中国物理 B》,2014年第23卷第1期
   The high power GaN-based blue light emitting diode(LED) on an 80-μm-thick GaN template is proposed and even realized by several technical methods like metal organic chemical vapor deposition(MOCVD), hydride vapor-phase epitaxial(HVPE), and laser lift-off(LLO). Its advantages are demonstrated from material quality and chip processing. It is investigated by high resolution X-ray diffraction(XRD), high resolution transmission electron microscope(HRTEM), Rutherford back-scattering(RBS), photoluminescence, current-voltage and light output-current measurements. The width of(0002) reflection in XRD rocking curve, which reaches 173 for the thick GaN template LED, is less than that for the conventional one, which reaches 258. The HRTEM images show that the multiple quantum wells(MQWs) in 80-μmthick GaN template LED have a generally higher crystal quality. The light output at 350 mA from the thick GaN template LED is doubled compared to traditional LEDs and the forward bias is also substantially reduced. The high performance of 80-μm-thick GaN template LED depends on the high crystal quality. However, although the intensity of MQWs emission in PL spectra is doubled, both the wavelength and the width of the emission from thick GaN template LED are increased. This is due to the strain relaxation on the surface of 80-μm-thick GaN template, which changes the strain in InGaN QWs and leads to InGaN phase separation.    

3.  Time—Resolved Photoluminescence Studies of AlInGaN Alloys  
   董逊 黄劲松 黎大兵 刘祥林 徐钟英 王占国《中国物理快报》,2003年第20卷第7期
   We study the two samples of AlInGaN,i.e.,1-μm Gan grown at 1030℃ on the buffer and followed by a 0.6μm-thick epilayer of AlInGaN under the low pressure of 76 Torr and the AlInGaN layer deposited diectly on the buffer layer without the high-temperature GaN layer,by temperature-dependent photoluminescence(PL) spectroscopy and picosecond time-resolved photoluminescence(TRPL) spectroscopy.The TRPL signals of both the samples were fitted well as a stretched exponential decay at all temperatures,indicating significant disorder in the material.We attribute the disorder to nanoscale quantum dots or discs of high indium concentration.Temperature dependence of dispersive exponent β shows that the stretched exponential decay of the two samples comes from dfferent mechanisms.The different depths of the localization potential account for the difference,which is illustrated by the results of temperature dependence of radiative recombination lifetime and PL peak energy.    

4.  Growth of strain-compensated InGaAs/GaAsP multiple quantum wells by MOVPE  
   于永芹  张晓阳  黄柏标  尉吉勇  周海龙  潘教青  秦晓燕  任忠祥《中国光学快报(英文版)》,2003年第1卷第1期
   InGaAs/GaAsP strain-compensated multiple quantum wells (SCMQWs) and strained InGaAs/GaAsmultiple quantum wells (MQWs) were grown on GaAs substrates by metal organic vapor phase epitaxy(MOVPE). The results of double crystal X-ray diffraction (DCXRD) revealed that strain relief had beenpartly accommodated by the misfit dislocation formation in the strained MQW material. It led to thatthe full width half maximums (FWHMs) of superlattice satellite peaks are broader than those of SCMQWstructures, and there was no detectable room temperature photoluminecence(RT-PL)for the strained    

5.  Effects of polarization and p-type GaN resistivity on the spectral response of InGaN/GaN multiple quantum well solar cells  
   杨静  赵德刚  江德生  刘宗顺  陈平  李亮  吴亮亮  乐伶聪  李晓静  何晓光  王辉  朱建军  张书明  张宝顺  杨辉《中国物理 B》,2014年第6期
   Effects of polarization and p-type GaN resistivity on the spectral response of InGaN/GaN multiple quantum well(MQW) solar cells are investigated. It is found that due to the reduction of piezoelectric polarization and the enhancement of tunneling transport of photo-generated carriers in MQWs, the external quantum efficiency(EQE) of the solar cells increases in a low energy spectral range(λ 370 nm) when the barrier thickness value decreases from 15 nm to 7.5 nm. But the EQE decreases abruptly when the barrier thickness value decreases down to 3.75 nm. The reasons for these experimental results are analyzed. We are aware that the reduction of depletion width in MQW region, caused by the high resistivity of the p-type GaN layer may be the main reason for the abnormally low EQE value at long wavelengths(λ 370 nm).    

6.  Intra-acceptor hole relaxation in Be δ-doped GaAs/AlAs multiple quantum wells  
   李素梅  郑卫民  宋迎新  刘静  初宁宁《中国物理 B》,2009年第18卷第9期
   This paper studies the dynamics of intra-acceptor hole relaxation in Be δ-doped GaAs/AlAs multiple quantum wells(MQW) with doping at the centre by time-resolved pump-probe spectroscopy using a picosecond free electron laser for infrared experiments.Low temperature far-infrared absorption measurements clearly show three principal absorption lines due to transitions of the Be acceptor from the ground state to the first three odd-parity excited states respectively.The pump-probe experiments are performed at different temperatures and different pump pulse wavelengths.The hole relaxation time from 2p excited state to 1s ground state in MQW is found to be much shorter than that in bulk GaAs,and shown to be independent of temperature but strongly dependent on wavelength.The zone-folded acoustic phonon emission and slower decay of the wavefunctions of impurity states are suggested to account for the reduction of the 2p excited state lifetime in MQW.The wavelength dependence of the 2p lifetime is attributed to the diffusion of the Be atom δ-layer in quantum wells.    

7.  Indium-Induced Effect on Polarized Electroluminescence from InGaN/GaN MQWs Light Emitting Diodes  
   阮军  于彤军  贾传宇  陶仁春  王占国  张国义《中国物理快报》,2009年第8期
   Polarization-resolved edge-emitting electroluminescence (EL) studies of In GaN/GaN MQWs of wavelengths from near-UV (390nm) to blue (468nm) light-emitting diodes (LEDs) are performed. Although the TE mode is dominant in all the samples of InGaN/GaN MQW LEDs, an obvious difference of light polarization properties is found in the InGaN/GaN MQW LEDs with different wavelengths. The polarization degree decreases from 52.4% to 26.9% when light wavelength increases. Analyses of band structures of InGaN/GaN quantum wells and luminescence properties of quantum dots imply that quantum-dot-like behavior is the dominant reason for the low luminescence polarization degree of blue LEDs, and the high luminescence polarization degree of UV LEDs mainly comes from QW confinement and the strain effect. Therefore, indium induced carrier confinement (quantum-dot-like behavior) might play a major role in the polarization degree change of InGaN/GaN MQW LEDs from near violet to blue.    

8.  EFFECT OF SURFACE ENERGY ON DISLOCATION-INDUCED FIELD IN HALF-SPACE WITH APPLICATION TO THIN FILM-SUBSTRATE SYSTEMS  
   Bob Svendsen《Acta Mechanica Solida Sinica》,2009年第22卷第5期
   In this work the elastic field of an edge dislocation in a half-space with the effect of surface energy has been obtained. The elastic field is then used to study the image force on the dislocation, the critical thickness for dislocation generation in epitaxial thin films with strain mismatch and the yielding strength of thin films on substrates. The results show that the image forces on the dislocation deviate from the conventional solutions when the distance of the dislocation from the free surface is smaller than several times of the characteristic length. Also due to the effect of surface energy, the critical thickness for dislocation generation is smaller than that predicted by the conventional elastic solutions and the extent of the deviation depends on the magnitude of mismatch strain. In contrast, the effect of surface energy on the yielding strength for many practical thin films can be neglected except for some soft ones where the characteristic length is comparable to the thickness.    

9.  High quality above 3-μm mid-infrared InGaAsSb/AIGaInAsSb multiple-quantum well grown by molecular beam epitaxy  
   邢军亮  张宇  徐应强  王国伟  王娟  向伟  倪海桥  任正伟  贺振宏  牛智川《中国物理 B》,2014年第1期
   The GaSb-based laser shows its superiority in the 3-4 ~tm wavelength range. However, for a quantum well (QW) laser structure of InGaAsSb/AIGaInAsSb multiple-quantum well (MQW) grown on GaSb, uniform content and high com- pressive strain in InGaAsSb/A1GaInAsSb are not easy to control. In this paper, the influences of the growth tempera- ture and compressive strain on the photoluminescence (PL) property of a 3.0μm lnGaAsSb/A1GaInAsSb MQW sample are analyzed to optimize the growth parameters. Comparisons among the PL spectra of the samples indicate that the Ino.485GaAso.184Sb/Alo.3Gao.45Ino.25Aso.22Sbo.78 MQW with 1.72% compressive strain grown at 460 ~C posseses the op- timum optical property. Moreover, the wavelength range of the MQW structure is extended to 3.83 μm by optimizing the parameters.    

10.  The low-temperature mobility of two-dimensional electron gas in AlGaN/GaN heterostructures  
   张金风  毛维  张进城  郝跃《中国物理 B》,2008年第17卷第7期
   To reveal the internal physics of the low-temperature mobility of two-dimensional electron gas (2DEG) in Al- GaN/GaN heterostructures, we present a theoretical study of the strong dependence of 2DEG mobility on Al content and thickness of AlGaN barrier layer. The theoretical results are compared with one of the highest measured of 2DEG mobility reported for AlGaN/GaN heterostructures. The 2DEG mobility is modelled as a combined effect of the scat- tering mechanisms including acoustic deformation-potential, piezoelectric, ionized background donor, surface donor, dislocation, alloy disorder and interface roughness scattering. The analyses of the individual scattering processes show that the dominant scattering mechanisms are the alloy disorder scattering and the interface roughness scattering at low temperatures. The variation of 2DEG mobility with the barrier layer parameters results mainly from the change of 2DEG density and distribution. It is suggested that in AlGaN/GaN samples with a high Al content or a thick AlGaN layer, the interface roughness scattering may restrict the 2DEG mobility significantly, for the AlGaN/GaN interface roughness increases due to the stress accumulation in AlGaN layer.    

11.  High quality above 3-μm mid-infrared InGaAsSb/AlGaInAsSb multiple-quantum well grown by molecular beam epitaxy  
   邢军亮  张宇  徐应强  王国伟  王娟  向伟  倪海桥  任正伟  贺振宏  牛智川《中国物理 B》,2014年第23卷第1期
   The GaSb-based laser shows its superiority in the 3–4 μm wavelength range. However, for a quantum well(QW) laser structure of InGaAsSb/AlGaInAsSb multiple-quantum well(MQW) grown on GaSb, uniform content and high compressive strain in InGaAsSb/AlGaInAsSb are not easy to control. In this paper, the influences of the growth temperature and compressive strain on the photoluminescence(PL) property of a 3.0-μm InGaAsSb/AlGaInAsSb MQW sample are analyzed to optimize the growth parameters. Comparisons among the PL spectra of the samples indicate that the In0.485GaAs0.184Sb/Al0.3Ga0.45In0.25As0.22Sb0.78MQW with 1.72% compressive strain grown at 460 C posseses the optimum optical property. Moreover, the wavelength range of the MQW structure is extended to 3.83 μm by optimizing the parameters.    

12.  Effects of InGaN barriers with low indium content on internal quantum efficiency of blue InGaN multiple quantum wells  
   汪莱  王嘉星  赵维  邹翔  罗毅《中国物理 B》,2010年第19卷第7期
   Blue In0.2 Ga0.8N multiple quantum wells (MQWs) with Inx Ga1xN (x=0.01 0.04) barriers are grown by metal organic vapour phase epitaxy.The internal quantum efficiencies (IQEs) of these MQWs are studied in a way of temperature-dependent photoluminescence spectra.Furthermore,a 2-channel Arrhenius model is used to analyse the nonradiative recombination centres (NRCs).It is found that by adopting the InGaN barrier beneath the lowest well,it is possible to reduce the strain hence the NRCs in InGaN MQWs.By optimizing the thickness and the indium content of the InGaN barriers,the IQEs of InGaN/InGaN MQWs can be increased by about 2.5 times compared with conventional InGaN/GaN MQWs.On the other hand,the incorporation of indium atoms into the intermediate barriers between adjacent wells does not improve IQE obviously.In addition,the indium content of the intermediate barriers should match with that of the lowest barrier to avoid relaxation.    

13.  Numerical analysis of In0.53 Ga0.47 As/InP single photon avalanche diodes  
   周鹏  李淳飞  廖常俊  魏正军  袁书琼《中国物理 B》,2011年第20卷第2期
   A rigorous theoretical model for In 0.53 Ga 0.47 As/InP single photon avalanche diode is utilized to investigate the dependences of single photon quantum efficiency and dark count probability on structure and operation condition.In the model,low field impact ionizations in charge and absorption layers are allowed,while avalanche breakdown can occur only in the multiplication layer.The origin of dark counts is discussed and the results indicate that the dominant mechanism that gives rise to dark counts depends on both device structure and operating condition.When the multiplication layer is thicker than a critical thickness or the temperature is higher than a critical value,generation-recombination in the absorption layer is the dominative mechanism;otherwise band-to-band tunneling in the multiplication layer dominates the dark counts.The thicknesses of charge and multiplication layers greatly affect the dark count and the peak single photon quantum efficiency and increasing the multiplication layer width may reduce the dark count probability and increase the peak single photon quantum efficiency.However,when the multiplication layer width exceeds 1 μm,the peak single photon quantum efficiency increases slowly and it is finally saturated at the quantum efficiency of the single photon avalanche diodes.    

14.  Structural, electrical and optical characterization of InGaN layers grown by MOVPE  
   Yildiz A  ztürk M Kemal  Bosi M  zelik S  Kasap M《中国物理 B》,2009年第18卷第9期
   We present a study on n-type ternary InGaN layers grown by atmospheric pressure metalorganic vapour phase epitaxy(MOVPE) on GaN template/(0001) sapphire substrate.An investigation of the different growth conditions on n-type InxGa1 xN(x = 0.06 0.135) alloys was done for a series of five samples.The structural,electrical and optical properties were characterized by high resolution x-ray diffraction(HRXRD),Hall effect and photoluminescence(PL).Experimental results showed that different growth conditions,namely substrate rotation(SR) and change of total H2 flow(THF),strongly affect the properties of InGaN layers.This case can be clearly observed from the analytical results.When the SR speed decreased,the HRXRD scan peak of the samples shifted along a higher angle.Therefore,increasing the SR speed changed important structural properties of InGaN alloys such as peak broadening,values of strain,lattice parameters and defects including tilt,twist and dislocation density.From PL results it is observed that the growth conditions can be changed to control the emission wavelength and it is possible to shift the emission wavelength towards the green.Hall effect measurement has shown that the resistivity of the samples changes dramatically when THF changes.    

15.  ELECTROREFLECTANCE SPECTRA OF GexSi1-x/Si STRAINED LAYER MULTIPLE-QUANTUM WELLS  
   潘士宏  黄硕  汪忠和  陈卫  张存洲  盛篪  王迅《中国物理》,1994年第3卷第3期
   We have investigated the optical transitions above the fundamental gap of a set of GexSi1-x/Si strained layer multiple-quantum wells by electroreflectance (ER). The sam-ples were grown by molecular beam espitaxy (MBE). The thickness of the strained layer of GexSi1-x was 5nm with Ge concentration x in the range from 0.4 to 0.5, and the Si barrier layer greater than 16nm. Considering the energy shift caused by strain and quantum well confinement, we were able to clearly recognize the transitions from different quantum well structures associated with the critical points E0, E′0, and E1. The transitions of the critical points E0 and E′0, which are very weak in bulk mateials, are apparently enhanced in the quantum well structures.    

16.  Defects in GaN Films Grown on Si(111) Substrates by Metal-Organic Chemical Vapour Deposition  
   胡桂青 孔翔 万里 王乙潜 段晓峰 陆沅 刘祥林《中国物理快报》,2003年第20卷第10期
   We report the transmission-electron microscopy study of the defects in wurtzitic GaN films grown on Si(111) substrates with AlN buffer layers by the metal-organic chemical vapour deposition method. The In0.1 Ga0.9N/GaN multiple quantum well (MQW) reduced the dislocation density by obstructing the mixed and screw dislocations passing through the MQW. No evident reduction of the edge dislocations density by the MQW was observed. It was found that dislocations with screw component can be located at the boundaries of sub-grains slightly in-plane misoriented.    

17.  Epitaxial evolution on buried cracks in a strain-controlled AlN/GaN superlattice interlayer between AlGaN/GaN multiple quantum wells and a GaN template  
   黄呈橙  张霞  许福军  许正昱  陈广  杨志坚  唐宁  王新强  沈波《中国物理 B》,2014年第10期
   Epitaxial evolution of buried cracks in a strain-controlled AlN/GaN superlattice interlayer(IL) grown on GaN template, resulting in crack-free AlGaN/GaN multiple quantum wells(MQW), was investigated. The processes of filling the buried cracks include crack formation in the IL, coalescence from both side walls of the crack, build-up of an MQW-layer hump above the cracks, lateral expansion and merging with the surrounding MQW, and two-dimensional step flow growth.It was confirmed that the filling content in the buried cracks is pure GaN, originating from the deposition of the GaN thin layer directly after the IL. Migration of Ga adatoms into the cracks plays a key role in the filling the buried cracks.    

18.  Photoluminescence and lasing properties of InAs/GaAs quantum dots grown by metal-organic chemical vapour deposition  
   梁 松  朱洪亮  潘教青  赵玲娟  王鲁峰  周 帆  舒惠云  边 静  安 欣  王 圩《中国物理 B》,2008年第17卷第11期
   Photoluminescence (PL) and lasing properties of InAs/GaAs quantum dots (QDs) with different growth procedures prepared by metalorganic chemical vapour deposition are studied. PL measurements show that the low growth rate QD sample has a larger PL intensity and a narrower PL line width than the high growth rate sample. During rapid thermal annealing, however, the low growth rate sample shows a greater blueshift of PL peak wavelength. This is caused by the larger InAs layer thickness which results from the larger 2-3 dimensional transition critical layer thickness for the QDs in the low-growth-rate sample. A growth technique including growth interruption and in-situ annealing, named indium flush method, is used during the growth of GaAs cap layer, which can flatten the GaAs surface effectively. Though the method results in a blueshift of PL peak wavelength and a broadening of PL line width, it is essential for the fabrication of room temperature working QD lasers.    

19.  Structural and Photoluminescence Properties for Highly Strain-Compensated InGaAs/InA1As Superlattice *  
   顾溢  张永刚  李爱珍  王凯  李成  李耀耀《中国物理快报》,2009年第7期
   The effects of strain compensation are investigated by using twenty periods of highly strain-compensated InGaAs/InA1As superlattice. The lattice mismatches of individual layers are as high as about 1%, and the thicknesses are close to critical thicknesses. X-ray diffraction measurements show that lattice imperfectness is not serious but still present, though the structural parameters are within the range of theoretical design criteria for structural stability. Rough interfaces and composition fluctuations are the primary causes for lattice imperfecthess. Photoluminescence measurements show the large thermally activated nonradiative recombination in the sample. In addition, the recombination process gradually evolves from exeitonic recombination at lower temperatures to band-to-band recombination at higher temperatures, which should be considered in device applications.    

20.  Growth and Optical Properties of Double Heterostructure GaN/InGaN/GaN Films with Large Composition  
   周劲 张国义《中国物理快报》,2002年第19卷第5期
   The double heterostructure GaN/InGaN/GaN films with different thicknesses of the InGaN layer were grown at 780℃ or 800℃ by metal-organic chemical vapour deposition.The samples were investigated using x-ray diffraction (XRD),room-temperature photoluminescence (PL) and Raman scattering.The dependences of the samples on both the growth temperature and the thickness of the InGaN layer were studied.The composition of InGaN was determined by the results of XRD,and the bowing parameter of InGaN was calculated in terms of the PL spectra.When the thickness of the InGaN layer was reduced,the phase separation of InGaN was found in some samples.The raman frequency of the A1(LO) and E2(low) modes in all the samples shifted and did not agree with Vegard‘s law.    

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