O482.31 95032051MOCVD的InGaAs/GaAs应变层量子阱的低温光致发光研究=Studies on low temperature photo-lumineseence spectra of InGaAs/GaAs stra-ined quantum wells by MOCVD[刊,中]/王小军,王启明,庄婉如,郑婉华(中科院半导体所...O482.31 95032051MOCVD的InGaAs/GaAs应变层量子阱的低温光致发光研究=Studies on low temperature photo-lumineseence spectra of InGaAs/GaAs stra-ined quantum wells by MOCVD[刊,中]/王小军,王启明,庄婉如,郑婉华(中科院半导体所集成光电子学国家重点联合实验室.北京(100083))。展开更多
This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence (PL) measurements.With increasing cap layer...This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence (PL) measurements.With increasing cap layer thickness,the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal-optical (LO) phonon,described by Huang-Rhys factor,increases remarkably due to an enhancement of the internal electric field.With increasing excitation intensity,the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases.These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.展开更多
Low temperature photoluminescence(PL) measurements have been performed for a set of GaN/AlxGa1-xN quantum wells(QWs). The experimental results show that the optical full width at half maximum(FWHM) increases relativel...Low temperature photoluminescence(PL) measurements have been performed for a set of GaN/AlxGa1-xN quantum wells(QWs). The experimental results show that the optical full width at half maximum(FWHM) increases relatively rapidly with increasing Al composition in the AlxGa1-xN barrier, and increases only slightly with increasing GaN well width. A model considering the interface roughness is used to interpret the experimental results. In the model, the FWHM's broadening caused by the interface roughness is calculated based on the triangle potential well approximation. We find that the calculated results accord with the experimental results well.展开更多
With annealing temperature kept at 1573 K, the effects of annealing time on stability of the intrinsic defects in epitaxial unintentionally doped 4H-SiC prepared by low pressure chemical vapour deposition have been st...With annealing temperature kept at 1573 K, the effects of annealing time on stability of the intrinsic defects in epitaxial unintentionally doped 4H-SiC prepared by low pressure chemical vapour deposition have been studied by electron spin resonance (ESR) and low temperature photoluminescence. This paper reports the results shown that annealing time has an important effect on the intrinsic defects in unintentionally doped 4H-SiC when annealing temperature kept at 1573 K. When the annealing time is less than 30 min, the intensity of ESR and photoluminescence is increasing with annealing time prolonged, and reaches the maximum when annealing time is 30 min. Then the intensity of ESR and photoluminescence is rapidly decreased with the longer annealing time, and much less than that of as-grown 4H-SiC when annealing time is 60 min, which should be related with the interaction among the intrinsic defects during the annealing process.展开更多
Effects of SiO2 encapsulation and rapid thermal annealing on the optical properties of a GaNAs/GaAs single quantum well (SQW) are studied by low-temperature photoluminescence (LTPL). After annealing at 800℃ for 30s, ...Effects of SiO2 encapsulation and rapid thermal annealing on the optical properties of a GaNAs/GaAs single quantum well (SQW) are studied by low-temperature photoluminescence (LTPL). After annealing at 800℃ for 30s, a blueshift of the LTPL peak energy for the SiO2-capped region is 25meV and that for the bare region is 0.8 meV. The results can attribute to the nitrogen reorganization in the GaNAs/GaAs SQW. It is also shown that the nitrogen reorganization can be obviously enhanced by SiO2 cap-layer. A simple model is used to describe the SiO2-enhanced blueshift of the LTPL peak energy. The estimated activation energy of the N atomic reorganization for the samples annealing with and without SiO2 cap-layer are 2.9eV and 3.1 eV, respectively.展开更多
Unintentionally doped GaN films grown by MOCVD were irradiated with neutrons at room temperature. In order to investigate the influence of neutron irradiation on the optical properties of GaN films, persistent photoco...Unintentionally doped GaN films grown by MOCVD were irradiated with neutrons at room temperature. In order to investigate the influence of neutron irradiation on the optical properties of GaN films, persistent photoconductivity(PPC) and low temperature photoluminescence(PL) measurements were carried out. Pronounced PPC was observed in the samples before and after neutron irradiation without the appearance of a yellow luminescence(YL) band in the PL spectrum, suggesting that the origin of PPC and YL are not related. Moreover, PPC phenomenon was enhanced by neutron irradiation and quenched by the followed annealing process at 900 C. The possible origin of PPC is discussed.展开更多
CuPt-type ordering with undesirable properties always occurs in GalnP at growth conditions that are very close to those leading to the highest quality material in metal organic chemical vapor deposition.In this work,h...CuPt-type ordering with undesirable properties always occurs in GalnP at growth conditions that are very close to those leading to the highest quality material in metal organic chemical vapor deposition.In this work,highly disordered GalnP with high crystalline quality was obtained by optimizing growth conditions.Roomtemperature and low-temperature photoluminescence(PL) spectra of AlGaInP/GaInP/AlGaInP double heterostructures(DHs) reveal that the band edge emission intensity is enhanced by optimizing growth temperature,Ⅴ/Ⅲ ratio,and reactor pressure at the expense of low energy peak originating from spatially indirect recombination due to the ordering-related defects.The DH sample with less ordering-related defects demonstrates a longer effective minority carrier lifetime,consequently,the GalnP solar cell shows a significant improvement in the performance.展开更多
文摘O482.31 95032051MOCVD的InGaAs/GaAs应变层量子阱的低温光致发光研究=Studies on low temperature photo-lumineseence spectra of InGaAs/GaAs stra-ined quantum wells by MOCVD[刊,中]/王小军,王启明,庄婉如,郑婉华(中科院半导体所集成光电子学国家重点联合实验室.北京(100083))。
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60876007 and 10974165)the Research Program of Xiamen Municipal Science and Technology Bureau,China (Grant No. 2006AA03Z110)
文摘This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence (PL) measurements.With increasing cap layer thickness,the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal-optical (LO) phonon,described by Huang-Rhys factor,increases remarkably due to an enhancement of the internal electric field.With increasing excitation intensity,the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases.These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.
基金supported by the National Basic Research Program of China(Grant No.2012CB619306)the National High Technology Research and Development Program of China(Grant No.2011AA03A101)
文摘Low temperature photoluminescence(PL) measurements have been performed for a set of GaN/AlxGa1-xN quantum wells(QWs). The experimental results show that the optical full width at half maximum(FWHM) increases relatively rapidly with increasing Al composition in the AlxGa1-xN barrier, and increases only slightly with increasing GaN well width. A model considering the interface roughness is used to interpret the experimental results. In the model, the FWHM's broadening caused by the interface roughness is calculated based on the triangle potential well approximation. We find that the calculated results accord with the experimental results well.
基金supported by the National Natural Science Foundation of China (Grant No.60876061)Pre-Research Foundation (Grant No.9140A08050508)the 13115 Innovation Engineering of Shanxi,China (Grant No.2008ZDKG-30)
文摘With annealing temperature kept at 1573 K, the effects of annealing time on stability of the intrinsic defects in epitaxial unintentionally doped 4H-SiC prepared by low pressure chemical vapour deposition have been studied by electron spin resonance (ESR) and low temperature photoluminescence. This paper reports the results shown that annealing time has an important effect on the intrinsic defects in unintentionally doped 4H-SiC when annealing temperature kept at 1573 K. When the annealing time is less than 30 min, the intensity of ESR and photoluminescence is increasing with annealing time prolonged, and reaches the maximum when annealing time is 30 min. Then the intensity of ESR and photoluminescence is rapidly decreased with the longer annealing time, and much less than that of as-grown 4H-SiC when annealing time is 60 min, which should be related with the interaction among the intrinsic defects during the annealing process.
文摘Effects of SiO2 encapsulation and rapid thermal annealing on the optical properties of a GaNAs/GaAs single quantum well (SQW) are studied by low-temperature photoluminescence (LTPL). After annealing at 800℃ for 30s, a blueshift of the LTPL peak energy for the SiO2-capped region is 25meV and that for the bare region is 0.8 meV. The results can attribute to the nitrogen reorganization in the GaNAs/GaAs SQW. It is also shown that the nitrogen reorganization can be obviously enhanced by SiO2 cap-layer. A simple model is used to describe the SiO2-enhanced blueshift of the LTPL peak energy. The estimated activation energy of the N atomic reorganization for the samples annealing with and without SiO2 cap-layer are 2.9eV and 3.1 eV, respectively.
基金This work was supported by National Natural Science Foundation of China （Nos. 61422503, 21541013 and 61376104）, Natural Science Foundation of Jiangsu Province （No. BK20150596）, Jiangsu key laboratory for advanced metallic materials （No. BM2007204）, the open research funds of Key Laboratory of MEMS of Ministry of Education （SEU, China）, and the Funda- mental Research Funds for the Central Universities. The authors would like to thank Prof. Zhenhua Qiao from USTC, China for helpful discussions.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20111317120005)the Key Program for Science and Technology Research of Higher Education Institution of Hebei Province,China(No.ZD2010124)the National Natural Science Foundation of China(No.61076004)
文摘Unintentionally doped GaN films grown by MOCVD were irradiated with neutrons at room temperature. In order to investigate the influence of neutron irradiation on the optical properties of GaN films, persistent photoconductivity(PPC) and low temperature photoluminescence(PL) measurements were carried out. Pronounced PPC was observed in the samples before and after neutron irradiation without the appearance of a yellow luminescence(YL) band in the PL spectrum, suggesting that the origin of PPC and YL are not related. Moreover, PPC phenomenon was enhanced by neutron irradiation and quenched by the followed annealing process at 900 C. The possible origin of PPC is discussed.
基金Project supported by the National Natural Science Foundation of China(No.61376065)the Suzhou Science and Technology Project(No.ZXG2013044)
文摘CuPt-type ordering with undesirable properties always occurs in GalnP at growth conditions that are very close to those leading to the highest quality material in metal organic chemical vapor deposition.In this work,highly disordered GalnP with high crystalline quality was obtained by optimizing growth conditions.Roomtemperature and low-temperature photoluminescence(PL) spectra of AlGaInP/GaInP/AlGaInP double heterostructures(DHs) reveal that the band edge emission intensity is enhanced by optimizing growth temperature,Ⅴ/Ⅲ ratio,and reactor pressure at the expense of low energy peak originating from spatially indirect recombination due to the ordering-related defects.The DH sample with less ordering-related defects demonstrates a longer effective minority carrier lifetime,consequently,the GalnP solar cell shows a significant improvement in the performance.
