环境减灾-1A卫星(又称多任务小卫星)是亚太多边空间合作的重要任务之一,Ka频段试验分系统(Ka Band Experimental Subsystem,简称KABES)项目作为环境减灾-1A卫星上的试验载荷对于推动亚太多边空间合作具有十分重要的意义。KABES是泰国负...环境减灾-1A卫星(又称多任务小卫星)是亚太多边空间合作的重要任务之一,Ka频段试验分系统(Ka Band Experimental Subsystem,简称KABES)项目作为环境减灾-1A卫星上的试验载荷对于推动亚太多边空间合作具有十分重要的意义。KABES是泰国负责的分系统,其主要任务是在环境减灾-1A卫星上使用Ka频段进行泰国境内地面站与卫星之间数据传输的试验。文章提出了KABES有效载荷的技术方案,阐述了主要关键技术,该分系统已完成星地对接,且在轨运行正常,成功交付用户。展开更多
GaN films with different thicknesses of Al composition graded AlGaN buffer are grown on substrates of Si(111)by metal-organic chemical vapor deposition(MOCVD).The thicknesses of graded AlGaN buffer are fixed at 200 nm...GaN films with different thicknesses of Al composition graded AlGaN buffer are grown on substrates of Si(111)by metal-organic chemical vapor deposition(MOCVD).The thicknesses of graded AlGaN buffer are fixed at 200 nm,300 nm,and 450 nm,respectively.Optical microscopy,atomic force microscopy,x-ray diffraction,and Raman spectroscopy are employed to characterize these samples.We find that the thickness of the graded AlGaN buffer layer plays a key role on the following growth of GaN films.The optimized thickness of the graded AlGaN buffer layer is 300 nm.Under such conditions,the GaN epitaxial film is crack-free,and its dislocation density is the lowest.展开更多
A new mechanism of light-to-electricity conversion that uses InGaN/GaN QWs with a p-n junction is reported.According to the well established light-to-electricity conversion theory,quantum wells（QWs） cannot be used i...A new mechanism of light-to-electricity conversion that uses InGaN/GaN QWs with a p-n junction is reported.According to the well established light-to-electricity conversion theory,quantum wells（QWs） cannot be used in solar cells and photodetectors because the photogenerated carriers in QWs usually relax to ground energy levels,owing to quantum confinement,and cannot form a photocurrent.We observe directly that more than 95% of the photoexcited carriers escape from InGaN/GaN QWs to generate a photocurrent,indicating that the thermionic emission and tunneling processes proposed previously cannot explain carriers escaping from QWs.We show that photoexcited carriers can escape directly from the QWs when the device is under working conditions.Our finding challenges the current theory and demonstrates a new prospect for developing highly efficient solar cells and photodetectors.展开更多
文摘环境减灾-1A卫星(又称多任务小卫星)是亚太多边空间合作的重要任务之一,Ka频段试验分系统(Ka Band Experimental Subsystem,简称KABES)项目作为环境减灾-1A卫星上的试验载荷对于推动亚太多边空间合作具有十分重要的意义。KABES是泰国负责的分系统,其主要任务是在环境减灾-1A卫星上使用Ka频段进行泰国境内地面站与卫星之间数据传输的试验。文章提出了KABES有效载荷的技术方案,阐述了主要关键技术,该分系统已完成星地对接,且在轨运行正常,成功交付用户。
基金Supported by the National High-Technology Research and Development Program of China under Grant Nos 2011AA03A112 and 2011AA03A106the National Natural Science Foundation of China under Grant Nos 60890192,50872146 and 60877006.
文摘GaN films with different thicknesses of Al composition graded AlGaN buffer are grown on substrates of Si(111)by metal-organic chemical vapor deposition(MOCVD).The thicknesses of graded AlGaN buffer are fixed at 200 nm,300 nm,and 450 nm,respectively.Optical microscopy,atomic force microscopy,x-ray diffraction,and Raman spectroscopy are employed to characterize these samples.We find that the thickness of the graded AlGaN buffer layer plays a key role on the following growth of GaN films.The optimized thickness of the graded AlGaN buffer layer is 300 nm.Under such conditions,the GaN epitaxial film is crack-free,and its dislocation density is the lowest.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574362,61210014,and 11374340)the Innovative Clean-energy Research and Application Program of Beijing Municipal Science and Technology Commission,China(Grant No.Z151100003515001)
文摘A new mechanism of light-to-electricity conversion that uses InGaN/GaN QWs with a p-n junction is reported.According to the well established light-to-electricity conversion theory,quantum wells（QWs） cannot be used in solar cells and photodetectors because the photogenerated carriers in QWs usually relax to ground energy levels,owing to quantum confinement,and cannot form a photocurrent.We observe directly that more than 95% of the photoexcited carriers escape from InGaN/GaN QWs to generate a photocurrent,indicating that the thermionic emission and tunneling processes proposed previously cannot explain carriers escaping from QWs.We show that photoexcited carriers can escape directly from the QWs when the device is under working conditions.Our finding challenges the current theory and demonstrates a new prospect for developing highly efficient solar cells and photodetectors.
