基于GaN材料的耐高温、抗辐照等优越特性,使其与Si材料相比,更适用于航空航天以及太空探测领域.本文采用AlGaN/GaN高电子迁移率晶体管(high electron mobility transistor,HEMT)作为探测器的前置放大电路,并测试了HEMT器件在不同工作温...基于GaN材料的耐高温、抗辐照等优越特性,使其与Si材料相比,更适用于航空航天以及太空探测领域.本文采用AlGaN/GaN高电子迁移率晶体管(high electron mobility transistor,HEMT)作为探测器的前置放大电路,并测试了HEMT器件在不同工作温度时的S参数,对器件的小信号模型参数进行提取,得出AlGaN/GaN HEMT器件小信号等效高温电路模型的参数变化.结果表明,温度升高对器件小信号模型的本征参数会有很大的影响,因此高温情况下的小信号建模仍然必不可少.展开更多
NiO-SnO2 composite nanofibers were synthesized via electrospinning techniques and characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy.T...NiO-SnO2 composite nanofibers were synthesized via electrospinning techniques and characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy.Three types of sensor were applied to investigate the sensing properties of these nanofibers.Sensors A were fabricated by mixing the nanofibers with deionized water,and then grinding and coating them on ceramic tubes to form indirect heated gas sensors.Microsensors B(with an area of 600 μm×200 μm) were formed by spinning nanofibers on Si substrates with Pt signal electrodes and Pt heaters.Sensors C were fabricated by spinning nanofibers on plane ceramic substrates(with a large area of 13.4 mm×7 mm) with Ag-Pd signal electrodes only.The operating temperatures of sensors A and B were controlled by adjusting heater currents,and the operating temperatures of sensors C were controlled by adjusting an external temperature control device.Experimental results show that sensors C possess the highest sensing properties,such as high response values(about 42 to 100 μL/L ethanol),quick response/recovery speeds(the response and recovery times were 4 and 7 s,respectively),and excellent consistencies.These phenomena were explained by the retained fiber morphology and suitable sensor area.The presented results can provide some useful information for the design and optimization of one-dimensional nanomaterial-based gas sensors.展开更多
Cone-shaped patterned sapphire substrate was prepared by inductively coupled plasma etching and GaN nucleation layer was grown on it by metal-organic chemical vapor deposition.A selective growth of GaN nucleation laye...Cone-shaped patterned sapphire substrate was prepared by inductively coupled plasma etching and GaN nucleation layer was grown on it by metal-organic chemical vapor deposition.A selective growth of GaN nucleation layer was found on the slope of the cone-shaped patterned sapphire substrat,and the distribution morphology of GaN had significantly changed after it was recrystallized.GaN selective growth and redistribution were analyzed by investigating the distribution of crystallographic planes on the cone surface and the atom array of specific planes at atom level.展开更多
文摘基于GaN材料的耐高温、抗辐照等优越特性,使其与Si材料相比,更适用于航空航天以及太空探测领域.本文采用AlGaN/GaN高电子迁移率晶体管(high electron mobility transistor,HEMT)作为探测器的前置放大电路,并测试了HEMT器件在不同工作温度时的S参数,对器件的小信号模型参数进行提取,得出AlGaN/GaN HEMT器件小信号等效高温电路模型的参数变化.结果表明,温度升高对器件小信号模型的本征参数会有很大的影响,因此高温情况下的小信号建模仍然必不可少.
基金supported by the National High Technology Research and Development Program of China (2009AA03Z401)the Scientific Research Foundation for Doctoral Program of Liaoning Province of China (20101016)Research Fund for the Doctoral Program of Higher Education of China (20110041120045)
文摘NiO-SnO2 composite nanofibers were synthesized via electrospinning techniques and characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy.Three types of sensor were applied to investigate the sensing properties of these nanofibers.Sensors A were fabricated by mixing the nanofibers with deionized water,and then grinding and coating them on ceramic tubes to form indirect heated gas sensors.Microsensors B(with an area of 600 μm×200 μm) were formed by spinning nanofibers on Si substrates with Pt signal electrodes and Pt heaters.Sensors C were fabricated by spinning nanofibers on plane ceramic substrates(with a large area of 13.4 mm×7 mm) with Ag-Pd signal electrodes only.The operating temperatures of sensors A and B were controlled by adjusting heater currents,and the operating temperatures of sensors C were controlled by adjusting an external temperature control device.Experimental results show that sensors C possess the highest sensing properties,such as high response values(about 42 to 100 μL/L ethanol),quick response/recovery speeds(the response and recovery times were 4 and 7 s,respectively),and excellent consistencies.These phenomena were explained by the retained fiber morphology and suitable sensor area.The presented results can provide some useful information for the design and optimization of one-dimensional nanomaterial-based gas sensors.
基金Supported by the National Natural Science Foundation of China（Nos.61223005, 61376046）, the Program for New Century Excellent Talents in University of China（Nos.NCET-12-0236, NCET-13-0254）, the Science and Technology Developing Project of Jilin Province, China （No.20130204032GX） and the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory in the Fifth Electronics Research Institute of Ministry of Industry and Information Technology of China（No.ZHD201204）.
文摘Cone-shaped patterned sapphire substrate was prepared by inductively coupled plasma etching and GaN nucleation layer was grown on it by metal-organic chemical vapor deposition.A selective growth of GaN nucleation layer was found on the slope of the cone-shaped patterned sapphire substrat,and the distribution morphology of GaN had significantly changed after it was recrystallized.GaN selective growth and redistribution were analyzed by investigating the distribution of crystallographic planes on the cone surface and the atom array of specific planes at atom level.
