Output current of double heterojunction uni-travelling-carrier phototransistor
Received:December 28, 2016  Revised:April 15, 2017  download
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Author NameAffiliationE-mail
LIU Shuo College of Electronic Science and Technology,Faculty of Information Technology,Beijing University of Technology liushuo8721@163.com 
XIE Hong-Yun College of Electronic Science and Technology,Faculty of Information Technology,Beijing University of Technology xiehongyun@bjut.edu.cn 
SUN Dan College of Electronic Science and Technology,Faculty of Information Technology,Beijing University of Technology  
LIU Rui College of Electronic Science and Technology, Faculty of Information Technology, Beijing University of Technology  
WU Jia-Hui College of Electronic Science and Technology, Faculty of Information Technology, Beijing University of Technology  
ZHANG Wan-Rong College of Electronic Science and Technology,Faculty of Information Technology,Beijing University of Technology  
Abstract:In this paper, the output current characteristics within a large range of incident light power of a double heterojunction uni-travelling-carrier phototransistor (UTC-DHPT) were analyzed in detail and compared with a single heterojunction phototransistor (SHPT) simultaneously. Firstly, the output current of UTC-DHPT is smaller than that of SHPT under small power incident light because the UTC-DHPT’s absorption section is only the base region, which is smaller than SHPT’s absorption section consisting of base and collector. Secondly, benefiting from the double hetero-junction, the photogenerated carriers are only generated in base in UTC-DHPT, and there are few photogenerated holes accumulated in the collector junction interface. The space charge effect, which is seriously in SHPT, is effectively alleviated. Furthermore, the saturation of the output current under small power incident light, which always occurs in SHPT, is avoided. Therefore, UTC-DHPT has a larger quasi linear range than SHPT. Lastly, the uni-travelling transportation in UTC-DHPT make photogenerated holes in the base region reach to the emitter junction interface by the rapid relaxation, and thereby effectively reduce the emitter junction barrier. This would increase the number of electrons transmitting from the emitter to the base in the unit-time, and the emitter junction injection efficiency is improved. Thus, UTC-DHPT can obtain higher output current than SHPT under the high power incident light.
keywords:phototransistor  uni-travelling-carrier  output current  space charge effect  emitter junction injection efficiency
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Copyright:《Journal of Infrared And Millimeter Waves》