Theoretical model for bound-to-continuum multiple quantum well infrared photodetector

• Main Authors: Yi-Jung Hsieh, 謝宜靜
• Other Authors: M. P. Houng;Y. H. Wang
• Format: Others
• Language: en_US
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/92735641885728635248

碩士 === 國立成功大學 === 電機工程研究所 === 82 === In this thesis, we present a theoretical model for bound-to- continuum state intersubband optical transition so as to provide a detail design rule for bound-to-continuum multiple quantum well infrared photodetector. The positions of subband levels will directly decide the absorption wavelength of photodetector, we develop an energy- and spatial-dependent effective mass approach method to calculate the subband structures of bound states and continuum states. Furthermore, by our theoretical calculation results above, we can understand how the absorption peak wavelength and bandwidth vary with the quantum well parameters (such as well width, barrier height and barrier width). As shown in the theoretical calculations, we note that the bound-to-continuum state intersubband optical transition has smaller optical absorption coefficient than bound-to-bound state intersubband optical transition, and these extended state detectors of the front are based on hot-electron transport above the quantum well barriers, the photoexcited electrons do not have to escape from the quantum well via tunneling. Thus the thickness of the barriers can be significantly increased, dramatically reducing the dark current. This is the reason why the bound-to-continuum multiple quantum well infrared photodetectors have larger responsivity than bound-to-bound multiple quantum well infrared photodetectors. The theoretical analysis included optical absorption, quantum efficiency, responsivity, and detectivity allow a better optimization of the QWIP performance.