1997•Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIERequires access
Nonlinear photoresponse of quantum well infrared photodetectors at high-excitation power
M. Ershov, Hui C. Liu, M. Buchanan, Z. R. Wasilewski
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Abstract
Nonlinear photoresponse effects at high excitation power in quantum well infrared photodetectors (QWIPs) are studied both experimentally and theoretically. The photoconductivity nonlinearity is mainly caused by a redistribution of the electric potential at high power, which leads to a decrease of electric field in the bulk of the QWIP. As a result of the decreased field, the photoexcited electron escape probability and drift velocity decrease, resulting in a decrease of responsivity. These effects are strongly influenced by QWIP structural parameters and operating conditions. In QWIPs with a few QWs the IR power required to observe a decrease of responsivity is much lower than that needed to cause the saturation of the intersubband absorption. Key factors in designing a QWIP with a suppressed nonlinearity are discussed.