Photocurrent anomaly in double-barrier quantum well structures

摘要

Abstract: We investigated the intersubband photocurrent as a function of the bias voltage and the incident wavelength in n-type photovoltaic GaAs/AlAs/Al$-0.3$/Ga$-0.7$/As double-barrier quantum well (DBQW) infrared detectors. The significant photovoltaic behavior of the detectors arises from a segregation of the dopant during the growth process. For an externally applied bias voltage, which compensates the internal space-charge field, the photocurrent exhibits a multiple sign change for varying incident wavelengths. This observation can be understood in the context of resonant coupling between the excited state in the GaAs quantum well and states, which are confined in the Al$-0.3$/Ga$-0.7$/As-region. This coupling leads to an enhancement of the tunneling rates through the AlGaAs barriers and to a partial localization of the above barrier states in the GaAs region. !19