Electric Field Effects on Bound to Quasibound Intersubband Absorption and Photocurrent in GaAs/AlGaAs Quantum Wells
Bound to quasi-bound intersubband transitions in multiquantum wells are of particular interest for high responsivity infrared photodetectors. However, contrary to the bound-to-bound case, no systematic comparison between photoconduction (PCS) and absorption (AS) spectra has been performed in that system. We have used Fourier Transform Infrared Spectroscopy to determine simultaneously the influence of an applied electric field on AS and PCS spectra. Two kinds of well are under study: a symmetric square and an asymmetric step quantum well, both with a quasi-bound excited state. Absorption and photocurrent spectra are found to be different in shape. Moreover, the electric field dependence of the spectra is different: photocurrent threshold is red shifted, whereas the absorption peak follows Stark shift effect. This suggests a sequential mechanism involved in the photocurrent collection, governing the response lineshape of the detector.
KeywordsRecombination Fourier Transform Infrared Spectroscopy GaAs Deconvolution Acoustics
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