Simple models of semiconductor-based double barrier resonant tunneling structures predict a large accumulation of charge carriers in the structure. These carriers can be excited optically from one subband to another generating photocurrent. In this work we have investigated the photo-induced current due to intersubband excitation in double barrier structures. We have found that the origin of the photocurrent is accumulation of quantized carriers in the emitter-barrier junction of the structure, rather than accumulation of carriers in the double barrier quantum well. This photon assisted tunneling process in double barrier structures may be used for infrared detection.
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Acknowledgements—This work was supported in part by a grant from the A. D. Bergmann fund. One of us (C.M.) would like to thank the Levi Eshkol foundation for the support. We gratefully acknowledge helpful discussions with Prof. N. Ben-Yosef.