Abstract

The increasing performances of quantum-well infrared photodetectors allow them to be considered as a potential alternative to HgCdTe detectors.¹ However, despite intensive work, the shape and the electric-field behavior of photocurrent spectra are still unexplained.² At steady state the photocurrent is due to the contribution of different complex mechanisms: the balance between photoionization and capture in the quantum well (QW) as well as scattering in the barrier conduction band. In this communication we show how we can have access to the photoionzation mechanism alone, by studying the transient photocurrent from a multiple-quantum well structure in a Schottky diode. Indeed, the initial decay rate of the transient signal is a direct measurement of the photoionization cross section, and the infrared absorption spectrum yields the optical cross section, both quantities being related by the escape probability from the QW’s.³

© 1993 Optical Society of America