Change in sign of the photocurrent in a coherent asymmetric superlattice

We study the photocurrent induced in an asymmetric superlattice as a function of the frequency of applied radiation. In order to investigate the principal features, we consider the simplest finite-period structure: one containing an asymmetric unit formed of two narrow quantum wells. It is found that the main features of the photocurrent-frequency curve are insensitive to the number of periods. Considering a single-unit structure, we find simple equations for the photocurrent reversal points. The oscillations in sign of the photocurrent are shown to result from quantum interference of the electron waves reflected at the interfaces in the structure. Using our model, we approximate an experimental structure and explain the observed photocurrent reversal.© 1995 American Institute of Physics.

Duke Scholars

Author Harold U. Baranger Physics