Photo-induced current in n-AlGaAs/GaAs heterojunction channels driven by local illumination at the edge regions of Hall bar

摘要

We observe photocurrents induced in an n-AlGaAs/GaAs heterojunction of Hall bar geometry, when its edge region is irradiated by unpolarized near-infrared laser beam at normal incidence. The magnitude and direction of the photocurrent depend sensitively on the beam position, the current reaching its maximum for the beam centered at the edge of the Hall bar. The experimental findings are well explained by a theory based on the Boltzmann kinetic equation, in which the photocurrent is ascribed to the anisotropic momentum distribution of photo-excited electrons at the channel edge. By comparing the measured photocurrents with the theory, the recombination time of the photo-excited electrons is also evaluated.