Effect of lateral transport of photoinduced charge carriers in a heterostructure with a two-dimensional electron gas

Abstract

It is shown that the nonequilibrium charge carriers produced by a local optical disturbance of the heterostructure with a two-dimensional electron gas are transported in the plane of the structure over an extremely large distance from the excitation location, which greatly exceeds the diffusion length in the bulk. The effect is attributable to the fact that the photogenerated electrons and holes are separated by the built-in electric field of the heterojunction to opposite edges of the buffer layer, where they are transported along parallel planes. The distance over which the nonequilibrium carrier density spreads reaches large values because of 1) the high conductivity of two-dimensional electrons, 2) the barrier for electron-hole recombination, and 3) hole drift in the electric field produced by the charge of nonequilibrium carriers in the plane of the structure.