Photon-Drag Effect in Intersubband Absorption by a Two-Dimensional Electron Gas

Intersubband transitions stimulated by a light wave propagating in the plane of a two-dimensional electron gas are accompanied by a "photon-drag" current due to the momentum imparted by the absorbed photons. In a high-mobility electron gas at low temperatures, a peculiar effect is predicted to occur as a result of the difference in the momentum relaxation times in the ground and the excited subbands. This effect permits the implementation of novel far-infrared detectors, as well as a new type of spectroscopy containing information about the momentum-relaxation kinetics in 2D subbands.