GIANT PHOTOCURRENT IN 2D STRUCTURES IN A MAGNETIC-FIELD PARALLEL TO THE 2D LAYER

A giant photocurrent has been observed in a GaSb/InAs/GaSb structure with a single quantum well in a magnetic field B directed parallel to the surface of the sample. This current flows in the plane of the 3D layer, in the direction perpendicular to the magnetic field. It does not depend on the direction of the exciting light. Its shape is that of the laser pulse (tau-p = 100 ns). Its magnitude increases with increasing B. The current density reaches 10 kA/cm2 in a magnetic field as low as B = 4.5 T, at a light intensity I = 2 kW/cm2. A model is proposed for this effect on the basis of the existence of a loop of extrema in the energy spectrum of the electrons in the well.