Dispersion and instability of drift waves in a fine-layered semiconductor structure

Drift waves in a fine-layered periodic semiconductor structure subjected to an electric field that induces the drift of charge carriers of different signs are considered. It is shown that the drift waves in this structure can propagate at an angle to the direction of the current, while their properties are governed by the thickness of the layers and the propagation direction. These waves are formed of concentration waves in separate layers and, thus, are “collective” waves. The conditions for origination of instabilities and analytical relations for increments are derived. Origination of instabilities is related to the energy exchange between drift waves in separate layers.