DRIFT CURRENT AND THERMAL PRESSURE EFFECTS IN THE ELECTROMAGNETIC INSTABILITIES OF PERIODIC SEMICONDUCTOR SUPERLATTICES

摘要

We investigate the electromagnetic instabilities of an infinite periodic superlattice consisting of alternating spatially dispersive (nonlocal) and nonspatially dispersive (local) layers. We extend the results of Martin and Wallis [Phys. Rev. B 46, 12 448 (1992)] to include the effects of the electron thermal pressure gradient besides a dc drift current. In the case of zero pressure gradient, the dispersion relation shows branches not reported before. We also found that the thermal pressure changes the range of wave vectors where instabilities occur. [References: 8]