Excitation of Thermomagnetic Waves in Multi-Valley Semiconductors of the GaAs Type

Abstract

It has been shown that in two-valley semiconductors, in the presence of a temperature gradient, a thermomagnetic wave is excited, which propagates perpendicularly to the temperature gradient. Such an unstable wave is excited at an electric field value where ionization, recombination and generation processes do not occur. Then the total concentration of charge carriers remains constant. The Gunn effect in GaAs was discovered in samples with ohmic contacts. However, obtaining true ohmic contacts in experiments is difficult; therefore, the injection of charge carriers at the contacts must be considered. It is necessary to calculate the impedance of the crystal in the presence of injection and to determine the capacitive and inductive nature of this impedance. The excited wave in GaAs, under the conditions considered, depends on the frequency of hydrodynamic wave. The electric field acts between the valleys The Gunn effect was observed in GaAs at values of crystals of the axes. For other crystallographic orientations, the frequency and growth rate take different values. In our theoretical study, an isotropic sample was used, following Gunn’s experiments. Of course, theoretical investigations in anisotropic samples are also of significant scientific interest.