Thermopower and thermomagnetic effects in kane semiconductors under conditions of electron and phonon heating and their mutual drag

Abstract

AbstractThe thermopower and the transverse Nernst‐Ettingshausen (NE) effect of degenerate semiconductors with Kane electron spectrum are considered taking account of electron and phonon heating and their mutual drag. It is established that in absence of a mutual drag and phonon heating the electron part of the thermopower Ve as well as the NE voltage U grow sharply on raising the external electric field strength ˜ E4 while the phonon part of the thermopower Vp does not depend upon E. It is shown that the phonon heating leads to a growth of the phonon parts Vp and Up with E: Vp ˜ E2 and Up ˜ E6. The nonparabolicity of the electron spectrum results in the growth of the phonon parts and the decrease of the electron parts of the thermopower and NE voltage if the phonons are nonheated. Mutual drag leads to a higher growth of all the above‐mentioned effects on raising the mutual drag degree γ0 if the electrons and phonons are heated. In the parabolic case under the conditions of a strong mutual drag (γ0 → 1) Up = 0. If the electrons are scattered by piezoacoustic phonons in a weak magnetic field the electron part of the NE coefficient Qe firstly decreases with growing γ0 (being positive), reaches zero at γ0 = 2/9, and then reverses its sign and grows in magnitude. A similar situation takes place in a strong magnetic field also, the only difference is that Qe = 0 at γ0 = 2/5.