Electron-phonon processes in semiconductors at low temperatures

Abstract

The thermal conductivity and thermopower are simultaneously studied in the semiconductors HgSe, HgTe, InP, GaAs, Cd x H1 − x Te, and Ag2S in which the effect of electron drag by phonons was detected at low temperatures T. It is found that x = 1–3 in the dependences K ph ∝ T −x . It is shown that the underestimated values of x are caused by phonon scattering at certain defects. It is also found that the maxima of K ph(T) and αph(T) coincide in all studied crystals, except for Ag2S. For the first time, it is found that the strong effect αph ∝ T −3 is observed in Ag2S, the αph maximum is at T = 16 K, and the K ph maximum is at 27 K. The results obtained are in agreement with Callaway and Herring theory. The effect of magnetic field on the drag thermopower αph(T) in n-Cd x H1−x Te (in which the strong dependence αph ∝ T −3 and the strong effect of the magnetic field on it are detected) is considered for the first time. The results are compared with the Askerov theory. The force parameter A ph(ɛ) of the drag effect and its dependence on magnetic field are determined.