Electron-phonon processes in semiconductors at low temperatures

The thermal conductivity and thermopower are simultaneously studied in the semiconductors HgSe, HgTe, InP, GaAs, CdxH1 − xTe, 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 Kph ∝ 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 Kph(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 Kph 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-CdxH1−xTe (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 Aph(ɛ) of the drag effect and its dependence on magnetic field are determined.