Electron relaxation mechanisms in n-Bi-Sb semiconducting alloys

The magnetic field dependence of diffusion thermal electromotive force α₂₂(H) (∇||C₁) in degenerate n-Bi-Sb semiconducting alloys, in which only L electrons participate in transfer phenomena, had a maximum at H || C₃. The electron relaxation time was determined from the magnetic field value corresponding to this maximum. The dependences of the electron relaxation time on temperature and the concentration of alloy components and the dopant (on the concentration of electrons) were used to separate electron relaxation time components corresponding to scattering by phonons, ionized impurities, and component concentration fluctuations. The latter ("alloy") mechanism of electron scattering by concentration fluctuations was for the first time considered for Bi-Sb alloys; its contribution was found to be comparable with those of the other scattering mechanisms. The obtained relaxation times were used to calculate theoretical magnetic field dependences of thermal electromotive force and the Nernst-Ettingshausen coefficient. The calculation results were in satisfactory agreement with experiment.