Magnetic field dependence of the thermoelectric power of [formula omitted] - type gallium arsenide in the extreme quantum limit

Abstract

The effect of the quantization of the electron energy levels in a strong transverse magnetic field H on the low-temperature thermoelectric power (TEP) S of a high-purity isotropic semiconductor ( n - type gallium arsenide GaAs) is investigated theoretically. The “electron-diffusion” ( S e ) and “phonon-drag” ( S p ) components of S( = S e + S p ) are calculated in the extreme quantum limit, when all the electrons in the conduction band are concentrated in the lowest Landau level. The transition to nondegeneracy, which takes place when the bottom of the lowest Landau level is driven through the Fermi level, has a large effect on the variations of S e and S p with magnetic field. The results are illustrated with numerical calculations for n - type GaAs at 4.2 K with 1.2 × 10 16 cm -3 electrons.