Electric Field Dependence of Galvanomagnetic Properties inn-Type InSb at 77 °K

Abstract

The electric field dependence of galvanomagnetic properties in $n$-type InSb has been measured at 77 °K by employing a special method in which the transverse magnetic field $\overrightarrow{\mathrm{B}}$ is applied parallel or at small angles to the surface of very thin specimens to reduce the influence of inhomogeneities in the impurity concentration. The advantages of this magnetic field orientation are illustrated by comparisons made with measurements done for $\overrightarrow{\mathrm{B}}$ normal to the surface. It is experimentally determined that (i) quantum effects become noticeable at 2kG; (ii) impurity scattering is less important in the quantum region; (iii) the electron mobility becomes independent of both impurity concentration and magnetic field at high electric fields; (iv) the electron mobility shows an ${E_i}^{-\frac{1}{2}}$ (where $E_i$ is the electric field component parallel to the current) dependence in the high electric field region, which is consistent with acoustic-phonon scattering; and (v) time-dependent effects, believed to result from changing surface conditions, are noticed at magnetic fields above 2 kG when $\overrightarrow{\mathrm{B}}$ is normal to the surface. These spurious effects are not observed when transverse magnetoresistance is measured with $\overrightarrow{\mathrm{B}}$ parallel to the surface of the specimen, i.e., when the Hall field is along the thin (∼ 25μ) dimension.