High Field Magnetoresistance and Random Inhomogeneities in n-Type Germanium

Abstract

The magnetoresistance of n-type germanium has been measured at 64°K, 77°K and 90°K up to 90 kgauss, the specimens being doped with 6.1×10¹³∼8.3×10¹⁶ arsenic or antimony per cm³. The transverse magnetoresistance ratio ρ(H)⁄ρ(0) increases linearly with increasing field; the higher the electron mobility is the larger this ratio becomes. This fact can be accounted for by Herring’s theory for inhomogeneous medium. The longitudinal magnetoresistance at high fields also shows a little increase linearly with the field, which contradicts the usual theory of magnetoresistance and also Herring’s theory. A correlation has been found to exist between the linear increase of the transverse case and that of the longitudinal case. Saturation magnetoresistance and mobility-anisotropy K=μ_||⁄μ_⊥ have been estimated using the correlation. Scattering-anisotropy K_τ=τ_||⁄τ_⊥ for lattice scattering is estimated to be about 1.3 and K_τ for ionized impurity scattering to be about 7.