Anisotropic Mobilities in Plastically Deformed Germanium

Abstract

We have measured the carrier density as a function of temperature in n‐type germanium which has been plastically deformed by bending, and find that it can be accounted for on the basis of Read's theory if the dislocation acceptor level lies 0.18 to 0.20 ev below the conduction band. The analysis indicates that the dislocation density introduced by plastic bending is about 8 times the theoretical equilibrium density that would correspond to zero internal stress. We observe that the mobility for current flow along the bending axis is the normal mobility, which indicates that the dislocations are parallel to the bending axis, although they may zig‐zag with line segments along (110) type directions. The mobility perpendicular to the bending axis is in qualitative agreement with the theory given by Read, although the theory tends to underestimate the reduction of mobility below 50°K. We have extended Read's theory to the case where the current flows along the bending axis and the magnetic field is perpendicular to the bending axis.