Macroscopic Plastic Properties of Dislocation-Free Germanium and Other Semiconductor Crystals. I. Yield Behavior

Abstract

Dislocation‐free crystals of the semiconductor elements germanium and silicon and the compounds indium antimonide and gallium antimonide have been deformed in tension over a range of temperatures, initial dislocation densities, and strain rates. In all of the dislocation‐free crystals, plastic deformation occurs at stresses that are low compared to those predicted from theory. The large yield drop observed in all four types of crystals is related to the dynamical behavior of dislocations during the early stages of plastic flow. There is a marked effect of the initial dislocation density on the maximum and flow stresses reached during yielding. Dislocations introduced by surface damage also reduce the observed yield drop. The pronounced yield drop and relatively large strain rate dependence of the maximum stress are a direct result of the relatively small stress dependence of dislocation velocities in semiconductor crystals. The temperature dependence of the maximum and flow stresses also appears to be related to the temperature dependence of dislocation velocities in semiconductors.