Hardness, Yield Strength, and Dislocation Velocity in Elemental and Compound Semiconductors

Abstract

Current knowledge on macroscopic plasticity indications, i.e., hardness and yield strength, and on microscopic indication, i.e., velocity of individual dislocations, in elemental and IV–IV, III–V, and II–VI compound semiconductors including GaN and ZnSe are reported and discussed on their mutual correlations. The Vickers hardness of the semiconductors can provide conventional information on the material plasticity in a wide temperature range up to their melting points over a wide range of size scales in various material forms. Hardness H_v in diamond- and sphalerite-type semiconductors has a universal relationship on their temperature dependence similar to the yield strength τ_y with a relation H_v=(70–100) τ_y in the low temperature region. Yield strength obtained by normal tensile or compression tests are expressed by an experimental equation as a function of the strain rate and temperature. The velocities of various types of dislocations measured directly in several semiconductors are described with an empirical equation as a function of the stress and the temperature. Through the analysis of yield strength data in terms of the collective motion of dislocations during the plastic deformation, the dislocation motion, rate-controlling plastic deformation, are deduced. The activation energy for dislocation motion has a linear relation to the band gap energy, depending on the types of semiconductors, elemental, III–V compounds, and II–VI compounds.