The yield point of In-doped GaAs between 500 and 900 °C

Abstract

In-doped (5×1019/cm3) GaAs single crystals with 〈123〉 orientation are compressed at different strain rates and temperatures between 500 and 900 °C. Two different regimes are observed. At high strain rates and temperatures below 700 °C, the strain-rate dependence of the lower yield stress is characterized by a power law with a stress exponent of 3.7, while its temperature dependence obeys an Arrhenius law with an activation energy of 0.93 eV. The latter value is smaller than that found for undoped GaAs, but the stress exponent is practically unchanged. This regime is interpreted in terms of a kink mechanism; the rate-controlling process is assumed to be governed by a strong interaction of In atoms with α dislocations. The regime occurring at low strain rates and temperatures above 700 °C is characterized by strong hardening and a weak temperature and strain-rate dependence of the lower yield stress. This behavior is ascribed to a direct alloying effect. Different types of interaction between dislocations and impurities are discussed. The knowledge of the strain-rate dependence of the lower yield stress, besides its temperature dependence, is a prerequisite for the interpretation of the measurements.