TEMPERATURE-DEPENDENCE OF ELASTIC NONLINEARITIES IN SINGLE-CRYSTAL GALLIUM-ARSENIDE

The six third-order elastic moduli (TOEM) of single-crystal gallium arsenide were determined by a combination of measurements of ultrasonic second-harmonic generation, and pressure dependence of the second-order elastic moduli, at room temperature. In the temperature range 77-300 K, the nonlinearity parameter for the propagation directions [100], [110], and [111] was measured. Utilizing the Keating model, these data were used in evaluating all six TOEM as a function of temperature. The TOEM C111, C144, and C456 tum out to be nearly constant in the above temperature range. The Cauchy relations seem to be obeyed somewhat better as 0 K is approached. The measured values of the TOEM have been employed in calculating a Murnaghan equation of state, which predicts a somewhat higher volume change than the measured one. The elastic Gruneisen constants deduced from the TOEM are in reasonable agreement with the thermal ones in the high-temperature limit.