Elastic properties of GaAs obtained by inversion of laser-generated surface acoustic wave measurements

The surface acoustic wave (SAW) velocity with respect to propagation angle on a crystal substrate is dependent on the elastic constants of the crystal. Measurement of the SAW velocity dispersion with angle gives us information about these constants but one needs to solve the inverse problem of SAW propagation in order to obtain the elastic constants (C₁₁, C₁₂, C₄₄). In this work we investigate, both experimentally and theoretically, SAW velocity behaviour on (001), (111) and (311) GaAs. Several different acoustic modes can be measured on each surface. Using the measured velocity dispersion curves on each surface we derive elastic constants by inversion, and examine the potential of the inversion method to accurately derive elastic constant values for measurements on each cut. We find that, by combining multiple mode curves, this method allows measurement of elastic constants with high accuracy, particularly for the off-axis constant C₁₂.