Anisotropic propagation of GHz surface and bulk acoustic waves in gallium arsenide studied by random scattering

TL;DR

This study combines theory and experiment to analyze the anisotropic propagation of GHz acoustic waves in gallium arsenide, providing insights for optimizing acoustic devices through understanding mode coupling, velocities, and scattering effects.

Contribution

We developed a numerical model for angle-dependent acoustic velocities and validated it experimentally, demonstrating omnidirectional propagation via random scattering in gallium arsenide.

Findings

Validated theoretical model with experimental measurements

Achieved omnidirectional propagation through random scattering

Provided a versatile code for different materials

Abstract

Understanding the complex anisotropic acoustic propagation in crystals is crucial for optimizing the performance of surface and bulk acoustic wave devices. Here, we investigate the anisotropy and coupling of GHz acoustic modes in (001)-cut gallium arsenide through theory and experiment. We first numerically calculate the angle-dependent phase velocities for surface and bulk modes, and we provide a code which can easily be adapted to different material systems. We validate our theoretical model experimentally by exciting surface modes with an interdigital transducer, and achieve omnidirectional acoustic propagation through random scattering of the acoustic waves. We measure the complex acoustic field with a scanning optical interferometer, and extract the angle-dependent velocities of surface and bulk modes using Fourier domain analysis. Our method could be used for the optimization of GHz-range classical and quantum acoustic devices, by studying losses of surface and bulk modes.