Determination of elastic constants using a scanning acoustic microscope

A cubic single crystal of GaAs with two polished (100)-surfaces was examined with a scanning acoustic microscope (SAM) in transmission mode. The images of the transmitted ultrasound amplitude measured at frequencies of 350–400 MHz contain sufficient information about the acoustic anisotropy of the crystal to determine the complete set of the three elastic constants C₁₁, C₁₂, C₄₄ numerically. This was done by an interactive fitting procedure correlating simulated images with the measured one. This technique seems to be universally applicable to virtually all sorts of single crystals. Compared to plane wave investigations it saves preparatory labour since one single crystal orientation suffices for a determination of all elastic constants.