Piezoelectric effects of single-crystal GaAs and multi-layered AlxGa1-xAs/GaAs material measured by the Michelson interferometer

The inverse piezoelectric effect, in which the strains were electrically induced, in a single crystal of GaAs and in a multilayer structure of AlxGa1-xAs/GaAs was measured using a simple optical system, i.e., Michelson interferometer. An ac driving voltage was applied to the sample to produce a change in the order of 10-13 m in sample thickness. These changes were detected by the optical system to give the sample displacement as a function of applied driving voltage. The slope of the plot of this relationship led to the piezoelectric coefficients of (2.8±0.1)×10-12 and (3.9±0.1)×10-12 m/V for GaAs and AlxGa1-xAs/GaAs, respectively. The first agreed well with reported values and the latter was the first report for AlxGa1-xAs/GaAs. Owing to the equality for the inverse effect and the direct effect, in which an electric field can be mechanically induced, it is anticipated that in the absence of external electric field, the internal piezoelectric field can be induced in the multi-layered semiconductor.