Photoacoustic effect of piezoelectric ZnO thin films

This paper describes the photoacoustic (PA) effect of piezoelectric ZnO thin films. The one-dimensional theory of the PA-effect was derived. The relationships between PA-signals and modulation frequency, thin film properties such as piezoelectric coefficients, dielectric constant, specific heat and thermal conductivity coefficient were obtained. The experimental results on the PA-effect of sputter-deposited ZnO thin films exhibited good agreement with the theoretical analysis. The piezoelectric stress coefficients, e₃₃ and e₃₁, of some ZnO films were determined from the PA-signals, typical values of which are 0.82 C/m² and -0.43 C/m², respectively.