Piezoelectric photoacoustic evaluation of Si wafers with buried structures

The piezoelectric photoacoustic evaluation of Si wafers with buried structures is studied experimentally and theoretically. In the experiment, the authors have detected and imaged the Sb-doped regions in a Si wafer covered by an epitaxial Si layer with about 10-mum thickness. In order to explain the experimental results, the one-dimensional multilayered model with discontinuous thermal impedance between the neighboring layers is used, and the expressions for the thermal and acoustic fields in the sample and PZT transducer are also presented. Moreover, numerical calculations in accordance with the practical experimental conditions have been carried out.