Photoacoustic Measurement of Non-radiative States and Defects in CdS and Si with ZnO Transducer

Abstract

Non-radiative states and defects in CdS and Si were studied at room temperature by means of a new photoacoustic (PA) technique. Signal detection was carried out by a ZnO transducer which operates in a wideband and high-frequency range. The fine structures due to A, B, C excitons and due to seven impurity states in CdS were observed as the maxima or minima in the PA spectra. It was also found that the spatial distribution of mechanical damage and defects in CdS and Si can be observed in the PA signals by scanning the laser beam spot across the sample.