Photoacoustic and Photoluminescence Measurements of Defects in Semiconductors

Abstract

Photoacoustic (PA) and photoluminescence (PL) measurements were carried out simultaneously at room temperature in order to get new spectroscopic informations on defects in semiconductors. PA signal was detected with a piezoelectric transducer (ZnO film) coated by sputtering onto the back surface of the sample. From the experimental results, it was shown that a dark-line-defect (DLD), an oxidation layer and surface states on GaAs surface, and a thin a-Si layer on Si surface act as spatially localized non-radiative regions. In our PAS system, the piezoelectric detector of ZnO film could detect very sensitively the PA signal from such localized non-radiative regions. The bending model for PA detection was applied to analyses of our experimental results. Then, we discussed the local heating effects at the defects for PA detection nechanism with the piczoelectric transducer.