Investigation of the Ion Defect States by Photoacoustic Spectroscopy

The ion defect states in SiO₂ film on Si substrata (SiO ₂/Si) was investigated by photoacoustic (PA) spectroscopy. The amplitude and phase spectra were measured and analyzed in dependence on the energy of excitation optical beam in the sub-bandgap region. In the energy range near the energy gap of Si, the PA spectra are the consequence of the ion-defect states formed on dielectric-semiconductor interface. The sub-bandgap PA spectra are proposed to obtain the energy-dependent distribution of interface states in SiO₂-Si system with different concentration of Na-ions