Investigation of the interface states in the SiO$_2$ – Si system by photoacoustic method

The interface states in SiO$_2$ – Si system was investigated by photoacoustic (PA) spectroscopy. The amplitude and phase spectra were measured and analyzed in dependence on the wavelength of excitation optical beam. In the energy range above the 1.11 eV, the spectral characteristic has a typical form for optical interference. The phase PA spectra of Si wafer and SiO$_2$/Si structure are the same in the energy range above the energy gap of Si. In the energy range below the energy gap of Si, the PA spectra is the consequence of the carrier trapping states formed on dielectric-semiconductor interface