Energy spectra and dynamics of surface states on silicon investigated by the photoacoustic method

Abstract

The spectral and dynamic characteristics of surface energy states (SES) on a Si wafer are investigated by photoacoustic (PA) spectroscopy. The PA spectra were measured as a function of the wavelength and modulation frequency of the excitation optical beam by the PA spectrometer. The PA amplitude spectra of Si samples of various surface quality were studied at room temperature in the spectral range of the excitation optical energy beam from 0.7 to 1.5 eV and for various modulation frequencies. The difference in PA amplitude spectra of an as-received Si wafer and a Si wafer with a mechanically roughened surface for various modulation frequencies indicates the energy distribution and the dynamics of the SES. A change in the PA amplitude signal for various modulation frequencies indicates the temporal distribution of the SES for a fixed energy of excitation.