Investigation of interface and surface energy states in semiconductors by PA method

The photoacoustic (PA) signal should generally change with the extent of damage, in the form of surface energy states (SES) or interface energy states (IES). For a mechanically, chemically or particles processed (Ar-plasma etching, ion implantation, etc) semiconductor surface, the measured PA signal can be expect to increase as a consequence of the surface (interface) optical, thermal and carrier transport properties changes. The SES on Si wafer and IES in SiO₂ film/Si substrate are investigated by PA spectroscopy. The sub-bandgap PA spectra are used to obtain the energy-dependent distribution of SES or IES.