Sub-band-gap surface photovoltage in Si/SiO2structures with quasi-continuously distributed interface traps and a deep. In level in the semiconductor bulk

Computer simulation studies of sub-band-gap surface photovoltage (SPV) spectra of Si/SiO2 structures with optically active quasi-continuously distributed interface traps (ITS) and an In deep bulk level (DBL) are presented. The calculations have been carried out at T = 93 K for a variety of exciting light intensities. In order to separate the IT and DBL contributions to the SPV spectra, two Si/SiO2 structures have been considered separately. The substrate in the first structure contains only shallow B acceptors and that in the second structure only deep In acceptors. In the (Si: B)/SiO2 case the SPV spectrum has been explained in terms of a proper model for the IT optical behaviour. The theoretical results have been experimentally verified and the IT photoionization cross-sections have been determined. In the (Si: In)/SiO2 case the conditions have been found under which both IT and In DBL influence the SPV spectra behaviour. The possibility of determining basic DBL optical parameters has been shown.