Description:
We have used deep level transient spectroscopy (DLTS) and electron spin resonance (ESR) to investigate the interface states on oxidized silicon. Measurements were performed before and after soft x-ray irradiation. Before irradiation, the ESR Pb peak, corresponding to the DLTS 0.3-eV peak, was observed using both methods. After irradiation, it was unchanged when we used ESR, whereas DLTS showed a general increase in the number of interface states over the band gap. No structure in the DLTS signal was seen in the region where the 0.3-eV peak is situated. We have thus shown that soft x-ray irradiation does not affect the Pb interface trap, but that it gives rise to a broad distribution of non-ESR-active interface traps, instead.