Hot hole effect on surface-state density and minority-carrier generation rates in Si-MOS diodes measured by DLTS

Hot hole effects in Si-MOS diodes were investigated with the Deep Level Transient Spectroscopy (DLTS) technique. The DLTS measurement was successfully applied to determine the surface state density in MOS diodes as low as 1.5 × 10⁹cm^-2. eV^-1and also surface minority-carrier generation velocity which could be separated from bulk generation with the aid of the Zerbst method. It was found that pulses higher than the breakdown voltage excited hot holes and increased both the surface-state density and the surface generation velocity, but no change was observed in the bulk generation lifetime. The degradation rate was dependent upon the excess voltage and insensitive to the oxidation methods; dry or steam. A strong correlation between surface-state density and minority-carrier generation velocity was also observed.