DCIV and Spectral Charge-Pumping Studies of -Ray and X-ray Irradiated Power VDMOSFET Devices

This paper reports the total dose effects and post-irradiation anneal effects on the two recombination current peaks and the bottom current in commercial power VDMOSFET devices irradiated with Cs -ray or X-ray radiation. The two interface recombination current peaks show a slightly different rate of increase as a function of the radiation dose. Slightly different diode ideality factors are found in an n-channel device, 1.70 0.10, 1.60 0.10 and 1.20 0.10 for the two DCIV current peaks and the bottom current, respectively. The saturation current of the gated diode, i.e., VDMOSFET, normalized by the input capacitance is shown to be a good parameter to monitor the interface state density. Spectral charge pumping data show that, of the above-midgap interface traps in an n-channel device, the energy below about + 0 18 eV has a most significant increase in radiation-induced trap density and these traps may be responsible for the DCIV current peaks.