Investigation of possible sources of 1/f noise in irradiated n-channel power MOSFETs

1/f noise in irradiated n-channel power MOSFETs is compared to interface- and oxide-trapped charge densities. The noise follows the bias dependences predicted by an equation based on the number fluctuation model derived for noise in the saturation region. The magnitude of the noise switched between two distinct levels when the bias was reversed during post-irradiation annealing. The noise did not correlate well with interface traps or oxide trapped charge. Border traps provide a reasonable explanation, with charge compensation being an important effect. During positive-bias annealing, near-interfacial traps are compensated and no longer contribute to the 1/f noise. However, when the bias is reversed, the traps are decompensated and the noise increases again