• Characterization of the effects of radiation-induced charge on the 1/f noise properties of power DMOS transistors

      Babcock, Jeffrey Archimedes, 1961- (The University of Arizona., 1991)
      This thesis investigates the effects of ionizing radiation on the noise properties of n-channel power DMOS transistors. The pre-irradiation noise power spectral density of these transistors was found to vary as 1/ flambda where lambda (the slope of the noise power spectral density when plotted on a log-log scale) ranged from approximately 0.5 to 1.0. Radiation-induced trapped charge density was found to have a large effect on the magnitude and slope of the noise. Irradiation of devices was found to produce a more uniform distribution in time constants leading to the more ideal 1/f noise power spectrum as total dose increased. Polarity of bias applied during post-radiation anneal was found to force a distribution in time constants leading to an increase in lambda for devices under negative gate bias and a decrease in lambda for devices under positive gate bias. Radiation hardness of power MOSFETs was investigated as a function of their pre-irradiation 1/f noise. No correlation was found between noise magnitude and device hardness.