ANALYSIS OF GAMMA-IRRADIATION INDUCED DEGRADATION MECHANISMS IN POWERVDMOSFETS

In this paper, a detailed analysis of gamma-irradiation induced degrad ation of threshold voltage and gain factor in power VDMOSFETs, as well as the underlying changes in gate oxide charge and interface trap den sities, is presented. Also, an analysis of the electrochemical mechani sms responsible for creation of the gate oxide charge and interface tr aps is performed, and a generalized model which explains in detail exp erimental results obtained is proposed. Finally, degradation of the th reshold voltage and the underlying degradation mechanisms are analyzed in terms of the radiation tolerance of the power VDMOSFETs, with emph asis on the possibilities for its improvement.