The effects of ionizing-radiation-induced oxide-trapped and interface-trapped charges on gate-charge measurements of power MOSFETs are investigated. Both radiation-hardened and commercial DMOS power transistors are tested in this study. Experimental results show that: (1) the radiation-induced interface-trapped charge is related to the changes in the plateau length, and (2) the radiation-induced charges at threshold can be directly measured from the changes in the gate-to-source charge. A new charge separation technique based on the gate-charge measurement is developed. Moreover, the radiation-induced changes in the gate-charge curve provide information on the shift in threshold voltage, the increase in the plateau length, and the effective changes in gate-to-source capacitance and charge. This information should be used by the power-supply designers to compensate for radiation-induced changes in the power-MOSFET characteristics.
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