Study of power MOSFET under irradiation condition

Power MOSFET IRF540N and IRF9530 were irradiated by X-ray and gamma ray, and the relationship of their threshold voltage and absorbed dose was studied. It is found that the change of threshold voltage value fits in exponential law with absorbed dose,which is caused by the effect of space charge and interface charge.The space charges affect threshold voltage of MOSFET varying linearly with absorbed dose,and the interface charges have a compensational role to space charges,it affects threshold voltage varying linearly with square of absorbed dose．