Semi-numerical modelling of an n-channel irradiated MOSFET

A semi-numerical model of a metal-oxide-semiconductor field effect transist or (MOSFET) has been developed for theoretical examination of the effect of ionizing radiation on the characteristics of the device. The present model utilizes the radiation-induced changes in the flat-band voltage to estimat e the change in the surface charge carrier concentration which in turn chan ges the mobility of the surface channel and affects the source-to-drain cur rent. For the first time a model of an irradiated MOSFET has been presented that incorporates the effect of both transverse and longitudinal electric fields in the transport of the carriers in the surface channel. The present model can also be used to determine the characteristics of the device in t he pre-irradiated condition. The validity of the model has been established by comparing and contrasting the results in the preirradiated condition wi th those obtained using other models, including two-dimensional models. The results obtained on the basis of our model are compared with reported expe rimental results and also a SPICE (Level 3) model in the post-irradiated co ndition. It is found that our model gives a better fit to the reported expe rimental results as compared with SPICE models. The present model is expect ed to yield fairly accurate results for estimation of I-D-V-D characteristi cs and the transfer characteristics, even for a short channel device.