Effect of gate interface on performance degradation of irradiated SiC-MESFET

The radiation damages and their degradation mechanism of device performance on 4H-SiC Metal Schottky Field Effect Transistors (MESFETs), which have been irradiated at room temperature with 2 MeV electrons and 20 MeV protons, is studied together with recovery behavior. No performance degradation is observed by 1x1012 e/cm2 and 5x1011 p/cm2, while a slight increase of the linear drain current together with a decrease of the threshold voltage are noticed above higher fluence. The damage coefficient for protons is about three orders of magnitude larger than that for electrons. The radiation source dependence of the device performance degradation is attributed to the difference of mass and the possibility of nuclear collision for the formation of lattice defects. Based on thermal annealing results of electron-irradiated MESFETs, it is found that the recovery of the drain current characteristics principally takes place from 100 deg. C, and that the drain current recovers to the pre-rad value after 200 deg. C annealing, while capacitance and induced deep levels do not recover. From the results annealing behavior with 0.27 eV, it is concluded that the degradation of the drain current is mainly sensitive to the decrease of the Schottky barrier height at the gate contact