Gamma irradiation impact on GaN quasi-vertical Schottky barrier diodes

The impact of gamma irradiation on GaN quasi-vertical Schottky barrier diodes (SBDs) has been investigated for the first time. Compared with original GaN SBDs, the ideality factor decreases from 1.2 to 1.01?1.02 and the on/off ratio increases from 10(9) to 10(12) for the irradiated GaN SBDs. The reduction of dynamic on-resistance from 0.67 m? cm(2) to 0.54 m? cm(2) was observed at the quiescent bias of???100 V compared with the original SBDs. The temperature dependent current characteristics has revealed the existence of Schottky barrier inhomogeneities at the anode/GaN Schottky interface, and the level of barrier inhomogeneities can be effectively suppressed after gamma irradiation. Based on x-ray photoelectron spectroscopy, cathodoluminescence and x-ray diffraction results, the interface state density at the interface and the deep electron trap in the bulk GaN are reduced after gamma irradiation. The voltage dependent capacitance-frequency measurements further confirm that the interface trap states dominate the degraded characteristics of pre-irradiated devices and the trap time constant is estimated to be in the range of 5 ?s to 50 ?s.