Total Ionizing Dose Radiation Damage to the Schottky Contact Super Barrier Rectifier

In this article, the damage of total ionizing dose (TID) radiation to the Schottky contact super barrier rectifier (SSBR) is studied by experiments and simulations. For SSBR, the different coupling between the Schottky contact barrier and super barrier (named the coupling relationship for SSBR) yields the optimal relationship between the forward and reverse characteristics. Although the TID irradiation affects the Schottky barrier height for metal/p-Si contacts. However, at a total dose of 250 krad (Si), the barrier height remains virtually unchanged. Therefore, the TID damage mainly affects the super barrier part (MOS channel) of the SSBR. Experiment results show that the TID damage increases the reverse leakage of SSBR because of the charge accumulation in the gate oxide during irradiation. However, it has little effect on the forward voltage primarily because, the fact that the threshold of the MOS channel in SSBR is very low (determined by the operation mechanism of SSBR), and in power SSBRs, the on-resistance mainly stems from the epitaxial layer, while the MOS channel resistance contributes only a small part, i.e., the barrier at the MOS channel has a limited effect on the forward voltage. Post-irradiation measurements also reveal that SSBR exhibits the most significant change in reverse leakage when subjected to a positive bias during irradiation. Finally, a method, that is, choosing a larger Schottky barrier and a smaller super barrier during device design, is presented and verified by simulations to mitigate the impact of TID effects for SSBR.