Influence of non-uniform interface defect clustering on field-effect mobility in sic mosfets investigated by local deep level transient spectroscopy and device simulation

It has recently been shown that interface defect density (Dit) at SiO2/SiC interfaces can have non-uniform clustered distribution through the measurement by local deep level transient spectroscopy (local DLTS). Here we investigate the influence of the non-uniform Dit clustering on the field-effect mobility in SiC metal-oxide-semiconductor field effect transistors (MOSFETs) by device simulation. We develop a three dimensional numerical model of a SiC MOSFET, which can incorporate actual Dit distributions measured by local DLTS. Our main result is that the impact of the non-uniform Dit clustering on field-effect mobility is negligible for a SiC MOSFET with high Dit formed by dry thermal oxidation but it becomes significant for that with lower Dit by post-oxidation annealing. The result indicates that channel mobility can be further improved by making Dit distribution uniform as well as reducing Dit.