Influence of Non-Uniform Interface Defect Clustering on Field-Effect Mobility in SiC MOSFETs Investigated by Local Deep Level Transient Spectroscopy and Device Simulation

摘要

It has recently been shown that interface defect density (D_(it)) at SiO_2/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 D_(it) 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 D_(it) distributions measured by local DLTS. Our main result is that the impact of the non-uniform D_(it) clustering on field-effect mobility is negligible for a SiC MOSFET with high D_(it) formed by dry thermal oxidation but it becomes significant for that with lower D_(it) by post-oxidation annealing. The result indicates that channel mobility can be further improved by making D_(it) distribution uniform as well as reducing D_(it).