Evaluation of Channel Mobility Extraction Methods Using Source-Separated Single Cell Structure for UMOSFET on 4H-SiC

This article evaluates four methods for extracting channel mobility using source-separated single cell (SSSC) structure: parallel, series, hybrid, and separated source electrode Kelvin (SSEK). These methods are applied to UMOSFET for direct channel mobility extraction. The first two methods can not eliminate the influence of the resistance at the drain side, and the measured mobility is a mixed result of the left and right channels. The measurement and extraction procedure of the Hybrid method is more complex. Among these methods, SSEK is the simplest and allows for the analysis of the left and right channel characteristics. The channel of the UMOSFET closest to the accurate a-face exhibits lower threshold voltage, higher field-effect mobility, and lower temperature dependence. These characteristics are believed to result from fewer SiO₂/silicon carbide (SiC) interface traps.