Experimental Investigation and Improvement of Channel Mobility in 4H-SiC Trench MOSFETs

This study proposes a method for evaluating the channel mobility for 4H-SiC trench MOSFETs. To calculate the channel mobility, the parasitic resistance, which mainly consists of the drift layer resistance, is removed based on a simple model of series resistance. The dominant component of carrier scattering, including optical phonon scattering, is analyzed using the proposed mobility model. The proposed method is used to evaluate the effect of the surface morphology of trench sidewalls on channel mobility for the first time. When the surface is atomically flat, there is a large increase in channel mobility. This increase is caused by the suppression of Coulomb scattering due to dangling bonds at SiC surfaces.