LAUSR

Abstract The effective mobility in 4H-SiC trench metal-oxidesemiconductor field-effect transistors (MOSFETs) with an n-channel region on the 1 1 - 00 face, corresponding to the trench sidewalls, is investigated. Using a previously proposed mobility model, which includes Coulomb scattering mobility ( μ C ), surface roughness scattering mobility ( μ S R ) and optical phonon scattering mobility ( μ O P ), the dependence of the effective field (Eeff) on μ O P is studied experimentally. It is found that for the trench MOSFETs with a drift layer, μ O P is proportional to Eeff−1, whereas for trench MOSFET without a drift layer, it is proportional to Eeff−0.3, which is consistent with reports on phonon scattering mobility in SiC lateral MOSFETs fabricated on 0001 and 000 1 - faces. The results suggest that the proposed mobility model is effective, and that the dependence of Eeff on μ O P is not affected by the plane orientation of SiC and needs to be evaluated with the drift layer resistance removed. A method for evaluating the carrier transport properties of trench MOSFETs with a drift layer is also proposed.