An investigation of the structures and design parameters of 4H-SiC trench inversion-channel MOSFETs using a two-dimensional (2D) numerical device simulation is presented. Material parameters have been adjusted appropriately for the 4H-SiC poly-type and a systematic characterisation and optimization of a specific trench MOSFET with a 1.2 kV blocking voltage capability has been performed. Simulations have concentrated on optimizing the p-type doping concentration at the trench bottom, to keep the breakdown electric field in the oxide under its critical value. The trench depth was also examined and optimized to give a better on-state performance. For the MOSFET structure examined, a minimized on-state resistance of 53 m Omega cm(2) was obtained. (c) 2005 Elsevier Ltd. All rights reserved.