Systematic Investigation of 4H-SiC Trench Properties Dependence on Channel Concentration, Crystallographic Plane, and MOS Interface Treatment

We have systematically investigated the trench properties of 4H-SiC for p-type channel doping level formed by epitaxial growth, crystallographic plane, and MOS interface treatment. Our results show that the channel mobilities on the (1-100), (11-20), (-1100), and (-1-120) planes gradually decreased in the range from 1 × 1016 to 1 × 1017 cm-3 as the epitaxial channel concentration increased. An inevitable tradeoff existed between channel mobility (field-effect mobility, µFE) and threshold voltage (Vth) in trench MOSFETs. Furthermore, the maximum µFE at a channel concentration of 1 × 1017 cm-3 was 95 cm2·V-1·s-1 on the (11-20) plane with wet + hydrogen (H2) annealing, 83 cm2·V-1·s-1 on the (1-100) plane with wet + H2 annealing and 57 cm2·V-1·s-1 on the (1-100) plane with nitric oxide annealing.