Inversion layer carrier concentration and mobility in 4H–SiC metal-oxide-semiconductor field-effect transistors

Free electron concentration and carrier mobility measurements on 4H–SiC metal-oxide-semiconductor inversion layers are reported in this article. The key finding is that in state-of-the-art nitrided gate oxides, loss of carriers by trapping no longer plays a significant role in the current degradation under heavy inversion conditions. Rather, it is the low carrier mobility (maximum∼60 cm2 V−1 s−1) that limits the channel current. The measured free carrier concentration is modeled using the charge-sheet model and the mobility is modeled by existing mobility models. Possible mobility mechanisms have been discussed based on the modeling results.