Effects of interface state density on 4H-SiC n-channel field-effect mobility

We investigated the effects of D-IT at the interface between SiO2 and Si-, C-, and a-face 4H-SiC in n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) that were subjected to dry/nitridation and pyrogenic/hydrotreatment processes. D-IT at E-C - E-T = 0.2 eV was evaluated by the C - psi(S) method using MOS capacitors and was accurately reflected in the subthreshold slope of the MOSFETs. The peak field-effect mobility was inversely proportional to D-IT. The mobility for the a-face MOSFETs was 1.5 times or more higher than the other faces mobilities, indicating that mobility limiting factors other than D-IT(0.2 eV) may exist for the Si- and C-face interfaces. (C) 2014 AIP Publishing LLC.