Mobility improvement of 4H-SiC (0001) MOSFETs by a three-step process of H2 etching, SiO2 deposition, and interface nitridation

Abstract 4H-SiC(0001) metal-oxide-semiconductor field-effect transistors (MOSFETs) and MOS capacitors were fabricated by the following procedures: H2 etching, SiO2 deposition, and nitridation, and their electrical characteristics were evaluated. Substantially low interface state densities (4–6 × 1010 cm−2 eV−1) and high channel mobilities (80–85 cm2 V−1 s−1) were achieved by N2 annealing or NO annealing after H2 etching and SiO2 deposition. The threshold voltage of the MOSFETs fabricated with N2 annealing was shifted negatively when the oxide was formed by deposition. On the other hand, normally-off operation and high channel mobility were compatible for the MOSFETs fabricated with NO annealing.