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

Abstract

Abstract 4H-SiC(0001) metal-oxide-semiconductor field-effect transistors (MOSFETs) and MOS capacitors were fabricated by the following procedures: H 2 etching, SiO 2 deposition, and nitridation, and their electrical characteristics were evaluated. Substantially low interface state densities (4–6 × 10 10 cm −2 eV −1 ) and high channel mobilities (80–85 cm 2 V −1 s −1 ) were achieved by N 2 annealing or NO annealing after H 2 etching and SiO 2 deposition. The threshold voltage of the MOSFETs fabricated with N 2 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.