Growth and characterization of nitrogen-doped C-face 4H-SiC epilayers

Abstract

In this paper, nitrogen-doped 4H-Silicon carbide (SiC) epilayers are grown on 4° off-axis 〈 0 0 0 1 ¯ 〉 C-face 4H-SiC substrates by horizontal hot-wall chemical vapor deposition. Surface morphology of the epilayers shows a strong dependence on N 2 flow, C/Si ratio and growth temperature. Surface defect densities are higher for samples grown under high C/Si ratio and high N 2 flow condition. Lightly doped epilayers with low defect densities have been achieved by growing under optimized conditions. Macrostep bunching is observed on epilayers grown under high N 2 flow condition. The degree of step bunching manifests a dependence on N 2 flow. Possible impurity-induced step-bunching mechanism is discussed to explain the results. Lightly doped C-face 4H-SiC epilayers exhibit a site-competition effect, while heavily doped epilayers do not. Schottky barrier diodes fabricated on C-face 4H-SiC epilayers are shown to be comparable to or outperform those on Si-face epilayers.