Structural and electrical properties of unintentionally doped 4H-SiC epitaxial layers—Grown by hot-wall CVD

Abstract

This paper focuses on growth of 4H−SiC epitaxial layers using the hot-wall CVD technique. The relation between the growth regime like total flow, system pressure, C/Si ratio and growth temperature and the characteristics of nominally undoped epilayers, such as thickness uniformity and background doping concentration have been investigated. The epitaxial layers were investigated by optical microscopy, capacitance-voltage measurements, x-ray rocking curve maps, electron channelling patterns and secondary ion mass spectroscopy. Layers up to 40 μm in thickness with a variation of about ±4% and with residual n-type doping levels in the low 10¹⁴ cm⁻³ ranges have been obtained on Si faces wafers. SIMS measurements have shown that the impurity concentration of acceptors like B and Al is below 2×10¹⁴ cm⁻³.