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

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, syst em pressure, C/Si ratio and growth temperature and the characteristics of n ominally undoped epilayers, such as thickness uniformity and background dop ing concentration have been investigated. The epitaxial layers were investi gated by optical microscopy, capacitance-voltage measurements, x-ray rockin g curve maps, electron channelling patterns and secondary ion mass spectros copy. Layers up to 40 mum in thickness with a variation of about +/-4% and with residual n-type doping levels in the low 10(14) cm(-3) ranges have bee n obtained on Si faces wafers. SIMS measurements have shown that the impuri ty concentration of accepters like B and Al is below 2 x 10(14) cm(-3).