6H and 4H-SiC Bulk Growth by PVT and Advanced PVT (APVT)

摘要

Ⅱ-Ⅵ, Inc. is a commercial supplier of high-quality SiC substrates (including 2-inch and 3-inch diameter) for RF and power applications to the US market. Semi-insulating 6H-SiC single crystals, doped with vanadium and undoped (vanadium-free), as well as n-type 4H crystals have been grown using the PVT and Advanced PVT (APVT) growth techniques. The APVT process incorporates insitu synthesis and growth of of SiC crystal from Si and C precursors. Grown 6H-SiC and 4H-SiC crystals have been extensively characterized with respect to their purity, crystal quality and electrical properties. COREMA resistivity maps demonstrate that V-compensated boules exhibited axially and radially uniform resistivity around 10~(11) Ω·cm at room temperature. Undoped (V-free) wafers contained residual boron and nitrogen at levels below 10~(16) atoms/cm~3, and demonstrated semi-insulating properties (resistivity between 10~6 and 10~(11) Ω·cm) as a result of compensation by native point defects with deep levels in the bandgap. The undoped semi-insulating crystals grown by APVT contained boron and nitrogen at 1.9·10~(15) cm~(-3) and 3.8·10~(15) cm~(-3), respectively. High-quality 2-inch SiC wafers exhibited micropipe densities on the order of 10 cm~(-2) and dislocation density on the order of 10~4 cm~(-2).