Excess carrier lifetimes in bulk 2in SiC wafers were measured by microwave photoconductivity decay (µ-PCD). The mapping technique was used to obtain the lifetime distribution over the entire wafer. Birefringence images and X-ray topographs of the wafers were observed in order to determine the structural defect distribution. The net donor concentration distribution was also observed by capacitance-voltage measurements. By comparing lifetime maps with the structural defect distribution, it was found that relatively long lifetime regions corresponded to regions with high-density structural defects. The net donor concentration did not show a clear influence upon the carrier lifetimes. It was confirmed that surface recombination had a negligible effect upon the carrier lifetimes, and therefore the lifetimes obtained from mapping measurements were mainly dominated by carrier recombination behavior in the bulk of the wafers.

Excess Carrier Lifetime Measurement of Bulk SiC Wafers and Its Relationship with Structural Defect Distribution. T.Mori, M.Kato, H.Watanabe, M.Ichimura, E.Arai, S.Sumie, H.Hashizume: Japanese Journal of Applied Physics, 2005, 44[12], 8333-9