Excess Carrier Lifetime Mapping for Bulk SiC Wafers by Microwave Photoconductivity Decay Method and Its Relationship with Structural Defect Distribution

摘要

Excess carrier lifetime in commercially available bulk 2 in. 4H- and 6H-SiC wafers were characterized by the microwave photoconductivity decay (μ-PCD) method. We obtained maps of the lifetime in the entire wafer. In each wafer, we observed several small regions in which the lifetime is relatively longer than the rest of the wafer. We also observed the birefringence and X-ray Lang topograph for the wafers in order to see structural defect distribution and measured net donor concentrations within the wafers. From comparison of the lifetime maps with structural defect observation, the long lifetime regions was found to correspond to regions with high density of structural defects.