Wafer-scale analysis of GaN substrate wafer by imaging cathodoluminescence

Abstract

With the progress in large-size high-quality GaN substrates, wafer-scale analysis is needed to evaluate homogeneity and defect distribution. We demonstrate the mapping of a 2 inch GaN substrate wafer based on the imaging cathodoluminescence technique. Macro pit defects with sizes varying from microns to millimeters are visualized and classified into three types according to their optical and structural properties. The formation mechanisms of the different types of pit defects are discussed with consideration of the facet growth involved in substrate growth.