Luminescence imaging — a well-established technique to study material- and device-related problems

The assessment of the lateral homogeneity of substrates and epitaxial layers requires techniques that are capable of measuring the full wafer area as well as microscopic defect structures. Optical imaging combines fast, nondestructive data acquisition with high lateral resolution. The present technical status of two complementary imaging techniques — photoluminescence topography and photoluminescence microscopy — are reviewed. Typical examples of material and process analysis with photoluminescence topography are reported, including the assessment of epitaxial layer and substrate homogeneity as well as detailed investigations to determine the mesoscopic distribution of acceptors in semi-insulating GaAs. To demonstrate the merits of photoluminescence microscopy, luminescence images of substrate and growth-induced defect structures in epitaxial layers are presented. Recent photoluminescence microscopy investigations of the failure mechanisms responsible for performance degradation of laser diodes are described.