Luminescence imaging - a well-established technique to study material- anddevice-related problems

The assessment of the lateral homogeneity of substrates and epitaxial layer s requires techniques that are capable of measuring the full wafer area as well as microscopic defect structures. Optical imaging combines fast, nonde structive data acquisition with high lateral resolution. The present techni cal status of two complementary imaging techniques - photoluminescence topo graphy and photoluminescence microscopy - are reviewed. Typical examples of material and process analysis with photoluminescence topography are report ed, including the assessment of epitaxial layer and substrate homogeneity a s well as detailed investigations to determine the mesoscopic distribution of accepters in semi-insulating GaAs. To demonstrate the merits of photolum inescence microscopy, luminescence images of substrate and growth-induced d efect structures in epitaxial layers are presented. Recent photoluminescenc e microscopy investigations of the failure mechanisms responsible for perfo rmance degradation of laser diodes are described. (C) 1999 Elsevier Science S.A. All rights reserved.