Cathodoluminescence spectroscopy studies of laser-annealed metal-semiconductor interfaces

We have extended cathodoluminescence spectroscopy (CLS) to the study of new compound and defect formation at metal-semiconductor interfaces. CLS provides evidence for Cu₂ S and/or impurity band formation after laser annealing Cu on UHV-cleaved CdS. A1 deposition on UHV-cleaved CdS followed by laser annealing leads to formation of at least two deep levels distributed at different depths from the initial interface. The energies, densities, and spatial distribution of these levels depend sensitively on the laser intensity and the presence or absence of particular metal overlayers. These results demonstrate the utility of CLS in revealing electronic features of the buried metal-semiconductor interface while still maintaining depth resolution on the order of hundreds of A or less.