PHOTOEMISSION ELECTRON-MICROSCOPY OF SCHOTTKY CONTACTS

We demonstrate a new application of photoemission electron microscopy (PEEM) for the investigation of Schottky contacts. As an example we ha ve investigated the changes in contrast in PEEM images when silver is deposited on a lateral p-n diode structure on a Si(100) surface. In ag reement with recent studies by other groups, we find three-dimensional island growth in the multilayer regime at low temperatures when silve r is grown on the clean silicon surface. We also find three-dimensiona l growth when silver is deposited on a thin, wet chemically formed oxi de layer. In both cases, the p-doped regions appear brighter than the n-doped regions in the PEEM image. When the silver layer is heated to 900 degrees C the islands disappear. For the case of silver on the oxi de-free Si(100) surface, the p regions remain brighter than the n regi ons. In the case of silver growth on an intermediate oxide layer, the contrast in the image changes dramatically during heating. The experim ental results are interpreted in terms of the band bending caused by i nterface states. (C) 1998 Elsevier Science B.V.