Photoemission electron microscopy of Schottky contacts

Abstract

We demonstrate a new application of photoemission electron microscopy (PEEM) for the investigation of Schottky contacts. As an example we have 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 agreement with recent studies by other groups, we find three-dimensional island growth in the multilayer regime at low temperatures when silver is grown on the clean silicon surface. We also find three-dimensional growth when silver is deposited on a thin, wet chemically formed oxide 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°C the islands disappear. For the case of silver on the oxide-free Si(100) surface, the p regions remain brighter than the n regions. In the case of silver growth on an intermediate oxide layer, the contrast in the image changes dramatically during heating. The experimental results are interpreted in terms of the band bending caused by interface states.