BALLISTIC-ELECTRON-EMISSION MICROSCOPY AT METAL GAP(110) INTERFACES - ELECTRON-TRANSPORT AND SCHOTTKY-BARRIER HEIGHTS

Ballistic-electron emission microscopy (BEEM) was performed for Au and Mg films on n-type GaP(110). BEEM spectra taken with tip voltages up to 6 eV reveal a strong dependence of the spectral shape on metal-film thickness and on the type of the metal. Monte Carlo simulations of the electron transport allow a quantitative description of the BEEM current, and provide information on the tunneling process, on hot-electron transport in the metal film, on transmission across the interface, and on impact ionization within the semiconductor. In addition, the simulations quantitatively account for the observed dependence of the BEEM current on topographic features. The Schottky-barrier heights were also found to increase with the thickness of the metal film, demonstrating that Schottky-barrier formation is not yet completed when the overlayer metallizes.