SURFACE EFFECTS IN BALLISTIC-ELECTRON-EMISSION MICROSCOPY

Tn situ ballistic-electron-emission microscopy (BEEM) and scanning tunneling spectroscopy have been performed at 77 K on CoSi2/Si(111) films grown by molecular beam epitaxy. Different atomic surface structures induce significant variations of the BEEM current. For the first time periodic surface structures could be imaged at atomic resolution by BEEM. This surface effect is explained by the energy distribution of the injected electrons, which is influenced by surface-induced variations of the tunneling barrier height. Quantum size effects in the local density of states can be correlated with subtle features in the BEEM spectra.