Surface and bulk band-structure effects on CoSi2/Si(111) ballistic-electron emission experiments - art. no. 205325

A theoretical model of ballistic-electron-emission microscopy (BEEM) based on linear combination of atomic orbitals Hamiltonians and Keldysh Green's f unctions is applied to analyze experimental data obtained for CoSi2 /Si(111 ) contacts. Hot electrons injected from a scanning tunneling microscope tip into the silicide film form a highly focused beam, which even after propag ation through films of moderate thickness is narrow enough to allow the obs erved atomic resolution of interfacial point defects. On (2x1) reconstructe d domains a certain fraction of the initial current is injected into locali zed surface states, leading to the reported contrast in BEEM images, reflec ting the topography at the surface. These results confirm that band-structu re effects, both in the bulk and at the surface of the metallic overlayer, intricately influence the interface-related information contained in BEEM d ata. It is found that for a careful analysis of experimental results, a the oretical model going beyond the ballistic hypotesis is required.