Elastic scattering and the lateral resolution of ballistic electron emission microscopy: Focusing effects on the Au/Si interface

Ballistic electron emission microscopy (BEEM) currents for Au-Si interfaces are analyzed using a Keldysh method that takes into account the elastic propagation of electrons through the metallic layer. Our analysis shows that electrons being transmitted through the metal are focused along specific directions. This is easily understood in terms of the metallic Fermi surface characteristics. Using these ideas, we can explain both the behavior of the different Au/Si interfaces and the high lateral resolution found for BEEM experiments.