MEASUREMENT OF HOT-ELECTRON SCATTERING PROCESSES AT AU SI(100) SCHOTTKY INTERFACES BY TEMPERATURE-DEPENDENT BALLISTIC-ELECTRON-EMISSION MICROSCOPY/

Ballistic-electron-emission microscopy measurements have been performe d on n-type Au/Si(100) interfaces for injection energies up to 1.2 eV over a range of Au overlayer thicknesses from similar to 65 to similar to 340 A at both room temperature and 77 K. Hot-electron attenuation lengths in the Au overlayer have been determined to be 133+/-2 Angstro m at room temperature and 147+/-6 Angstrom at 77 K over the energy ran ge of 0.92-1.20 eV above the Fermi level. The lack of energy dependenc e and the relatively small temperature-dependent change in the attenua tion lengths that have been measured indicate that electron scattering with defects is the dominant mechanism affecting hot-electron transpo rt in these Au overlayers. The ratio of the zero-thickness collection current at 77 K to that at room temperature has been measured to be 1. 79+/-0.09. This large increase in the collection efficiency at 77 K is attributed primarily to the large temperature dependence of the trans verse acoustic-phonon population in Si. Images with significant reduct ions in the collection current at topographic locations that have a la rge surface gradient have been obtained at room temperature. Calculati ons, which assume that the probability of transmission across the inte rface is independent of the transverse momentum of the electron, corre late well with the experimentally observed reductions. This result ind icates that the injected electrons remain Forward focused with little broadening as they pass through the Au overlayer, which implies that e lastic scattering at the Au/Si interface accounts for the observation from previous Au/Si ballistic-electron-emission microscopy studies tha t transverse momentum is not conserved.