Spatially and energy resolved hot electron transport through metal-oxide-silicon structures

The tip of a scanning tunneling microscope was based to inject hot electrons into thin Pd layers of Pd-SiO2-Si structures incorporating 7S-450 Angstrom thermally grown oxides. The collector currents emanating from the n-type Si(100) substrates for tip biases V-T greater than or similar to 4 V were measured as a function of eV(T) (electron energy) for different oxide biases V-ox applied independently across the oxide layers. Threshold shifts with increasing positive V-ox were observed for the first time and are attributed to image force lowering of the oxide potential near the metal-oxide interface, The shifts agree well with those predicted by classical image farce theory. A zero field threshold energy of 3.99 +/- 0.02 eV for the Pb-SiO2 interface was deduced, Image force effects were also incorporated into Monte Carlo caiculations of tl-se energy dependent electron transmission probability T-ox across a 150 Angstrom oxide. Favorable comparisons with experiment are observed.