Injection and Emission of Hot Electrons in Thin-Film Tunnel Emitters

Abstract

Results of studies of Al‐Al₂O₃‐(Au or Al) thin‐film emission diodes are in agreement with a model based on electron injection by internal TF emission with subsequent energy loss in the insulating film, characterized by isotropic scattering with energy loss ΔE=0.1 eV and mean free path λ_i=6 Å. The experimental results for Au overlayer films are found to be consistent with a modified ballistic transport model allowing weak elastic interactions, with a value for the electron‐electron scattering mean free path at 7.0‐V bias of λ_e∼47 Å. Low‐energy electron bombardment of the thin‐film sample is found to allow detection of overlayer‐film porosity, and a quantitative assessment of hot electron emission through holes in Au overlayer films is obtained. The results indicate that preferential electron emission through holes in pure Au films is not of significance over the entire range of Au film thicknesses studied; this conclusion is substantiated by results obtained with composite Al‐Au‐overlayer films.