Emission of energetic electrons from tunnel junctions

Energetic (hot) electrons can be emitted from Al-Al2O3-Au tunnel junctions. This emission supports a recently proposed hot-electron picture for light emission from tunnel junctions. A transfer ratio curve shows that a fraction approaching 1% of the injected, hot tunneling electrons retain sufficient normal energy to surmount the Au-vacuum surface barrier and be collected if the Au work function is lowered by the evaporation of 3-4 monolayers of cesium. Fitting tunneling junction I-V curves by two different methods gives a tunneling barrier 2-4 eV high and 15-19 thick. These barrier parameters are comparable to those of light-emitting tunnel junctions.