VACUUM EMISSION OF HOT-ELECTRONS FROM INSULATING AND SEMICONDUCTING-FILMS

Monte Carlo calculations and vacuum emission experiments have been shown to be powerful tools to investigate the high field electronic transport in metal-insulator-semiconductor and metal-semiconductor-insulator-semiconductor layer devices. Direct proof of hot-electron acceleration in semiconducting ZnS:Mn electroluminescent layers by means of vacuum emission and energy analysis in a spherical grid analyzer has been given as it was earlier for insulating a layer of SiO2. The energy distributions show strong peaking in the low-energy region around 3 eV as well as a high-energy tail exceeding even 20 eV. The enhanced emission of low-energy electrons with increasing field F indicates impact valence band excitation and direct avalanching in thin insulating and semiconducting films of sufficient thickness, than it has been predicted by strong acoustic phonon coupling and intervalley scattering.