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

Monte Carlo calculations and vacuum emission experiments have been sho wn to be powerful tools to investigate the high field electronic trans port in metal-insulator-semiconductor and metal-semiconductor-insulato r-semiconductor layer devices. Direct proof of hot-electron accelerati on in semiconducting ZnS:Mn electroluminescent layers by means of vacu um emission and energy analysis in a spherical grid analyzer has been given as it was earlier for insulating a layer of SiO2. The energy dis tributions show strong peaking in the low-energy region around 3 eV as well as a high-energy tail exceeding even 20 eV. The enhanced emissio n of low-energy electrons with increasing field F indicates impact val ence band excitation and direct avalanching in thin insulating and sem iconducting films of sufficient thickness, than it has been predicted by strong acoustic phonon coupling and intervalley scattering.