Electron Transport in Thin Insulating Films

Experiments on the electron transport through thin insulating barriers have been performed with diodes of Ta-Ta_2O_5-Au, Ta-Ta_2O_5-Al, Ta-Ta_2O_5-Bi, Zn-ZnO-Au, Al-Al_2O_3-Al and Al-Al_2O_3-Au. The analysis of the dependence of current on temperature and film thickness allows a distinction of two cases: imperfect and perfect dielectrics. In the former case the mechanism for electron transport is field ionisation of trap-type states at low temperatures and thermal ionisation of this states at higher temperatures. In the latter case Schottky-Emission and field emission have been observed.