POLARITY DEPENDENCE OF HOT-ELECTRON-INDUCED TRAP CREATION IN METAL-OXIDE-SEMICONDUCTOR CAPACITORS

Using thin metal gate electrodes, we have injected electrons into silicon dioxide films from the gate electrode and from the silicon substrate using internal photoemission. We have measured the hot-electron-induced electron trap density and centroid as a function of the average applied field and bias polarity for samples that have been in storage for a number of years and for samples recently fabricated. We found a greater density of traps generated for injection from the gate than from the silicon substrate. For the "aged" samples, the charge centroid of the electron traps is found close to the aluminum/silicon dioxide interface for low electric fields implying a large density of background traps close to this interface. For the "dry" samples the low-field centroid is found close to the center of the silicon dioxide film. As the field exceeds the electron heating threshold (congruent-to 1.5 MV/cm), the charge centroid for all samples is found to move towards the cathode/silicon dioxide interface.