Electron injection and trap filling in insulating layers

On the basis of a model of the real insulating layer within a MIS structure, taking into account small interface regions with trap densities by at least one or two orders of magnitude larger than the trap density of the bulk, electron injection and trap filling of these regions is calculated. Experimental results agree very well with predictions of the trap-filling model. In thermal SiO2 layers trap densities in the interface region are found to be about 0.6 to 8 × 1010 cm−2 with larger values at the silicon side. The corresponding values of Si3N4 layers are found to be about 6 × 1011 to 6 × 1012 cm−2 with larger values at the metal side. From the time constants of trap filling of about 120 s the widths of the interface regions follow to be about 32 Å.