A model for the electrical conduction in polysilicon oxide

A model is presented for the current injection in oxide layers on polycrystalline silicon. The model is based on the representation of the interface by a collection of asperities with different heights. The electric field at the asperities, the resulting Fowler-Nordheim injection, and the trapping of charge carriers are calculated numerically. A uniform distribution of traps is assumed in the oxide. The presence of electron traps has been demonstrated by thermal detrapping experiments. From a comparison with experiments it turns out that the magnitude of the electric field at the interface exhibits an exponential distribution. Using this distribution, a simple equation is derived for the current-voltage characteristics of polyoxides.