Defect and impurity states in silicon nitride

The electronic levels associated with silicon and nitrogen dangling bonds and Si-H, N-H, and Si-Si units within bulk Si3N4 have been calculated using the tight-binding and recursion methods. The Si dangling bond, the Si-H σ state and the Si-Si σ state all lie in the gap. The Si-Si σ state lies in midgap and could be a long-term hole trap. The Si dangling bond state lies just below the conduction band and could act as a very efficient electron trap.