Electronic structures of silicon nitride revealed by tight binding calculations

A new tight binding (TB) potential model was proposed for determining the electronic structures of ionic-covalent materials. In the TB model, the matrix elements were determined from the atomic characteristics of the crystal. The atomic parameters of the solid were determined based on the general quantum principles and no adjustable parameter was needed. Electronic structures of amorphous silicon nitride (Si₃N₄) were calculated using this method. A good agreement between the calculated and experimental values in terms of fundamental properties such as the position of the valence-band edge, the conduction-band edge, and the energy bandgap were obtained. Charge transfer between the silicon and nitrogen atoms was also precisely calculated in this work.