Electronic structure of amorphousSi3N4in the cluster-Bethe-lattice approximation

Abstract

We present a calculation of the electronic structure of amorphous ${\mathrm{Si}}_3$ ${\mathrm{N}}_4$, using a model tight-binding Hamiltonian with a basis set of Si 3s and 3p, and N 2s and 2p orbitals. Clusters of 13 atoms, centered at either a Si or a N atom, are constructed using structural data from crystalline β-${\mathrm{Si}}_3$ ${\mathrm{N}}_4$. These clusters are employed to generate a self-consistent transfer-matrix approximation for an infinite effective medium (Bethe lattice). The local and average densities of states are evaluated using standard one-particle Green’s operator techniques. We also simulate photoemission spectra by weighting orbitally decomposed partial densities of states with appropriate photoemission cross sections. Our results are in good agreement with recent experimental data.