We study the bonding character, electronic structure, and defects of amorphous Si through first-principles molecular-dynamics simulations. We generate the disordered Si network from the quenching of incompletely melted samples and find more dangling bonds than floating bonds, while in previous liquid-quench simulations more floating-bond defects were generated. The structural parameters such as the pair-correlation and bond-angle distribution functions are in good agreement with experimental data. The electronic structures of the dangling and floating bonds in the amorphous network are examined by analyzing the angular momentum decomposition of the local density of states. The localized states in the gap are found to be mostly p-like at a threefold coordinated site, consistent with the picture that paramagnetic active defects in amorphous Si are due to dangling bonds.

• Received 6 September 1994

DOI:https://doi.org/10.1103/PhysRevB.50.18083