Silicon Nitride is found to have a valence band maximum of nitrogen lone pair p electrons because of the planar nitrogen site. This contrasts with the usual lone pair semiconductors, such as SiO2, caused by a p4 valence configuration. Consequently although the valence band density of electron states shows a lone pair band and a deeper bonding band as usual, impurities have a greater effect in the nitride than in conventional lone pair semiconductors. Hole transport is also discussed.

Electronic structure of silicon nitride

Properties of amorphous hydrogenated silicon, with special emphasis on preparation by sputtering

Luminescence and ESR studies of defects in hydrogenated amorphous silicon

A microscopic model based on charge-induced breaking of weak Si-Si bonds is proposed as an explanation for the experimentally observed increase of the dangling-bond density in a-Si: H upon illumination, charge injection, and doping. Energetic aspects of the conversion between weak and dangling bonds and implications for the electronic density of states of a-Si: H are described, and the relation of the model to negative4 defects in this material is discussed.

Weak bond-dangling bond conversion in amorphous silicon

We review the bonding in a wide range of non-crystalline materials, such as the elemental and compound amorphous semiconductors, liquid semiconductors and, briefly, some oxide glasses and amorphous silicon dioxide. The review concentrates on the experimental determination of electronic structure from photoemission, optical spectra and core spectra and on its theoretical description, particularly using tight-binding methods. The review also describes the bonding at defects in amorphous semiconductors and in particular that of dopants and hydrogen in hydrogenated amorphous silicon (a-Si:H).

Electronic structure of amorphous semiconductors

A novel mechanism for spin-pairing at defect centres in amorphous silicon is proposed and discussed in terms of simple chemical bond arguments. Unlike the case of chalcogenide glasses (or amorphous...

S. R. Elliott

Papers

Defect states in amorphous silicon