ELECTRONIC-STRUCTURE OF PHOSPHORUS IN DOPED AMORPHOUS HYDROGENATED SILICON

The electronic structure of impurities in hydrogenated amorphous silicon (a-Si:H) is investigated. The formation energies of phosphorus dopant atoms in a-Si:H are calculated, and used to infer the energetically favored bonding configurations. The large and negative formation energy found for electronically inactive, pyramidally bonded (non-dopant) phosphorus atoms is consistent with their prevalence in phosphorus-doped a-Si:H. Phosphorus dopant atoms are found to be energetically favored to occur in the vicinity of Si-H bonds. The effects of charge transfer reactions on the stability of neutral phosphorus dopant atoms in the proximity of silicon dangling bonds are considered. The results here accord well with a variety of experimental data, including nuclear magnetic resonance and electron spin resonance measurements on a-Si:H.