Local bonding configuration of phosphorus in doped and compensated amorphous hydrogenated silicon

From an analysis of ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ nuclear-magnetic-resonance spectra, the chemical nature and local bonding of phosphorus in samples of amorphous hydrogenated silicon ($a-\mathrm{S}\mathrm{i}:\mathrm{H}$) have been determined. Overlapping spectra of threefold- and fourfold-coordinated phosphorus may be separated on the basis of dipolar couplings and identified on the basis of chemical shifts. At low concentrations of phosphorus, the ratio of threefold- to fourfold-coordinated phosphorus is approximately 4 to 1. The magnitudes of the ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$-${}_{}{}^1{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^1{}_{}{}^{}\mathrm{H}$-${}_{}{}^1{}_{}{}^{}\mathrm{H}$ dipolar couplings indicate that fourfold-coordinated phosphorus is located at internal hydrogenated surfaces. Finally, the increase of fourfold-coordinated sites in compensated $a-\mathrm{S}\mathrm{i}:\mathrm{H}$ suggests the formation of boron-phosphorus complexes.