A nuclear magnetic resonance study of phosphorus-doped polycrystalline silicon

Abstract

We report the results of a phosphorus-31 and silicon-29 nuclear magnetic resonance spectroscopy study. Amorphous silicon thin films were deposited by plasma-enhanced chemical vapor deposition with one percent phosphine in silane. The films were subsequently annealed at 700 and 800 °C to produce a fine-grained polycrystalline material with the majority of phosphorus atoms segregated at grain boundaries. The chemical shift of the phosphorus spectra indicates that the phosphorus nuclei are fourfold coordinated at the grain boundaries. Results of spin-echo experiments show that phosphorus atoms segregated to grain boundaries reside in at least three regions of differing phosphorus density. Silicon-29 data show a large dispersion of chemical shifts characteristic of disordered materials.