Energy distribution of grain boundary traps in semi-insulating polycrystalline silicon films doped with oxygen

Abstract

The energy distribution of the grain boundary traps in semi-insulating polycrystalline silicon (SIPOS) films prepared by low pressure chemical vapor deposition (LPCVD) is determined for various oxygen contents taking account of the segregation effect of phosphorus. The energy distribution of the grain boundary traps is expressed as a Gaussian distribution. The surface trap density of the grain boundary and the energy band gap of the films increase with increasing oxygen content. Both peaks of the energy distribution of the donor- and acceptor-type traps are located at 0.49 eV over the valence band in case of poly-Si films, but moves toward the midgap as oxygen content increases in case of SIPOS films.