Light-induced excess conductivity and the role of argon in the deposition of doping-modulated amorphous silicon superlattices

Abstract

Amorphous silicon pnpn ... structures that exhibit the phenomenon of light-induced excess conductivity (LEC) have been deposited in a single-chamber glow discharge deposition system by simple control of gas flows. This phenomenon is negligible when the doped silane is undiluted but clearly evident when the silane is diluted in argon. Experiments were performed in which argon dilution was only used for specific regions of the structure. The LEC effect was found to occur if argon dilution was used during the deposition of any fraction of the superlattice layers. These experiments rule out mechanisms requiring phosphorus-boron defect complexes or interface states.