EFFICIENT DEFECT PASSIVATION BY HOT-WIRE HYDROGENATION

Atomic hydrogen, produced at a hot wire, passivates bulk defects in po lycrystalline silicon without damaging surface regions. Solar cells fr om such polycrystalline silicon respond much more favorably to hot-wir e hydrogenation than to low-energy ion implantation or a direct-curren t plasma treatment. Hot-wire passivation yields a hydrogen concentrati on close to the surface of 8X10(19) cm(-3) and improves the minority c arrier diffusion length of solar cells by up to 100%. Implantation as well as conventional plasma treatment result in lower hydrogen concent ration and, consequently, in much smaller improvements of diffusion le ngths. (C) 1997 American Institute of Physics.