“…Under many conditions, HWCVD results in low-temperature epitaxy of silicon on c-Si substrates [4] at temperatures as low as 195 -C. In high-efficiency heterojunction solar cells, a thin (¨5 nm) intrinsic a-Si:H layer must be interposed between the base wafer and the heavily doped a-Si:H emitter [5], because intrinsic a-Si:H has a far lower density of defects than a doped a-Si:H layer [6]. A lower density of mid-gap trap states reduces the trap-assisted inter-band tunneling-recombination rate across the a-Si/c-Si interface, thereby suppressing deleterious saturation current.…”