Highly efficient microcrystalline silicon solar cells deposited from a pure SiH_4 flow

摘要

A time-resolved optical emission spectroscopic study identified transient behavior of the excited SiH emission in a parallel plate SiH_4/H_2 plasma. The transient behavior could be prevented by filling the background gas with H_2 prior to plasma ignition. Applying this condition, state-of-the-art microcrystalline silicon (μc-Si:H) could be deposited irrespective of the applied H_2 flow, ultimately demonstrated by a 9.5% efficient solar cell deposited from pure SiH_4. The results are discussed in terms of SiH_4 back diffusion: an initial diffusion flux of SiH_4 from the reactor's dead volume back into the plasma.