Cluster-eliminating filter for depositing cluster-free a-Si:H films by plasma chemical vapor deposition

A cluster-eliminating filter is developed to reduce a volume fraction VF of amorphous silicon nanoparticles above approximately 1 nm in size (referred to as a cluster) incorporated into a-Si:H films. The filter reduces the VF value by using the difference between a sticking probability of clusters and a surface reaction probability of SiH3 radicals, which are the predominant deposition radicals. By employing the filter together with a cluster-suppressed plasma chemical vapor deposition reactor, the VF value is reduced below 1180 compared to that for the conventional device quality films. Such cluster-free a-Si:H films have an extremely small hydrogen concentration associated with Si- H2 bonds below 5.46× 10-3 at. %.