Cluster Incorporation into A-Si:H Films Deposited Using H$_{2}$+SiH$_{4}$ Discharge Plasmas

Light-induced degradation is the most important issue for hydrogenated amorphous silicon (a-Si:H) solar cells. Our previous results have suggested that incorporation of clusters into films is responsible for the light-induced degradation. Therefore, it is important to control the incorporation of clusters. Recently, we have developed multi-hollow discharge plasma CVD method, by which clusters are driven toward the downstream region and high quality a-Si:H films can be deposited in the upstream region [1]. Here, we report effects of H$_{2}$ dilution on cluster incorporation. Cluster size was measured by TEM, and the incorporation amount of clusters was measured with quartz crystal microbalances [2]. H$_{2}$ dilution leads to smaller clusters and the cluster incorporation in the upstream region increases with H$_{2}$ dilution because the diffusion velocity of such small clusters much surpasses gas flow velocity.\\[4pt] [1] K. Koga, et. al., Jpn. J. Appl. Phys. \textbf{44} (2005) L1430.\\[0pt] [2] Y. Kim, et. al., Jpn. J. Appl. Phys. \textbf{52} (2013) 01AD01.