Hydrogen Plasma Post-Deposition Treatment for Passivation of a-Si/c-Si Interface for Heterojunction Solar Cell by Correlating Optical Emission Spectroscopy and Minority Carrier Lifetime

Excellent passivation at the a-Si:HI c-Si interface is required for high efficiency heterojunction solar cells. Hydrogen plasma treatment after the a-Si deposition has been considered as an effective and manufacturable method to saturate the surface dangling bonds. In this paper the correlation between H2 plasma composition and passivation quality of the a-Si:H films has been investigated using optical emission spectroscopy and minority carrier lifetime. Increasing the H2 pressure to 2750 mT lead to an implied Voc of 739 mV and effective lifetime >1900 μs, which were 13 mV and 300 μs, respectively, greater than the baseline. Cells with efficiency > 18% were fabricated. Comparison of implied JV curves indicates significant loss in Voc during deposition of the doped layers and metal contacts.