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:H/ 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 H
₂
plasma composition and passivation quality of the aSi:H films has been investigated using optical emission spectroscopy and minority carrier lifetime. Increasing the H
₂
pressure to 2750 mT lead to an implied V
_oc
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 V
_oc
during deposition of the doped layers and metal contacts.