Abstract
Silicon heterojunction solar cells have high open-circuit voltages thanks to excellent passivation of the wafer surfaces by thin intrinsic amorphous silicon (a-Si:H) layers deposited by plasma-enhanced chemical vapor deposition. We show a dramatic improvement in passivation when H-2 plasma treatments are used during film deposition. Although the bulk of the a-Si:H layers is slightly more disordered after H-2 treatment, the hydrogenation of the wafer/film interface is nevertheless improved with as-deposited layers. Employing H-2 treatments, 4 cm(2) heterojunction solar cells were produced with industry-compatible processes, yielding open-circuit voltages up to 725 mV and aperture area efficiencies up to 21%. (C) 2011 American Institute of Physics. [doi:10.1063/1.3641899]