Descoeudres, A.Barraud, L.De Wolf, S.Strahm, B.Lachenal, D.Guérin, C.Holman, Z. C.Zicarelli, F.Demaurex, B.Seif, J.Holovsky, J.Ballif, C.2011-10-242011-10-242011-10-24201110.1063/1.3641899https://infoscience.epfl.ch/handle/20.500.14299/71873WOS:000295853500075Silicon 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 H2 plasma treatments are used during film deposition. Although the bulk of the a-Si:H layers is slightly more disordered after H2 treatment, the hydrogenation of the wafer/film interface is nevertheless improved with as-deposited layers. Employing H2 treatments, 4 cm2 heterojunction solar cells were produced with industry-compatible processes, yielding open-circuit voltages up to 725 mV and aperture area efficiencies up to 21. © 2011 American Institute of Physics.Amorphous-SiliconSolar-CellsSpectroscopic Ellipsometrytext::journal::journal article::research article