Influence of Deposition Parameters of Sputtered ITO/Ag Back Contacts on the Performance of a-Si:H / μc-Si:H Solar Cells

• DOI: 10.4229/27theupvsec2012-3dv.2.48
• Publication Date: 2012-10-26
• Authors: Janez Kovač; Miroslav Mikolášek; G. Schöpe; Andreas Bauer; Uta Gerhards; Etienne Moulin; U. Zastrow; J. Hüpkes; Ivan Hotový
• Keywords: Deposition

Magnetron-sputtered ITO/Ag back contacts were deposited on amorphous/microcrystalline silicon (a-Si:H/μc-Si:H) tandem junction solar cells in superstrate configuration and concurrently also on Corning glass substrates. The investigations were focused on identifying the influence of the deposition parameters of sputtered ITO layers on performance of a-Si:H/μc-Si:H solar cells. The ITO sputtering process was varied in terms of oxygen concentration in the sputtering gas and total gas pressure, while sufficient conductivity of ITO layers for application as back contacts was ensured. JV characterization of fabricated cells was performed both in the dark and under AM1.5 illumination. The external quantum efficiency of the solar cells as well as their absorption was measured. Electrical and optical properties of ITO layers deposited on Corning glass were characterized, too. Major influence of deposition process of ITO layers on electrical performance of solar cells due to increase of oxygen concentration has been revealed. Decline of FF and Voc and increase in dark current saturation density indicate deteriorated interface between bottom n-layer and the ITO layer or of the n-layer itself. On the other hand, there is no indication that severe plasma-related damage limits electrical cell performance of the cells deposited with varied total gas pressure.<br/>27th European Photovoltaic Solar Energy Conference and Exhibition; 2701-2705<br/>