Regensburg 2013 – scientific programme

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DS: Fachverband Dünne Schichten

DS 32: Poster Session IV: Atomic layer deposition; Organic thin films; Organic Electronics and Phototovoltaics; Organic Materials for Spintronics - from spinterface to devices; Thin film photovoltaic materials and solar cells

DS 32.52: Poster

Thursday, March 14, 2013, 17:00–20:00, Poster B2

Plasma induced nitrogen incorporation in CdTe-layers for solar cell applications — •Martin Salge, Claudia Schnitter, Christoph Heisler, Christian Kraft, and Werner Wesch — Friedrich-Schiller-Universität Jena, Institut für Festkörperphysik, Helmholtzweg 3, 07743 Jena, Germany

CdTe is a promising absorber material for solar cells considering its direct band gap of 1.5 eV. CdTe solar cells feature low production costs per watt and reach efficiencies of about 17 % on a laboratory scale. The intrinsic p-type doping level of CdTe used for solar cell application is typically 10¹⁴ cm⁻³. However, the efficiency can be increased further by raising the doping level by several orders of magnitude [1]. Using group-V-elements as a dopant on tellurium lattice sites is one possibility to achieve an increase in carrier concentration. Thereby, nitrogen is a promising material because in CdTe it creates doping energy levels within the band gap close to the valence band edge. In this experiment nitrogen ions were incorporated by a plasma source simultaneously to the physical vapor deposition of the CdTe-layer. Several source parameters during the absorber deposition were varied and their effects on the solar cell characteristics were studied. It was found that the solar cell characteristics and the p-type doping of CdTe absorber layers decrease significantly with increasing acceleration voltage of the N-ions. Possible reasons for that are under investigation.
[1] Sites, J. R. und J. Pan, Thin Solid Films, 515:6099, 2007