@misc{BaerKlaerWeinhardtetal., author = {B{\"a}r, Marcus and Klaer, Joachim and Weinhardt, Lothar and Wilks, Regan G. and Krause, Stefan and Blum, Monika and Yang, Wan Li and Heske, Clemens and Schock, Hans-Werner}, title = {Cu 2-x S Surface Phases and Their Impact on the Electronic Structure of CuInS 2 Thin Films - A Hidden Parameter in Solar Cell Optimization}, series = {Advanced Energy Materials}, volume = {3}, journal = {Advanced Energy Materials}, number = {6}, issn = {1614-6840}, pages = {777 -- 781}, abstract = {The surface properties of CuInS 2 (CIS) thin-fi lm solar cell absorbers are investigated by a combination of electron and soft X-ray spectroscopies. Spatially separated regions of varying colors are observed and identifi ed to be dominated by either CuS or Cu 2 S surface phases. After their removal by KCN etching, the samples cannot be distinguished by eye and the CIS surface is found to be Cu-defi cient in both regions. However, a signifi cantly more pronounced off-stoichiometry in the region initially covered by Cu 2 S can be identifi ed. In this region, the resulting surface band gap is also signifi cantly larger than the E g Surf of the initially CuS-terminated region. Such variations may represent a hidden parameter which, if overlooked, induces irreproducibility and thus prevents systematic optimization efforts.}, language = {en} }