Bär, M.; Schubert, B.-A.; Marsen, B.; Krause, S.; Pookpanratana, S.; Unold, T.; Weinhardt, L.; Heske, C.; Schock, H.-W.: Native oxidation and Cu-poor surface structure of thin film Cu2ZnSnS4 solar cell absorbers. Applied Physics Letters 99 (2011), p. 112103/1-3
10.1063/1.3637574
Abstract:
Air-exposed Cu2ZnSnS4 (“CZTS”) thin-film solar cell absorbers have been investigated by surface-sensitive x-ray photoelectron and x-ray-excited Auger electron spectroscopy, as well as by bulk-sensitive energy dispersive x-ray spectroscopy. We find a native surface oxidation of (mainly) tin, but also (to a lesser extent) of zinc and sulfur. Comparing the bulk and surface composition of clean CZTS absorbers, we find evidence for a Cu-poor region at the surface of the absorber, best described by a Cu-free Zn-Sn-S surface layer.