Title :
Influence of humidity on polycrystalline Cu(In,Ga)Se2 thin films for solar cells: a study of Na and H2O coadsorption
Author :
Heske, C. ; Richter, G. ; Chen, Zhonghui ; Fink, R. ; Umbach, E. ; Riedl, W. ; Karg, F.
Author_Institution :
Exp. Phys. II, Wurzburg Univ., Germany
Abstract :
Photoelectron spectroscopy (XPS, UPS) has been employed to study the influence of humidity on external and internal surfaces of RTP-processed polycrystalline Cu(In,Ga)Se2 thin films for solar cells. Various interactions of deliberately deposited or segregated Na with adsorbed H2O have been found. The Na content at the CIGS surface is changed by an H2O-induced segregation of Na at low temperatures (100 K) and by reaction and desorption at higher temperatures. Further reactions, such as the passivation of as-deposited “metallic” Na and the formation of a Na-O-CIGS complex influence the electronic structure (i.e. the workfunction and band bending) and are thus of great importance for the electrical performance of corresponding solar cells
Keywords :
X-ray photoelectron spectra; X-ray spectroscopy; adsorption; copper compounds; humidity; indium compounds; passivation; photoelectron spectroscopy; rapid thermal processing; sodium; solar cells; ternary semiconductors; water; work function; 100 K; Cu(InGa)Se2; H2O; H2O coadsorption; H2O-induced segregation; Na; Na coadsorption; Na content; Na-O-CIGS complex; band bending; electrical performance; electronic structure; external surfaces; humidity; internal surfaces; passivation; polycrystalline Cu(In,Ga)Se2 thin films; rapid thermal processing; solar cells; workfunction; Annealing; Glass; Humidity; Passivation; Photovoltaic cells; Solar energy; Sputtering; Substrates; Temperature; Transistors;
Conference_Titel :
Photovoltaic Specialists Conference, 1996., Conference Record of the Twenty Fifth IEEE
Conference_Location :
Washington, DC
Print_ISBN :
0-7803-3166-4
DOI :
10.1109/PVSC.1996.564264
