Non-destructive optical analysis of band gap profile, crystalline phase, and grain size for Cu(In,Ga)Se2 solar cells deposited by 1-stage, 2-stage, and 3-stage co-evaporation
Article first published online: 4 FEB 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Progress in Photovoltaics: Research and Applications
How to Cite
Ranjan, V., Begou, T., Little, S., Collins, R. W. and Marsillac, S. (2013), Non-destructive optical analysis of band gap profile, crystalline phase, and grain size for Cu(In,Ga)Se2 solar cells deposited by 1-stage, 2-stage, and 3-stage co-evaporation. Prog. Photovolt: Res. Appl.. doi: 10.1002/pip.2350
- Article first published online: 4 FEB 2013
- Manuscript Accepted: 17 OCT 2012
- Manuscript Revised: 31 AUG 2012
- Manuscript Received: 20 JUN 2012
- Department of Energy. Grant Number: DE-EE0005400
- Cu(In,Ga)Se2 (CIGS);
- thin film solar cells;
- optical properties;
Cu(In,Ga)Se2 (CIGS) thin films co-evaporated by 1-stage, 2-stage, and 3-stage processes have been studied by spectroscopic ellipsometry (SE). The disappearance of a Cu2-xSe optical signature, detected by real time SE during multistage CIGS, has enabled precise endpoint control. Band gap energies determined by SE as depth averages show little process variation for fixed [Ga]/([In] + [Ga]) atomic ratio, whereas their broadening parameters decrease with increasing number of stages, identifying successive grain size enhancements. Refined SE analysis has revealed band gap profiling only for 3-stage CIGS. Solar cells incorporating these absorbers have yielded increased efficiencies in correlation with phase control, grain size, and band gap profiling. Copyright © 2013 John Wiley & Sons, Ltd.