Open this publication in new window or tab >>Show others...
2012 (English)In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 20, no 3, p. 284-293Article in journal (Refereed) Published
Abstract [en]
We use secondary-ion mass spectrometry, X-ray diffraction and scanning electron microscopy to investigate the development over time of compositional gradients in Cu(In,Ga)Se2 thin films grown in three-stage co-evaporation processes and suggest a comprehensive model for the formation of the well-known ‘notch’ structure. The model takes into account the need for compensating Cu diffusion by movement of group-III ions in order to remain on the quasi-binary tie line and indicates that the mobilities of In and Ga ions differ. Cu diffuses towards the back in the second stage and towards the front in the third, and this is the driving force for the movement of In and Ga. The [Ga]/[In + Ga] ratio then increases in the direction of the respective Cu movement because In has a higher mobility at process conditions than has Ga. Interdiffusion of In and Ga can be considerable in the (In,Ga)2Se3 film of the first stage, but seems largely to cease in Cu(In,Ga)Se2 and shows no signs of being boosted by the presence of a Cu2Se layer.
Place, publisher, year, edition, pages
John Wiley & Sons, 2012
Keywords
CIGS, three‐stage process, gradient, SIMS
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-151408 (URN)10.1002/pip.1134 (DOI)000302946900005 ()
2011-04-112011-04-112017-12-11Bibliographically approved