Applied Surface Science, Vol.288, 109-114, 2014
The influence of different locations of sputter guns on the morphological and structural properties of Cu-In-Ga precursors and Cu(ln,Ga)Se-2 thin films
The influence of two different locations of sputter guns on the morphological and structural properties of Cu-In-Ga precursors and Cu(In,Ga)Se-2 (CIGS) thin films was investigated. All the precursors contained cauliflower-like nodules, whereas smaller subnodules were observed on the background. All the precursors revealed apparent three-layered structures, and voids were observed at the CIGS/SLG interface of Sets 1 and 2 films rather than Set 3 film. EDS results indicated that all CIGS thin films were Cu-deficient. Based on the grazing incidence X-ray diffraction (GIXRD) patterns, as-selenized films showed peaks corresponding to the chalcopyrite-type CIGS structure. Depth-resolved Raman spectra showed the formation of a dominant CIGS phase inside the films for all the as-selenized samples investigated, and of an ordered vacancy compound (OVC) phase like Cu(In,Ga)(3)Se-5 or Cu(In,Ga)(2)Se-3.5 at the surface and/or CIGS/SLG interface region of Sets 2 and 3 films. No evidence was obtained on the presence of an OVC phase in Set 1 CIGS film, which may be speculated that long-time annealing is contributed to suppress the growth of OVC phases. The results of the present work suggest that the metallic precursors deposited with the upright-location sputter gun might be more appropriate to prepare CIGS thin films than those sputtered with the titled-location gun. (C) 2013 Elsevier B.V. All rights reserved.
Keywords:Tilted location;Upright location;Cu(In,Ga)Se-2 (CIGS);Raman spectra;Ordered vacancy compounds (OVC)