Phase identification and AES depth profile analysis of Cu(In,Ga)Se2 thin films

Abstract

This work presents results related with phase identification and study of the homogeneity in the chemical composition of Cu(In,Ga)Se 2 (CIGS) thin films grown by a chemical reaction of the precursor species evaporated sequentially on a soda-lime glass substrate, in a two or three-stage process. For that, the CIGS samples were characterized through X-ray diffraction (XRD) and Auger Electron Spectroscopy (AES) depth profile measurements, respectively. The presence of secondary phases growing superficially was identified through small angle XRD measurements. Theoretical simulation of the XRD spectra, carried out with the help of the PowderCell package, confirmed this result. The results showed that the deposition conditions affect the homogeneity of the chemical composition of the CIGS films, as well as the phase in which these films grow. In general, the samples grown in a two stage process present a mixture of the Cu(In,Ga)Se 2 phase with the secondary In 2 Se 3 and Cu 2 Se phases, whereas, the films grown in a three stage process do it, mainly, in the Cu(In,Ga)Se 2 phase with a tetragonal (chalcopyrite type) structure and better homogeneity. CIGS films with characteristics like those found for the three stage samples, have demonstrated good properties for its use as absorber layers in thin film solar cells.

Structure evolution in CIGS deposition: An X-ray diffraction analysis with Rietveld whole-pattern refinement

“…processes where the In and Ga are evaporated first and the Cu is turned on and off at different while the substrate temperature is ( Figure 1) has become especially widely used, since it has been shown to lead to enhanced efficiency in laboratory samples [3]. However, a stage process may introduce gradations into a film and ay require multiple diffusion processes to achieve a uniform…”

Self-Assembled Hierarchical Nanostructures Composed of Novel Chalcopyrite Nanosheets for Photovoltaic Properties

“…This achievement may allow the fabrication of CIGS this is more suitable to be used in pilot production lines for large area PV modules. 11 Nevertheless, the implementation of this technique still poses an array of challenges in terms of satisfying the requirements of low cost and high "throughput" for commercialization of CIGS modules. For instance, PVD techniques require high vacuum and thermal requirements making them expensive and inhibit scalability.…”