Structural peculiarities of CCSVT grown CuGaSe2 thin films

The microstructure of the CuGaSe2 CGSe thin films deposited by a novel chemical close spaced vapor transport CCSVT technique on clean and Mo coated soda lime glass SLG substrates has been investigated by transmission electron microscopy TEM . The CGSe bulk and the interface between the CGSe and Mo films have been investigated. The as grown CGSe films possess high bulk crystalline quality. At the CGSe Mo interface a MoSe2 interfacial layer 20 40 nm has been observed and also an excess of Ga. Additionally, composition measurements and depth profiling of the elements were performed by elastic recoil detection analysis ERDA . It has been found that the CGSe constituent elements are homogeneously distributed in the bulk, whereas the surface composition is influenced by the [Ga] [Cu] ratio in the film. With the [Ga] [Cu] ratio increase, the CGSe surface composition changes from Ga and Cu poor, and Se rich to Cu poor, and Ga and Se rich. Photoluminescence PL spectroscopy has been used as a complementary technique to study the defect profiles at the CGSe front and rear sides as a function of the [Ga] [Cu] ratio. The PL data support the results of structural investigations, pointing out higher Ga concentration at the films rear side. Keywords CuGaSe2; Microstructure; CCSVT; TEM; ERDA; P