Modification of surface and interface of copper indium gallium selenide films with sulfurization

In this work, sulphur distribution in the surface, bulk of the copper indium gallium selenide (CIGS) thin films and CIGS/Mo interface after sulfurization was investigated. The morphology of surfaces and cross sections of thin films were observed by Scanning Electron Microscopy (SEM). X-Ray Diffraction (XRD), Raman spectra and X-Ray Photoelectron Spectroscopy (XPS) were used to study the phases, structures and chemical components of the thin films. After sulfurizaion, the grain size became larger and a sulphur-contained phase could be found in the XRD pattern. Interestingly, Raman and XPS indicated that the sulphur was not only rich in the surface but also in the CIGS/Mo interface. In addition, the chemical state of indium in the surface had also been modified by the annealing treatment. Those results help us to understand the complicated interface behaviour of CIGS solar cell and be benefit for the improvement of the devices.