Preparation of CIGS thin films by HiPIMS or DC sputtering and various selenization processes

CuIn1-xGaxSe2 (CIGS) thin films were prepared by the sputtering of metallic precursors Cu, In, Ga in HiPIMS (High Power Impulse Magnetron Sputtering) or DC magnetron and subsequently selenized in an atmosphere of pure Se or Ar+Se. The average absorbed power and discharge current were the same in the HiPIMS and DC plasma. The basic aim of this work was to compare the structural properties of the CIGS films as a function of magnetron excitation mode and selenization thermal treatment conditions. Film characteristics were measured using X-ray diffraction, scanning electron microscopy, Raman spectroscopy, energy-dispersive X-ray spectroscopy and other techniques. All the CIGS films revealed the chalcopyrite crystal structure with a preferential (112) orientation. Only a very small influence of magnetron excitation mode on thin film properties was observed. On the other hand, selenization in Ar+Se atmosphere led to bigger grain size, better crystallinity and a significantly higher level of Ga substitution.