and Metallurgy in Krakow, Poland, has recently published the latest results from its study of the manufacturing of CuInSe 2 (CIS) thin films by selenization of Cu-In alloy precursors in a graphite container.
The copper-indium alloy was formed by magnetron sputtering of Cu/In multilayers. By sequential deposition of Cu and In, a 20 alternate layer structure with total thickness varying from 250 to 500 nm was obtained; the Cu/In ratio was altered by adjusting the layer deposition time.
The phases obtained by X-ray diffraction (XRD) for metallic precursor films were identified as Cu 2 In, CuIn, Cu 11 In 9 or CuIn 2 . To produce CuInSe 2 the alloys were annealed with elemental selenium between 400 and 500Β°C by adopting the two-step temperature profile. The selenized films were characterized using XRD to identify the phases and scanning electron microscopy to observe the surface morphology.
The chalcogenization process parameters, mainly heating temperature, time and Se pressure, significantly influence the properties of obtained CIS films. Heat treatment of Cu-In multilayers deposited by sputtering produces alloys with stable phases influenced mainly by the Cu/In ratio. The alloys are good precursors for CuInSe 2 formation by selenization, except from very Cuor In-rich samples. Selenization conducted in a partially closed graphite container with excess elemental Se allows for fabrication of good quality, well-crystallized films. SEM images of the film surface for chalcogenized sample confirm the conclusions drawn from XRD measurements. Between the crystallites of CuSe on the surface of the film, the crystallites of CuInSe 2 phase (holes) can be seen. This is also confirmed by elemental composition measurements. The good crystallinity of the CuInSe 2 phase can be associated with the increased Se vapor pressure that results from the construction of a graphite box. T. Pisarkiewicz and H. Jankowski: Vacuum 70(2/3) 435-438 (10 March 2003).