Reactive magnetron sputtering of CuInS2 solar cells the influence of the deposition conditions on structural and electronic properties and solar cell efficiency

CuInS2 thin films have been prepared by reactive magnetron sputtering from metallic copper and indium targets in an argon hydrogen sulfide atmosphere Ar H2S . The influence of the total sputtering pressure in the range from 0.5 to 2 Pa, the Cu to In ratio 0.9 to 2.3 and the substrate temperature in the range from 350 to 500 C were investigated. For substrate temperatures higher than 450 C the films consist of the chalcopyrite phase of CuInS2, while at lower temperatures also the CuAu type ordered phase of copper indium disulfide can be obseved by XRD and Raman spectroscopy. Solar cells prepared from the best CuInS2 absorber films showed efficiencies higher than 10 , a value, which is comparable to the best cells prepared by the sequential process, i.e. by sulfurization of Cu In sandwich films. This result is promising for a prospective large scale magnetron sputter deposition process for the complete solar cell