Preparation of CuInSe 2 and CuInS 2 films by reactive annealing in H 2Se OR H 2S

Abstract

The conversion of CuIn films prepared by the electrodeposition of a CuIn alloy, by plating indium on copper or by the electron beam evaporation of CuIn (onto molybdenum or titanium substrates) into CuInSe 2 and CuInS 2 by annealing in flowing H 2Se or H 2S was studied. Compositional changes in the films during annealing (usually resulting in indium depletion) were found to occur and were ascribed to chemical vapour transport of In 2Se(S) away from the film. The resulting copper excess segregated to the surface of the films as Cu x Se(S) ( x = 1.6 – 1.7), leaving the bulk of the film as 5% – 10% copper-rich CuInSe(S) 2. This surface Cu x Se(S) could be dissolved by a short immersion in KCN solution, leaving a coherent, essentially pinhole-free layer of 5% – 10% copper-rich chalcopyrite CuInSe(S) 2. Longer immersion times, or anodization, in KCN caused increasing copper and selenium, and to a lesser extent sulphur depletion, allowing indium-rich films to be obtained.