STUDY OF THE SELENIUM INCORPORATION IN SPUTTERED CU, IN ALLOYS

Thin CuInSe2 films have been prepared in a two stage process by sputtering on Mo/glass substrates alternate Cu, In layers followed by selenization by vacuum evaporation. The compostional and the structural analysis of the compounds has been carried out by EDS and XRD, respectively. Selenium incorporated in the ternary compound assumes a constant value around 48% (at/at) while the Cu/In ratio ranges between 0.8 and 1.2. As the copper content is further lowered, selenium decisively increases up to almost 51% when Cu/In is 0.6. The inversion point in the Se-Cu/In diagram has been correlated to the formation of a secondary phase identified as the chalcopyrite vacancy-variant compound CuIn3Se5 (OVC). The results are independent on the type of metallic precursors and on their preparation conditions.