Phase evolution of CIGS alloyed compound synthesis by direct melting method

The phase evolution of a CIGS alloyed compound synthesized by a direct melting method was investigated. The phase evolution and chemical composition were analyzed by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) measurements. Differential thermal and thermogravimetry analysis (DT/TGA) was performed on the mixed elements to clarify the types of reactions involved. A stoichiometric mixture of the element (purity: 99.99%) was sealed under vacuum in a quartz ampoule to prevent selenium loss. During heating at high temperatures, the elements reacted to form a compounds and a self mixing process occurred, to produce a stoichiometric composition. Selenium reacted preferentially with copper, indium and gallium to form CuSe, In2Se3 and GaSe at low temperatures. As the temperature was increased, ternary CuInSe2 and the initiation of quaternary CuGa0.3In0.7Se2 began to form due to a reaction between binary phases with selenium. Upon heating to 1200 °C for 10 h a quaternary CIGS compound formed with a single-phase chalcopyrite structure and a (112) preferential orientation.