Phase relations in the ternary Cu–Ga–In system

The phase relations of the Cu–Ga–In system were investigated in a composition range which is relevant for the production of Cu(In,Ga)Se2 based thin film solar cells. The alloys Cu16(In1 − yGay)9, Cu9(Ga,In)4 and elemental In could be identified as the equilibrium phases of a ternary subsystem in the Cu–Ga–In phase diagram. The coexisting phases are well developed until 220 °C. In the case of Cu9Ga4 it is remarkable that the solubility of In in Cu9Ga4 highly increases with increasing temperature. Consequences for the selenization of metallic Cu–In–Ga precursors are discussed.