Abstract
This study determines phase equilibria of the Cu-In-Se system. The liquidus projection of the Cu-In-Se system is experimentally determined and the InSe-CuSe isoplethal section is assessed. Ternary Cu-In-Se alloys are prepared. Their microstructures are metallographically examined, and their primary solidification phases are determined. The Cu-In-Se ternary system has 15 primary solidification phases: Cu, β2-Cu4In, γ-Cu9In4, η-Cu2In, Cu11In9, In, In4Se3, InSe, In6Se7, In2Se3, Se, CuSe2, CuSe, β1-Cu2Se and CuInSe2. A very unusual feature of the Cu-In-Se liquidus projection is its large miscibility gap extending from the Cu-Se side to the In-Se side. The InSe-CuSe isoplethal section cuts through the CuInSe2 ternary compound which is of high photovoltaic application interests. Differential thermal analysis is used to determine the liquidus temperatures along the InSe-CuSe isoplethal section and the invariant reactions in the Cu-In-Se liquidus projection. The phase boundaries of the InSe-CuSe isoplethal section are modified based on the determined Cu-In-Se liquidus projection