Another route to fabricate single-phase chalcogenides by post-selenization of Cu–In–Ga precursors sputter deposited from a single ternary target

Single-layered precursors comprising In and Cu11(In,Ga)9 were fabricated by one-step sputtering of a Cu–In–Ga ternary target, subsequently covered by an evaporated Se layer as the source of post-selenization, involving low-temperature (100 °C) homogenization and high-temperature (⩾450 °C) chalcogenization treatments. Initially it appears that the post-selenization process is inappropriate to fabricate device-quality CIGS absorber layers because the composite precursor is converted into (In,Ga)2Se3 and Cu3Se2 with segregated phases and roughened topography. However, adequately controlling the processing steps leads to a fully microstructure-homogenized precursor, offering a new route and chemical reaction process to fabricate Cu(In,Ga)Se (CIGS) absorber layer with sounding crystallinity.