Cu(InGa)Se2 thin film photovoltaic absorber formation by rapid thermal annealing of binary stacked precursors

Phase evolution during the synthesis of Cu(InGa)Se2 from glass/Mo/(In1-xGax)2Se3/CuSe bilayer precursors were investigated by in-situ high-temperature X-ray diffraction. With Se overpressure, CuSe was transformed to CuSe2 at 220 degree C. The CuSe2 phase returned to CuSe by releasing Se at its peritectic point of 330 degree C, where the formation of Cu(InGa)Se2 phase was initiated as well. Rapid thermal processing of bilayer precursors showed the potential of fast formation of Cu(InGa)Se2 within 2-5min reaction with fairly uniform Ga and In depth profile. Further annealing with Se overpressure caused the formation of MoSe2 at the interface of Mo and Cu(InGa)Se2.