Deposition temperature dependent properties of MOCVD grown polycrystalline CuGaSe2 thin films and solar cells

Metal organic vapour deposition (MOCVD) was employed to deposit polycrystalline CuGaSe₂ films and solar cells on glass. Deposition temperature was varied between 570°C and 450°C. Continuous CuGaSe₂ films were obtained at a deposition temperature of 450°C. Even at this low deposition temperatures the photoluminescence (PL) of the films is dominated by near band gap emission. Depending on the composition the PL spectra are dominated by different donor acceptor pair transitions. Solar cells are processed from these 400 nm thick films and the compositional dependence of the photovoltaic parameters is discussed, especially the increase of the open circuit voltage up to 821 mV under 100 mW/cm² AM1.5 with increasing Ga content