CuGaO2 thin film synthesis using hydrogen-assisted pulsed laser deposition

Phase formation, crystallinity, and orientation of CuGaO2 thin films is reported in which hydrogen gas is utilized as a reducing reactant during growth to drive the valence state of Cu to +1. At relatively low growth temperatures, the films are a mixture of CuGaO2, Cu2O, and CuGa2O4. At higher temperatures, the majority phase is CuGaO2. The use of H-2 during film growth facilitated the formation of the delafossite phase. Phase purity is further improved via high temperature annealing. The formation of the delafossite phase via post-annealing treatment is in agreement with the thermodynamic equilibrium studies of the Cu-Ga-O system, showing that the CuGaO2 phase is thermodynamically stable under the conditions considered. With the post-annealing process, we achieved phase-pure CuGaO2 films with p-type resistivity on the order of 30 Omega cm and carrier density of mid-10(17) cm(-3).