Fabrication of β-AgGaO2 thin films by radio frequency magnetron sputtering

Thin films of β-AgGaO2, were fabricated on (0001)-Al2O3 substrates by radio frequency magnetron sputtering. β-AgGaO2 is a ternary oxide semiconductor possessing a wurtzite-derived β-NaFaO2-type structure. The effects of changing experimental parameters including sputtering atmosphere, pressure and substrate temperature were investigated. The effects of the sputtering conditions on the composition, phase, morphology and optical transmission of the films were determined. A highly crystalline β-AgGaO2 film was obtained by deposition at 200 °C under a 15% O2 atmosphere at a pressure of 0.5 Pa. This film was (001)-oriented, similar to wurtzite-type phases. The energy band gap of β-AgGaO2 was determined to be 2.2 eV from its photocurrent spectrum.