Optical and structural properties of single phase epitaxial p-type transparent oxide thin films

The growth of single-crystal like epitaxial CuAlO₂ thin films on c-plane sapphire substrate by a polymer-assisted deposition (PAD) was described. The appearance of only diffraction peaks indicated that the film was preferentially oriented along the c-axis perpendicular to the substrate phase. The in-plane orientation between the film and the substrate was determined by XRD φ-scans from Al₂O₃ and CuAlO₂ respectively. The fundamental absorption, which corresponds to the electron excitation from the valance band to the conduction band, was used to determine the optical bandgap of semiconductor materials. Results show that the CuAlO ₂ films are highly resistive with room-temperature resistivity around 10⁵ Ωcm. The film is dense and uniform with no detectable microcracks.