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RESEARCH PRODUCT

Electronic structure of p-type ultraviolet-transparent conducting CuScO2 films

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Abstract We investigate the electronic structure of CuScO 2 thin films grown on sapphire and mica substrates by pulsed laser deposition. X-ray diffraction and microanalysis confirm that the films have the expected delafossite crystal structure and stoichiometric proportions. The electronic structure is investigated by means of X-ray and ultraviolet photoelectron spectroscopy. Electronic states in the range 0–1350 eV are identified, making reference to theoretical density-of-states calculations up to 80 eV. Photoelectron spectra near the Fermi energy confirm the p-character of the films. Optical absorption spectroscopy shows that the films are transparent up to 3.7 eV and exhibit an intense excitonic peak, with a direct gap energy of 4.24 ± 0.05 eV at room temperature. Ab initio band structure calculations confirm the direct character of CuScO 2 and allow for an assignment of the direct gap to an electronic transition at the L point of the rhombohedral Brillouin zone.