Structures and characteristics of delafossite CuCr1-xO2 thin films prepared by pulsed laser deposition

Abstract

The effects of Cr-stoichiometry on the structural, electrical and optical properties of delafossite-type CuCrO2 thin films are reported. Thin films were grown by pulsed laser deposition on glass and c-sapphire single-crystal substrates, and the effects of increased temperature on the thin film properties were examined. The substrate temperature and oxygen partial pressure were found to be important processing parameters for fabricating delafossite thin films. The electrical properties of the thin films generally improved with increasing substrate temperature. The properties of the thin films depend on the crystallinity. The improvements in crystallinity and electrical conductivity were made by increasing the Cr-deficiency in the CuCr1-xO2 system. By optimising processing parameters, the electrical conductivity of a CuCr1-xO2 thin film was 8.30 S/cm (x = 0.00) and this increased with the introduction of Cr-deficiency to 21.03 S/cm (x = 0.03) with a mean optical transmittance of 60%. The bandgaps of the thin films ranged from approximately 3.00 to 3.22 eV.