Enhanced transparent conducting performance of Bi₂Sr₂Co₂O₈ thin films by adding gold nanoparticles

Gold (Au) nanoparticles were introduced into thin films of layered cobaltites to decrease the sheet resistance and improve the transparent conducting performance of the films. c-axis-oriented Bi₂Sr₂Co₂O₈ thin films dispersed with Au particles with diameters of about 5–10 nm were obtained by pulsed laser ablation of a Bi₂Sr₂Co₂O₈ ceramic target on which a piece of fan-shaped Au foil was attached. The resulting Bi₂Sr₂Co₂O₈/Au composite thin films, with the Au concentration of about 1.6 at.%, showed a very low resistivity of about 3.0 mΩ cm at room temperature and a reasonable optical transmittance of about 48 % in the visible range, resulting in a high figure of merit of about 2270 MΩ⁻¹. This value is comparable to those reported for the state-of-the-art p-type transparent conducting oxides and is about 1.7-fold higher than that of the pure Bi₂Sr₂Co₂O₈ thin films.