Impact of Annealing on the Conductivity of Amorphous Carbon Films Incorporating Copper and Gold Nanoparticles Deposited by Pulsed Dual Cathodic Arc

Abstract

AbstractThe influence of annealing in argon at 300 °C on the conductivity, phase stability and electronic structure of hydrogen‐free amorphous carbon (a‐C) films containing copper (a‐C:Cu) and gold (a‐C:Au) nanoclusters was investigated. The motivation of this work is twofold: (1) to study the thermal stability of a‐C:Cu and a‐C:Au films and (2) to point out the relevance of X‐ray absorption near edge structure (XANES) technique to study the structural evolution of metal‐doped a‐C nanocomposites. The films were produced at room temperature using a selective‐bias pulsed dual‐cathode arc deposition technique. Compositional analysis was performed with secondary neutral mass spectroscopy whereas grazing incidence X‐ray diffraction (GIXRD) was used to monitor phase transformation and identify the dispersion or agglomeration of the crystallites within the carbon matrix. XANES spectra at the C‐K was used to investigate the effect of annealing in argon on the electronic structure of the a‐C matrix, while Cu K and Au L‐edges were investigated on a‐C:Cu and a‐C:Au samples, respectively, to study the nanocluster evolution. XANES showed that the a‐C host matrix increased its graphitic character and that stress was relieved upon annealing. No relevant changes were observed in the Au arrangements in a‐C:Au films. In the case of the a‐C:Cu samples, the Cu‐K XANES spectra indicated the formation of Cu2O crystals which correlated well with GIXRD spectra and the decrease in conductivity.