Effect of post-annealing on the properties of copper oxide thin films obtained from the oxidation of evaporated metallic copper

Vitor Figueiredo, Elangovan Elamurugu, Gonçalo Gonçalves, Pedro Miguel Cândido Barquinha, Luis Miguel Nunes Pereira, N. Franco, Eduardo Alves, Rodrigo Ferrão de Paiva Martins, E. Fortunato

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193 Citations (Scopus)

Abstract

Thin films of copper oxide were obtained through thermal oxidation (100-450 degrees C) of evaporated metallic copper (Cu) films on glass substrates. The X-ray diffraction (XRD) studies confirmed the cubic Cu phase of the as-deposited films. The films annealed at 100 degrees C showed mixed Cu-Cu(2)O phase, whereas those annealed between 200 and 300 degrees C showed a single cubic Cu(2)O phase. A single monoclinic CuO phase was obtained from the films annealed between 350 and 450 degrees C. The positive sign of the Hall coefficient confirmed the p-type conductivity in the films with Cu(2)O phase. However, a relatively poor crystallinity of these films limited the p-type characteristics. The films with Cu and CuO phases show n-type conductivity. The surface of the as-deposited is smooth (RMS roughness of 1.47 nm) and comprised of uniformly distributed grains (AFM and SEM analysis). The post-annealing is found to be effective on the distribution of grains and their sizes. The poor transmittance of the as-deposited films (<1%) is increased to a maximum of similar to 80% (800 nm) on annealing at 200 degrees C. The direct allowed band gap is varied between 2.03 and 3.02 eV.
Original languageEnglish
Pages (from-to)3949-3954
Number of pages6
JournalApplied Surface Science
Volume254
Issue number13
DOIs
Publication statusPublished - 30 Apr 2008

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