In-situ Raman spectroscopy and X-ray diffraction studies of the structural transformations leading to the SrCu2O2 phase from strontium–copper oxide thin films deposited by metalorganic chemical vapor deposition

SrCu2O2 (SCO) thin films were obtained by annealing strontium–copper oxide films grown on silicon substrate by metalorganic chemical vapor deposition. The phase transformations occurring in the films during different annealing conditions were studied by in-situ Raman spectroscopy and X-ray diffraction (XRD) combined with ex-situ XRD and Fourier Transformed Infrared Spectroscopy measurements. The first transformation was characterized by the decomposition of SrCO3 and CuO mainly into the Sr14Cu24O41 phase when the films were annealed in oxygen atmosphere. The transformation of this phase into the expected SCO phase was observed after subsequent annealing under Ar. In-situ studies revealed that the SCO phase is preserved at room temperature only when the film is cooled down very quickly.

► Metalorganic chemical vapor deposition of Sr–Cu–O (Cu/Sr = 2) precursor films.
► Transformation of Sr–Cu–O films into the SrCu2O2 phase by annealing.
► Formation of the SrCu2O2 phase by a two-step annealing process.
► A very fast cooling is crucial to stabilize the SrCu2O2 phase at room temperature.