Deposition and characterization of 1D RuO2 nanocrystals by reactive sputtering

Well-aligned 1D RuO2 nanocrystals (NCs) have been grown on sapphire (SA)(1 0 0), SA(0 0 1) and LiNbO3 (LNO)(1 0 0) substrates via reactive magnetron sputtering using a Ru metal target. The surface morphology, structural and spectroscopic properties of the as-deposited NCs are characterized using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and micro-Raman spectroscopy (RS). FESEM micrographs show that NCs grown on SA(1 0 0)/LNO(1 0 0) are vertically aligned, while NCs grown on SA(0 0 1) show in-plane alignment with mosaic structure. The XRD results indicate that the NCs are (0 0 1) and (1 0 0) oriented on SA(1 0 0)/LNO(1 0 0) and SA(0 0 1) substrates, respectively. A strong substrate effect on the alignment of the RuO2 NCs deposition has been observed and the probable mechanism for the formation of these NCs has been discussed. The usefulness of the Raman spectroscopy as a structural characterization technique of NCs has been demonstrated.