Abstract. Chemical deposition methods like MOD and MOCVD are promising approaches for coated conductors (CCs) due to their reduced cost and easy scaling.High quality La2Zr2O7 (LZO) buffer layers were prepared by MOD on Ni-5%at.W (NiW) RABiTS and subsequent YBCO layers (450 to 800 nm thick) were deposited by pulsed injection MOCVD, leading to a simple low cost architecture NiWRABiTS/LZOMOD/YBCOMOCVD. In this novel combination of MOD and MOCVD approach, a single LZOMOD buffer layer is sufficient to ensure structural compatibility between YBCO and NiW, and protect the substrate from oxidation during YBCO MOCVD. YBCO films were epitaxially grown on LZO and exhibited critical current densities Jc close to 1 MA/cm2 at 77 K with a critical temperature Tc = 91 K and ∆Tc < 1 K.

Cobalt oxide films were grown by pulsed liquid injection MOCVD using Co(thd) 2 dissolved in monoglyme as the precursor. The structure, morphology, and growth rate of the layers deposited on silicon substrates were studied as a function of solution concentration, deposition temperature, and oxygen partial pressure. X-ray diffraction (XRD) of films deposited from 350 C to 540 C showed a pure Co 3 O 4 spinel structure and no CoO was detected, even at the lowest oxygen pressure. X-ray photoelectron spectroscopy (XPS) was used to study the surface composition and oxidation states. Surprisingly, XPS spectra recorded for most of the films seemed to correspond to CoO. This unexpected oxidation state on the surface was assigned to the effect of the high density of edges and corners present in the surface morphology.

International audienceX-ray diffraction (XRD) and Raman spectroscopy were used to investigate stress dependence on thickness in PbTiO3 (PTO) films grown by pulsed liquid injection Metalorganic Chemical Vapor Deposition on a LaAlO3 (001) substrate (LAO). Films on sapphire substrate (R-plane) were used as polycrystalline film reference. Epitaxial PTO films with a dominant c-domain structure are grown on LAO substrate whereas films on sapphire are polycrystalline. A detailed investigation of the PTO/LAO film microstructure by XRD gives evidence of PTO twinning. Both techniques reveal that PTO films are under tensile in-plane stresses. The study of the film thickness dependence of microstrains, grain size, volume fraction of a-domains as well as surface morphology of PTO/LAO films indicates that these parameters are clearly correlated. A change in the relaxation mechanism between 65 and 125 nm of film thickness has been evidenced. A c parameter gradient occurs throughout the film depth; it originates in stress relaxation due to a thickness increase. Raman spectra of PTO films allowed in-plane residual stress values to be estimated from the Raman shifts and are in good agreement with those determined by XRD. Both techniques also indicate that thinner films are more stressed and residual stresses are partially relaxed with increasing thickness. Moreover, a-domains are more stressed than c-domains. The two components of the large A1(2TO) and A1(3TO) Raman modes have been associated with a- and c-domains and their intensity ratio clearly correlated with the volume fraction of a-domains

No abstract

No abstract