Volatile Heterobimetallic Complexes from PdIIand CuIIβ-Diketonates: Structure, Magnetic Anisotropy, and Thermal Properties Related to the Chemical Vapor Deposition of Cu-Pd Thin Films

A novel approach for preparing volatile heterometallic complexes for use as precursors for the chemical vapor deposition of various materials is reported. New Cu¢Pd complexes based on b-diketonate units were prepared, and their structures and compositions were determined. [PdL2*CuL2] (1) and [PdL2*Cu(tmhd)2] (2) (L=2-methoxy-2,6,6-trimethylheptane-3,5-dionate; tmhd=2,2,6,6- tetramethylheptane-3,5-dionate) are 1D coordination polymers with alternating metal complexes, which are connected through weak interactions between the Cu atoms and the OCH3 groups from the ligand of the Pd complexes. The volatility and thermal stability were studied using thermogravimetric and differential thermal analyses and mass spectrometry. Compound 1 vaporizes without decomposition into monometallic complexes. It exhibits magnetic anisotropy, which was revealed from the angular variations in the EPR spectrum of a single crystal. The vapor thermolysis process for 1 was investigated using mass spectrometry, allowing the process to be framed within the temperature range of 200–3508C. The experimental data, supported by QTAIM calculations of the allowed intermolecular interactions, suggest that 1 likely exists in the gas phase as bimetallic molecules. Compound 1 proved to be suitable as a single-source precursor for the efficient preparation of Cu¢Pd alloy films with tunable Cu/Pd ratio. A possible mechanism for the film growth is proposed based on the reported data

MONITORING COMPOSITION AND STRUCTURE OF MOCVD ZrO2-BASED MULTICOMPONENT FILMS BY INNOVATIVE MIXED METAL-ORGANIC PRECURSORS

Three volatile mixed-metal precursors [ZrL4Pb(hfa)2] (1), [ZrL4PbL2] (2), and [ZrL4La(dpm)3] (3) (L = 2-methoxy-2,6,6-trimethyl-3,5-heptanedionate; dpm = 2,2,6,6-tetramethyl-3,5-heptanedionate; hfa = 1,1,1,5,5,5-hexafluore-2,4-pentanedionate) are used to prepare ZrO2-based multicomponent films by metalorganic chemical vapor deposition (MOCVD). The deposition experiments are carried out in a hot-wall reactor at 600-750 °C on silicon substrates under 20 Torr in the presence of oxygen. According to X-ray powder diffraction, the main crystal phases in the films prepared from precursors 1 and 2 are solid solutions based on tetragonal and cubic ZrO2. Lead does not form separate crystal phases but is dissolved in the oxide form within the ZrO2 matrix, as is indicated by X-ray photoelectron spectroscopy data. La2Zr2O7 films are prepared from 3 using two ways of precursor supply: evaporation in argon and by direct liquid injection (DLI). It is shown that the composition and structure of obtained films are determined by the precursor composition. The results obtained for thermal behavior of precursors in condensed and gas phases are discussed

In- and out-plane transport properties of chemical vapor deposited TiO2 anatase films

Due to their polymorphism, TiO2 films are quintessential components of state-of-the-art functional materials and devices for various applications from dynamic random access memory to solar water splitting. However, contrary to other semiconductors/dielectric materials, the relationship between structural/morphological and electrical properties at the nano and microscales remains unclear. In this context, the morphological characteristics of TiO2 films obtained by metal–organic chemical vapor deposition (MOCVD) and plasma-enhanced chemical vapor deposition (PECVD), the latter including nitrogen doping, are investigated and they are linked to their in- and out-plane electrical properties. A transition from dense to tree-like columnar morphology is observed for the MOCVD films with increasing deposition temperature. It results in the decrease in grain size and the increase in porosity and disorder, and subsequently, it leads to the decrease in lateral carrier mobility. The increase in nitrogen amount in the PECVD films enhances the disorder in their pillar-like columnar morphology along with a slight increase in density. A similar behavior is observed for the out-plane current between the low temperature MOCVD films and the undoped PECVD ones. The pillar-like structure of the latter presents a lower in-plane resistivity than the low temperature MOCVD films, whereas the out-plane resistivity is lower. The tree-like columnar structure exhibits poor in- and out-plane conductivity properties, whereas pillar-like and dense TiO2 exhibits similar in- and out-plane conductivities even if their morphologies are noticeably different

Chemical vapor deposition of pyrolytic carbon on polished substrates

Pyrolytic carbon thin (4-100 nm) films were obtained from méthane in a hot wall reactor on optically polished inert substrates by varying the déposition time and temperature. They were characterized by all modes of TEM. They are composed in majority of lamellar pyrocarbon whose thickness and disorder increases with increasing temperature. Isotropic carbon islands are also observed at the upper surface of the film

Growth mechanisms of MOCVD processed Ni thin films

The main gaseous by-products during the processing of nickel films by MOCVD from nickelocene have been analyzed by on-line mass spectrometry. The evolution of relative concentration of CH4, C5H6, and C5H10 with time, pressure, temperature, and hydrogen flow has been quantified and related with the characteristics, mainly carbon content, of the Ni films. The obtained results allowed to investigate the dissociation of nickelocene leading to the growth of Ni films. Two possibilities are proposed to prevail : Either the metal-ligand bond is dissociated, and the ligand is hydrogenated and desorbed, or the ligand itself is decomposed on the surface leading to the incorporation of carbon in the deposits. The process is controled by a Langmuir-Hinshelwood mechanism based on a competitive coverage of the surface by nickelocene or hydrogen atoms

Chemical Vapour Deposition processes of metallic amorphous or nanocrystalline thin films

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Spouted bed metallorganic chemical vapor deposition of ruthenium on NiCoCrAlYTa powders

This paper reports on the spouted bed metallorganic chemical vapor deposition (SBMOCVD) of ruthenium on NiCoCrAlYTa commercial powders. The aim is to propose an economic, versatile and time saving process for the screening of the doping by platinum group elements of thermal barrier coatings applied on gas turbine engine blades, in order to improve their oxidation and corrosion resistance. Information on the spouting of the NiCoCrAlYTa powders and on the SBMOCVD reactor is provided in the first part of the paper. Following, two deposition routes for the CVD of ruthenium starting form ruthenocene are described. The first implies high temperature reaction with hydrogen and yields crystalline Ru nanoparticles on the surface of the powders. The second is a low temperature reaction with oxygen. It yields ruthenium oxide which in turn is reduced in situ to yield amorphous Ru. Both processes lead to uniform doping of the powders