Multifunctional Manganese Single Source Precursor for the Selective Deposition of MnF2 or Mn3O4

AbstractA novel Mn(II) precursor, the Mn(hfa)2●tmeda, was successfully applied to the deposition of manganese containing nanostructures in Metal Organic Chemical Vapor Deposition (MOCVD) processes at atmospheric and reduced pressure. Experimental data evidenced that different phases were obtained, selectively and reproducibly, on varying the operating pressure. Manganese difluoride (MnF2) nanorod assemblies were obtained under atmospheric pressure, while hausmannite (Mn3O4) nanostructured films were obtained under reduced pressure. X-ray diffraction patterns in grazing incidence mode and energy dispersive X-ray analyses confirmed the phase nature and composition of the manganese containing nanostructures. Field-emission scanning electron microscopy images evidenced the nanostructure morphology of both the MnF2 and Mn3O4 phases

Editorial

This volume presents the papers for 19th European Conference on Chemical Vapor Deposition (EuroCVD19), Varna, Golden Sands, Bulgaria, from 1st - 6th September 2013

Fabrication of Europium-Doped CaF2 Films via Sol-Gel Synthesis as Down-Shifting Layers for Solar Cell Applications

In the present work, an in-depth study on the sol-gel process for the fabrication of Eu-doped CaF2 materials in the form of thin films has been addressed for the production of down-shifting layers. Fine-tuning of the operative parameters, such as the annealing temperature, substrate nature and doping ion percentage, has been finalized in order to obtain Eu(III)-doped CaF2 thin films via a reproducible and selective solution process for down-shifting applications. An accurate balance of such parameters allows for obtaining films with high uniformity in terms of both their structural and compositional features. The starting point of the synthesis is the use of a mixture of Ca(hfa)(2)center dot diglyme center dot H2O and Eu(hfa)(3)center dot diglyme adducts, with a suited ratio to produce 5%, 10% and 15% Eu-doped CaF2 films, in a water/ethanol solution. A full investigation of the structural, morphological and compositional features of the films, inspected using X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX), respectively, has stated a correlation between the annealing temperature and the structural characteristics and morphology of the CaF2 thin films. Interestingly, crystalline CaF2 films are obtained at quite low temperatures of 350-400 degrees C. The down-shifting properties, validated by taking luminescence measurements under UV excitation, have allowed us to correlate the local environment in terms of the degree of symmetry around the europium ions with the relative doping ion percentages

A One-Pot Synthesis of "K(hfa) glyme" Adducts: Effect of the Polyether Length on the Ion Coordination Sphere

AbstractPotassium complexes are starting to gather more and more interest from academia and industry because of their intriguing application possibilities. Novel adducts of potassium hexafluoroacetylacetonato [K(hfa)] with polyethers (monoglyme, diglyme, triglyme, and tetraglyme) were synthesized through a single step reaction and characterized through FT‐IR spectroscopy as well as 1H and 13C NMR spectroscopy. Single crystal X‐ray diffraction studies enabled the identification of fascinating K coordination polymeric networks

Highly Tunable MOCVD Process of Vanadium Dioxide Thin Films: Relationship between Structural/Morphological Features and Electrodynamic Properties

: The monoclinic structures of vanadium dioxide are widely studied as appealing systems due to a plethora of functional properties in several technological fields. In particular, the possibility to obtain the VO2 material in the form of thin film with a high control of structure and morphology represents a key issue for their use in THz devices and sensors. Herein, a fine control of the crystal habit has been addressed through an in-depth study of the metal organic chemical vapor deposition (MOCVD) synthetic approach. The focus is devoted to the key operative parameters such as deposition temperature inside the reactor in order to stabilize the P21/c or the C2/m monoclinic VO2 structures. Furthermore, the compositional purity, the morphology and the thickness of the VO2 films have been assessed through energy dispersive X-ray (EDX) analyses and field-emission scanning electron microscopy (FE-SEM), respectively. THz time domain spectroscopy is used to validate at very high frequency the functional properties of the as-prepared VO2 films

Two-step MAPbI3 deposition by low-vacuum proximity-space-effusion for high-efficiency inverted semitransparent perovskite solar cells

The innovative two-step Low Vacuum-Proximity Space Effusion (LV-PSE) method exploits the conversion of a textured PbI2 layer into MAPbI3 by adsorption–incorporation–migration of energetic MAI molecules, thus enabling a best efficiency of 17.5% in 150 nm thick layers

Solid-State Fabrication of Cu2O/CuO Hydroxide Nanoelectrode Array onto Graphene Paper by Thermal Dewetting for High-Sensitive Detection of Glucose

Nanostructures of Cu2O/CuO hydroxide suitable for the electrochemical determination of glucose are obtained by solid‐state dewetting of CuO layers 6, 8, and 31 nm thin deposited by sputtering onto 240 μm‐thick graphene paper. Solid‐state dewetting in nitrogen produces a partial decomposition of CuO into Cu2O and Cu. X‐ray diffraction patterns reveal the presence of high‐index crystallographic facets, which are reactive and useful toward glucose oxidation to gluconolactone. Typically, morphology studied by scanning electron microscopy reveals faceted nanoparticles with an average size below 200 nm. X‐ray photoelectron spectroscopy shows that the nanostructure surfaces of Cu2O and metallic copper exposed to natural ambient are promptly reoxidized and hydroxidized to a mixture of CuO and Cu(OH)2. Electrochemical characterization in amperometric mode reveals linear response to glucose concentration in the range from 50 to 10 × 10−3 m, sensitivity up to 83 μA cm−2 mm −1, and limit of detection up to 3.6 × 10−6 m. Good combination of low cost and simplicity of preparation with low limit of detection, high sensitivity, and wide linear range makes the proposed electrodes suitable for a variety of applications ranging from health to food and beverage industries

Precursor adsorption efficiency of titanium tetra isopropoxide in the presence of a barium beta-diketonate precursor

Barium titanate is a promising candidate for integrated photonic application due to its high electro-optic coefficient; therefore the need arises for a suitable deposition technique which provides high film quality at low temperatures (below 500 degrees C) and reasonable growth rates. We report on combinatorial high vacuum chemical vapor depositions of titanium(IV) tetra isopropoxide and barium hexafluoroacetylacetonate (hfa)-tetraglyme on silicon substrates aiming at the deposition of barium titanate. The barium precursor was synthesized and characterized regarding its evaporation kinetics. Co-depositions of both precursors were carried out in the absence and presence of reactive gas partners such as H-2, H2O, O-2 and O-3. Plain substrates deposited in the absence of ozone, however, do not show any titanium incorporation. We call this phenomenon obviating precursor interaction. Elongated masking structures were designed and manufactured on silicon substrates to modify locally the precursor impinging rate of one of both precursors to study the nature of this obviating behavior. It was found, that the blocking results from a reduced sticking coefficient, i.e. a fast desorption of the precursor prior to decomposition. When adding ozone, distinct, sharply separated regions were identified on the substrate, which we separate, according to their chemical composition and morphology, into TiO2, Ba-containing and barium and titanium mixed deposit. We found that the transition between TiO2 and Ba-deposit is dependent on the titanium to barium precursor impinging ratio. Depending on the barium precursor flux, the third region of mixed deposition of barium and titanium forms in the Ba deposit. The mixed deposit indicates a promising starting point for a combinatorial high vacuum chemical vapor deposition optimization to evaluate the feasibility of a high quality barium titanate film by this technique. (C) 2013 Elsevier B.V. All rights reserved