Search results for "thin film"
showing 10 items of 1200 documents
Thermal sensor based on a polymer nanofilm
2016
In this work, we have developed a thermal sensor based on poly(3,4 ethylenedioxythiophene) (PEDOT) nanofilms as thermoelectric material. The PEDOT nanofilms have been synthesized by the electrochemical polymerization method. The thicknesses of the films were around 120 nm. The doping level of PEDOT was controlled by chemical reduction using hydrazine. The achieved Seebeck coeficient is 40 uV/K. A PEDOT nanofilm was integrated into an electronic circuit that amplifies the voltage originated from the Seebeck effect. The temperature increment produced by a fingerprint touching the film is enough to switch on a light emitting diode. Peer Reviewed
Reactivity of Nickel(II) Porphyrins in oCVD Processes—Polymerisation, Intramolecular Cyclisation and Chlorination
2019
Abstract Oxidative chemical vapour deposition of (5,15‐diphenylporphyrinato)nickel(II) (NiDPP) with iron(III) chloride as oxidant yielded a conjugated poly(metalloporphyrin) as a highly coloured thin film, which is potentially useful for optoelectronic applications. This study clarified the reactive sites of the porphyrin monomer NiDPP by HRMS, UV/Vis/NIR spectroscopy, cyclic voltammetry and EPR spectroscopy in combination with quantum chemical calculations. Unsubstituted meso positions are essential for successful polymerisation, as demonstrated by varying the porphyrin meso substituent pattern from di‐ to tri‐ and tetraphenyl substitution. DFT calculations support the proposed radical oxi…
Grafting and characterization of dodecylphosphonic acid on copper: Macro-tribological behavior and surface properties
2013
International audience; Thin film of n-dodecylphosphonic acid (DDPA) was prepared on a copper oxide substrate via a molecular self-assembly process. The composition, structure, organization, surface energy, morphology, and electrochemical behavior of the DDPA filmwere characterized bymeans of X-ray photoelectron spectroscopic analysis (XPS), polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), contact angle measurement v(CAM), microscopic observations, and electrochemistry. The friction behavior of the DDPA film adsorbed on copper oxide substrate sliding against a Si3N4 ball was examined on a linear reciprocating tribological tester. Worn surfaces of the DDPA film…
Antimony-121 Mössbauer spectra of organoantimony derivatives containing Sb-Sb bonds
1994
121-Sb Mossbauer data are reported for a number of organoantimony rings and catena-stibanes. These compounds are representative of RSb(Sb)2 and R2SbSb type of coordination, and spectral parameters are compared and discussed in relation to RSbCl2 and R2SbCl systems. Although the trend in isomer shift is similar, the present compounds show slightly less negative isomer shift values together with a remarkable reduction of the quadrupolar coupling constant. A rationalization of the quadrupolar interaction in the above series of compounds appears feasible by using point charge model calculations whose results, in terms of bonding, indicate a large contribution of p-electron density along Sb-Sb b…
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1997
The fundamental absorption edge of amorphous, polycrystalline and crystalline tungsten trioxide (WO3) thin films obtained by different techniques (thermal evaporation, rf plasma sputtering, chemical gas transport) was investigated. Special attention was paid to correct measurements of absorption values of all WO3 thin films taking into account the scattered light, interference effects and reflection losses. The indirect edge at 2.70 eV was determined for crystalline WO3, but for crystal WO3:Ti the direct edge in the same place (2.72 eV) was found. For polycrystalline WO3 thin film first edge transition located at 2.76 eV had a quadratic dependence similar to the amorphous film at a higher p…
Study of the MOCVD growth of ZnO on GaAs substrates: Influence of the molar ratio of the precursors on structural and morphological properties
2007
Abstract ZnO thin films were grown by metal-organic chemical vapour deposition (MOCVD) on GaAs(100) and GaAs(111)A substrates. The growth experiments were performed at temperatures ranging from 290 to 500 ∘C and atmospheric pressure. Diethylzinc (DEZn) and tertiary butanol (tBuOH) were used as Zn and O precursors, respectively. The crystallinity of the grown films was studied by X-Ray Diffraction (XRD) and the thickness and morphology were investigated by Scanning Electron Microscopy (SEM). The influence of substrate orientation and molar ratio of the precursors on the crystalline orientation and morphology of the ZnO grown films was analysed.
Structure and Microscopic Magnetism of Epitaxial Ni-Mn-Ga Films
2012
We report on the structural and magnetic properties of epitaxial thin films of the ferromagnetic shape memory material Ni–Mn–Ga prepared by DC magnetron sputter deposition. Different substrate materials, i.e., MgO(100) and Al2O3(11−20) allow for a tailored epitaxial growth. Using a sacrificial chromium buffer layer freestanding epitaxial films are obtained. In combination with photolithography partially freestanding structures such as microbridges are fabricated. The complex martensite crystal structure in substrate-constrained and freestanding films is studied by means of X-ray diffraction. The identified asymmetric twin variant configuration is associated with a macroscopic surface patter…
Relationship between microscopic and macroscopic structures of organic thin films for SHG
1993
The experiments described in this paper were undertaken in order to obtain information about the relationship between the structure and non-linear optical properties (second-harmonic generation) of organic thin films. For this purpose, two closely related dyes, diones and tetrones, were compared, both of which are shown to have large hyperpolarisabilities. Their microscopic properties are investigated by conformational analysis and electron diffraction. It could be shown that detailed knowledge about the structure and the adjacent neighbour packing can be obtained from conformational analysis and electron diffraction in order to understand the non-linear optical properties of the two dyes.
Electrochemical and chemical synthesis of CIS/Zn(S,O,OH) for thin film solar cells
2014
In this work, we are reporting results on the electrodeposition of the CuInSe2 thin films on molybdenum thin foil substrates. We have used an aqueous non-buffered electrolyte and a careful choice of deposition parameters to ensure a good quality and composition of the deposited films. In addition, CdS was replaced in the buffer layer with a wider bandgap Zn(S,O,OH) film obtained by chemical bath deposition. The deposited films were annealed in inert atmosphere at different temperatures. The influence of annealing temperature on the properties of the films is briefly discussed. Films were also characterized by photoelectrochemical and I-V measurements. Structural characterization was carried…
Enhanced plasmonic processes in amino-rich plasma polymer films for applications at the biointerface
2021
A new plasmonic biosensor was developed in a planar chip-based format by coupling the plasmonic properties of gold nanoparticles (Au NPs) with the mechanical and bioadhesive features of unconventional organic thin films deposited from plasma, namely primary amine-based plasma polymer films (PPFs). A self-assembled layer of spherical Au NPs, 12 nm in diameter, was electrostatically immobilized onto optically transparent silanised glass. In the next step, the Au NP layer was coated with an 18 nm polymeric thick PPF layerviathe simultaneous polymerization/deposition of a cyclopropylamine (CPA) precursor performed by radio frequency discharge, both in pulsed and in continuous wave modes. The CP…