Thin Films and Coatings

Remarkable enantioselectivity of molecularly imprinted TiO2 nano-thin films

by Roman Selyanchyn

TiO2 nano-thin films with imprinted (R)- and (S)-enantiomers of propranolol, 1,1′-bi-naphthol, and... more TiO2 nano-thin films with imprinted (R)- and (S)-enantiomers of propranolol, 1,1′-bi-naphthol, and 2-(4-isobutylphenyl)-propionic acid were fabricated on quartz plates by spin-coating their solutions with Ti(O-nBu)4 in a toluene-ethanol mixture (1:1, v/v). After template removal, the imprinted films showed better binding for original templates than to the corresponding enantiomers. The assessment of template incorporation, template removal, and re-binding was conducted through UV-vis measurements. Significant enhancement of enantioselectivity was achieved by optimization of the film thickness and by heat-treatment of the imprinted films. After subtraction of non-specific binding, the optimized films provided chiral recognition with the enantioselectivity of almost 100% for (R)-propranolol and 95% for (S)-propranolol.

Deposition of nanocrystalline TiO2 thin films on PET at 130C

by Material Science

DOI: 10.1109/ASEMD.2011.6145136

A sol-gel method was used to produce thin films of the
anatase polymorph of titania on poly(ethylene... more A sol-gel method was used to produce thin films of the
anatase polymorph of titania on poly(ethylene Terephthalate)
(PET). This was done at a temperature of only 130°C, which
demonstrates the feasibility of the fabrication of flexible
photocatalyts, solar cells, and other semiconducting materials.
The films were ~570 nm thick and were comprised of grains of
15-25 nm diameter; these grains themselves consisted of
crystallites of 5-10 nm diameter

Sputtered nickel oxide thin film for efficient hole transport layer in polymer-fullerene bulk-heterojuntion organic solar cell

by Andriy Zakutayev

Thin Solid Films, 520, 3813 (2012)

BariumCopperChFluorine (Ch= Sulfur, Selenium, Tellurium) p-type transparent conductors

by Andriy Zakutayev

Thesis (Ph.D.)--Oregon State University, 2010.;ISBN: 9781124216355

BaCuChF (Ch = S, Se, Te) materials are chalcogen-based transparent conductors with wide optical band gaps (2.9 – 3.5... more BaCuChF (Ch = S, Se, Te) materials are chalcogen-based transparent conductors with wide optical band gaps (2.9 – 3.5 eV) and a high concentration of free holes (10¹⁸ – 10²⁰ cm⁻³) caused by the presence of copper vacancies. Chalcogen vacancies compensate copper vacancies in these materials, setting the Fermi level close to the valence band maximum. BaCuChF thin film solid solutions prepared by pulsed laser deposition (PLD) have tunable properties, such as lattice constants, conductivity and optical band gaps. BaCuSF and BaCuSeF materials also feature room-temperature stable 3D excitons with spin-orbit-split levels. BaCuTeF has forbidden lowest-energy optical transitions which extends its transparency range. BaCuChF surfaces oxidize when exposed to air, but can be protected using Ch capping layers. Polycrystalline BaCuSeF thin films have a 4.85 eV work function, a 0.11 eV hole injection barrier into ZnPc, and 0.00 eV valence band offset with ZnTe. BaCuSeF should have s similar band offset and similar interfacial properties with CdTe and Cu(InGa)Se₂, and BaCuSF should have no valence band offset with Cu₂ZnSnS₄, according to the transitivity rule. Therefore, BaCuSeF is suitable for applications as a p-layer in organic light-emitting diodes, p-i-n double-heterojunction and tandem chalcogenide solar cells.

The origin of electrical property deterioration with increasing Mg concentration in ZnMgO:Ga

by Andriy Zakutayev

Thin Solid Films 520, 367 (2012)

Inverse design approach to hole doping in ternary oxides: Enhancing p-type conductivity in cobalt oxide spinels

by Andriy Zakutayev

Phys. Rev. B 84, 205207 (2011)

Zn–Ni–Co–O wide-band-gap p-type conductive oxides with high work functions

by Andriy Zakutayev

MRS Communications 1, 23 (2011)

Band-structure, optical properties, and defect physics of the photovoltaic semiconductor SnS

by Andriy Zakutayev

Appl. Phys. Lett. 100, 032104 (2012

Surface origin of high conductivities in undoped In2O3 thin-films

by Andriy Zakutayev

Phys. Rev. Lett. 108, 016802 (2012)

Cation off-stoichiometry leads to high p-type conductivity and enhanced transparency in Co2ZnO4 and Co2NiO4 thin films

by Andriy Zakutayev

Phys. Rev. B 85, 085204 (2012)

Thickness Evolution of the Microstructural and Optical Properties of Si:H Films in the Amorphous-to-Microcrystalline Phase Transition Region

by Joshua Pearce

A. S. Ferlauto, G.M. Ferreira, R.J. Koval, J.M. Pearce, C.R. Wronski, R. W. Collins, M.M. Al-Jassim, and K.M. Jones, "Thickness Evolution of the Microstructural and Optical Properties of Si:H Films in the Amorphous-to-Microcrystalline Phase Transition Region" 29th IEEE Photovoltaic Specialists Conf. Proc., (IEEE, 2002) pp. 1076-1081, 2002.

The ability to characterize the phase of the intrinsic (i) layers incorporated into amorphous silicon [a-Si:H] and... more The ability to characterize the phase of the intrinsic (i) layers incorporated into amorphous silicon [a-Si:H] and microcrystalline silicon [μc-Si:H] thin film solar cells is critically important for cell optimization. In this research, a new method has been developed to extract the thickness evolution of the μc-Si:H volume fraction in mixed phase amorphous + microcrystalline silicon [(a+μc)-Si:H] i-layers. This method is based on real time spectroscopic ellipsometry measurements performed during plasma enhanced chemical vapor deposition of the films. In the analysis, the thickness at which crystallites first nucleate from the a-Si:H phase can be estimated, as well as the nucleation density and microcrystallite cone angle. The results show very good correlations with structural and electronic device measurements.

Optimization of open circuit voltage in amorphous silicon solar cells with mixed-phase (amorphous+nanocrystalline) p-type contacts of low nanocrystalline content

by Joshua Pearce

J. M. Pearce, N. Podraza, R. W. Collins, M.M. Al-Jassim, K.M. Jones, J. Deng, and C. R. Wronski "Optimization of Open-Circuit Voltage in Amorphous Silicon Solar Cells with Mixed Phase (Amorphous + Nanocrystalline) p-Type Contacts of Low Nanocrystalline Content", Journal of Applied Physics, 101(11), 114301, 2007.

Both the origins of the high open circuit voltages (VOC) in amorphous silicon solar cells having p layers prepared... more Both the origins of the high open circuit voltages (VOC) in amorphous silicon solar cells having p layers prepared with very high hydrogen dilution and the physical structure of these optimum p layers remain poorly understood topics, with several studies offering conflicting views. This work attempts to overcome the limitations of previous studies by combining insights available from electronic measurements, real time spectroscopic ellipsometry, atomic force microscopy, and both high-resolution transmission electron microscopy (TEM) and dark field TEM of cross sections of entire solar cells. It is found that solar cells fabricated with p layers having a low volume fraction of nanocrystals embedded in a protocrystalline Si:H matrix possess lower recombination at the i/p interface than standard cells and deliver a higher VOC. The growth of the p layers follows a thickness evolution in which pure protocrystalline character is observed at the interface to the i layer. However, a low density of nanocrystallites nucleates with increasing thickness. The advantages offered by the protocrystalline character associated with the amorphous phase of the mixed-phase (amorphous+nanocrystalline) p layers prepared with excess H2 dilution account for the improved VOC of the optimum p layers. In this model, the appearance of a low volume fraction of nanocrystals near the top transparent conductor interface is proposed to be incidental to the high VOC.

Highly conductive electrostatically assembled porphyrazine films

by Grégoire Demets

Analytical Model for the Optical Functions of Indium Gallium Nitride with Application to Thin Film Solar Photovoltaic Cells

by Joshua Pearce

Dirk V. P. McLaughlin and J.M. Pearce, “Analytical Model for the Optical Functions of Indium Gallium Nitride with Application to Thin Film Solar Photovoltaic Cells”, Materials Science and Engineering: B, 177, 239-244 (2012).

This paper presents the preliminary results of optical characterization using spectroscopic ellipsometry of wurtzite... more This paper presents the preliminary results of optical characterization using spectroscopic ellipsometry of wurtzite indium gallium nitride (InxGa1-xN) thin films with medium indium content (0.38<x<0.68) that were deposited on silicon dioxide using plasma-enhanced evaporation. A Kramers-Kronig consistent parametric analytical model using Gaussian oscillators to describe the absorption spectra has been developed to extract the real and imaginary components of the dielectric function ({\epsilon}1, {\epsilon}2) of InxGa1-xN films. Scanning electron microscope (SEM) images are presented to examine film microstructure and verify film thicknesses determined from ellipsometry modelling. This fitting procedure, model, and parameters can be employed in the future to extract physical parameters from ellipsometric data from other InxGa1-xN films.

DEM Simulation of Continuous Tablet Coating: Effects of Tablet Shape and Fill Level on Inter-Tablet Coating Variability

by Stefan Radl

Electrical and gas sensing properties of polyaniline-chloroaluminium phthalocyanine composite thin films

by Mohammad Javad Jafari

The European Physical Journal Applied Physics

Electrical and gas sensing properties polyaniline-chloroaluminium phthalocyanine (PAni-ClAlPc) composite thin films... more Electrical and gas sensing properties polyaniline-chloroaluminium phthalocyanine (PAni-ClAlPc) composite thin films were investigated to study the gas sensing behavior of composites. Devices (chemiresistor gas sensors) were prepared by spin coating method from PAni as the base of composites and ClAlPc (with different concentrations) as the second component onto interdigitated electrodes. The sensitivity, reversibility, response and recovery time of these thin films on exposure to different concentrations (0–2000 ppm) of CO2 gas and the suitability of different composites as materials to be used in practical gas sensors at different temperatures were investigated. The sensitivity factor of composites was obtained in a range between 0.05–7.20. PAni + 10% ClAlPc was the perfect candidate composite to fabricate gas sensor at 300 K and PAni + 15% ClAlPc at 350 K. Thus, (PAni-ClAlPc) composites have better response than pure PAni. After that, devices were exposed to humidity, an unexpected behavior was absorbed. Conductivity of thin films were increased on exposure lower RH% and decreased on higher RH%. Finally, 1000 ppm CO2 was mixed to humidity and introduced to chamber, obtained results showed the CO2 mixtures decreased the sensitivity of thin films in compare with pure CO2.

Optical and electrical properties of nanostructured heterojunction (Au|PdPc|ClAlPc|Al) and using as O2 sensor

by Mohammad Javad Jafari

The European Physical Journal Applied Physics

Nanostructure thin films and sandwich devices of palladium phthalocyanine (PdPc) and chloro-aluminum-phthalocyanine... more Nanostructure thin films and sandwich devices of palladium phthalocyanine (PdPc) and chloro-aluminum-phthalocyanine (ClAlPc) were prepared by thermal evaporation technique. Optical and struc- tural properties of nanostructure thin films were investigated by XRD, SEM and optical absorption. The SEM images demonstrated PdPc (40–60 nm) and ClAlPc (30–50 nm) nanostructures. XRD pat- terns showed that thin films are in α-phase at room temperature. Also, optical bandgap energy of thin films was calculated by optical absorption spectra. Heterojunction (Au|PdPc|ClAlPc|Al) and single layer (Au|PdPc|Al and Au|ClAlPc|Al) devices were fabricated. Electrical measurements demonstrated the semi-conducting and photo-conducting behavior of thin films. After that, devices were exposed to different concentrations of O2 at 300 K and 350 K and conductivity of thin films was increased on exposure to O2 . Heterojunction devices were more sensitive than other thin films and had better response and reversibility in comparison with single layer devices at 350 K. Finally, 10% O2 was mixed with different percentages of relative humidity and all results showed that the conductivity of thin films is reduced on exposure to O2 mixed to humidity.

THE DEVELOPMENT AND DIFFUSION OF POWDER COATINGS IN THE US AND EUROPE

by Lukas Brun

Substrate and material transfer effects on the surface chemistry and texture of diamond-like carbon deposited by plasma-enhanced chemical vapour deposition

by Benjamin Jones

B. J. Jones and  J. J. Ojeda
Surface and Interface Analysis (2012)
[In Press] http://dx.doi.org/10.1002/sia.4871

Highlights
This paper discusses the use of X-ray photoelectron spectroscopy (XPS) and X-ray excited Auger... more Highlights
This paper discusses the use of X-ray photoelectron spectroscopy (XPS) and X-ray excited Auger spectroscopy (XAES) to investigate carbon bonding. The paper demonstrates the application of these techniques to the analysis of diamond-like carbon thin films, and couples them with atomic force microscopy (AFM) measurements of topography for the development of coatings, for example in aerospace applications.

Abstract
Diamond-like carbon (DLC), a thin amorphous carbon film, has many uses in tribological systems. Exploiting alternative substrates and interlayers can enable the control of the hardness and modulus of the multilayer system and improve wear or friction properties. We used XPS and atomic force microscopy to examine DLC that had been concurrently coated on an epoxy interlayer and a steel substrate by plasma-enhanced chemical vapour deposition. sp2/sp3 ratios were calculated both by the deconvolution of the XPS C1s line and by the analysis of the C KLL Auger spectrum. Altering the substrate causes changes in the carbon bonding configuration, evident with the same trend through both analysis methods, although with differing absolute values, related to hydrogen and oxygen content. There is significant variation in the microscale surface texture, exhibited by both average roughness values and size and uniformity of surface asperities. This suggests that alteration to the film surface structure is a factor to be considered in addition to interface adhesion, hardness and elastic modulus in investigating substrates and interlayers for tribological coatings. Examination of a DLC film separately produced on a steel substrate, in comparison with that produced concurrently with a DLC coating on epoxy, shows the possibility of effects on the chemistry of the film through transfer of material from adjacent samples within the plasma deposition, related to heating, outgassing or sputtering processes. The possibility of such contamination has implications in coating parameter design and coating of multiple samples with plasma-enhanced chemical vapour deposition.


Keywords: Diamond; graphite; diamond-like carbon; DLC; amorphous carbon; X-ray; Auger; bonding; thin film; plasma enhanced chemical vapour deposition; surface morphology; surface chemistry;
substrate effects

Effect of Nb concentration on the structure,mechanical, optical and electrical properties of nanocrystalline Ti1-xNbxN thin films

by Vasu Kuraganti