Antibacterial properties of Cu-ZrO2 thin films prepared via aerosol assisted chemical vapour deposition

© 2015 The Royal Society of Chemistry. The antibacterial properties of a Cu-ZrO2 film grown via aerosol assisted chemical vapour deposition are presented. The composite film showed high activity against E. coli (Gram-negative) and S. aureus (Gram-positive) bacteria with 5 log10 (E. coli) and 4 log10 (S. aureus) decrease in viable bacteria achieved within 20 and 60 minutes respectively. These results were comparable to a pure copper film that was prepared under the same conditions. The composite film was characterized for material properties using a range of techniques including X-ray photoemission and X-ray diffraction

Transparent conductive aluminium and fluorine co-doped zinc oxide films via aerosol assisted chemical vapour deposition

Aerosol assisted chemical vapour deposition (AACVD) was employed to synthesise highly transparent and conductive ZnO, fluorine or aluminium doped and aluminium–fluorine co-doped ZnO thin films on glass substrates at 450 °C. All films were characterised by X-ray diffraction (XRD), wavelength dispersive X-ray spectroscopy (WDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV/Vis/Near IR spectroscopy. The films were 300–350 nm thick, crystalline and displayed high transparency at 550 nm (80–90%). The co-doped film consisted of 1 at.% fluorine and 2 at.% aluminium, exhibiting a charge carrier concentration and a charge carrier mobility of 3.47 × 1020 cm−3 and 9.7 cm2 V−1 s−1, respectively. The band gap of the co-doped film was found to be 3.7 eV and the plasma edge crossover was ca. 1800 nm. This film had a highly structured morphology in comparison to the un-doped and single doped ZnO films for transparent conducting oxide applications

Transparent conducting n-type ZnO:Sc-synthesis, optoelectronic properties and theoretical insight

A joint theoretical-experimental study has been carried out for Sc-doped ZnO (SZO), one of the lesser-studied n-type transparent conducting oxide materials. Density functional theory has been used to create a computational model of SZO, in order to provide a theoretical basis for experimentally-observed phenomena where growth conditions, dopability and electronic properties are concerned. Meanwhile a range of thin films of SZO have been synthesised via chemical vapour deposition in an attempt to (i) observe experimentally the theoretically predicted properties, thereby providing mutual validation of the studies; (ii) seek the optimum dopant quantity for minimal electrical resistivity, and; (iii) demonstrate that transparent and electrically conductive SZO can be synthesised by chemical vapour deposition means. The films exhibit resistivities as low as ρ = 1.2 × 10 -3 Ω cm, with carrier density n = 7.2 × 10 20 cm -3 and charge carrier mobility μ = 7.5 cm 2 V -1 s -1 . Low resistivity of the films was retained after 12 months in storage under ambient conditions, indicating strong atmospheric stability. The films exhibit a high degree of transparency with 88% transmission in the visible range (400-750 nm). A correction to the Tauc method was applied to estimate band gaps of Eoptg = 3.45 ± 0.03 eV in the most conductive SZO sample and Eoptg = 3.34 ± 0.03 eV in nominally undoped ZnO

Photo-activity and low resistivity in N/Nb Co-doped TiO2 thin films by combinatorial AACVD

A combinatorial aerosol assisted chemical vapour deposition (cAACVD) cation–anion co-doping study has been undertaken for the first time, which investigates the interplay of nitrogen and niobium co-dopants and the resultant functional properties within TiO2 thin films. This study advantageously creates a single doped TiO2 thin film which incorporates many compositions that transition from nitrogen doped TiO2 to niobium doped TiO2 across the film's width, in a single deposition. The film was split into a grid and the physical properties of each grid position characterised by X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and UV-visible transmission spectroscopy (UV/Vis). Functional properties such as photo-catalytic activity, water contact angles and resistivity were also characterised. The study was successful in creating and identifying the optimum dopant concentration at which these TiO2 films exhibited both a high rate of photo-activity and favourable transparent conducting oxide (TCO) properties. Whilst most co-doping studies report relatively homogenous film, the inhomogeneity of these films allows both functional properties to exist in conjunction. To the authors knowledge this is the first instance cation and anion co-doping has been explored in the combinatorial regime

A single-source precursor approach to solution processed indium arsenide thin films

This paper reports the synthesis of the novel single-source precursor, [{(MeInAstBu)3}2(Me2InAs(tBu)H)2] and the subsequent first report of aerosol-assisted chemical vapour deposition of InAs thin films. Owing to the use of the single-source precursor, highly crystalline and stoichiometric films were grown at a relatively low deposition temperature of 450 °C. Core level XPS depth profiling studies showed some partial oxidation of the film surface, however this was self-limiting and disappeared on etch profiles. Valence band XPS analysis matched well with the simulated density of state spectrum. Hall effect measurements performed on the films showed that the films were n-type with promising resistivity (3.6 × 10−3 Ω cm) and carrier mobility (410 cm2 V−1 s−1) values despite growth on amorphous glass substrates

Transparent and Conducting Boron Doped ZnO Thin Films Grown By Aerosol Assisted Chemical Vapor Deposition

ZnO based transparent conducting oxides are important as they provide an alternative to the more expensive Sn:In2O3 that currently dominates the industry. Here, we investigate B-doped ZnO thin films grown via aerosol assisted chemical vapour deposition. B:ZnO films were produced from zinc acetate and triethylborane using either tetrahydrofuran or methanol (MeOH) as the solvent. The lowest resistivity of 5.1 x 10-3 .cm along with a visible light transmittance of ~75 - 80% was achieved when using MeOH as the solvent. XRD analysis only detected the wurtzite phase of ZnO suggesting successful solid solution formation with B3+ substituting Zn2+ sites in the lattice. Refinement of the XRD patterns showed minimal distortion to the ZnO unit cell upon doping when MeOH was the solvent due to the immiscibility of the [BEt3] solution (1.0M solution in hexane) in methanol that limited the amount of B going into the films, thus preventing excessive doping

NetDiff – Bayesian model selection for differential gene regulatory network inference

Differential networks allow us to better understand the changes in cellular processes that are exhibited in conditions of interest, identifying variations in gene regulation or protein interaction between, for example, cases and controls, or in response to external stimuli. Here we present a novel methodology for the inference of differential gene regulatory networks from gene expression microarray data. Specifically we apply a Bayesian model selection approach to compare models of conserved and varying network structure, and use Gaussian graphical models to represent the network structures. We apply a variational inference approach to the learning of Gaussian graphical models of gene regulatory networks, that enables us to perform Bayesian model selection that is significantly more computationally efficient than Markov Chain Monte Carlo approaches. Our method is demonstrated to be more robust than independent analysis of data from multiple conditions when applied to synthetic network data, generating fewer false positive predictions of differential edges. We demonstrate the utility of our approach on real world gene expression microarray data by applying it to existing data from amyotrophic lateral sclerosis cases with and without mutations in C9orf72, and controls, where we are able to identify differential network interactions for further investigation

Transparent and conducting boron doped ZnO thin films grown by aerosol assisted chemical vapor deposition.

ZnO based transparent conducting oxides are important as they provide an alternative to the more expensive Sn : In O that currently dominates the industry. Here, we investigate B-doped ZnO thin films grown aerosol assisted chemical vapour deposition. B : ZnO films were produced from zinc acetate and triethylborane using either tetrahydrofuran or methanol (MeOH) as the solvent. The lowest resistivity of 5.1 × 10 Ω cm along with a visible light transmittance of ∼75-80% was achieved when using MeOH as the solvent. XRD analysis only detected the wurtzite phase of ZnO suggesting successful solid solution formation with B substituting Zn sites in the lattice. Refinement of the XRD patterns showed minimal distortion to the ZnO unit cell upon doping when MeOH was the solvent due to the immiscibility of the [BEt ] solution (1.0 M solution in hexane) in methanol that limited the amount of B going into the films, thus preventing excessive doping. [Abstract copyright: This journal is © The Royal Society of Chemistry.

Single Step Solution Processed GaAs Thin Films from GaMe 3 and BuAsH 2 under Ambient Pressure

This article reports on the possibility of low-cost GaAs formed under ambient pressure via a single step solution processed route from only readily available precursors, tBuAsH2 and GaMe3. The thin films of GaAs on glass substrates were found to have good crystallinity with crystallites as large as 150 nm and low contamination with experimental results matching well with theoretical density of states calculations. These results open up a route to efficient and cost-effective scale up of GaAs thin films with high material properties for widespread industrial use. Confirmation of film quality was determined using XRD, Raman, EDX mapping, SEM, HRTEM, XPS, and SIMS

Bismuth oxyhalides: synthesis, structure and photoelectrochemical activity

We report the synthesis and photoelectrochemical assessment of phase pure tetragonal matlockite structured BiOX (where X = Cl, Br, I) films. The materials were deposited using aerosol-assisted chemical vapour deposition. The measured optical bandgaps of the oxyhalides, supported by density functional theory calculations, showed a red shift with the increasing size of halide following the binding energy of the anion p-orbitals that form the valence band. Stability and photoelectrochemical studies carried out without a sacrificial electron donor showed the n-type BiOBr film to have the highest photocurrent reported for BiOBr in the literature to date (0.3 mA cm−2 at 1.23 V vs. RHE), indicating it is an excellent candidate for solar fuel production with a very low onset potential of 0.2 V vs. RHE. The high performance was attributed to the preferred growth of the film in the [011] direction, as shown by X-ray diffraction, leading to internal electric fields that minimize charge carrier recombination