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Abstract: Ultrathin layer chromatography (UTLC) is a relatively new variant of thin layer chromatography, with a 10 m thick monolithic silica sorbent layer that gives faster separations with lower limits of detection and reduced analyte and solvent volumes. We have produced UTLC plates with controllable nanostructure and thickness, and show that the layer separation characteristics depends on the film nanostructure. We also show that layers made with in-plane anisotropic nanostructures will exhibit a decoupling effect, where the analyte spots do not develop in the same direction as the solvent front movement. The added layer morphology and material selection adds a degree of freedom to UTLC, and may have applications in multi-dimensional TLC. [Copyright &y& Elsevier]

We report the fabrication and optical characterization of a tetragonal square spiral photonic crystal with a three-dimensional relative band gap of approximately 10% using the glancing angle deposition (GLAD) technique. This thin film structure is produced in a one-step process that is highly versatile as a wide range of crystal structures can be created simply through the variation of deposition parameters. Measurements indicate upper and lower frequency band edges at vacuum wavelengths of 2.50 and 2.75 μm, in the infrared region of the spectrum. [Copyright &y& Elsevier]

Abstract: Glancing angle deposition (GLAD) was used to deposit controlled-porosity TiO2 thin films of varying pore size and shape. Hybrid materials were fabricated by infiltrating the TiO2 films with poly(3-hexylthiophene) (P3HT) using a spin casting process, which were either employed as-cast or subjected to thermal processing. Photovoltaic devices fabricated using these hybrid materials were characterized as a function of TiO2 pore size and shape, and thermal processing. It was found that the optimum pore size was dependent on the thermal history of the sample. When as-cast hybrid materials were employed conversion efficiencies decreased with increasing pore size. When hybrid materials annealed above the melting point of P3HT were employed the trend was reversed, with conversion efficiency increasing with increasing pore size. Trends in conversion efficiency were found to correlate with P3HT crystallinity, demonstrating that optimum pore sizes for hybrid devices of this type are dependent on sample processing. [ABSTRACT FROM AUTHOR]

Highlights: [•] Study of anisotropic SiO2, Al2O3, TiO2, and ZrO2 GLAD UTLC stationary phases. [•] Chromatographic merits evaluated using carotenoid and food dye mixtures. [•] Separation performance depended on material, oxidation heat treatments, and UV irradiation. [•] First successful GLAD UTLC–ESI-MS recording of dyes on inorganic ultrathin films. [•] New GLAD UTLC layers may separate samples better than traditional miniaturized sorbents. [Copyright &y& Elsevier]

Abstract: Iron pyrite is a promising material for photovoltaic power production due to low material extraction and processing costs and high optical absorption. Reliable production of photovoltaic grade iron pyrite thin films has, however, been challenging. One potential fabrication route is the direct conversion of iron-to-iron pyrite by sulfur annealing (sulfurization). Bulk iron thin films are used typically but they can suffer from cracking or delamination. Herein we report the sulfurization of porous, columnar Fe films deposited with Glancing Angle Deposition (GLAD), which allows us to control the inter-column spacing (void-fraction) of the precursor film. We show that the morphology and microstructure of the iron pyrite films are strongly affected by the void-fraction. By precisely tuning the void-fraction of the precursor film at 82° oblique angle incidence deposition we can produce iron pyrite films with increased crystallite sizes >100nm with a uniform, crack-free, facetted granular microstructure. Large crystallites may reduce carrier recombination at grain boundaries, which is attractive for photovoltaic devices. Further increasing the void-fraction produces a columnar iron pyrite structure. We also report composition, electrical and optical characterization including a 27ps lifetime of photocarriers measured with ultrafast optical-pump/THz-probe. Structured, porous precursors offer an alternate route to control microstructure and film stress during fabrication of iron pyrite thin films. [Copyright &y& Elsevier]

Abstract: Nb-doped TiO2 (TNO) has been widely explored as an alternative transparent conductor. TNO thin films have been fabricated by various deposition methods, and here we demonstrate fabrication by evaporation of sol–gel synthesized TNO source material. A range of Nb x Ti1− x O2 (x =0, 0.03, 0.06, 0.12, 0.24) compositions were synthesized, pressed into pellets, and deposited as thin films via electron beam evaporation. The thin films were characterized for composition by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy and for crystallinity by X-ray diffraction for the different Nb contents explored. Transparency, conductivity, and Haacke transparent conductor figure of merit values are reported for the evaporated TNO films as a function of Nb content, substrate heating temperature, and post deposition annealing conditions. Glancing angle deposition (GLAD) is used to demonstrate nanostructuring of evaporated TNO based on physical shadowing. Nanostructured GLAD TNO films of increased morphological complexity can be produced using this method, and could lead to unique transparent conductor device architectures. [Copyright &y& Elsevier]

Abstract: Nanopillar metal oxide thin films offer versatility as ultra high surface area supports and conductors. Metal oxide properties (e.g. stability, conductivity) can be tuned via phase and composition control to achieve desired application-specific functionality. Here we demonstrate phase control of high surface area thin films grown by glancing angle deposition and transformed to desired phases through high temperature annealing in a reducing environment. The post-annealed properties such as stoichiometry, phase, and morphology are shown to be largely dependent on initial film structure and hydrogen forming gas flow rate. Initially amorphous films of approximate stoichiometry Nb2O5 are transformed to NbO2 or NbN x O1−x through annealing. Transformation to oxygen-deficient phases is more easily achieved for films of higher initial porosity. Higher forming gas flow rates result in both increased oxygen removal and significantly less physical degradation of nanostructures. A phase map is included as a guide to phase formation and morphology control in annealed nanopillar niobium oxide films. [Copyright &y& Elsevier]

Abstract: A high-speed optical humidity sensor was fabricated from a nanostructured titanium dioxide thin film. A refractive index depth profile designed to yield a narrow-bandpass optical interference filter was obtained through nanoscale porosity variations produced by a physical vapor deposition technique known as glancing angle deposition (GLAD). The GLAD process provides film morphology control on the 10nm scale through a combination of deposition at highly oblique vapor incidence angles and controlled substrate motion. Under varying humidity conditions the transmittance spectrum of the filter shifts due to effective index changes of the porous structure resulting from water vapor adsorption/desorption. Performance analysis has shown that this device is highly sensitive, exhibits minimal hysteresis, and is extremely fast. The adsorption and desorption response times were measured to be 270ms and 160ms, respectively. [Copyright &y& Elsevier]