Commercial Glass Substrates Research Articles

Characterization of Chiral Nanostructured Surfaces Made via Colloidal Lithography.

Optically anisotropic materials were produced via colloidal lithography and characterized using scanning electronic microscopy (SEM), confocal microscopy, and polarimetry. A compact hexagonal array mask composed of silica sub-micron particles was fabricated via the Langmuir-Blodgett self-assembly technique. Subsequently, the mask pattern was transferred onto monocrystalline silicon and commercial glass substrates using ion beam etching in a vacuum. Varying the azimuthal angle while etching at oblique incidence carved screw-like shaped pillars into the substrates, resulting in heterochiral structures depending on the azimuthal angle direction. To enhance the material's optical properties through plasmon resonance, gold films were deposited onto the pillars. Polarimetric measurements were realized at normal and oblique incidences, showing that the etching directions have a clear influence on the value of the linear birefringence and linear dichroism. The polarimetric properties, especially the chiroptical responses, increased with the increase in the angle of incidence.

Fabrication and processing of bacterial cellulose/silver nanowire composites as transparent, conductive, and flexible films for optoelectronic applications

AbstractThis work reports on the engineering and fabrication of transparent, conductive, and flexible films made as a composite of bacterial cellulose microfibers (BMF), a polymer (either PVA or PEO), and silver nanowires (AgNWs) as viable and cost‐effective replacements to commercial indium‐tin oxide (ITO) and fluorine‐doped tin oxide (FTO) transparent conductors. The studies conducted indicate that the optical and mechanical properties of BMF‐polymer substrates are tuneable by varying the ratio of BMF to polymer. An optimized ratio of 70:30 of BMF to polymer was established for BMF‐PVA and BMF‐PEO composites. The optimized composite films were coated with varying amounts of AgNWs. As the AgNW loading increased, the deposition density of AgNW networks increased, while the sheet resistance and optical transmittance decreased. The optimum AgNW loading was determined at 0.20 mg for both composite films. The BMF‐PVA‐AgNW film displayed transmittance between 81% and 71% and an average resistivity of 9.462 ± 0.588 Ω/sq while the BMF‐PEO‐AgNW films showed transmittance between 73% and 65% and an average resistivity of 9.388 ± 0.1.375 Ω/sq. These properties compared well to that of commercial ITO and FTO glass substrates. The findings promote cellulose‐based composites as low‐cost, lightweight, and durable substrates for optoelectronic applications.

Variable-Capacitance Sensor to Measure the Evaporation Rate and Lifetime of Microliter Droplets

This article presents a variable-capacitance sensor for sessile droplet evaporation rate and lifetime measurements. The sensor consists of a plane-parallel-electrode capacitor with a commercial glass substrate inserted within. The glass substrate has a concave cavity at its center to deposit a liquid droplet for its measurement. An air gap is left between the substrate and the upper electrode to allow for the droplet’s evaporation. The main advantage of this configuration is that it fixes the position and geometric shape of the droplet. An analytical model based on the local-height approximation is developed to calculate the capacitance of the device, with and without a liquid droplet. Its validity is initially tested comparing with finite element calculations. Then, using the analytical model we simulate the capacitance signal during the evaporation of a sessile droplet and compare it with experimental results finding very good correspondence. The differential capacitance signal follows closely the volumetric changes of the droplet. The evaporation kinetics and lifetime of 3.5 ± 0.1 microliter droplets of ethanol and methanol mixtures are presented. We also show that the evaporation kinetics and lifetime of a droplet can be used to reveal the presence of a surfactant at very low concentrations. The results presented demonstrate the ability of the sensor to monitor the evaporating droplet from start to end.

Opto-electronic properties of Zr[formula omitted]Hf[formula omitted]O[formula omitted]/Al/Zr[formula omitted]Hf[formula omitted]O[formula omitted] thin-films: The influence of substrate temperature

The influence of substrate temperature on ZrxHf1−xO2/Al/ZrxHf1−xO2 trilayer thin-films deposited on n-type Si(100) and commercial glass substrates using magnetron sputtering technique is systematically investigated with the substrate temperature ranging from 25 to 300°C. The deposited films are characterized by x-ray reflectivity (XRR), grazing incidence x-ray diffraction (GI-XRD), x-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE-SEM), atomic force microscopy (AFM), cross-sectional transmission electron microscope (TEM), energy-dispersive x-ray spectroscopy (EDX) and UV–VIS spectroscopy to study the microstructural, morphological and optical properties. Capacitance–voltage (C–V) and current–voltage (I–V) measurements are performed to investigate the electrical properties of the trilayer thin-films. Physical characterization reveals that as the substrate temperature rises, the crystalline quality of the trilayer thin-films improves. Further, a rise in substrate temperature causes an increase in surface roughness and grain size. The trilayer thin-film deposited at 300°C shows improved optical transmittance over wavelengths 400–1100 nm. In addition this trilayer thin-film demonstrates highest figure of merit, lower leakage current as well as improved breakdown performance. Hence, ZrxHf1−xO2/Al/ZrxHf1−xO2 thin-film prepared at 300°C could be used in opto-electronic devices.

On the Effect of Thermal Processing on Sn Diffusion and Efficiency Enhancement in Hematite/FTO Photoanodes

The frequently underestimated effects of “in air” thermal treatment processing conditions such as temperature, duration, and heating and cooling rates in the design and efficiency of photoelectrodes fabricated for academic studies onto the most common commercial transparent conductive glass substrate i.e. fluorine-doped tin oxide (FTO) were investigated by XRD, XPS, SEM, conductive AFM, electrochemical impedance spectroscopy (EIS) as well as direct current (DC) and photoelectrochemical (PEC) measurements. The PEC response of Hematite photoanode thin films consisting of short nanorods thermally treated at 400 °C and 800 °C upon fast or extended time conditions is inhibited by factors such as crystallinity, Sn diffusion, or substrate integrity. A “fast” thermal treatment in air at 750 °C provided the best synergy between charge transfer resistance, Sn-diffusion from the FTO substrate, nanorod dimensions, reduced recombination, improved charge separation and minimized substrate damage. This study does offer valuable fundamental and practical insights for a better understanding of the benefits and drawbacks of photoelectrode thermal processing, which is critical for the improvement of the PEC performance-reproducibility relationship for FTO-based solar water splitting systems and devices.

A potential method to induce hydrophobicity on glass surface while retaining its anti-reflective abilities

Fabrication of anti-reflective and hydrophobic glass surfaces has been an active area of research. It has been reported that most of the coatings developing methods produces fragile and thin coatings which consequently have limited practical usage because of their abrasion-sensitivity. However, with thicker coatings, transparency of glass gets compromised, rendering it inoperable to be used in applications requiring transparency. To overcome the problem there is a need to have a solution that can practically produce glass substrates having hydrophobic properties without significant loss in transmittance, making them useful in anti-reflective hydrophobic applications. The presented work focuses on utilizing the effects of surface roughness and surface chemistry on commercial grade glass substrates to produce robust hydrophobic surfaces without appreciable compromise on transmittance. Metal Assisted Chemical Etching (MACE) was used to develop controlled structured surface roughness on the glass substrate whereas the surface chemistry was modified via silane treatment. The results demonstrated surface roughness and surface chemistry are both equivalently important to achieve an optimum surface having hydrophobic properties without any major transmittance lost. Successful implementation of the silver (Ag) particle assisted MACE process and chemistry modification of the glass surface resulted in contact angles above 100° with nearly 2–3% transmission lost in reference to the transmittance of parent glass substrates.

Rectifying ZnO-Na/ZnO-Al aerogels p-n homojunctions.

Semiconductor ZnO aerogels were synthesized by a sol–gel process with different concentrations (2.5–7.5 wt.%) of Al (n-type) or Na (p-type) and dried under supercritical CO2. The materials were calcined at 500 °C to remove the organic content and to crystallize the ZnO. The microstructure of the ZnO-based aerogels comprises a porous structure with hexagonal and platelet-shaped interconnected particles. The bandgap of the aerogels doped with Al decreased significantly compared to pure, undoped ZnO aerogels, while their specific surface area increased. For the electrical characterization of the ZnO–Na/ZnO–Al junctions, the doped ZnO aerogels were deposited on commercial glass substrates coated with indium tin oxide (ITO) by drop casting method. The I-V curves of the p-n homojuntions revealed a characteristic diode rectifying behavior.

Synthesis and characterization of Mn composition effect on CdSe thin films

Cadmium Selenide (CdSe) doped with (Mn) Manganese Chloride grown, on commercial glass substrate usingChemical Bath Deposition Method. Growth time was kept at 1-2 hours. Magnese Chloride (Mncl2) was used for dopant. CdMnSe films so obtained were characterized using X-Ray Diffraction, Scanning Electron Microscopy, EdAX, andUV-Visible spectrophotometer and photoluminescence studies respectively. XRD study confirms that CdSe films are polycrystalline in nature and have cubic structure. The Debye-Scherer formula was used to calculate average particle size of pure and doped CdSe film. Thus, the particle size was decrease on doping. The effect of doping concentration Mn on the luminescence spectra of CdSe was studied. The emission spectra revealed that the intensity increased considerably in the presence of dopant ions. It is clearly observed from the surface morphological studies by SEM that the as-deposited CdSe and doped Mn concentration films are nanocrystalline, homogenous, without cracks or holes and well covered to the glass substrate. FE-SEM images show spherical particles having uniform distribution. Roughness of the films were totally eliminated. EDAX patterns confirms the presence of Cadmium, Selenide and Magnese chloride elements (2%, 5%)in sample. Optical band gap of pure CdSe film comes out to be 2.1 eV.After doping energy band gap was decreasing. Copyright © 2017 VBRI Press.

Study of optical properties of ZnS and MnZnS (ZnS/MnS) nanostructure thin films; Prepared by microwave-assisted chemical bath deposition method

The main objective of this work is the preparation of ZnS and MnZnS (ZnS/MnS) nanostructure thin films in an ammonia-free solution by microwave-assisted chemical bath deposition (MA-CBD) method and decreasing consume of energy via decreasing deposition time from several hours to several minutes compared to conventional CBD method. ZnS and MnZnS films were deposited on commercial microscope slide glass substrates using acetic acid as a safe complexing agent. Growth rate of the film thickness was obtained approximately 1.8–2.0 nm/min. The influence of [S2−/Zn2+] molar ratio on the formation, quality, and optical properties of the films was investigated. X-ray diffraction results approved the formation of MnS/ZnS hybrid films with a cubic structure for the ZnS and MnS. Atomic force microscopy (AFM) measured the average of roughness around 6.4 nm. Field emission scanning electron microscopy (FE-SEM) exhibited that the layers were dense, homogenous, and free of pinhole or crack with very small particles at about 10–40 nm. Energy-dispersive X-ray spectrometer (EDX) revealed the presence of the Mn in the ZnS thin film and confirmed the deficiency of sulfide in the films. Fluorescence (FL) emission spectra of the films showed a strong dependence on composition as well as population (density) of defect states such as S vacancies. UV–vis results indicated that all films are highly transparent, and their band gap energy varies from 3.6eV to 3.85eV.

RF-sputtered V2O5 thin films on two different glass substrates

Thin V2O5 films were deposited on two different commercial soda-lime glass substrates (A and B) by O2 reactive radio frequency magnetron sputtering using a vanadium target. The influences of the surface energy and roughness of the substrates on the structure and atomic bonding of the films were examined. The film on substrate A was polycrystalline, with eight crystal orientations, whereas the film on substrate B yielded an intense (001) diffraction peak of α-V2O5 and a weak (200) peak of β-V2O5, indicating preferred orientation along these planes. Structural analyses indicated that substrate B with lower surface energy and higher roughness enhanced the formation of a layered α-V2O5 structure.

Nano fibers of lead free perovskite Cesium Titanium Bromide (CsTiBr3) thin films by in-house deposition technique

A novel lead free nano fibers of Cesium Titanium Bromide (CsTiBr3) perovskite is synthesized on commercial glass substrate by a two stage deposition method for the first time. Cesium Bromide thin film prepared by vacuum evaporation by resistive heating is the substrate for deposition of Titanium Bromide (TiBr4) vapor by an in-house deposition arrangement. The duration of deposition of TiBr4 vapor on CsBr thin film plays a key role on the structural, compositional and morphological properties of CsTiBr3. The mechanism behind the formation of nano fibers of CsTiBr3 from polygonal grains of CsBr is discussed in detail. The grain boundary grooving of CsBr polygonal grains influences the evolution and dimension of CsTiBr3 nano fibers. The nano fiber structure and lead free nature makes this novel perovskite a promising candidate for sensors, nanolasers and for future nanoelectronics.

OPTICAL PROPERTIES OF ZnO FILMS PREPARED BY CBD TECHNIQUE

Thin films of zinc oxide (ZnO) with ammonia solution to 300ml of aqueous solution Zn(NO3)2 . 6H2O (0.3M) are created via (CBD) technique on commercial glass substrates with bath temperature (80± 5) °C and annealing temperatures at (373, 473 and 573)K at constant time of 1h. The deposited films optical absorbance was defined utilizing SP3000NANO optima (UV-V is spectrophotometer) and shows that the optical energies gaps for ZnO films increase slightly through a rise in temperature of annealing of the samples at 373K and 473K and register around 3.77eV and 3.78eV respectively. While the energy gap decreases to 3.73eV with increase the annealing temperature at 573K. The wide band gap ZnO has applications of wide array in areas include solar cells, light conductors, chemical sensors and ultraviolet laser diodes.

Assembly of efficient Ag/n-Si/Cu2CdSnS4/Au for photovoltaic cell utilities

Assembly of earth-abundant and cheap kesterite thin films is significant to produce inexpensive photovoltaic cells. Here, uniform, crystalline Cu2CdSnS4 (CCTS4) thin films were deposited on commercial glass substrate by spray pyrolysis method with thickness (215, 246, 328 and 385) at 450 °C. The structural, optical, electrical, and photovoltaic studies of the deposited CCTS4 films were tested by different analysis. The various values of structural constants of CCTS4 films were examined with film thickness. The XRD experiments appeared that the CCTS4 films prove a polycrystalline nature and tetragonal shape. The CCTS4 films observed a direct optical transition and decreased with film thickness increased. The thickness 385 nm of CCTS4 thin film was selected to fabricate the Ag/n-Si/CCTS4/Au Hetero-Junction because it exhibits high values of absorption coefficient and optical conductivity. The fabricated CCTS4/n-type Si Hetero-Junction showed efficiency about 4.1%.

Sputtered VO2 coatings on commercial glass substrates for smart glazing applications

VO2 is a well-known thermochromic material that can be potentially applied as a coating on “smart” glazing systems. In this work VO2 thermochromic films, were grown by the rf sputtering technique on two different types of commercial glass substrates, namely fused silica and float glass, at the low deposition temperature of 300 °C. The optimum deposition conditions, in order to succeed the thermochromic monoclinic phase of VO2(M), were investigated and found to be subject to substrate and thickness. It was observed that on the float glass substrate, only films with thicknesses below 50 nm grown with 3% O2 in plasma exhibited a thermochromic behavior, displaying a critical transition temperature of TC = 46.1 °C, width of transmittance hysteresis loop at 2000 nm ΔTC = 9.1 °C, IR-switching ΔTrIR = 14.6%, integrated solar transmittance modulation ΔTrsol = 1.3% and integrated luminous transmittance at 25 °C equal to Trlum = 36.6%. In contrast, films deposited on fused silica glass demonstrated a thermochromic phase, for all thicknesses, when grown with 1% O2 in the plasma. These thermochromic films were characterized by much lower TC(<40 °C) and ΔTC<10 °C, along with significant thickness variations of the ΔTrIR, ΔTrsol and Trlum parameters. Finally, rapid thermal annealing (RTA) was used and found to enhance the thermochromic performance of films deposited on float glass, with thickness greater than 50 nm. These differences might be attributed to the different composition of each kind of glass, as well as to diffusion phenomena between film and substrate.

Bipolar resistive switching studies in amorphous barium titanate thin films in Ag/am-BTO/ITO capacitor structures

The electroforming free bipolar resistive switching characteristics of amorphous barium titanate (am-BTO) thin films in Ag/am-BTO/ITO capacitor structures were systematically evaluated. The dot point capacitor structures were fabricated by using RF-DC sputtering deposition on ITO coated commercial glass substrates. Varied thicknesses of 142, 100, and 70 nm am-BTO thin films were utilized as a switching medium for exploring the resistive switching phenomena. The amorphous nature and topographical surface were probed with X-ray diffraction and atomic force microscopy techniques. The on/off resistance ratios, SET, RESET voltages, retention, and endurance parameters extracted from current-voltage (I-V) measurements demonstrate stable resistive switching. Space charge limited current conduction and ohmic conduction phenomena were found to be dominant in high resistance and low states of the junctions. The rupture formation upon the Ag active electrode and reduction in capacitance after the application of voltage specify the silver Ag+ ion mediated filament conduction mechanism for the observed bipolar switching phenomena.

Fabrication and characterization of multifunctional thin multi-layer films for transparent conducting oxides

Dielectric/metal/dielectric (D/M/D) multi-layer thin films have been fabricated on a well-properly clean Mari-Enfield (commercial) glass substrate using an electron beam evaporation technique. In these three-layer nanostructures, different metals, i.e., Silver (Ag), Aluminium (Al), and Copper (Cu) have been selected as inter-layer while Hafnium oxide (HfO2) used as a dielectric material. The substrate temperature during fabrication was kept at 150 °C, and the overall thickness of these sandwiched structures was 25 nm, i.e., Dielectric =10 nm (top layer), Metal =5 nm (inter-layer), and Dielectric =10 nm (bottom layer). X-ray diffraction (XRD) and atomic force microscopy (AFM) was used for the structural and surface analysis, respectively. XRD patterns indicate that these D/M/D layers were poly-crystalline with monoclinic phase, while the crystallinity of Cu based films were relatively better than Al or Ag. AFM micrographs reveal the smooth surfaces with low values of average and/or root mean surface (RMS) roughness. Optical properties were measured by using UV/VIS/NIR dual-beam lambda-9 spectrophotometer. The better transmission (in the visible region) and reflection (in the near-infrared region) may be a favorable characteristic for energy-efficient applications, heat mirror, and transparent conductive oxide, etc. Using measured transmission and reflection, various optical constants such as refractive index, extinction coefficient, and energy losses, etc. have been calculated. The electrical properties of these multi-layer films were determined through Keithley-2400 source meter using a four-point probe method. Sheet resistance values for Ag, Al and Cu based films are 5.62, 5.75, and 6.23 Ω/square, respectively.

Deposition of anti‐fog coatings on glass substrates using the jet of an open‐to‐air microwave argon plasma at atmospheric pressure

AbstractThis study reports a one‐step process for the formation of anti‐fog coatings on commercial glass substrates using the jet of an open‐to‐air microwave argon plasma at atmospheric pressure with hexamethyldisiloxane (HMDSO) as the precursor for plasma‐enhanced chemical vapor deposition. Optical microscopy and broadband light transmittance measurements revealed significant precursor fragmentation and gas phase association reactions when HMDSO was injected close to the tube outlet, resulting in powder‐like, hydrophobic, and semiopaque glass surfaces. On the contrary, injection of HMDSO close to the substrate led to smoother, homogeneous, hydrophilic, and transparent glass surfaces. In addition, transmittance measurements at 590 nm in humid air according to American Society for Testing and Materials standard tests revealed superior anti‐fogging properties to plasma‐treated glass substrates. On the basis of the optical emission and absorption spectroscopy measurements, electrons, metastable argon atoms, and hot neutral argon atoms were mostly responsible for the significant precursor fragmentation close to the tube outlet, whereas the contribution of hot neutrals and ultraviolet photons became important close to the substrate.

Tailoring the coefficient of thermal expansion of ternary nickel alloys through compositional control and non-contact measurements

Abstract The majority of microelectromechanical systems (MEMS) are made of silicon, however, future applications will be used in extreme environments, especially at elevated temperatures, and require materials with enhanced properties. Use of metal alloys in these applications will require microscale manufacturability, a balance of physical and mechanical properties and dimensional stability. Here, we emphasized dimensional stability by reducing the coefficient of thermal expansion (CTE) and present an optical non-contact method for measuring the thermal expansion of planar thin films. A combinatorial approach was employed to determine the CTE of nickel-molybdenum-tungsten (Ni-Mo-W) sputter deposited films over a range of compositions, and the addition of Mo and W is shown to significantly decrease and provide a route for tailoring the CTE with compositional control. Ni-Mo-W alloys were revealed to have CTE values ranging from 8–12 × 10−6/°C, matching that of commercial glass substrates that are employed in numerous MEMS devices.

CHARACTERISTICS OF pH VARIATION ON STRUCTURAL AND OPTICAL PROPERTIES OF NANOCRYSTALLINE SnO2 THIN FILMS BY CBD TECHNIQUE

Transparent nanostructure Tin dioxide (SnO2) films with three different pH values (pH= 9, 10 and 11) were deposited on a commercial glass substrate by simple chemical bath deposition (CBD) technique, and there Structural and optical properties were characterized. The structural analysis revealed that the grown thin film exhibit tetragonal structure, small roughness and have nanocrystalline grains on the surface. While the optical results shows that the films have high transmittance (˃ 80 %) and the values of the optical energy gap (Eg) was 3.94, 3.84 and 3.73 eV for pH= 9, 10 and 11 respectively. These values of (Eg) greater than of bulk SnO2 (Eg≈ 3.6 eV) due to the quantum size effect.

CHARACTERISTICS OF pH VARIATION ON STRUCTURAL AND OPTICAL PROPERTIES OF NANOCRYSTALLINE SnO2 THIN FILMS BY CBD TECHNIQUE

Transparent nanostructure Tin dioxide (SnO2) films with three different pH values (pH= 9, 10 and 11) were deposited on a commercial glass substrate by simple chemical bath deposition (CBD) technique, and there Structural and optical properties were characterized. The structural analysis revealed that the grown thin film exhibit tetragonal structure, small roughness and have nanocrystalline grains on the surface. While the optical results shows that the films have high transmittance (˃ 80 %) and the values of the optical energy gap (Eg) was 3.94, 3.84 and 3.73 eV for pH= 9, 10 and 11 respectively. These values of (Eg) greater than of bulk SnO2 (Eg≈ 3.6 eV) due to the quantum size effect.