Borosilicate Glass Substrates Research Articles

Development of highly-mechanically polished metal-substrate for neutron supermirrors

A small-angle neutron scattering instrument using an ellipsoidal focusing mirror has been developed at Hokkaido University and a prototype machine (mfSANS) has been installed at the JRR-3 research reactor at Japan Atomic Energy Agency (JAEA). They are based on an ellipsoidal focusing mirror on a borosilicate glass substrate. It turned out that borosilicate glass was very brittle and difficult to machine or polish it to the required surface-finishing process. In order to improve this situation, we decided to develop a method to create a metal substrate based ellipsoidal focusing mirror. As the first step, test pieces of flat and ellipsoidal surface neutron supermirrors using metal substrates were fabricated. They were first roughly shaped by a conventional numerically controlled (NC) cutting machine and amorphous NiP was plated. They were then machined using an ultrahigh precision cutting (UPC) method and finished by NC polishing techniques. Surface roughness of Ra ≈ 0.78 nm and surface figure error of submicrometer were realized so far.

Effect of high temperature deposition on the diffusion of nickel in amorphous silicon thin films

The diffusion of nickel into amorphous Si (a-Si) thin films and the growth of different nickel silicides is reported. a-Si and Ni films were deposited on Borosilicate Glass substrates and annealed in vacuum at temperatures from 200 to 500°C. The average grain size of the films increases from 150 nm to 360 nm with deposition temperature. Cross-sectional scanning electron microscopy and energy dispersive x-ray spectroscopy have been used in conjunction to reveal the process of diffusion. It is inferred from x-ray diffraction and Raman spectroscopy analysis on these stacks that Ni3Si is formed at 200°C, NiSi at 300°C and NiSi2 at 400°C. This study reveals that Ni-Si bilayer films deposited at an elevated temperature and subsequently annealed at the deposition temperature formed monophase Ni silicides.

Capillary filling speed of ferrofluid in hydrophilic microscope slide nanochannels

The capillary filling speed of ferrofluid in hydrophilic nanofluidic channels is investigated under various temperature and constant magnetic field conditions. Nanochannels with depths ranging from 50 to 150 nm and widths of 30 to 200 μm are fabricated on borosilicate glass substrates using buffered oxide wet etching and glass–glass fusion bonding techniques. The capillary filling speed of the ferrofluid is measured experimentally and compared with the theoretical results predicted by the classical Washburn equation. It is found that the experimental filling speed is significantly slower than the theoretical filling speed due to the erroneous assumption in the Washburn model of a constant contact angle irrespective of the flow rate and the presence of flow obstructions. The experimental results show that the filling speed reduces with a reducing channel depth, an increasing ferrofluid concentration, a lower operating temperature and an increased filling length. However, the filling speed is enhanced in the presence of an external magnetic field.

Tip-Enhanced Raman Spectroscopy of Combed Double-Stranded DNA Bundles

Double-stranded (ds) DNA of a λ-phage virus are combed on octadecyltrichlorosilane (OTS)-modified borosilicate glass substrates and investigated by means of tip-enhanced Raman spectroscopy (TERS) u...

Physicochemical Properties of Gold Nanostructures Deposited on Glass

Properties of gold films sputtered onto borosilicate glass substrate were studied. UV‐Vis absorption spectra were used to investigate optical parameters. XRD analysis provided information about the gold crystalline nanostructure, the texture, and lattice parameter and biaxial tension was also determined by the XRD method. The surface morphology was examined by atomic force microscopy (AFM); chemical structure of sputtered gold nanostructures was examined by X‐ray photoelectron spectroscopy (ARXPS). The gold crystallites are preferentially [111] oriented on the sputtered samples. Gold deposition leads to dramatic changes in the surface morphology in comparison to pristine glass substrate. Oxygen is not incorporated into the gold layer during gold deposition. Experimental data on lattice parameter were also confirmed by theoretical investigations of nanoclusters using tight‐binding potentials.

Measuring the localized surface plasmon resonance effect on large arrays (5 mm × 5 mm) of gold and aluminum nanoparticles on borosilicate glass substrates, fabricated by electron beam lithography

Metal nanoparticles have interesting optical properties, in particular, the localized surface plasmon resonance effect (LSPR), which can be used in a range of applications such as photon detectors, photovoltaics, and biosensors. The theory of LSPR is complex, and hence, it is very important to develop reliable model systems, where the properties of the particles can be investigated under controlled conditions. Important parameters, which influence the frequency and intensity of the LSPR, are size, shape, and spacing of the individual nanoparticles, as well as the metal and the surrounding medium. For applications related to photovoltaics, in particular, it is important to investigate the effect of nanoparticles, covering large areas to mimic realistic operating conditions. Here, the authors present a preparation method and optical investigations of LSPR for large arrays (5 mm × 5 mm) of gold and aluminum nanoparticles ranging in diameter from 44 to 140 nm (corresponding to around 120 million particles). The authors compare and see that the LSPR measurements have a good agreement with previously published results from the literature. These measurements from the literature were mostly performed on much smaller arrays. The authors briefly discuss the effect of depositing the nanoparticles on an indium-tin-oxide-coated glass instead of a bare glass substrates and point out an interesting scanning electron microscopy imaging artifact when measuring the samples deposited directly on nonconductive substrates. A shrinkage effect is seen due to sample charging, causing the measured dimensions to appear smaller than the physical size of the object.

A system for measuring complex dielectric properties of thin films at submillimeter wavelengths using an open hemispherical cavity and a vector network analyzer

Quasi-optical (QO) methods of dielectric spectroscopy are well established in the millimeter and submillimeter frequency bands. These methods exploit standing wave structure in the sample produced by a transmitted Gaussian beam to achieve accurate, low-noise measurement of the complex permittivity of the sample [e.g., J. A. Scales and M. Batzle, Appl. Phys. Lett. 88, 062906 (2006); R. N. Clarke and C. B. Rosenberg, J. Phys. E 15, 9 (1982); T. M. Hirovnen, P. Vainikainen, A. Lozowski, and A. V. Raisanen, IEEE Trans. Instrum. Meas. 45, 780 (1996)]. In effect the sample itself becomes a low-Q cavity. On the other hand, for optically thin samples (films of thickness much less than a wavelength) or extremely low loss samples (loss tangents below 10(-5)) the QO approach tends to break down due to loss of signal. In such a case it is useful to put the sample in a high-Q cavity and measure the perturbation of the cavity modes. Provided that the average mode frequency divided by the shift in mode frequency is less than the Q (quality factor) of the mode, then the perturbation should be resolvable. Cavity perturbation techniques are not new, but there are technological difficulties in working in the millimeter/submillimeter wave region. In this paper we will show applications of cavity perturbation to the dielectric characterization of semi-conductor thin films of the type used in the manufacture of photovoltaics in the 100 and 350 GHz range. We measured the complex optical constants of hot-wire chemical deposition grown 1-μm thick amorphous silicon (a-Si:H) film on borosilicate glass substrate. The real part of the refractive index and dielectric constant of the glass-substrate varies from frequency-independent to linearly frequency-dependent. We also see power-law behavior of the frequency-dependent optical conductivity from 316 GHz (9.48 cm(-1)) down to 104 GHz (3.12 cm(-1)).

Nb concentration dependent nanoscale electrical transport properties of granular Ti1−x Nb x N thin films

Granular Ti1−xNbxN thin films, 0 ≤ x ≤ 0.77, were deposited on borosilicate glass substrates by RF magnetron sputtering. Conductive-atomic force microscopy (C-AFM) was employed to study the local electrical transport properties of Ti1−xNbxN thin films. Topography images reveal that the grain size in the films increased from 30 to 90 nm, as x increased from 0 to 0.77. For a constant applied voltage of 1 V, the local leakage current in Ti1−xNbxN films increased with an increase in x value. The measured current is in the order of nA and its flow is filamentary in nature. Current–voltage characteristics measured at different locations on each current image revealed that the local resistance drastically decreased with an increase in Nb concentration. Electron-grain boundary scattering and the presence of native oxide states are responsible for the increase in the local electrical resistance of the films.

Microfabrication of dielectric barrier discharge plasma actuators for flow control

Dielectric barrier discharge (DBD) plasma actuators are a popular type of actuator used in active flow control. However, their performance and broader application are restricted by the manufacturing methods currently employed. A methodology is proposed, with an emphasis on material durability when exposed to plasma, to build more robust plasma actuators, which takes advantage of microfabrication techniques. Thin film electrodes are precisely deposited onto alkali free borosilicate glass substrates, which resist degradation in the presence of plasma, resulting in the batch construction of repeatable actuators with consistent physical and operational properties. The robustness of different electrode materials to the plasma environment is considered via SEM images, EDX elemental analysis and through the homogeneity of the plasma formation.

A wet chemical preparation of transparent conducting thin films of Ga-doped ZnO nanoparticles

Crystalline gallium doped zinc oxide (GZO) nanopowders were synthesized using hydrothermal treatment processing. The doping concentration affected the phase structure as well as the shape of the nanopowder from nano rod-like structure to nanoparticulate one. The specific BET surface area increases with increasing the gallium doping concentration. Transparent conducting films were deposited on borosilicate glass substrate by spin coating using sols containing GZO nanoparticles dispersed in 1-propanol. The films are crystalline with a hexagonal structure. The effect of Ga doping concentration, sintering temperature and thickness of the layers has been investigated. The lowest resistivity achieved was 6.4 × 10−2 Ω cm for a thickness of 150 nm. The films present a transmittance in the visible range as high as 90 %.

Gold nanoparticles deposited on glass: physicochemical characterization and cytocompatibility

Properties of gold films sputtered under different conditions onto borosilicate glass substrate were studied. Mean thickness of sputtered gold film was measured by gravimetry, and film contact angle was determined by goniometry. Surface morphology was examined by atomic force microscopy, and electrical sheet resistance was determined by two-point technique. The samples were seeded with rat vascular smooth muscle cells, and their adhesion and proliferation were studied. Gold depositions lead to dramatical changes in the surface morphology and roughness in comparison to pristine substrate. For sputtered gold structures, the rapid decline of the sheet resistance appears on structures deposited for the times above 100 s. The thickness of deposited gold nanoparticles/layer is an increasing function of sputtering time and current. AFM images prove the creation of separated gold islands in the initial deposition phase and a continuous gold coverage for longer deposition times. Gold deposition has a positive effect on the proliferation of vascular smooth muscle cells. Largest number of cells was observed on sample sputtered with gold for 20 s and at the discharge current of 40 mA. This sample exhibits lowest contact angle, low relative roughness, and only mild increase of electrical conductivity.

Atomic Layer Deposition of Al‐doped ZnO Films Using Aluminum Isopropoxide as the Al Precursor

AbstractAl‐doped ZnO (AZO) films are deposited at 200°C by atomic layer deposition (ALD) on borosilicate glass and Si(001) substrates using diethylzinc (DEZ) and aluminum isopropoxide (AIP) as the Zn and Al precursors, respectively. The effect of the Zn/Al ALD cycle ratio and the AIP source temperature on the Al dopant concentration and resistivity of AZO films is carefully investigated. By changing the AIP temperature from 115°C to 135°C, at the optimal Zn/Al cycle ratio of 19:1, the Al dopant concentration ([Al]/([Al] + [Zn])) in AZO films varies from 0.15 at.‐% to 2.32 at.‐%. The 60 nm thick AZO films deposited at an AIP temperature of 120°C show the lowest resistivity of 9.4 × 10−4 Ω cm, with better optical transparency.

2D plasmonic gold nano-patches for linear and nonlinear applications

We demonstrate the fabrication of a 2D periodic arrangement of gold square nano-patches on both silicon and borosilicate glass substrates whose optical properties can be exploited for both linear and nonlinear applications. The comparison between numerical and experimental results, combined with high-resolution scanning electron microscopy images highlights the importance of the geometry and the fine shape in the determination of the square gold nano-patches optical properties.

Crystallite size and film–substrate interface mediated structural evolution of silicon thin films

The effect of crystallite size and the film–substrate interface on the crystal structure of Si nanoparticles leading to the stabilization of wurtzite structure in Si films is reported. Bilayers of Ni(50nm)/Si(400nm) were deposited on fused silica (FS) and borosilicate glass (BSG) substrates by electron beam evaporation. The as deposited films, which were amorphous, crystallized at a post deposition annealing temperature of 400°C on BSG and 500°C on FS substrates. Electron diffraction studies showed that the nanocrystalline Si on BSG crystallized into the wurtzite structure with a crystallite size of 45nm. In contrast, the nanocrystals of Si on FS crystallized in the diamond cubic structure with a crystallite size of 220nm. The presence of the wurtzite phase is confirmed by the Raman line at 504cm−1, whereas the signature of the cubic phase appears at 520cm−1. The composites with Si in the wurtzite structure exhibit higher refractive index of 2.10 (at 1000nm) than the films with Si in the diamond cubic structure 1.95 (at 1000nm). The optical band gap in both cases is 2.1eV. The stabilization of the wurtzite phase is attributed to the lower crystallite size of Si on the borosilicate glass substrate.

The improvement in the electrical properties of nanospherical ZnO:Al thin film exposed to irradiation using a Co-60 radioisotope

Al doped ZnO (ZnO:Al) thin films were prepared using a sol–gel dip coating technique and deposited on borosilicate glass substrates. The irradiation treatment, was conducted using Co-60 radioisotope, played an important role in enhancing electrical properties. The absorbed dose was a key parameter to decrease the electrical resistivity and to increase carrier density and carrier mobility of nanospherical ZnO:Al thin film. ZnO:Al thin film with the doping of Al at 0.8at% had the lowest electrical resistivity and the highest optical transmittance after the irradiation treatment. Optical properties, such as transmittance and reflectance, were affected at an absorbed dose of 0.2Gy. The curves of optical density were improved at ∼380, 420, and 520nm in visible range after the irradiation process. Besides, another characteristic optical density band between∼900 and 1100nm was enhanced by gamma irradiation. It has been suggested that the mechanism of absorption is related to an allowed direct transition at the irradiated ZnO:Al thin film on borosilicate glass. The optical band gap of the ZnO:Al thin films broadened with increasing doping concentration. However, there is a decrease in optical energy gap of ZnO:Al thin film along with the absorbed dose of the film.

Optical characteristics of wurtzite ZnTe thin films

The growth of wurtzite ZnTe thin films with thickness between 250 and 1000nm on borosilicate glass substrates by electron beam evaporation is reported. The formation of the wurtzite structure was confirmed using X-ray diffraction. The films showed diffraction peaks originating from the (110), (016) and (116) planes, indicating absence of any preferred orientation. The transmission of all the films was of the order of 80% in the near IR region. The refractive index of the wurtzite ZnTe phase increased with increase in thickness from 3.0 at 250nm to 4.2 for the 1000nm thickness film at a wavelength of 1800nm. The optical band gap of these films increased with thickness showing values of 0.85, 0.9 and 0.98eV at 250, 400 and 1000nm thickness, respectively. Chemical composition studies revealed that the films were mildly non-stoichiometric with excess Te. Comparison with the zinc blende structure of ZnTe shows that the wurtzite structure has a higher refractive index, lower band gap and lower charge carrier concentration.

Intrinsic Nitrogen‐doped CVD‐grown TiO2 Thin Films from All‐N‐coordinated Ti Precursors for Photoelectrochemical Applications

AbstractN‐doped titanium dioxide (TiO2) thin films are grown on Si(100) and indium tin oxide (ITO)‐coated borosilicate glass substrates by metal‐organic (MO)CVD. The intrinsic doping of TiO2 thin films is achieved using all‐nitrogen‐coordinated Ti precursors in the presence of oxygen. The titanium amide‐guanidinate complex, [Ti(NMe2)3(guan)] (guan = N,N′‐diisopropyl‐2‐dimethylamidoguanidinato) has been developed to compensate for the thermal instability of the parent alkylamide [Ti(NMe2)4]. Both of these amide‐based compounds are tested and compared as precursors for intrinsically N‐doped TiO2 at various deposition temperatures in the absence of additional N sources. The structure and morphology of TiO2 thin films are characterized by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Rutherford back scattering (RBS), nuclear reaction analysis (NRA), and secondary ion mass spectrometry (SIMS) analyses are performed to determine N content and distribution in the films. The optical and photoelectrochemical properties of TiO2 thin films on ITO substrates are also examined. N‐doped TiO2 thin films, grown from [Ti(NMe2)3(guan)] at 600 °C, exhibit the lowest optical absorption edge (3.0 eV) and the highest visible light photocurrent response. When compared to undoped TiO2, while in UV light photoconversion efficiency decreases significantly, the intrinsically N‐doped TiO2 shows enhanced photocurrents under visible light irradiation.

Tungsten-doped vanadium dioxide thin films on borosilicate glass for smart window application

Tungsten-doped VO2 (W–VO2) thin films with low metal–semiconductor transition temperature (Tt) of 34°C were grown on borosilicate glass substrates by reactive ion beam sputtering at room-temperature (RT) followed by a post annealing process. In order to investigate the thermal process effect, four samples S1–S4 were annealed at different temperatures of 490, 530, 570 and 610°C, respectively. X-ray photoelectron spectroscope and Raman measurements demonstrate that the tungsten atoms have been successfully doped into VO2 films. Unlike VO2 thin films which should be annealed at critical temperature, well crystallized W–VO2 films can be annealed in a wide temperature range, i.e. 530–570°C, as revealed by both electrical and optical property investigations. Besides, the infrared (IR) transmittance measured below/above Tt illustrates that W–VO2 films possess excellent switching efficiency, i.e. 33% at 2500nm for S3. Above all, the near RT phase transition, RT deposition, easy control of annealing process and high IR switching efficiency make the W–VO2 thin film a promising material for application of smart windows.

Preparation and characterization of sputtered aluminum and gallium co-doped ZnO films as conductive substrates in dye-sensitized solar cells

Aluminum and gallium co-doped zinc oxide (GAZnO) films were deposited on borosilicate glass substrates by radio frequency (rf) magnetron technique. The effects of substrate temperature on the structural, optical and electrical properties of the sputtered films were investigated. X-ray diffraction measurement revealed mixed orientations for films prepared at low substrate temperatures, while films prepared at high temperatures were oriented mainly along the (002) direction. Optical transmittance data indicated that the transparency of all the films was above 80% within the visible spectrum, while the electrical resistivity and mobility were improved with increasing substrate temperatures reaching maximum values at 350°C. Finally, using GAZnO films prepared at 300°C and 350°C as transparent conductive substrates in a solar cell sensitized with a metal-free organic dye, light-to-electrical energy conversion efficiency of 3.5 and 3.7% under AM 1.5 irradiation (1000Wm−2 simulated sunlight) was recorded, respectively.

Surface smoothing of glass substrate by irradiation of ionic liquid ion beams

ABSTRACTSurface smoothing of a barium borosilicate glass substrate by irradiation of ionic liquid ion beams were investigated. 1-ethyl-3-methylimidaolium tetrafluoroborate (EMIM-BF4) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) were used for the source liquid. Surface roughness represented as the arithmetic mean value decreased from 0.17 nm to 0.13 nm by the BMIM-PF6 negative ion beam. Secondary electron microscope (SEM) observation for the glass surface irradiated with the BMIM-PF6 negative ion beam showed a clear image without an electrical charge-up, though the EMIM-BF4 negative ion beam irradiated glass yielded a charged up image. X-ray photoelectron spectroscopy (XPS) analysis implied that the surface layer including cation-anion pair of BMIM-PF6 was deposited by the BMIM-PF6 negative ion beam irradiation, while an insulated surface with barium fluoride was formed by the EMIM-BF4 negative ion beam irradiation.