Corning Glass Research Articles

Effect of Oxygen Plasma Treatment on Characteristics of TiO$_{2}$ Photodetectors

In this study, titanium dioxide (TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) films were prepared on Corning glass substrates by radio frequency (RF) magnetron sputtering and treated with different O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plasma conditions, and then were used to fabricate metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors (PDs). The effects of the changes on TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> films were investigated by using field-emission scanning electron microscope (FE-SEM), photoluminescence (PL) system and four-point probe measurement. With a 360-nm illumination and 5 V applied bias, it was found that the responsivities of the fabricated TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> PDs with 0, 1, 2, and 3 min O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plasma treatment were 36, 144, 153, and 53 A/W, respectively.

Long wavelength infrared detection using amorphous InSb and InAs0.3Sb0.7

The structural, electronic, and optical properties of amorphous InSb and InAs0.3Sb0.7 films deposited on Corning glass, Al2O3 CdZnTe, SiO2-Si, and CaF2 substrates by Radio Frequency (RF) magnetron sputtering have been studied as they relate to Mid and Long Wavelength Infrared (MWIR and LWIR) detection. Depositions at elevated substrate temperature and pressure of <10mTorr Ar showed an emergence of crystalline grains with strong X-ray diffraction peaks at the (111) and (220) orientations. Electronically, the amorphous InSb and InAs0.3Sb0.7 films deposited at 300K show hopping conduction with resistance in InSb ranging from 44 to 1.1E8Ω-cm at 300K and 84K, respectively. Optical analysis using Fourier transform infrared spectroscopy (FTIR) shows the absorption of these films has an absorption tail, which shows the differing activation energies in InSb and InAs0.3Sb0.7. Amorphous InSb and InAs0.3Sb0.7 films showed responsivity in excess of 100V/W for 6μm thick films held at 233K.

Silencer of Death Domains (SODD) Inhibits Skeletal Muscle and Kidney Enriched Inositol 5-Phosphatase (SKIP) and Regulates Phosphoinositide 3-Kinase (PI3K)/Akt Signaling to the Actin Cytoskeleton

Phosphoinositide 3-kinase (PI3K) regulates cell polarity and migration by generating phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P(3)) at the leading edge of migrating cells. The serine-threonine protein kinase Akt binds to PI(3,4,5)P(3), resulting in its activation. Active Akt promotes spatially regulated actin cytoskeletal remodeling and thereby directed cell migration. The inositol polyphosphate 5-phosphatases (5-ptases) degrade PI(3,4,5)P(3) to form PI(3,4)P(2), which leads to diminished Akt activation. Several 5-ptases, including SKIP and SHIP2, inhibit actin cytoskeletal reorganization by opposing PI3K/Akt signaling. In this current study, we identify a molecular co-chaperone termed silencer of death domains (SODD/BAG4) that forms a complex with several 5-ptase family members, including SKIP, SHIP1, and SHIP2. The interaction between SODD and SKIP exerts an inhibitory effect on SKIP PI(3,4,5)P(3) 5-ptase catalytic activity and consequently enhances the recruitment of PI(3,4,5)P(3)-effectors to the plasma membrane. In contrast, SODD(-/-) mouse embryonic fibroblasts exhibit reduced Akt-Ser(473) and -Thr(308) phosphorylation following EGF stimulation, associated with increased SKIP PI(3,4,5)P(3)-5-ptase activity. SODD(-/-) mouse embryonic fibroblasts exhibit decreased EGF-stimulated F-actin stress fibers, lamellipodia, and focal adhesion complexity, a phenotype that is rescued by the expression of constitutively active Akt1. Furthermore, reduced cell migration was observed in SODD(-/-) macrophages, which express the three 5-ptases shown to interact with SODD (SKIP, SHIP1, and SHIP2). Therefore, this study identifies SODD as a novel regulator of PI3K/Akt signaling to the actin cytoskeleton.

Influence of deposition regime on physical properties of gallium doped zinc oxide films

Zinc oxide films doped by gallium were deposited using RF diode sputtering from a ceramic ZnO + 2% Ga2O3 target on Corning glass in argon atmosphere. Samples were supported in three different positions against a substrate holder – horizontal, and at 60 and 80° to the horizontal position. Two series of samples 700–1000 nm in thickness were prepared: one at room temperature (RT) and the second at 200 °C. XRD, optical and electrical experiments indicated that the films are polycrystalline having average crystallite sizes from 30 to 80 nm, integrated transmittances in the range of 400–1000 nm increased from 85 to 90 per cent and optical band-gap values increased from 3 to 3.2 eV with higher deposition temperature. The resistivity of the obliquely sputtered samples positioned at 80° to the substrate holder was one order lower than the horizontally positioned samples. No significant changes were observed in case of optical properties of the films in dependence on the tilt-angle.

Characterization of gallium–nitrogen co-doped zinc oxide thin films prepared by RF diode sputtering

We investigated the possibility of achieving p-type zinc oxide (ZnO) by RF diode sputtering and gallium–nitrogen co-doping. ZnO:Ga:N thin films were prepared with a different N2 content in Ar/N2 working gas, ranging from 0 to 100%, and at a varying substrate temperature, from room temperature (RT) to 300 °C. A hole conduction with maximum carrier concentration of 2.6 × 1018 cm−3, mobility of 2 cm2/Vs and resistivity of 1.5 Ω cm resulted from deposition at RT with 100% N2. It arose from N incorporation and formation of NO acceptors. In the secondary ion mass spectrometry (SIMS) depth profiles of the co-doped films were observed NO/NO2 negative ions. Average transmittance (including Corning glass substrate) across the visible spectrum varied (60 ÷ 66%) with increasing nitrogen content (50 ÷ 100% N2). As the substrate temperature increased (RT – 300 °C), highly transparent (T ∼72–83%) and conductive (electron concentrations of 1017–1019 cm−3) n-type ZnO:Ga:N films were attained. Reduction of optical band gap (Eg) (∼3.13–3.08 eV) was observed for co-doped ZnO films. Atomic force microscopy (AFM) images revealed that the films grown at RT have roughness of approximately 5.3 nm while roughness of those grown at 300 °C is approximately 3.9 nm.

Ion sputter etching of ZnO:Ga thin film surfaces

In this article the modification of surface morphology of ZnO:Ga (GZO) thin films by ion sputter etching is presented. GZO thin films were prepared at room temperature on Corning glass substrates by both normal and oblique angle RF diode sputtering from ZnO:2%Ga ceramic target in Ar gas. Ion sputter etching was performed by RF re-sputtering of GZO thin films on substrates. During RF sputter etching, Ar pressure of 1.3Pa and RF power of 250W were kept constant, only the time of sputter etching was changed. Ion sputter etching had remarkable influence on surface morphology of GZO thin films: increase of roughness Rq and the “homogenization” of film surfaces, i.e. skewness (Rsk) and spikiness (Rku) parameters (Rsk≈0/Rku≈3).Surface root-mean-square roughness (Rq) increased from 15.3nm (after sputter deposition) to 29.1nm (after ion sputter etching). For obliquely thin films increased from 16.5nm (after sputter deposition) to 38.2nm. Changes of these parameters Rq, Rsk, Rku influenced optical properties of GZO films, increased Haze parameter up to values 7.7% and width of optical band gap 3.44eV, respectively.

Effective production of the biodiesel additive STBE by a continuous flow process

A new fuel additive, namely solketal tert-butyl ether (STBE), was developed and optimized under continuous flow conditions using a Corning® Advanced-Flow™ glass reactor. STBE was obtained in two steps from glycerol, a renewable building-block produced in large amount in the processing of biodiesel. The advantages of the highly engineered Corning glass reactor included high mixing and heat-exchange efficiency, chemical resistance under corrosive flow conditions and a small hold-up. A robust, continuous, green and safe industrial-scale process is described.

Electrical properties of vacuum-annealed titanium-doped indium oxide films

Titanium-doped indium oxide (ITiO) films were deposited on Corning glass 2000 substrates at room temperature by radio frequency magnetron sputtering followed by vacuum post-annealing. With increasing deposition power, the as-deposited films showed an increasingly crystalline nature. As-deposited amorphous ITiO films obtained at 20 W began to crystallize at the annealing temperature of 155 °C. Although there was no significant change in the crystalline structure of the films, electron mobility improved gradually with further increase in the annealing temperature. After post-annealing at 580 °C, the highest electron mobility of 50 cm 2 V −1 s −1 was obtained. Compared with the amorphous ITiO films, the ITiO films with a certain degree of crystallinity obtained at high deposition power were less affected by the vacuum annealing. Their electron mobility also improved due to post-annealing, but the increase was insignificant. After post-annealing, the optical transmission of the 325 nm-thick ITiO films showed approximately 80% at wavelengths ranging from 530 to 1100 nm, while the sheet resistance decreased to 10 Ω/sq. This makes them suitable for use as transparent conductive oxide layers of low bandgap solar cells.

Thickness Dependent Magnetic and Structural Properties of CoxCr1–x Thin Films Evaporated on Si(100) and Glass Substrates

Series of Co(x)Cr(1-x) thin films have been prepared by thermal evaporation onto Si(100) and Corning glass substrates, x ranging from 1 to 0.60, and the magnetic layer thickness from 17 to 220 nm. The dependence of the magnetic and crystallographic properties on the thickness of CoCr layers have been investigated. The chromium content effect on the saturation magnetization of the films has also been examined. Microscopic characterizations of the films, performed with X-ray diffraction (XRD) measurements, infer that all the samples are composed of hcp phase crystallites with good orientation of the c axis showing a (0001) preferred orientation. The grain size increases with thickness. Atomic force microscopy (AFM) observations show very smooth film surfaces, the highest rms value being 18 amgstroms. The saturation magnetization M(s) was found to decrease from 1400 emu/cm3 to a few emu/cm3 as x decreases from 1 to 0.60, for all values of the thickness. In-plane squareness up to S = 0.83 has been observed for the CoCr/Si thinnest film, and S = 0.90 for the Co/Si thinnest film, too. Magnetic Force Microscopy (MFM) study points out the absence of stripe domains equilibrium magnetization structure for the CoCr thin films whereas the thick Co films present a well defined stripe pattern. From the magnetocrystalline anisotropy field H(a) values extracted from the fit of the BLS spectra, we have computed effective magnetic anisotropy factors K(u), as well. Their negative values for the CoCr samples confirm an in-plane magnetic anisotropy for the thin film magnetization.

Optical properties of amorphous hydrogenated and microcrystalline silicon films prepared by plasma enhanced chemical vapor deposition and re‐crystallized at moderate temperatures

AbstractAmorphous hydrogenated silicon films different in thickness (600 – 2400 nm) were deposited by plasma enhanced chemical vapour deposition on Corning glass substrates at 250 °C using silan 10% / argon 90% gas mixture. The samples were consequently isothermally heated in a high temperature vacuum chamber at 0.1 Pa and at temperatures from 580 to 620 °C. In order to evaluate structural and optical properties of the films X‐ray diffraction analysis, Raman spectrometry and optical spectrophotometry were used. Crystalline state (amorphous or microcrystalline), optical band gaps, refractive indices, extinction coefficients, absorption coefficients were determined. X‐ray diffraction analysis indicated that originally deposited films were amorphous with different degree of homogeneity depending on the film thickness. After the heat treatment the films became polycrystalline with crystallite sizes 40‐50 nm without particular dependence on the recrystallization process used. Raman spectrometry confirmed the results obtained from X‐ray diffraction and furthermore revealed the residual amorphous phase 20–25% in volume. Optical spectrophotometry has shown that the values of refractive indices of thermally treated films approach the mono‐crystalline silicon refractive index. Extinction coefficients of the thermally treated films are slightly higher than those for monocrystalline silicon. Absorption coefficients for thermally treated films reached quite high values near the absorption edge of the original amorphous material, which can be advantageous for tandem solar cell technologies. (© 2011 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Matrix Metalloproteinase (MMP)-9 Induced by Wnt Signaling Increases the Proliferation and Migration of Embryonic Neural Stem Cells at Low O2 Levels

Recent studies have shown that various neural and embryonic stem cells cultured in 1-8% oxygen (O(2)), levels lower than those typically used in cell culture (20.9%), displayed increased rates of proliferation; however, the molecular mechanisms underlying these changes are largely undefined. In this study, using rigorously controlled O(2) levels, we found that neural stem cells (NSCs) from embryonic day 15 rat cortex increased their rate of proliferation and migration in 1% O(2) relative to 20% O(2) without changes in viability. We sought to identify molecular changes in NSCs grown in 1% O(2) that might account for these increases. In 1% O(2), levels of the hypoxia-inducible transcription factor HIF-1α were transiently increased. Reduced adherence of NSCs in 1% O(2) to basement membrane-coated plates was observed, and quantitative RT-PCR analysis confirmed that the levels of mRNA for an assortment of cell adhesion and extracellular matrix molecules were altered. Most notable was a 5-fold increase in matrix metalloproteinase (MMP)-9 mRNA. Specific inhibition of MMP-9 activity, verified using a fluorescent substrate assay, prevented the increase in proliferation and migration in 1% O(2). The canonical Wnt pathway was recently shown to be activated in stem cells in low O(2) via HIF-1α. Inhibition of Wnt signaling by DKK-1 also prevented the increase in proliferation, migration, and MMP-9 expression. Thus, MMP-9 is a key molecular effector, downstream of HIF-1α and Wnt activation, responsible for increased rates of NSC proliferation and migration in 1% O(2).

High quality textured ZnO:Al surfaces obtained by a two-step wet-chemical etching method for applications in thin film silicon solar cells

ZnO:Al films deposited at 250 °C on Corning glass by radio frequency magnetron sputtering were studied for their use as front contact for thin film silicon solar cells. For this purpose, a two-step etching method combining different concentrations of diluted hydrochloric acid (from 0.1% to 3%) with different etching times was developed. Its influence on morphological, electrical and optical properties of the etched films was evaluated. This new etching method led to more uniform textured surfaces, where the electrical properties remained unchangeable after the etching process, and with adapted light scattering properties similar to those exhibited by commercial substrates.

Characterization of defects in hydrogenated amorphous silicon deposited on different substrates by capacitance techniques

Hydrogenated amorphous silicon (a-Si:H) thin films deposited on crystalline silicon and Corning glass substrate were analyzed using different capacitance techniques. The distribution of localized states and some electronic properties were studied using the temperature, frequency and bias dependence of the Schottky barrier capacitance and deep level transient spectroscopy. Our results show that the distribution of the gap states depends on the type of substrate. We have found that the films deposited on c-Si substrate represent only one positively charged or prerelaxed neutral deep state and one interface state, while the films deposited on glass substrate have one interface state and three types of deep defect states, positively or prerelaxed neutral, neutral and negatively charged.

Optical, electrical and morphological properties of transparent binary doped polyaniline thin films synthesized by in situ chemical bath deposition

The development of polymeric thin films has attracted attention in the optoelectronics field due to their transparency. The aim of the research presented was to obtain transparent polyaniline thin films by easy in situ oxidative polymerization of aniline with ammonium persulfate in the presence of a binary doping agent–poly(vinyl alcohol) mixture. Poly(acrylic acid), 2-acrylamido-2-methyl-1-propanesulfonic acid or sodium dodecylsulfate were mixed with hydrochloric acid to form the binary doping agents. Polyaniline thin films were produced during aniline polymerization on Corning glass slides immersed in the mixture in order to study their optical, electrical and morphological properties. The optical absorption coefficient and the energy band gap were evaluated by optical transmission of the films in the UV-visible spectral region. The optical absorption coefficient of all polyaniline films was of the order of 104 cm−1 with a maximum transmittance up to 80% at 550 nm. In order to investigate the effect of the mixture on the surface morphology and roughness of the films, atomic force microscopy was used. In general, surface roughness was reduced threefold by adding a mixture and optical transmission was increased by 20–30% without significantly affecting the absorption coefficient and the band gap of polyaniline. Islands and needle-like structures on the film surfaces were obtained from various mixtures affecting the conductivity; for example, 0.17 S cm−1 was obtained from needle-like morphology, while 1.9 × 10−4 S cm−1 was obtained from island morphology. Raman spectroscopy studies confirmed the presence of poly(vinyl alcohol) in the thin films. Copyright © 2011 Society of Chemical Industry

Electrical and Optical Properties of Indium and Aluminium Doped Zinc Oxide Films Prepared by RF Magnetron Sputtering

ZnO: In (IZO, 10wt % In2O3) and ZnO: Al (AZO, 1wt % Al2O3) films were deposited on Corning glass substrates by RF magnetron sputtering. The samples were either prepared on unheated substrates and post annealed in N2 at different temperatures, or prepared at elevated temperatures. Electrical, optical and structural properties were investigated as a function of deposition temperature and annealing temperature. Increasing the substrate heater temperature would lead to a decline in the electrical conductivity of IZO films, while AZO films showed unchanged performance in the substrate heater temperature range of 150 - 300°C. Post annealing appears to be an effective way to improve the electrical properties of both IZO and AZO films without sacrificing transparency. In this work, AZO films have higher conductivity and light transmission than IZO films.

Transparency and electrical properties of meshed metal films

Meshed silver/titanium films, deposited on a 1737 Corning glass substrate by radiofrequency (r.f.) magnetron sputtering and etched by wet process, have been studied. Sputtering parameters have been specifically optimized for thick Ag layer deposition (>3μm) and are discussed. An original excimer laser etching process is used for removing the resist for making the prototypes. Simple sheet resistance and optical transparency computings have been used for the theoretical study. A good agreement is obtained with the experimental results. Transparent and conducting samples have been realized with optical transmittances and sheet resistances ranging from 71% to 81% and from 0.023Ω/□ to 1.03Ω/□, respectively. Hence we demonstrate the independence between optical transparency and sheet resistance for this material AgGL (Ag Grid Layer). The relevance of the mesh structure has been highlighted by the achievement of samples with high level of transparencies and ultra-low sheet resistances.

Investigation of Molybdenum Doped ZnO Thin Films Prepared by Spray Pyrolysis Technique

Molybdenum doped zinc oxide thin films were deposited on the Corning glass substrates pre-heated to 400°C by spray pyrolysis technique. The effect of molybdenum doping concentration (0–2 at.%) on the structural and optical properties of zinc oxide thin films was studied. X-ray diffraction analysis confirmed that the molybdenum doped ZnO films belong to the hexagonal crystal structure of ZnO. Atomic force microscopic studies revealed the effect of molybdenum doping on the surface morphology of these films. The 1 at.% Mo doped ZnO exhibited highest average transmittance of ∼87% in the visible region (400–800 nm). Optical bandgap energy of the ZnO and Mo doped ZnO films lies in the range of 3.28–3.33 eV. Annealing of the high resistive ZnO and Mo doped ZnO films at 400°C in vacuum for 60 min improved their resistivity. The minimum resistivity of 4.7 × 10−2 Ω cm and the maximum carrier concentration of 1.27 × 1019 cm−3 were achieved for 1 at.% Mo doped ZnO films.

Characteristics of sputtered zinc-oxide films prepared by UBM sputtering for thin film transistors

In this work, we describe the characteristics of zinc-oxide (ZnO) thin films synthesized on Si (001) and Corning (7059) glass substrates by unbalanced magnetron (UBM) sputtering under various ZnO film thicknesses and RF powers. We investigated the characteristics of ZnO films' structural, optical, and electrical properties with various film thicknesses and RF powers for the active channel in a thin film transistor (TFT). We used the UBM sputtering system for high rate deposition of ZnO films. The ZnO film surface was rough and the grain size of the film increased with increasing RF power and film thickness. The electrical properties improved with the increase of RF power and film thickness. These results can be explained by the improvement of the crystallinity in the ZnO film related to the grain size increase with increasing RF power and ZnO film thickness.

Nucleocytoplasmic Shuttling of Dysbindin-1, a Schizophrenia-related Protein, Regulates Synapsin I Expression

Dysbindin-1 is a 50-kDa coiled-coil-containing protein encoded by the gene DTNBP1 (dystrobrevin-binding protein 1), a candidate genetic factor for schizophrenia. Genetic variations in this gene confer a susceptibility to schizophrenia through a decreased expression of dysbindin-1. It was reported that dysbindin-1 regulates the expression of presynaptic proteins and the release of neurotransmitters. However, the precise functions of dysbindin-1 are largely unknown. Here, we show that dysbindin-1 is a novel nucleocytoplasmic shuttling protein and translocated to the nucleus upon treatment with leptomycin B, an inhibitor of exportin-1/CRM1-mediated nuclear export. Dysbindin-1 harbors a functional nuclear export signal necessary for its nuclear export, and the nucleocytoplasmic shuttling of dysbindin-1 affects its regulation of synapsin I expression. In brains of sandy mice, a dysbindin-1-null strain that displays abnormal behaviors related to schizophrenia, the protein and mRNA levels of synapsin I are decreased. These findings demonstrate that the nucleocytoplasmic shuttling of dysbindin-1 regulates synapsin I expression and thus may be involved in the pathogenesis of schizophrenia.

MiR-200a Regulates Epithelial-Mesenchymal to Stem-like Transition via ZEB2 and β-Catenin Signaling

The emerging concept of generating cancer stem cells from epithelial-mesenchymal transition has attracted great interest; however, the factors and molecular mechanisms that govern this putative tumor-initiating process remain largely elusive. We report here that miR-200a not only regulates epithelial-mesenchymal transition but also stem-like transition in nasopharyngeal carcinoma cells. We first showed that stable knockdown of miR-200a promotes the transition of epithelium-like CNE-1 cells to the mesenchymal phenotype. More importantly, it also induced several stem cell-like traits, including CD133(+) side population, sphere formation capacity, in vivo tumorigenicity in nude mice, and stem cell marker expression. Consistently, stable overexpression of miR-200a switched mesenchyme-like C666-1 cells to the epithelial state, accompanied by a significant reduction of stem-like cell features. Furthermore, in vitro differentiation of the C666-1 tumor sphere resulted in diminished stem-like cell population and miR-200a induction. To investigate the molecular mechanism, we demonstrated that miR-200a controls epithelial-mesenchymal transition by targeting ZEB2, although it regulates the stem-like transition differentially and specifically by β-catenin signaling. Our findings reveal for the first time the function of miR-200a in shifting nasopharyngeal carcinoma cell states via a reversible process coined as epithelial-mesenchymal to stem-like transition through differential and specific mechanisms.