Corning Glass Research Articles

Schottky Diode Based on Microcrystalline Silicon Deposited at 165°C for RFID Application

The design and fabrication of high efficiency low cost electronics components for commercial and industrial applications is very challenging. In this paper we introduce a fabrication of Schottky diode dedicated to high frequency rectification. The devices are prepared on Corning glass substrate with a configuration Au /µc-Si:H /Al and by using microcrystalline silicon as semiconductor. Photolithographic masks are used for diodes fabrication. Two processes are carried out to optimize Schottky diode characteristics. Silicon films are deposited in an usual RF PECVD reactor at low temperature (165°C). Current - voltage (I-V) characteristics are measured and plotted to determine the different parameters of Schottky contact such as ideality factor and rectifying ratio. At 13.56 MHz which is common in RFID frequency application, this Schottky diode in association with parallel load capacitor can be used to build an efficient rectifier.

Frederic Stanley Kipping—Pioneer in Silicon Chemistry: His Life & Legacy

Frederic Stanley Kipping FRS is regarded as one of the founding fathers of silicon chemistry. In 57 research papers published between 1899 and 1944 he reported the first use of Grignard reagents to make alkylsilanes and arylsilanes and the prepartion of silicone oligomers and polymers. He coined the term ‘silicone’ in relation to these materials in 1904. His research formed the foundation for James Franklyn Hyde’s development of the first silicon based insulation materials at Corning Glass Works and then Dow Corning Corp., as well as inspiring Eugene G. Rochow’s work at General Electric Company in the development of the ‘direct method’ of silicone synthesis using silicon hydrides. Kipping was the first Sir Jesse Boot Professor of Chemistry at Nottingham University College and was married to Lily Holland whose sisters, Mina and Kathleen were married to two other prominent early 20th century British Chemists, William H. Perkin Jr. FRS and Arthur Lapworth FRS. This paper provides an insight into Professor Kipping’s life, personality and career.

Mutagenesis Reveals the Complex Relationships between ATPase Rate and the Chaperone Activities of Escherichia coli Heat Shock Protein 70 (Hsp70/DnaK)

The Escherichia coli 70-kDa heat shock protein, DnaK, is a molecular chaperone that engages in a variety of cellular activities, including the folding of proteins. During this process, DnaK binds its substrates in coordination with a catalytic ATPase cycle. Both the ATPase and protein folding activities of DnaK are stimulated by its co-chaperones, DnaJ and GrpE. However, it is not yet clear how changes in the stimulated ATPase rate of DnaK impact the folding process. In this study, we performed mutagenesis throughout the nucleotide-binding domain of DnaK to generate a collection of mutants in which the stimulated ATPase rates varied from 0.7 to 13.6 pmol/microg/min(-1). We found that this range was largely established by differences in the ability of the mutants to be stimulated by one or both of the co-chaperones. Next, we explored how changes in ATPase rate might impact refolding of denatured luciferase in vitro and found that the two activities were poorly correlated. Unexpectedly, we found several mutants that refold luciferase normally in the absence of significant ATP turnover, presumably by increasing the flexibility of DnaK. Finally, we tested whether DnaK mutants could complement growth of DeltadnaK E. coli cells under heat shock and found that the ability to refold luciferase was more predictive of in vivo activity than ATPase rate. This study provides insights into how flexibility and co-chaperone interactions affect DnaK-mediated ATP turnover and protein folding.

Biomimetic hierarchical ZnO structure with superhydrophobic and antireflective properties

A two step method, with a combination of top-down and bottom-up approaches, was developed for the fabrication of ZnO based hierarchical structures with nanorods on microcraters. A layer of well c-axis aligned, transparent, conductive ZnO thin film was deposited by pulsed DC sputtering on a Corning glass substrate. The microcraters were created with anisotropic etching on the as-deposited ZnO thin film. ZnO nanorods were then synthesized onto the etched film by means of metal organic chemical vapor deposition. The resulting hierarchical film exhibits a high water contact angle (>160°) with a low contact angle hysteresis (2°) and low reflection over a wide spectral range. This biomimetic material may find potential applications in many industrial fields, e.g., self-cleaning, solar cells, displays.

Effect of composition and deposition temperature on the characteristics of Ga doped ZnO thin films

ZnO films doped with Ga (GZO) of varying composition were prepared on Corning glass substrate by radio frequency magnetron sputtering at various deposition temperatures of room temperature, 150, 250 and 400 °C, and their temperature dependent photoelectric and structural properties were correlated with Ga composition. With increasing deposition temperature, the Ga content, at which the lowest electrical resistivity and the best crystallinity were observed, decreased. Films with optimal electrical resistivity of 2–3 × 10 −4 Ω cm and with good crystallinity were obtained in the substrate temperature range from 150 to 250 °C, and the corresponding C Ga/( C Ga + C Zn) atomic ratio was about 0.049. GZO films grown at room temperature had coarse columnar structure and low optical transmittance, while films deposited at 400 °C yielded the highest figure of merit (FOM) due to very low optical absorption despite rather moderate electrical resistivity slightly higher than 4 × 10 −4 Ω cm. The optimum Ga content at which the maximum figure of merit was obtained decreased with increasing deposition temperature.

Fabrication and Performance of ACTFEL Display Devices Using Manganese-Doped Zinc Germanate as a Green-Emitting Electroluminescent Layer

Alternating-current thin-film electroluminescent (ACTFEL) display devices fabricated using manganese-doped zinc germanate (Zn2GeO4:Mn) as a green-emitting electroluminescent layer material are described. The ACTFEL display devices were fabricated with a standard bottom emission structure having a multilayer stack of thin films in the metal/semiconductor/insulator/ metal (MSIM) configuration. The device was constructed on a transparent Corning glass substrate through which the emitted EL light passed. The Zn2GeO4:Mn emission layer was synthesized by using a RF magnetron sputter deposition method, followed by post-annealing at 700 C in air ambient for 1 hour. The obtained Zn2GeO4:Mn films were found to be polycrystalline with a rhombohedral crystal structure. A green emission spectrum with a maximum at approximately 538 nm was produced from the fabricated device. The chromaticity color coordinates of the EL emission were measured to be x = 0.308 and y = 0.657. The device demonstrated a sharp increase in the intensity of green EL emission upon increasing the AC peak voltage applied to the device above a threshold of 148 V.

Morphological and structural modifications induced in a-Si1−x C x :H films by excimer laser annealing

Hydrogenated amorphous silicon carbon films of different carbon content deposited by plasma enhanced chemical vapour deposition on Corning glass and crystalline silicon substrates have been irradiated by an excimer (KrF) laser. The properties of these samples were investigated by X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy before and after laser treatment, in order to understand the role of the carbon content as well as the substrate in the structural modifications. It has been demonstrated that the changes induced in the films by the laser treatment are independent of the substrate but depend on the carbon content which facilitates the crystallization process.

Hydrophobic vertically aligned carbon nanotubes on Corning glass for self cleaning applications

Vertically aligned carbon nanotubes were prepared by Plasma enhanced chemical vapor deposition (PECVD) on inexpensive Corning glass substrates using different under layers. The samples were functionalised by a simple 1H,1H-2H,2H perfluorodecyl-trichlorosilane (FDTS) and hexane mixture. The surface roughness of the CNTs and protective FDTS coating provides an ideal hydrophobic surface of around 141°. Auger spectroscopy analysis was performed to confirm fluorination of the sample. It was also found titanium provides a suitable under layer support for Ni catalyst due to the wetability of the two elements.

CdS films deposited by chemical bath under rotation

Cadmium sulfide (CdS) films were deposited on rotating substrates by the chemical bath technique. The effects of the rotation speed on the morphological, optical, and structural properties of the films were discussed. A rotating substrate-holder was fabricated such that substrates can be taken out from the bath during the deposition. CdS films were deposited at different deposition times (10, 20, 30, 40 and 50 min) onto Corning glass substrates at different rotation velocities (150, 300, 450, and 600 rpm) during chemical deposition. The chemical bath was composed by CdCl 2, KOH, NH 4NO 3 and CS(NH 2) 2 as chemical reagents and heated at 75 °C. The results show no critical effects on the band gap energy and the surface roughness of the CdS films when the rotation speed changes. However, a linear increase on the deposition rate with the rotation energy was observed, meanwhile the stoichiometry was strongly affected by the rotation speed, resulting a better 1:1 Cd/S ratio as speed increases. Rotation effects may be of interest in industrial production of CdTe/CdS solar cells.

Characteristics of ZnO:Al thin films co-doped with hydrogen and fluorine

Fluorine and hydrogen co-doped ZnO:Al (AZO) films were prepared by radio frequency (rf) magnetron sputtering of ZnO targets containing 1 wt.% Al 2O 3 on Corning glass at substrate temperature of 150 °C with Ar/CF 4/H 2 gas mixtures, and the structural, electrical and optical properties of the as-deposited and the vacuum-annealed films were investigated. In as-deposited state, films with fairly low resistivity of 3.9–4 × 10 −4 Ω cm and very low absorption coefficient below 900 cm −1 when averaged in 400–800 nm could be fabricated. After vacuum-heating at 300 °C, the minimum resistivity of 2.9 × 10 −4 Ω cm combined with low absorption loss in visible region, which enabled the figure of merit to uplift as high as 4 Ω −1, could be obtained for vacuum-annealed film. It was shown that, unlike hydrogenated ZnO films which resulted in degradation upon heating in vacuum at moderately high temperature, films with fluorine addition could yield improved electrical properties mostly due to enhanced Hall mobility while preserving carrier concentration level. Furthermore, stability in oxidizing environment could be improved by fluorine addition, which was ascribed to the filling effect of dangling bonds at the grain boundaries. These results showed that co-doping of hydrogen and fluorine into AZO films with low Al concentration could be remarkably compatible with thin film solar cell applications.

Photocatalytic degradation of stearic acid by ZnO thin films and nanostructures deposited by different chemical routes

The structural, morphological and photocatalytic properties of ZnO thin films and nanostructures deposited on Corning glass substrates via various chemical routes were investigated. It is demonstrated that the structural and morphological characteristics of the samples depend drastically on deposition technique and parameters. ZnO nanostructured films, nanopetals and nanowires were systematically obtained by varying the experimental conditions. Sol–gel method leads to the formation of dense ZnO nanostructured thin films with a preferred growth orientation along the (0 0 2) crystallographic direction, while ultrasonic spray pyrolysis results in ZnO nanopetals, their dimensions increasing with spraying time. On the other hand, highly oriented ZnO nanowires were obtained via aqueous solution growth on seeded Corning substrates. All ZnO samples show remarkable photocatalytic activity regarding the degradation of stearic acid, which is attributed to their good crystallinity and large surface area. In particular, ZnO nanowires exhibit an outstanding photocatalytic activity, degrading stearic acid by almost 93% in 30 min. This behaviour is mainly due to their high surface-to-volume ratio.

Characterizations of nanostructured silicon‐carbon films deposited on p‐layer by PECVD

AbstractNanostructured silicon carbon films composed of silicon nanocrystallites embedded in the amorphous silicon carbon matrix are prepared by a rf‐PECVD system at 250 °C from silane and methane gas mixture highly diluted in hydrogen onto 7059 Corning glass and p‐layer deposited on tin oxide substrates by varying rf power from 25 to 65 W. The structural and compositional properties of the films have been investigated. The study demonstrates that rf power controls the crystalline fraction as well as the silicon crystallite size and that p‐layer/tin oxide structure enhances the nucleation of silicon grains as compared to Corning glass (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Preparation and characterization of flash-evaporated CuInSe 2/CuGaSe 2 thin films

Deposition of CuInSe 2 thin film on CuGaSe 2 thin film (CuInSe 2/CuGaSe 2) has been prepared by flash evaporation technique on Corning glass substrates heated at T s = 250 °C and annealed at 450 °C in an argon atmosphere. The properties of the resulting films have been examined by scanning electron microscopy (SEM) and X-ray diffraction. The optical measurements have been carried out in the wavelength range 500–3000 nm. X-ray diffraction revealed that the film was single-phase with chalcopyrite structure and has a preferred orientation along the (1 1 2) plane. The determined lattice parameters were a = 5.75 Å and c = 11.56 Å. SEM micrographs revealed grain sizes ranging from 0.03 μm to 0.04 μm. The thickness of the thin films is around 0.8 μm. The absorption coefficient of this film was above 2.25 × 10 4 cm −1 and the band gap was found to be 1.14 eV. The annealing in Ar did not influence the composition of the layers considerably but improved the crystalline structure quality.

Study of structural and optical properties of Sb doped ZnO thin films deposited by spin coating method

Structural and optical properties of Sb doped ZnO thin films have been investigated. The films were prepared by chemical colloidal route and deposited on Corning glass substrates using spin coating method. It is found that Sb doping of ZnO thin films highly alters the surface morphology, the crystallite sizes and the optical band gap of the films.

High substrate temperature induced anomalous phase transition temperature shift in sputtered VO 2 thin films

Vanadium dioxide (VO 2) thin films were deposited onto Corning glass substrates by rf reactive inverted cylindrical magnetron sputtering at different substrate temperatures ( T s) ranging from 450 to 600 °C. The influence of substrate temperature on the structural and optical properties was systematically investigated. It revealed that the crystallinity of the VO 2 films improved significantly with T s. The substrate temperature to obtain films with transition temperature ( T c ∼ 70 °C) similar to VO 2 bulk single crystal was 450–500 °C, while high substrate temperatures from 550 to 600 °C tend to shift T c towards higher temperatures from 75 to 80 °C keeping the sharpness of the transition unaltered. Even if the variation of the T c of VO 2 is not dramatic “variation from 70 to 80 °C” with increasing T s is substantial for undoped VO 2 thin films. This sizeable variation of ∼10 °C confirms the tunability of the T c of VO 2 through T s.

Metal-free CNTs grown on glass substrate by microwave PECVD

We investigated the growth of metal-free carbon nanotubes (CNTs) on glass substrates with a microwave plasma enhanced chemical-vapor deposition (MPECVD) method. An amorphous carbon (a-C) layer was used as a catalyst layer to grow metal-free CNTs. The a-C layer was deposited on Corning glass substrates with a RF magnetron sputtering method using a carbon target at room temperature. The CNTs were prepared with the use of a MPECVD method by using methane (CH 4) and hydrogen (H 2) gas. We have pretreated a-C catalyst layer using H 2 plasma at 600 °C for 3 min, and the CNTs were grown with the different thickness of a-C catalyst layer for 30 min at 600 °C. Also, we investigated the growth trend of the CNTs against the growth time with the substrate of a-C catalyst layer that has optimized thickness. Field-emission scanning electron microscopy (FE-SEM) images showed the growth trend of the CNTs against the thickness of a-C catalyst layer and growth time. Raman spectroscopy of CNTs shows that the grown CNTs were multi-walled. Energy dispersive spectroscopy (EDS) measurements confirmed that the CNTs consisted solely of carbon.

A simple method toward high density SrM dot arrays

Strontium ferrite thin films have been deposited on Corning glass with Au underlayer by using DC magnetron sputtering system. Au island structure can be formed on Corning glass by heating the substrate over 100°C. In order to achieve higher Au dot density and consequently higher density of SrM, an attempt to decreasing Au thickness has been carried out. The maximum of coercivity and remanent squareness ratio in perpendicular direction are almost constant at 2.3kOe and 0.45, respectively, at Au underlayer thickness from 4nm to 8nm. The magnetic interaction between SrM grains prepared on Au nano-dots is less than that for the continuous film.

ZnO Films Growth at Different Temperature on the Substrate of Corning Glass by MOCVD

We deposited ZnO films on Corning glass substrate by metal-organic chemical vapor deposition (MOCVD). We found the diffraction (002) peak at ~34.46°, indicating that the ZnO thin films were C-oriented. ZnO films were highly transparent with a transmission ratio larger than 85% in the visible range. The surface morphology of the films was observed by atomic force microscopy (AFM).

Heme-binding Protein HRG-1 Is Induced by Insulin-like Growth Factor I and Associates with the Vacuolar H+-ATPase to Control Endosomal pH and Receptor Trafficking

Endocytosis and trafficking of receptors and nutrient transporters are dependent on an acidic intra-endosomal pH that is maintained by the vacuolar H(+)-ATPase (V-ATPase) proton pump. V-ATPase activity has also been associated with cancer invasiveness. Here, we report on a new V-ATPase-associated protein, which we identified in insulin-like growth factor I (IGF-I) receptor-transformed cells, and which was separately identified in Caenorhabditis elegans as HRG-1, a member of a family of heme-regulated genes. We found that HRG-1 is present in endosomes but not in lysosomes, and it is trafficked to the plasma membrane upon nutrient withdrawal in mammalian cells. Suppression of HRG-1 with small interfering RNA causes impaired endocytosis of transferrin receptor, decreased cell motility, and decreased viability of HeLa cells. HRG-1 interacts with the c subunit of the V-ATPase and enhances V-ATPase activity in isolated yeast vacuoles. Endosomal acidity and V-ATPase assembly are decreased in cells with suppressed HRG-1, whereas transferrin receptor endocytosis is enhanced in cells that overexpress HRG-1. Cellular uptake of a fluorescent heme analogue is enhanced by HRG-1 in a V-ATPase-dependent manner. Our findings indicate that HRG-1 regulates V-ATPase activity, which is essential for endosomal acidification, heme binding, and receptor trafficking in mammalian cells. Thus, HRG-1 may facilitate tumor growth and cancer progression.

Electrical and optical properties of (PPh 4) 2[Fe(CN) 5NO] non-crystalline thin films prepared with the vacuum thermal evaporation technique

Molecular-material thin films of (PPh 4) 2[Fe(CN) 5NO] and a double potassium salt from 1,8-dihydroxyanthraquinone have been prepared by vacuum thermal evaporation on Corning glass substrates and crystalline silicon wafers. The surface morphology, thickness and structure of the deposited films were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), ellipsometric measurements, ultraviolet–visible (UV–vis) and Fourier-transform infrared (FT-IR) spectroscopies. The amorphous films show the same intra-molecular bonds as the IR spectroscopic studies, which suggests that the thermal evaporation process did not alter the initial chemical structures. The conductivity and the electrical-conduction mechanism in the thin films were also investigated. Finally, the optical band gap ( E g) of these molecular complexes was evaluated from optical absorption measurements.