Sputtered Oxide Layers Research Articles

Simultaneous improvement of corrosion resistance and bioactivity of a titanium alloy via wet and dry plasma treatments

The fabrication of bioactive oxide layers on Ti–6Al–4V alloy by combining of wet and dry plasma methods for optimizing the chemical stability and biological activity together was reported. To achieve this goal, dry plasma sputtering depositions of Mg and Zn in the RF and DC modes, respectively, were performed for 5 and 20 min on the surface of titanium oxide obtained by wet plasma electrolytic oxidation of Ti–6Al–4V alloy substrate. Zn and Mg particles were successfully introduced into the titanium oxide layer which not only leads to decrease the fraction and size of microdefects but also increases the fraction of biocompatible anatase phase in compassion to that in the un-sputtered oxide layer. The corrosion resistance of sputtered oxide layers was superior to the un-sputtered layer. Regarding the hydroxyapatite formation and cell proliferation, Zn and Mg particles incorporated in less amounts in the sample sputtered for 5 min were of considerable significance in facilitating the nucleation and growth of hydroxyapatite and proliferation of MC3T3-E1 on the surface of this sample. Thus, the oxide layer containing Zn and Mg particles would be used as a promising implant material due to its great intrinsic chemical stability and osteointegration ability.

Amorphous optical coatings of present gravitational-wave interferometers**This article is dedicated to the memory of L Balzarini.

We report on the results of an extensive campaign of optical and mechanical characterization of the ion-beam sputtered oxide layers (Ta2O5, TiO2, Ta2O5–TiO2, SiO2) within the high-reflection coatings of the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors: refractive index, thickness, optical absorption, composition, density, internal friction and elastic constants have been measured; the impact of deposition rate and post-deposition annealing on coating internal friction has been assessed. For Ta2O5 and SiO2 layers, coating internal friction increases with the deposition rate, whereas the annealing treatment either erases or largely reduces the gap between samples with different deposition history. For Ta2O5–TiO2 layers, the reduction of internal friction due to TiO2 doping becomes effective only if coupled with annealing. All measured samples showed a weak dependence of internal friction on frequency [ϕc(f) = afb, with −0.208 < b < 0.140 depending on the coating material considered]. SiO2 films showed a mode-dependent loss branching, likely due to spurious losses at the coated edge of the samples. The reference loss values of the Advanced LIGO and Advanced Virgo input (ITM) and end (ETM) mirror HR coatings have been updated by using our estimated value of Young’s modulus of Ta2O5–TiO2 layers (120 GPa) and are about 10% higher than previous estimations.

Roll-to-roll thin film coating on fluoropolymer webs – Status, challenges and applications

Thin film deposition on fluoropolymer webs – both in vacuum and at atmospheric pressure – faces several critical challenges such as poor mechanical and thermo-mechanical properties – especially low dimensional stability and low elastic modulus, high and textured surface roughness and low adhesion of thin films.This paper discusses critical process parameters in roll-to-roll processing for both vacuum processes and wet coating processes with respect to the unique properties of fluoropolymer webs. Reactively sputtered oxide layers as well as wet coated ORMOCER® layers are deposited on ETFE, PVDF and ECTFE webs to form single- and multi-layer permeation barrier systems. The influence of relevant process parameters on the layer adhesion and permeation barrier performance is reviewed. Permeation barrier coatings have been selected as main application for this study, because they are very sensitive to substrate surface irregularities and mechanical damage due to low adhesion, high strain or roll-to-roll processing issues and therefore are a good measure for the quality of the coating on the substrate.Both the wet coated ORMOCER® layers and reactively sputtered zinc-tin oxide (ZTO) layers show surprisingly good adhesion on both ETFE and PVDF surfaces. Both ZTO and – with adhesion promotion treatment – also aluminum oxide (Al2O3) layers have the potential for low water transmission rates (WVTR) below 5·10−2g/(m2d) at 38°C/90% r.h. on these substrates. Further reduction of the WVTR is demonstrated with a combination of wet coated ORMOCER® layers and sputtered ZTO layers yielding a WVTR of 1·10−3g/(m2d) at 38°C/90% r.h. These values were achieved using adapted process parameters and layer stack designs such as reduced web tension and lower layer thicknesses. The results shown in this paper demonstrate the potential of coated fluoropolymer webs for functionalization of membrane roofs and façades with flexible thin film solar cells; thermal insulation and solar control functionality; flexible thin film electroluminescent and OLED lighting panels as well as electrochromic devices.

The Oxide TFT By Anodic Oxidation

Oxide-TFTs (thin film transistors) have been studied and are being applied to the AMLCD and AMOLED. One advantage of the oxide TFT is higher mobility than amorphous silicon TFT. The oxide material such as IGZO (indium gallium zinc oxide) is sputtered for the active layer. In this experiment, we used anodic oxide instead of sputtered oxide layer. Anodizing is to oxidize the metal by applying the positive voltage to the metal in the electrolyte. Al and Ti metals were anodized and the anodization is possible even at room temperature. There are two ways of the anodization, one is the barrier type and the other is the porous type. For the electrical device application, a barrier type anodic oxidation is necessary. In the case of Al, thickness of the barrier type anodic oxide is proportional to the anodizing voltage in the electrolyte of citric acid. The oxidation starts at a constant current mode and changes to the constant voltage mode. The anodic oxide of Al was used for the gate insulator of the oxide TFTs. On a glass substrate, gate electrode was patterned after deposition of Al by DC-Sputtering. The Al was anodized to form an Aluminum oxide for the gate insulator. After deposition of Ti, it was patterned for the source/drain electrodes and an active region. After coating photoresist, it was opened on the region where the metal should be anodized to be an active region. The oxidized region of the Ti becomes the active region of the TFT. After removing the photoresist, it was annealed under the oxygen ambient to improve the TFT characteristics. During the anodization, the adhesion of the photoresist to the metal was deteriorated and the anodic oxidation occurred under the photoresist. To solve the problem, we deposited silicon oxide before coating the photoresist. After developing photoresist for the opening of the photoresist, the wet etching of the silicon oxide was performed, which made it possible to accomplish the anodic oxidation without the adhesion problem.

Thermal and Environmental Stability of Semi-Transparent Perovskite Solar Cells for Tandems Enabled by a Solution-Processed Nanoparticle Buffer Layer and Sputtered ITO Electrode.

A sputtered oxide layer enabled by a solution-processed oxide nanoparticle buffer layer to protect underlying layers is used to make semi-transparent perovskite solar cells. Single-junction semi-transparent cells are 12.3% efficient, and mechanically stacked tandems on silicon solar cells are 18.0% efficient. The semi-transparent perovskite solar cell has a T 80 lifetime of 124 h when operated at the maximum power point at 100 °C without additional sealing in ambient atmosphere under visible illumination.

29.1: Ultra‐High Barriers for Encapsulation of Flexible Displays and Lighting Devices

AbstractA roll‐to‐roll manufactured ultra‐high permeation barrier film based on a multilayer stack of sputtered oxide layers and ORMOCER® interlayers is presented. The reproducible large‐area water vapor transmission rate is less than 8·10−5 g/(m2d) at ambient condition. The film has been evaluated as substrate for and encapsulation of flexible organic electronic devices.

Characterization of iron oxide layers using Auger electron spectroscopy

Metals can form several kinds of oxides. Iron forms wustite (FeO), magnetite (FeO + Fe 2O 3 or Fe 3O 4) and haematite (Fe 2O 3). Iron oxides, especially magnetite, are used for insulation between the lamellas of an electromotor made of electromagnetic sheet. In this work, iron oxide layers were characterized on industrial samples of electromagnetic sheet by AES depth profile analysis, and iron oxides with known chemical composition were used as reference samples, i.e. a magnetite mineral and a standard haematite reference sample. The magnetite mineral was chosen because it can be found in nature in a very pure form. The selection of reference samples was also verified on samples with an oxide layer of known composition, which were prepared by sputter deposition. The composition of the sputtered oxide layers was analysed by the weight-gain method and Rutherford backscattering without the use of standard reference materials (SRM), and the results were then compared with those obtained by AES depth profile analysis.

An XPS investigation of the interaction mechanism between AlEt 3 and TiCl 4 supported on sputtered native SiO x layer

TiCl 4 supported on silicon oxide or magnesium halides is widely used as catalyst for olefin polymerization from the gas phase. These catalysts are usually activated with organoaluminum compounds such as triethylaluminum (AlEt 3). In the present study, the interaction mechanism between AlEt 3 and titanium chloride supported on a SiO x layer was investigated using X-ray photoelectron spectroscopy (XPS). A flat conductive Si wafer covered with a thin native SiO x layer, was used as support, in order to eliminate electrostatic charging effects during the XPS measurements and allow a more reliable identification of surface chemical species. It was found that the TiCl 4 vapors react with the sputtered oxide layer mainly through isolated surface Si–OH species leading to formation of Si–O–TiCl 3. There was no evidence of Ti reduction after the interaction with AlEt 3 vapors but only a small downward BE shift of the Ti 2p 3/2 peak. This behavior was attributed to the effect of alkylation of the titanium oxychloride species. On the basis of the present results it is proposed that the alkylation takes place by means of surface complex formation with AlEt x that may or may not be chemically bonded on the SiO x surface.

Comparison of the Semiconductive Properties of Sputter‐Deposited Iron Oxides with the Passive Film on Iron

The semiconducting properties of sputtered magnetite and oxidized magnetite layers with different Fe(II) contents were compared with the passive film on iron. Electrochemical impedance spectroscopy and photoelectrochemical experiments were carried out in borate buffer, pH 8.4. An evaluation of the impedance data according to the Mott‐Schottky concept showed that the capacitance of all films is linked with their doping concentrations rather than their thicknesses and that the doping species of the passive film on iron is Fe(II). For the passive film a potential‐dependent doping concentration was found. Photoelectrochemical investigation of the passive film and the sputtered oxide layers showed that for low doping concentrations, the photocurrent increases with doping, whereas for high doping concentrations, an increase in doping leads to a decrease of the photocurrent. Possible causes for this effect are discussed. Further, the combination of a light reflectance technique with photocurrent measurements allowed consideration of light absorption effects in the data treatment and separation of photocurrent contributions from the space‐charge layer from film‐thickness effects.

Characterization of r.f.-sputtered iron oxide films for modeling passive films

Iron oxide films were r.f.-sputtered on metallic, ceramic and polymeric substrates in order to study the structure, composition and the photo-electrochemical properties of the coatings. The formed iron oxide phase was found to depend on the substrate biasing during deposition. The main phases obtained were α-Fe2O3 and Fe3O4. The films had a tendency to form a columnar structure, which was more preferred on metallic substrates. The α-Fe2O3 target was found to be reduced during the sputtering, and a mixed oxide of α-Fe2O3 and Fe3O4 was formed. The orientation of the deposited films was found to be dependent on the formed phase, the substrate voltage and the target composition. The deposition rate was dependent on the formed phase, biasing and substrate material, as well as on the level of the reduction of the target. The films were nanocrystalline, having crystal sizes of 10 nm or less. The Fe★ content was found to have an effect on the measured photocurrents. Roughness of the semiconductor surface was noticed to have a strong influence on the AC impedance of the sputtered oxide layers. X-ray absorption near edge spectroscopy (XANES) measurements revealed further information on the oxidation state of the sputter-deposited iron oxide films.