Oxide Strip Research Articles

Manipulation of Photonic Jets of Topological Gratings Comprising ITO Strips and Nanowalls Using Refractive Indices of Dielectric Nanofilms

AbstractThis work proposes a quick measurement of the refractive index of dielectric nanofilm via a fabricated topological grating that comprises indium tin oxide (ITO) strips and nanowalls with an extremely high aspect ratio of 25. As the topological grating is capped with a dielectric nanofilm, the parabolic fields of the nanowalls destructively interfere with those of the ITO strips. This destructive interference weakens the photonic jets of the topological grating, decreasing its diffraction efficiency. The decrease in the diffraction efficiency determines the refractive index of the nanofilm without measuring its thickness in advance because the efficiency decrease is independent of the thickness. In other words, the photonic jets of the topological grating are manipulated by the refractive index of the nanofilm. The experimental results verify that refractive indices of titanium‐dioxide, silicon‐dioxide, and bovine‐serum‐albumin nanofilms with a thickness much smaller than the visible wavelengths can be measured by using the proposed topological grating. Therefore, topological gratings have great potential to develop advanced materials, fascinating devices, and innovative instruments.

Ultra-sensitive fan-folded thermally expandable surface reduced graphene oxide strips for fire early warning response

The increasingly frequent fire has brought serious harm to the safety of human life and property. The development of fire early warning materials with super sensitive temperature response has always been an urgent need in the field of fire safety. Herein, a surface reduced graphene oxide strip (RGOS) was fabricated by a simple chemical reduction and used as a fire early warning sensor via the facile fan-folding method. By controlling the reduction time of graphene oxide (GO) in the system of HI/CH3COOH/H3PO2, phosphorus-containing RGOS with different reduction degrees can be obtained. Compared with the pure GO strips, the RGOS exhibits improved flame retardancy. Structural observation and thermal analysis show that the introduction of phosphorus and the reduced graphene oxide (RGO) layer formed by surface reduction effectively inhibit the thermal degradation of the internal GO layer after encountering a high-temperature attack. More importantly, different from the previous GO-based sensors that rely on resistance transformation to generate fire alarm response, the fan-folded RGOS can rapidly expand to trigger a conductive contact after encountering high temperature or flame, thus providing an ideal fire early alarm response (∼3 s for 150 ℃, ∼0.5 s for flame). This work suggests that the RGOS is promising in the development of advanced materials as smart sensors for fire early warning.

Preparation and Thermoelectric Properties of Nano-Bismuth Telluride Film by High-Temperature Thermal Shock

Thermoelectric materials can directly convert thermal energy into electrical energy, realizing the recovery of waste heat. Bismuth Telluride (Bi-Te) is considered as a perfect candidate thermoelectric material which has great potential in the field of refrigeration and temperature sensor. However, in the field of intelligent wearable devices and integrated circuits, traditional Bi-Te block material is difficult to be directly used due to its poor flexibility. In this paper, a series of Bi-Te thin films were prepared by a self-designed high-temperature thermal shock equipment. This equipment can heat up the reduced graphene oxide strip to 1750 K in 20 ms, which features both high heating rate (8.2 × 104 K/s) and cooling rate (1.5 × 104 K/s). Thermoelectric films on different substrates were prepared via high-temperature thermal shock. Through regulating the temperature of evaporation source, the particle size and composition of Bi-Te thin films can be precisely modulated, thus optimizing the Seebeck coefficient of the films. The Seebeck coefficient of copper foil (Cuf)-based Bi-Te film can reach 345.41 μV/K, which was prepared by thermal-shocking the Bi-Te powders for 30 s at 900°C.

Analysis of the mechanism of chromatic aberration defects on A510L surface of high quality hot rolled pickled strip

In view of the chromatic aberration defects on the surface of hot-rolled strip A510L after pickling, the microscopic morphology features of different positions of the pickled strip surface were compared and analyzed by using laser confocal microscope (CLSM), and the generation mechanism of chromatic aberration defect was studied by using high-resolution scanning electron microscope and energy dispersive spectrometer (EDS). The results show that the main cause of surface chromatic aberration defects on the surface of pickling plate A510L is closely related to the interface state between hot-rolled raw material substrate and iron oxide scale, and there is an enrichment area of Fe2SiO4/FeO binary eutectic near the hot-rolled raw material substrate and iron oxide scale, and the proportion of Fe2SiO4 is higher as it approaches the strip steel matrix, and Fe2SiO4/FeO has a strong pinning effect, which leads to the adhesion of iron oxide scale. The existence of Fe2SiO4/FeO changes the structure of carbon steel iron oxide scale, which makes the bonding force between iron oxide scale and strip steel matrix increase the difficulty of pickling process, and finally presents the surface chromatic aberration defects after pickling.

Effect of Al content on microstructure and mechanical properties of atmosphere plasma sprayed AlxCoCrFeNi high-entropy alloy coatings under post-annealing

In this work, AlxCoCrFeNi (x = 0.2, 0.5, 1.0) high-entropy alloy (HEA) coatings were fabricated by atmosphere plasma spraying (APS) and then annealed at 600, 800, 1000 °C under Ar atmosphere. The as-sprayed HEAs exhibited lamellar microstructure of alloy phase with oxide strips. The Al content showed a positive and negative correlation with the formation of BCC (A2/B2) and FCC (A1) in the coatings, respectively. A symbiotic relationship between FCC and oxides was first proposed. During annealing, the transformation from mixed BCC to A2/B2 in HEA coatings was dominated by Al content, thus leading to unique microstructure at different temperatures. The hardness of as-annealed HEAs was determined by the morphology and distribution of Al-rich BCC phase. The HEA coating with higher Al content (x = 1.0) could keep high hardness under elevated annealing temperatures. While the coating with lower Al content (x = 0.2) showed stability both in microstructure and mechanical properties.

Printed in-plane electrolyte-gated transistor based on zinc oxide

Printed electronics is a reputable research area that aims at simple alternatives of manufacturing low-cost, eco-friendly, and biodegradable electronic devices. Among these devices, electrolyte-gated transistors (EGTs) stand out due to their simple manufacturing process and architecture. Here we report the study of printed EGTs with in-plane gate transistor (IPGT) architecture based on zinc oxide nanoparticles. The drain, source, and gate electrodes with two different W/L channel ratios were fabricated using a screen-printed carbon-based ink. We also produced a conventional top-gate transistor as a standard device, using the same structure of the IPGT described above with the addition of an indium tin oxide strip positioned over the electrolyte as the top-gate electrode. The IPGT with W/L = 5 presented a high mobility of 7.95 ± 0.55 cm2 V−1 s−1, while the W/L = 2.5 device exhibited a mobility of 3.03 ± 0.52 cm2 V−1 s−1. We found that the measured field-effect mobility of the device can be affected by the high contact resistance from the carbon electrodes. This effect could be observed when the device’s geometric parameters were changed. Furthermore, we also found that the IPGT with W/L = 5 exhibited higher values for mobility and transconductance than the top-gate transistor, showing that the IPGTs architecture is a good approach for cheap and printed transistors with performance comparable to standard top-gate EGTs.

The investigation of DARC etch back in DRAM capacitor oxide mask opening

Opening the silicon oxide mask of a capacitor in dynamic random access memory is a critical process on a capacitive coupled plasma (CCP) etch tool. Three steps, dielectric anti-reflective coating (DARC) etch back, silicon oxide etch and strip, are contained. To acquire good performance, such as low leakage current and high capacitance, for further fabricating capacitors, we should firstly optimize DARC etch back. We developed some experiments, focusing on etch time and chemistry, to evaluate the profile of a silicon oxide mask, DARC remain and critical dimension. The result shows that etch back time should be controlled in the range from 50 to 60 s, based on the current equipment and condition. It will make B/T ratio higher than 70% meanwhile resolve the DARC remain issue. We also found that CH2F2 flow should be ~15 sccm to avoid reversed CD trend and keep inline CD.

Unpredicted Internal Geometric Reconfiguration of an Enclosed Space Formed by Heteroepitaxy.

Epitaxial lateral overgrowth (ELO) over a free-standing dielectric mask is an unexplored territory in selective epitaxy growth (SEG) of semiconductors. By shrinking the dielectric mask dimension to the micron scale, the growth fronts from ELO are able to converge and coalesce, thus providing the freedom to engineer the interfacial structure between the epi-layer and dielectric mask. We demonstrate, herein, anomalous adatom diffusion and migration at the Ge/SiO2 interface upon SEG on a Si (100) wafer. We find, depending on the oxide strip length, a polyhedral cavity or tunnel can form on the oxide layer. More importantly, we observe a thermally induced substantial internal surface reconfiguration process of Ge atoms that connects two tunnels and one cavity in order to form a single tunnel. Defect-free Ge above the oxide strips is obtained after coalescence. Our findings yield new insight into adatom migration in an enclosed space, and the cavity and tunnel show the first known three-dimensional geometric configuration in selective heteroepitaxial structures.

Highly transparent conductors for optical and microwave access to spin-based quantum systems

Spin-based quantum systems are among the best sensors in terms of sensitivity and spatial resolution for a variety of physical properties. A key factor to broaden the range of applications is the control over the microwave field used to manipulate the quantum system. We present the implementation of a transparent microwave conductor, suitable for optical read-out of a spin-based quantum sensor. For this, the interaction of an indium tin oxide (ITO) strip line on diamond with nitrogen vacancy centres was investigated. The amorphous ITO can be fabricated at room temperature, has a transmittance larger than 80% in the visible spectrum and a low resistivity. We show that these strip lines are completely scalable which enables highly homogeneous microwave fields from the nanometre up to the millimetre scale. ITO structures can therefore serve as excellent transparent microwave conductors, widening the current use of spin-based quantum sensors.

Low-loss Ga:Er:LiTaO3 optical waveguide for integrated optics

Low-loss gallium(Ga3+)-diffused erbium(Er3+)-doped LiTaO3(Ga:Er:LiTaO3) channel waveguide was fabricated using erbium metal film diffusion followed by photolithographically patterned gallium oxide(Ga2O3) strip diffusion. Secondary ion mass spectrometry analysis shows that Er3+ concentration follows a Gaussian profile, Ga3+ concentration follows a sum of two error functions at the waveguide surface and a Gaussian profile in the depth direction. Optical studies show that the waveguide supports single-mode propagation at 1.5 μm wavelength with a coupling loss <1 dB and a waveguide loss 0.2(0.3) dB/cm for the TE(TM) mode, and with a small polarization dependence in mode field distribution. Stable optical gain of ∼1.0 dB/cm was measured at 1547 nm wavelength with 220 mW pump power of 980 nm wavelength, indicating good photorefractive damage resistance of the waveguide.

Tunable THz perfect absorber with two absorption peaks based on graphene microribbons

Perfect absorption is characterised by the complete suppression of incident and reflected electromagnetic wave, and complete dissipation of the incident energy. A tunable perfect terahertz (THz) absorber with two absorption peaks based on graphene is presented. The proposed structure consists of graphene microribbons sandwiched between aluminium oxide strips and polymethyl methacrylate slab on a silicon dioxide (SiO 2 ) layer which is covered by periodic gold (Au) ribbons, and the SiO 2 layer is supported by the Au substrate. The influence of the structural parameters on the absorption performance was analysed too. Especially, graphene can be used to design tunable THz devices due to its tunability of sheet conductivity which could be controlled by applying a bias voltage or chemical doping. A single-band perfect absorption can be achieved when the chemical potential is set to 0.1 eV. Interestingly, when the chemical potential changed to 0.6 eV, a dual-band absorption spectrum is obtained with absorption efficiency of the two peaks more than 90%. These results imply that the characteristics of graphene-based surface plasmon could be used to design novel THz devices in future.

Study on Microstructure and Properties of Iron Based Alloy Coating by Arc Spraying

Arc thermal spraying technology was used for the preparation of iron-based 08Mn2Si coating in automobile engine cylinder wall. Scanning electron microscopy (SEM) was used for the analysis of organizational characteristics of coating. The check agent (DPT-5) that was used to simulate oil was blotted out on the coating surface to study its permeability mechanism in pores. Under the wet and dry environment, the authors use the material with high temperature friction, wear tester to analyze the abrasion resistance and compare the result of grey cast iron. The research showed that the coating was constituted by flat particles which stacked on the base and presented a similar topology structure. Oxide strip was found between the particles. Unmelted particles, pores and cracking were the same as oxide strip in distribution. Pores were connected with each other by the gaps. The abrasion resistance of coating was better than grey cast iron in dry friction environment when seemed to be the same in oil friction. FeO and pores that existed in the coating were contributed to the anti-friction effect.

An ultra-sensitive and wideband magnetometer based on a superconducting quantum interference device

The magnetic field noise in superconducting quantum interference devices (SQUIDs) used for biomagnetic research such as magnetoencephalography or ultra-low-field nuclear magnetic resonance is usually limited by instrumental dewar noise. We constructed a wideband, ultra-low noise system with a 45 mm diameter superconducting pick-up coil inductively coupled to a current sensor SQUID. Thermal noise in the liquid helium dewar is minimized by using aluminized polyester fabric as superinsulation and aluminum oxide strips as heat shields. With a magnetometer pick-up coil in the center of the Berlin magnetically shielded room 2 (BMSR2), a noise level of around 150 aT Hz−1∕2 is achieved in the white noise regime between about 20 kHz and the system bandwidth of about 2.5 MHz. At lower frequencies, the resolution is limited by magnetic field noise arising from the walls of the shielded room. Modeling the BMSR2 as a closed cube with continuous μ-metal walls, we can quantitatively reproduce its measured field noise.

Ultrathin nano-sized Al2O3 strips on the surface of por-Si

The objective of this paper is to obtain nano-sized Al2O3 strips on the surface of nanoporous silicon surface as well as fundamental investigations of structural, optical and morphological properties of the materials.While analysing the results, we were able to prove for the first time that the use of ion plasma sputtering allows one to obtain ultrathin nanostructured Al2O3 films as unidirectional fibres arranged by 300–500nm away from one another on a porous silicon layer. Such mechanism of the growth of aluminium oxide strips is stipulated by the morphology of porous silicon layer obtained as a result of etching of the virgin silicon plate; that in turn determines distinctions in the morphology of ultra-thin Al2O3 film.The results of optical spectroscopy shows that the Al2O3 nano-sized strips of the heterophase structure of Al2O3/por-Si/Si(111) is good at transmitting electromagnetic radiation of 190–900nm. It is shown that the intensity of photoluminescence excited by the heterophase structure Al2O3/por-Si/Si(111) is by 30% higher than that excited by the film of the porous layer.The analysis of dispersion of refractive index in the investigated systems showed that its values for the heterophase structure Al2O3/por-Si/Si(111) in the entire range of the wavelengths of the deflection is considerably higher than that those ones of Al2O3 grown under similar conditions using single-crystalline silicon Si(111). In the wavelengths of 250–500nm the refractive index of the heterophase structure Al2O3/por-Si/Si(111) is similar to that one of por-Si used for growing of the heterophase structure.The observed maximum in the dispersion of the refractive index of Al2O3 nano-sized strips grown on por-Si is identical to the optical absorption edge of the aluminium oxide and is in the range of ~5.60eV. This is consistent with the results of calculations of the optical absorption spectrum for the heterophase structure Al2O3/por-Si/Si(111).The nano-sized structured strips of Al2O3 films on the surface of the heterophase structure can serve as optical transmission channels and are quite efficiently introduced into the standard practices, which is of significant importance for micro- and optoelectronics.

Evaluation of corrosion resistance of coated steel strips embedded in mortar under chloride exposure

Purpose – The purpose of this paper was mainly to select one of the three types of coatings for protection of steel used as reinforcement in composite pipes (thin steel shell covered by cement-mortar) subjected to chloride exposure. To achieve this target, an attempt was made to develop a simple methodology for evaluating the performance of corrosion protection measures in terms of chloride threshold level (CTL) and corrosion initiation time (TI). Design/methodology/approach – Bare, epoxy, red oxide and zinc primer-coated steel strips were embedded in cement mortar with sand/cement and water/cement ratios of 2 and 0.5 (by mass), respectively, to prepare the specimens which were exposed to chloride solution having a high concentration of 10 per cent NaCl. For determining the amounts of the water-soluble chloride diffused inside the specimens, powdered samples of mortar were collected from two different depths from the exposed surface of specimens on completion of each of the four different exposure times. The corrosion current densities were determined at two different stages. A step-by-step procedure for calculating CTL and TI using the measured chloride contents and corrosion current densities was established with the help of relevant information available in the literature. Findings – Based on the comparison of the values of CTL and TI calculated for bare steel and steel with all three types of coatings, utilizing the experimental data and the proposed calculation procedure, the epoxy-coated steel was found to have the best performance. Originality/value – This research has resulted into development of a simple methodology for evaluation of the performance of protective measures against corrosion of steel embedded in mortar or concrete exposed to chloride-bearing environment.

Contribution of shoreline erosion to nutrient loading of the Lake Diefenbaker reservoir, Saskatchewan, Canada

The nutrient budget of the Lake Diefenbaker reservoir (SK, CAN) is being developed as part of a larger multi-faceted trophic status study. However, it is currently unknown if shoreline erosion from the near vertical banks serves as a source of nutrients to the reservoir. Thus, the objective of this study was to quantify the annual nutrient loading to the reservoir through shoreline erosion, and the relative magnitude of erosion-derived inputs versus nutrient loading through the major tributary, the South Saskatchewan River (SSR). Nutrient status measurements indicate that Lake Diefenbaker algal populations would be responsive to additional inputs of phosphorus (P). We measured the total carbon (TC), total nitrogen (TN), Mehlich 3 P, and iron oxide strip extracted (FeO) P nutrient content by weight in the bank soils along the reservoir. Combined with shoreline erosion rates and lengths, the mean annual nutrient inputs for TC, TN, M3P, and FeO P were 57,500 kg year − 1 , 2100 kg year − 1 , 49.8 kg year − 1 and 30.0 kg year − 1 , respectively. We also compared nutrient content and inputs across bank classifications and land uses to identify factors contributing to nutrient loading through erosion and to determine potential areas for mitigation efforts. Relative to the primary nutrient loading from the SSR, bank soils represent less than 1% of the overall load. These measurements of nutrient inputs will allow us to assess the relative contribution of soil nutrients to prairie reservoirs and will serve as important baseline data for the reservoir. • Carbon, nitrogen, and phosphorus soil concentrations were measured around the reservoir. • Bank-specific erosion rates were used to determine annual nutrient input rates. • Nutrient input rates were compared between bank classifications and land uses. • Nutrient input through shoreline erosion was < 1% of the annual load. • Implications for reservoir management were identified.

Investigation of Chirped InAs/InGaAlAs/InP Quantum Dash Lasers as Broadband Emitters

In this paper, we assessed the effect of additionally broadened quantum dash (Qdash) optical transitions in the multi-stack dash-in-a-well laser structure at both, material and device level. A broad photoluminescence linewidth of ~ 150 nm demonstrates the formation of highly inhomogeneous InAs-dashes across the stacks. The transmission electron microscopy revealed small (large) average dash height from the Qdash stack with thick (thin) over grown barrier layer. The Fabry-Perot laser diodes fabricated from this chirped structure exhibits unique device physics under the short pulsewidth (SPW) and quasi-continuous wave (QCW) operation. Varying the ridge-width (W) from 2 to 4 μm showed quenching of ultrabroad lasing signature in the SPW operation, and consistent even for a wide 15 μm oxide strip laser diode. A lasing spectral split with reduced intensity gap in the center is observed in the QCW operation with the gap decreasing with increasing ridge-width. Such atypical lasing operation, influenced by the waveguiding mechanism is qualitatively realized by associating to the reduced vertical coupling effect of the Qdash stacks in the operation of small ridge-width lasers compared with large ridge-width and oxide stripe lasers, and leading to varying non-uniform distribution of carriers among the inhomogeneously broadened Qdash stacks in each case. Our chirped 2 × 830 μm ridge laser demonstrated marked improvement in the internal quantum efficiency (~ 80%) and -3 dB lasing bandwidth, centered at ~1.61 μm.

Microchip Device with 64-Site Electrode Array for Multiplexed Immunoassay of Cell Surface Antigens Based on Electrochemiluminescence Resonance Energy Transfer

This paper describes a novel on-chip microarray platform based on an electrochemiluminescence resonance energy transfer (ECL-RET) strategy for rapid assay of cancer cell surface biomarkers. This platform consists of 64 antigen-decorated CdS nanorod spots with the diameter of 1.0 cm uniformly distributed on 16 indium tin oxide (ITO) strips, which is coated with a multichannel decorated polydimethylsiloxane (PDMS) slice to realize multiplexed determination of antigens. To shorten the immune reaction time in the microchannels and simplify the device, magnetic stirring and four-channel universal serial bus (USB) ports for plug-and-play were used. When Ru(bpy)(3)(2+) labeled antibodies were selectively captured by the corresponding antigens on the CdS nanorod spot array, ECL-RET from the CdS nanorod (donor) by cathodic emission in the presence of K(2)S(2)O(8) to Ru(bpy)(3)(2+) (acceptor) occurred. With signal amplification of Ru(bpy)(3)(2+) and competitive immunoassay, carcinoembryonic antigen (CEA), α-fetoprotein (AFP), and prostate specific antigen (PSA) as models were detected on this microfluidic device via recording the increased ECL-RET signals on electrode surfaces. Furthermore, this multiplexed competitive immunoassay was successfully used for detecting cancer cell surface antigens via the specific antibody-cell interactions and cell counting via cell surface receptors and antigens on the CdS nanorod surface. This platform provides a rapid and simple but sensitive approach with microliter-level sample volume and holds great promise for multiplexed detection of antigens and antigen-specific cells.

Bioavailable Phosphorus in Animal Waste Amended Soils: Using Actual Crop Uptake and P Mass Balance Approach

Animal manure amended soils often contain large amounts of bioavailable phosphorus (P) and constitute high risk for the deterioration of surface water quality through eutrophication. Current standards set for the safe disposal of animal manure through soil application are based on the assumption that phosphorus in all P sources would behave similarly. The primary objective of this study was to understand the influence of P from several manure and mineral fertilizer sources applied at 0, 50, and 150 mg P kg(-1) on two measures of bioavailable P to six soils of different initial soil test P levels using corn (Zea mays L.) P uptake and an iron oxide strip method for soil analysis (FeO-P). Total net bioavailable P (TNBP) was calculated by subtracting total P uptake by corn after seven consecutive harvests in control treatments that did not receive P from the P uptake from P-amended treatments. Net biovavailable P after the first harvest (NBP1) was calculated in a similar fashion but only using data from the first harvest. Significant differences in TNBP and NBP1 were found when comparing P sources. The hog (Sus scrofa) manure had the greatest P bioavailability while turkey (Meleagris gallopava) litter had the lowest among the animal P sources across all soils and levels of P application. Significant differences were also found between soils with the highest amounts of TNBP and NBP1 found in the Woodson soil and lowest detected in the Crete soil for most P sources. The FeO-P method was useful in predicting TNBP from most P sources.

Electrochemiluminescence analysis of folate receptors on cell membrane with on-chip bipolar electrode

In this paper we report a transparent bipolar electrode based microfluidic chip-electrochemiluminescence (ECL) system for sensitive detection of folate receptors (FR) on cell membranes. This integrated system consists of a poly(dimethylsiloxane) (PDMS) layer containing a microchannel and a glass bottom sheet with indium tin oxide (ITO) strips as bipolar detectors. The ITO strips are fabricated using a PDMS micromold with carbon ink as a protective layer in place of traditional photoresist. The configuration of the bipolar electrode has great influence on the ECL intensity of Ru(bpy)(3)(2+)/tripropylamine(TPA) system. Further studies show that folic acid (FA) can strongly inhibit the ECL of the Ru(bpy)(3)(2+)/TPA system. Based on specific recognition between FA and FR on cell membrane, this microfluidic chip-ECL system is successfully applied for detecting the level of FR on human cervical tumor (HL-60) cells and MEF cells. It is found that the ECL intensity increases with the number of HL-60 cells in the range of 21 to 3.28 × 10(4) cells/mL. The average level of FR on HL-60 cells is calculated to be 8.05 ± 0.75 × 10(-18) mol/cell. While for MEF cells, it shows a much slower ECL increment than HL-60 cells due to the much lower FR level on MEF cells (5.30 ± 0.61 × 10(-19) mol/cell). Moreover, exocytosis of FA after FR mediated endocytosis was observed according to the change of the ECL signal with the incubation time of HL-60 cells in the FA- Ru(bpy)(3)(2+)/TPA system.