Continuous Process for the Etching, Rinsing and Drying of MEMS Using Supercritical Carbon Dioxide

Energy Technology Data Exchange (ETDEWEB)

Min, Seon Ki; Han, Gap Su; You, Seong-sik [Korea University of Technology and Education, Cheonan (Korea, Republic of)

2015-10-15

The previous etching, rinsing and drying processes of wafers for MEMS (microelectromechanical system) using SC-CO{sub 2} (supercritical-CO{sub 2}) consists of two steps. Firstly, MEMS-wafers are etched by organic solvent in a separate etching equipment from the high pressure dryer and then moved to the high pressure dryer to rinse and dry them using SC-CO{sub 2}. We found that the previous two step process could be applied to etch and dry wafers for MEMS but could not confirm the reproducibility through several experiments. We thought the cause of that was the stiction of structures occurring due to vaporization of the etching solvent during moving MEMS wafer to high pressure dryer after etching it outside. In order to improve the structure stiction problem, we designed a continuous process for etching, rinsing and drying MEMS-wafers using SC-CO{sub 2} without moving them. And we also wanted to know relations of states of carbon dioxide (gas, liquid, supercritical fluid) to the structure stiction problem. In the case of using gas carbon dioxide (3 MPa, 25 .deg. C) as an etching solvent, we could obtain well-treated MEMS-wafers without stiction and confirm the reproducibility of experimental results. The quantity of rinsing solvent used could be also reduced compared with the previous technology. In the case of using liquid carbon dioxide (3 MPa, 5 .deg. C), we could not obtain well-treated MEMS-wafers without stiction due to the phase separation of between liquid carbon dioxide and etching co-solvent(acetone). In the case of using SC-CO{sub 2} (7.5 Mpa, 40 .deg. C), we had as good results as those of the case using gas-CO{sub 2}. Besides the processing time was shortened compared with that of the case of using gas-CO{sub 2}.

Exploration of suitable dry etch technologies for directed self-assembly

Science.gov (United States)

Yamashita, Fumiko; Nishimura, Eiichi; Yatsuda, Koichi; Mochiki, Hiromasa; Bannister, Julie

2012-03-01

Directed self-assembly (DSA) has shown the potential to replace traditional resist patterns and provide a lower cost alternative for sub-20-nm patterns. One of the possible roadblocks for DSA implementation is the ability to etch the polymers to produce quality masks for subsequent etch processes. We have studied the effects of RF frequency and etch chemistry for dry developing DSA patterns. The results of the study showed a capacitively-coupled plasma (CCP) reactor with very high frequency (VHF) had superior pattern development after the block co-polymer (BCP) etch. The VHF CCP demonstrated minimal BCP height loss and line edge roughness (LER)/line width roughness (LWR). The advantage of CCP over ICP is the low dissociation so the etch rate of BCP is maintained low enough for process control. Additionally, the advantage of VHF is the low electron energy with a tight ion energy distribution that enables removal of the polymethyl methacrylate (PMMA) with good selectivity to polystyrene (PS) and minimal LER/LWR. Etch chemistries were evaluated on the VHF CCP to determine ability to treat the BCPs to increase etch resistance and feature resolution. The right combination of RF source frequencies and etch chemistry can help overcome the challenges of using DSA patterns to create good etch results.

Highly reflective Bragg gratings in slightly etched step-index polymer optical fiber.

Science.gov (United States)

Hu, Xuehao; Pun, Chi-Fung Jeff; Tam, Hwa-Yaw; Mégret, Patrice; Caucheteur, Christophe

2014-07-28

During the past few years, a strong progress has been made in the photo-writing of fiber Bragg gratings (FBGs) in polymer optical fibers (POFs), animated by the constant wish to enhance the grating reflectivity and improve the sensing performances. In this paper, we report the photo-inscription of highly reflective gratings in step-index POFs, obtained thanks to a slight etching of the cladding. We demonstrate that a cladding diameter decrease of ~12% is an ideal trade-off to produce highly reflective gratings with enhanced axial strain sensitivity, while keeping almost intact their mechanical resistance. For this, we make use of Trans-4-stilbenemethanol-doped photosensitive step-index poly(methyl methacrylate) (PMMA) POFs. FBGs are inscribed at ~1550 nm by the scanning phase mask technique in POFs of different external diameters. Reflectivity reaching 97% is achieved for 6 mm long FBGs, compared to 25% for non-etched POFs. We also report that a cladding decrease enhances the FBG axial tension while keeping unchanged temperature and surrounding refractive index sensitivities. Finally and for the first time, a measurement is conducted in transmission with polarized light, showing that a photo-induced birefringence of 7 × 10(-6) is generated (one order of magnitude higher than the intrinsic fiber birefringence), which is similar to the one generated in silica fiber using ultra-violet laser.

Alignment and Use of Self-Assembled Peptide Nanotubes as Dry-Etching Mask

DEFF Research Database (Denmark)

Andersen, Karsten Brandt; Castillo, Jaime; Bakmand, Tanya

2012-01-01

candidate for controlled nanofabrication without organic solvents. The present work demonstrates how this unique structure can be aligned, manipulated and used as both an etching mask in a dry etching procedure and as a lift-off material. As a further demonstration of the potential of this technique...

High rate dry etching of InGaZnO by BCl3/O2 plasma

Science.gov (United States)

Park, Wanjae; Whang, Ki-Woong; Gwang Yoon, Young; Hwan Kim, Jeong; Rha, Sang-Ho; Seong Hwang, Cheol

2011-08-01

This paper reports the results of the high-rate dry etching of indium gallium zinc oxide (IGZO) at room temperature using BCl3/O2 plasma. We achieved an etch rate of 250 nm/min. We inferred from the x-ray photoelectron spectroscopy analysis that BOx or BOClx radicals generated from BCl3/O2 plasma cause the etching of the IGZO material. O2 initiates the etching of IGZO, and Ar removes nonvolatile byproducts from the surface during the etching process. Consequently, a smooth etched surface results when these gases are added to the etch gas.

Dry etching characteristics of GaN for blue/green light-emitting diode fabrication

International Nuclear Information System (INIS)

Baik, K.H.; Pearton, S.J.

2009-01-01

The etch rates, surface morphology and sidewall profiles of features formed in GaN/InGaN/AlGaN multiple quantum well light-emitting diodes by Cl 2 -based dry etching are reported. The chlorine provides an enhancement in etch rate of over a factor of 40 relative to the physical etching provided by Ar and the etching is reactant-limited until chlorine gas flow rates of at least 50 standard cubic centimeters per minute. Mesa sidewall profile angle control is possible using a combination of Cl 2 /Ar plasma chemistry and SiO 2 mask. N-face GaN is found to etch faster than Ga-face surfaces under the same conditions. Patterning of the sapphire substrate for improved light extraction is also possible using the same plasma chemistry

Selective laser-induced photochemical dry etching of semiconductors controlled by ion-bombardment-induced damage

International Nuclear Information System (INIS)

Ashby, C.I.H.; Myers, D.R.; Vook, F.L.

1987-01-01

When a photochemical dry etching process requires direct participation of photogenerated carriers in the chemical reaction, it is sensitive to the electronic properties of the semiconductor. For such solid-excitation-based dry etching processes, the balance between reaction and carrier recombination rates determines the practical utility of a particular reaction for device fabrication. The distance from the surface at which the photocarriers are generated by light adsorption is determined by the absorption coefficient. In the absence of an external bias potential, only those carriers formed within a diffusion length of the surface space-charge region will have an opportunity to drive the dry etching reaction. When the absorption coefficient is high, most of the photons generate carriers within a diffusion length from the surface space-charge region, and the etching rate is largely determined by the balance between the rate of the carrier-driven reaction and the surface recombination velocity. When the recombination rate of free carriers in the bulk of the semiconductor is high, the effective diffusion length is reduced and fewer of the carriers generated in the subsurface region ever reach the surface. An important effect of ion bombardment is the creation of many lattice defects that increase the rate of recombination of electrons and holes. When a sufficient number of defects, which act as recombination sites, are formed during ion implantation, the recombination of photogenerated carriers at these defects in the subsurface region can greatly reduce the number of carriers which can reach the surface and drive a photochemical etching reaction

Effect of different air-drying time on the microleakage of single-step self-etch adhesives

Directory of Open Access Journals (Sweden)

Horieh Moosavi

2013-05-01

Full Text Available Objectives This study evaluated the effect of three different air-drying times on microleakage of three self-etch adhesive systems. Materials and Methods Class I cavities were prepared for 108 extracted sound human premolars. The teeth were divided into three main groups based on three different adhesives: Opti Bond All in One (OBAO, Clearfil S3 Bond (CSB, Bond Force (BF. Each main group divided into three subgroups regarding the air-drying time: without application of air stream, following the manufacturer's instruction, for 10 sec more than manufacturer's instruction. After completion of restorations, specimens were thermocycled and then connected to a fluid filtration system to evaluate microleakage. The data were statistically analyzed using two-way ANOVA and Tukey-test (α = 0.05. Results The microleakage of all adhesives decreased when the air-drying time increased from 0 sec to manufacturer's instruction (p < 0.001. The microleakage of BF reached its lowest values after increasing the drying time to 10 sec more than the manufacturer's instruction (p < 0.001. Microleakage of OBAO and CSB was significantly lower compared to BF in all three drying time (p < 0.001. Conclusions Increasing in air-drying time of adhesive layer in one-step self-etch adhesives caused reduction of microleakage, but the amount of this reduction may be dependent on the adhesive components of self-etch adhesives.

Optical detection of glucose and glycated hemoglobin using etched fiber Bragg gratings coated with functionalized reduced graphene oxide.

Science.gov (United States)

Sridevi, S; Vasu, K S; Sampath, S; Asokan, S; Sood, A K

2016-07-01

An enhanced optical detection of D-glucose and glycated hemoglobin (HbA1c ) has been established in this study using etched fiber Bragg gratings (eFBG) coated with aminophenylboronic acid (APBA)-functionalized reduced graphene oxide (RGO). The read out, namely the shift in Bragg wavelength (ΔλB ) is highly sensitive to changes that occur due to the adsorption of glucose (or HbA1c ) molecules on the eFBG sensor coated with APBA-RGO complex through a five-membered cyclic ester bond formation between glucose and APBA molecules. A limit of detection of 1 nM is achieved with a linear range of detection from 1 nM to 10 mM in the case of D-glucose detection experiments. For HbA1c , a linear range of detection varying from 86 nM to 0.23 mM is achieved. The observation of only 4 pm (picometer) change in ΔλB even for the 10 mM lactose solution confirms the specificity of the APBA-RGO complex coated eFBG sensors to glucose molecules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Response of murine bone marrow-derived mesenchymal stromal cells to dry-etched porous silicon scaffolds.

Science.gov (United States)

Hajj-Hassan, Mohamad; Khayyat-Kholghi, Maedeh; Wang, Huifen; Chodavarapu, Vamsy; Henderson, Janet E

2011-11-01

Porous silicon shows great promise as a bio-interface material due to its large surface to volume ratio, its stability in aqueous solutions and to the ability to precisely regulate its pore characteristics. In the current study, porous silicon scaffolds were fabricated from single crystalline silicon wafers by a novel xenon difluoride dry etching technique. This simplified dry etch fabrication process allows selective formation of porous silicon using a standard photoresist as mask material and eliminates the post-formation drying step typically required for the wet etching techniques, thereby reducing the risk of damaging the newly formed porous silicon. The porous silicon scaffolds supported the growth of primary cultures of bone marrow derived mesenchymal stromal cells (MSC) plated at high density for up to 21 days in culture with no significant loss of viability, assessed using Alamar Blue. Scanning electron micrographs confirmed a dense lawn of cells at 9 days of culture and the presence of MSC within the pores of the porous silicon scaffolds. Copyright © 2011 Wiley Periodicals, Inc.

Fabrication of Ni stamp with high aspect ratio, two-leveled, cylindrical microstructures using dry etching and electroplating

DEFF Research Database (Denmark)

Petersen, Ritika Singh; Keller, Stephan Sylvest; Hansen, Ole

2015-01-01

obtained by defining a reservoir and a separating trench with different depths of 85 and 125 μm, respectively, in a single embossing step. The fabrication of the required two leveled stamp is done using a modified DEEMO (dry etching, electroplating and molding) process. Dry etching using the Bosch process...... and electroplating are optimized to obtain a stamp with smooth stamp surfaces and a positive sidewall profile. Using this stamp, hot embossing is performed successfully with excellent yield and high replication fidelity....

Stimulus responsive hydrogel-coated etched fiber Bragg grating for carcinogenic chromium (VI) sensing

Science.gov (United States)

Kishore, Pabbisetti Vayu Nandana; Madhuvarasu, Sai Shankar; Moru, Satyanarayana

2018-01-01

This paper proposes a chemo-mechanical-optical sensing approach for the detection of carcinogenic chromium (VI) metal ion using an etched fiber Bragg grating (FBG) coated with stimulus responsive hydrogel. Hydrogel synthesized from the blends of (3-acrylamidopropyl)-trimethylammonium chloride, which is highly responsive to chromium ions suffers a volume change when placed in Cr solution. When the proposed sensor system is exposed to various concentrations of Cr (VI) ion solution, FBG peak shifts due to the mechanical strain induced by the swelling of the hydrogel. The peak shift is correlated with the concentration of the Cr (VI) metal ion. Due to the reduction in the cladding diameter of FBG, wastage of swelling force due to hydrogel on FBG is lowered and utilized for more wavelength peak shift of FBG resulting in the increase in the sensitivity. The resolution of the sensor system is found to be 0.072 ppb. Trace amounts of chromium (VI) ion as low as 10 ppb can be sensed by this method. The sensor has shown good sensitivity, selectivity, and repeatability. The salient features of the sensors are its compact size, light weight, and adoptability for remote monitoring.

Defect-selective dry etching for quick and easy probing of hexagonal boron nitride domains

Science.gov (United States)

Wu, Qinke; Lee, Joohyun; Park, Sangwoo; Woo, Hwi Je; Lee, Sungjoo; Song, Young Jae

2018-03-01

In this study, we demonstrate a new method to selectively etch the point defects or the boundaries of as-grown hexagonal boron nitride (hBN) films and flakes in situ on copper substrates using hydrogen and argon gases. The initial quality of the chemical vapor deposition-grown hBN films and flakes was confirmed by UV-vis absorption spectroscopy, atomic force microscopy, and transmission electron microscopy. Different gas flow ratios of Ar/H2 were then employed to etch the same quality of samples and it was found that etching with hydrogen starts from the point defects and grows epitaxially, which helps in confirming crystalline orientations. However, etching with argon is sensitive to line defects (boundaries) and helps in visualizing the domain size. Finally, based on this defect-selective dry etching technique, it could be visualized that the domains of a polycrystalline hBN monolayer merged together with many parts, even with those that grew from a single nucleation seed.

Design of experiment characterization of microneedle fabrication processes based on dry silicon etching

Science.gov (United States)

Held, J.; Gaspar, J.; Ruther, P.; Hagner, M.; Cismak, A.; Heilmann, A.; Paul, O.

2010-02-01

This paper reports on the characterization of dry etching-based processes for the fabrication of silicon microneedles using a design of experiment (DoE) approach. The possibility of using such microneedles as protruding microelectrodes able to electroporate adherently growing cells and record intracellular potentials motivates the systematic analysis of the influence of etching parameters on the needle shape. Two processes are characterized: a fully isotropic etch process and a three-step etching approach. In the first case, the shape of the microneedles is defined by a single etch step. For the stepped method, the structures are realized using the following sequence: a first, isotropic step defines the tip; this is followed by anisotropic etching that increases the height of the needle; a final isotropic procedure thins the microneedle and sharpens its tip. From the various process parameters tested, it is concluded that the isotropic fabrication is influenced mostly by four process parameters, whereas six parameters dominantly govern the outcome of the stepped etching technique. The dependence of the needle shape on the etch mask diameter is also investigated. Microneedles with diameters down to the sub-micrometer range and heights below 10 µm are obtained. The experimental design is performed using the D-optimal method. The resulting geometry, i.e. heights, diameters and radii of curvature measured at different positions, is extracted from scanning electron micrographs of needle cross-sections obtained from cuts by focused ion beam. The process parameters are used as inputs and the geometry features of the microneedles as outputs for the analysis of the process.

Design of experiment characterization of microneedle fabrication processes based on dry silicon etching

International Nuclear Information System (INIS)

Held, J; Gaspar, J; Ruther, P; Paul, O; Hagner, M; Cismak, A; Heilmann, A

2010-01-01

This paper reports on the characterization of dry etching-based processes for the fabrication of silicon microneedles using a design of experiment (DoE) approach. The possibility of using such microneedles as protruding microelectrodes able to electroporate adherently growing cells and record intracellular potentials motivates the systematic analysis of the influence of etching parameters on the needle shape. Two processes are characterized: a fully isotropic etch process and a three-step etching approach. In the first case, the shape of the microneedles is defined by a single etch step. For the stepped method, the structures are realized using the following sequence: a first, isotropic step defines the tip; this is followed by anisotropic etching that increases the height of the needle; a final isotropic procedure thins the microneedle and sharpens its tip. From the various process parameters tested, it is concluded that the isotropic fabrication is influenced mostly by four process parameters, whereas six parameters dominantly govern the outcome of the stepped etching technique. The dependence of the needle shape on the etch mask diameter is also investigated. Microneedles with diameters down to the sub-micrometer range and heights below 10 µm are obtained. The experimental design is performed using the D-optimal method. The resulting geometry, i.e. heights, diameters and radii of curvature measured at different positions, is extracted from scanning electron micrographs of needle cross-sections obtained from cuts by focused ion beam. The process parameters are used as inputs and the geometry features of the microneedles as outputs for the analysis of the process.

Dry etching of thin chalcogenide films

Energy Technology Data Exchange (ETDEWEB)

Petkov, Kiril [Acad. J. Malinowski Central Laboratory of Photoprocesses, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 109, 1113 Sofia (Bulgaria); Vassilev, Gergo; Vassilev, Venceslav, E-mail: kpetkov@clf.bas.b [Department of Semiconductors, University of Chemical Technology and Metallurgy, 8 Kl. Ohridsky Blvd., 1756 Sofia (Bulgaria)

2010-04-01

Fluorocarbon plasmas (pure and mixtures with Ar) were used to investigate the changes in the etching rate depending on the chalcogenide glasses composition and light exposure. The experiments were performed on modified commercial HZM-4 vacuum equipment in a diode electrode configuration. The surface microstructure of thin chalcogenide layers and its change after etching in CCl{sub 2}F{sub 2} and CF{sub 4} plasmas were studied by SEM. The dependence of the composition of As-S-Ge, As-Se and multicomponent Ge-Se-Sb-Ag-I layers on the etching rate was discussed. The selective etching of some glasses observed after light exposure opens opportunities for deep structure processing applications.

Composite shear bond strength to dry and wet enamel with three self-etch adhesives

Directory of Open Access Journals (Sweden)

Shafiee F

2006-01-01

Full Text Available Background and Aim: The bonding mechanisms of self etching primers, based upon the simultaneous etching and priming of dentin, simplifies the bonding technique, but the efficiency of these systems is still controversial. This study compared the shear bond strength of three self etch adhesive systems in dry and wet conditions. Materials and Method: In this experimental study, 77 intact bovine lower incisors with flat 600 grit sanded enamel surface were fixed in acrylic molds and divided into 7 groups, of 11 teeth. The enamel surfaces were treated according to a special procedure as follows: Group 1: Prompt L-Pop (PLP in dry condition, Group 2: Prompt L-Pop in wet condition, Group 3: Clearfield SE Bond (CSEB in dry condition, Group 4: Clearfield SE Bond in wet condition, Group 5: iBond (iB in dry condition, Group 6: iBond in wet condition, Group 7: Margin Bond (Control in dry condition. Surfaces were air dried for ten seconds, or blot dried in wet condition. Composite resin was bonded on the enamel and built up by applying a cylindric teflon split mold (4 mm height 2mm diameter. After 24 hours storage in dionized water at room temperature, all specimens were thermocycled and shear bond test was employed by a universal testing machine (Instron with a cross-head speed of 1mm/min. The shear bond strength was recorded in MPa and data were analyzed with ANOVA and Scheffe statistical tests. P<0.05 was considered as statistically significant. The mode of failure was examined under a stereomicroscope. Results: 1- Shear bond strength of CSEB in dry condition (21.5 ± 4.8 MPa was significantly higher than PLP and iB groups (p<0.0001. 2- Shear bond strength of iB and PLP groups in dry condition (9.60 ± 2.2, 9.49 ± 3 MPa were significantly lower than CSEB and control (2.99 ± 5.1 MPa (P<0.0001. 3- There was no significant difference between PLP and iB groups in dry condition (P=1. 4- Shear bond strength of CSEB in wet condition (21.8 ± 3 MPa was

Dry Phosphorus silicate glass etching and surface conditioning and cleaning for multi-crystalline silicon solar cell processing

International Nuclear Information System (INIS)

Kagilik, Ahmed S.

2014-01-01

As an alternative to the wet chemical etching method, dry chemical etching processes for Phosphorus silicate glass [PSG} layer removal using Trifluormethane/Sulfur Hexafluoride (CHF 3 / SF 6 ) gas mixture in commercial silicon-nitride plasma enhanced chemical vapour deposition (SiN-PECVD) system is applied. The dependence of the solar cell performance on the etching temperature is investigated and optimized. It is found that the SiN-PECVD system temperature variation has a significant impact on the whole solar cell characteristics. A dry plasma cleaning treatment of the Si wafer surface after the PSG removal step is also investigated and developed. The cleaning step is used to remove the polymer film which is formed during the PSG etching using both oxygen and hydrogen gases. By applying an additional cleaning step, the polymer film deposited on the silicon wafer surface after PSG etching is eliminated. The effect of different plasma cleaning conditions on solar cell performance is investigated. After optimization of the plasma operating conditions, the performance of the solar cell is improved and the overall gain in efficiency of 0.6% absolute is yielded compared to a cell without any further cleaning step. On the other hand, the best solar cell characteristics can reach values close to that achieved by the conventional wet chemical etching processes demonstrating the effectiveness of the additional O 2 /H 2 post cleaning treatment.(author)

Thermal and chemical treatment of polymer optical fiber Bragg grating sensors for enhanced mechanical sensitivity

DEFF Research Database (Denmark)

Pospori, Andreas; Marques, C. A. F.; Saez-Rodriguez, D.

2017-01-01

An investigation of the thermal annealing effects on the strain, stress, and force sensitivities of polymer optical fiber Bragg grating sensors is performed. We demonstrate for the first time that the fiber annealing can enhance both stress and force sensitivities of Bragg grating sensors......, with the possible cause being the molecular relaxation of the polymer when fiber is raised above the β-transition temperature. A simple, cost-effective, but well controlled method for fiber annealing is also presented in this work. In addition, the effects of chemical etching on the strain, stress, and force...... sensitivities have been investigated. Results show that fiber etching too can increase the force sensitivity, and it can also affect the strain and stress sensitivities of the Bragg grating sensors....

Thermal and chemical treatment of polymer optical fiber Bragg grating sensors for enhanced mechanical sensitivity

Science.gov (United States)

Pospori, A.; Marques, C. A. F.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.

2017-07-01

An investigation of the thermal annealing effects on the strain, stress, and force sensitivities of polymer optical fiber Bragg grating sensors is performed. We demonstrate for the first time that the fiber annealing can enhance both stress and force sensitivities of Bragg grating sensors, with the possible cause being the molecular relaxation of the polymer when fiber is raised above the β -transition temperature. A simple, cost-effective, but well controlled method for fiber annealing is also presented in this work. In addition, the effects of chemical etching on the strain, stress, and force sensitivities have been investigated. Results show that fiber etching too can increase the force sensitivity, and it can also affect the strain and stress sensitivities of the Bragg grating sensors.

Evolution of etched nuclear track profiles of alpha particles in CR-39 by atomic force microscopy

International Nuclear Information System (INIS)

Félix-Bautista, R.; Hernández-Hernández, C.; Zendejas-Leal, B.E.; Fragoso, R.; Golzarri, J.I.; Vázquez-López, C.; Espinosa, G.

2013-01-01

A series of atomic force microscopy (AFM) images of etched nuclear tracks has been obtained and used to calculate the nuclear track registration sensitivity parameter V(x) = Vt(x)/Vb. Due to the AFM limitations the samples were irradiated normally to the surface, and with energies attenuated in order to include the Bragg peak region in the AFM piezo-scanner z movement range. The simulation of the track profile evolution was then obtained. The different stages of etched nuclear track profiles were rendered. - Highlights: ► Using AFM we reach that Bragg peak region of etched tracks in CR-39. ► The etched track sensitivity V was calculated by data obtained by AFM. ► The evolucion of etched nuclear tracks was simulated by data achieved by AFM

Effects of 3D microlens transfer into fused silica substrate by CF{sub 4}/O{sub 2} dry etching

Energy Technology Data Exchange (ETDEWEB)

Grigaliūnas, Viktoras, E-mail: Viktoras.Grigaliunas@ktu.lt [Institute of Materials Science, Kaunas University of Technology, Barsausko 59, LT-51423 Kaunas (Lithuania); Jucius, Dalius; Lazauskas, Algirdas; Andrulevičius, Mindaugas; Sakaliūnienė, Jolita; Abakevičienė, Brigita; Kopustinskas, Vitoldas [Institute of Materials Science, Kaunas University of Technology, Barsausko 59, LT-51423 Kaunas (Lithuania); Smetona, Saulius [Qorvo, 7628 Thorndike Road Greensboro, NC 27409 United States (United States); Tamulevičius, Sigitas [Institute of Materials Science, Kaunas University of Technology, Barsausko 59, LT-51423 Kaunas (Lithuania)

2017-01-30

Highlights: • The etching rate of PMMA is dependent on the plasma etching time. • The etching rate ratio between PMMA and fused silica vary during plasma treatment. • The etching rate ratio variation must be assessed during the microlens design phase. - Abstract: Nowadays, 3D microoptical elements find a variety of applications from light emitting diodes and household appliances to precise medical endoscopes. Such elements, fabricated in a fused silica substrate by combining 3D e-beam patterning and dry etching, can be used as a mold for the high throughput replication in polymeric materials by UV nanoimprint technique. Flexible and precise control of 3D shape in the resist layer can be achieved by e-beam patterning, but it is also very important to know peculiarities of 3D pattern transfer from resist layer into the fused silica substrate. This paper reports on the effects of PMMA 3D microlens pattern transfer into fused silica substrate by CF{sub 4}/O{sub 2} dry etching. It is demonstrated that etching rate ratio between PMMA and fused silica changes during plasma treatment. Thus, the resulting shape of transferred 3D profile is different from the shape in PMMA and this variation must be assessed during the design phase.

Dry etching of ITO by magnetic pole enhanced inductively coupled plasma for display and biosensing devices

Energy Technology Data Exchange (ETDEWEB)

Meziani, T. [European Commission, Joint Research Centre, Institute for Health and Consumer Protection, 21020 Ispra (Vatican City State, Holy See,) (Italy)]. E-mail: tarik.meziani@jrc.it; Colpo, P. [European Commission, Joint Research Centre, Institute for Health and Consumer Protection, 21020 Ispra (Va) (Italy)]. E-mail: pascal.colpo@jrc.it; Lambertini, V. [Centro Ricerche Fiat, Strada Torino 50, 10043 Orbassano (TO) (Italy); Ceccone, G. [European Commission, Joint Research Centre, Institute for Health and Consumer Protection, 21020 Ispra (Va) (Italy); Rossi, F. [European Commission, Joint Research Centre, Institute for Health and Consumer Protection, 21020 Ispra (Va) (Italy)

2006-03-15

The dry etching of indium tin oxide (ITO) layers deposited on glass substrates was investigated in a high density inductively coupled plasma (ICP) source. This innovative low pressure plasma source uses a magnetic core in order to concentrate the electromagnetic energy on the plasma and thus provides for higher plasma density and better uniformity. Different gas mixtures were tested containing mainly hydrogen, argon and methane. In Ar/H{sub 2} mixtures and at constant bias voltage (-100 V), the etch rate shows a linear dependence with input power varying the same way as the ion density, which confirms the hypothesis that the etching process is mainly physical. In CH{sub 4}/H{sub 2} mixtures, the etch rate goes through a maximum for 10% CH{sub 4} indicating a participation of the radicals to the etching process. However, the etch rate remains quite low with this type of gas mixture (around 10 nm/min) because the etching mechanism appears to be competing with a deposition process. With CH{sub 4}/Ar mixtures, a similar feature appeared but the etch rate was much higher, reaching 130 nm/min at 10% of CH{sub 4} in Ar. The increase in etch rate with the addition of a small quantity of methane indicates that the physical etching process is enhanced by a chemical mechanism. The etching process was monitored by optical emission spectroscopy that appeared to be a valuable tool for endpoint detection.

Prevention of sidewall redeposition of etched byproducts in the dry Au etch process

International Nuclear Information System (INIS)

Aydemir, A; Akin, T

2012-01-01

In this paper we present a new technique of etching thin Au film in a dual frequency inductively coupled plasma (ICP) system on Si substrate to prevent the redeposition of etched Au particles over the sidewall of the masking material known as veils. First, the effect of the lithography step was investigated. Then the effects of etch chemistry and the process parameters on the redeposition of etched Au particles on the sidewall of the masking material were investigated. The redeposition effect was examined by depositing a thin Ti film over the masking material acting as a hard mask. The results showed that depositing a thin Ti film over the masking material prevents the formation of veils after etching Au in plasma environments for submicron size structures. Based on the results of this study, we propose a new technique that completely eliminates formation of veils after etching Au in plasma environments for submicron size structures. (paper)

A Study of Parameters Related to the Etch Rate for a Dry Etch Process Using NF3/O2 and SF6/O2

Directory of Open Access Journals (Sweden)

Seon-Geun Oh

2014-01-01

Full Text Available The characteristics of the dry etching of SiNx:H thin films for display devices using SF6/O2 and NF3/O2 were investigated using a dual-frequency capacitively coupled plasma reactive ion etching (CCP-RIE system. The investigation was carried out by varying the RF power ratio (13.56 MHz/2 MHz, pressure, and gas flow ratio. For the SiNx:H film, the etch rates obtained using NF3/O2 were higher than those obtained using SF6/O2 under various process conditions. The relationships between the etch rates and the usual monitoring parameters—the optical emission spectroscopy (OES intensity of atomic fluorine (685.1 nm and 702.89 nm and the voltages VH and VL—were investigated. The OES intensity data indicated a correlation between the bulk plasma density and the atomic fluorine density. The etch rate was proportional to the product of the OES intensity of atomic fluorine (I(F and the square root of the voltages (Vh+Vl on the assumption that the velocity of the reactive fluorine was proportional to the square root of the voltages.

Experimental and theoretical study of bragg-Fresnel optics etched on multilayer structures. Application: lenses for X-Ray imaging; Etude experimentale et theorique d`optiques de bragg-Fresnel gravees sur miroirs interferentiels multicouches. Application: lentilles pour l`imagerie X

Energy Technology Data Exchange (ETDEWEB)

Soullie, G.

1996-10-01

This work concerns the study of a new type of X-ray focusing optics known as Bragg-Fresnel lenses developed for imaging in the X and X-UV range. These optics, etched on multilayer structure, combine the focusing properties of zone plate with the Bragg reflection of multilayer used like support. Using synchrotron sources and a plasma source produced by a laser, we tested the efficiency and the spatial resolution of these lenses. With a monochromatic beam, we first obtained the image of a object by using the first order diffraction of an elliptical off-axis Bragg-Fresnel lens. By using only one part of a lens, the superposition of different diffraction orders in focal plane can be avoided, thus improving the image contrast. In order to evaluate the chromatic aberrations of these lenses, we have summed on the same image, three exposures at different energies in the band pass of the multilayer. To reduce these kind of aberrations, we used a system composed of two off-axis lenses. To simplify the alignment, we tested an elliptical off-axis lens associated with a lamellar grating. Thus we are able to validate the theoretical approximation of an off-axis Bragg-Fresnel lens to a variable spaced grating. Finally, to show the perturbation brought by the zeroth order, we successively imaged a laser plasma source with a centred and an off-axis elliptical lenses. As with the synchrotron source, a set of images of a test object enabled us to improve the spatial resolution. (author).

Fabrication of ultrahigh density metal-cell-metal crossbar memory devices with only two cycles of lithography and dry-etch procedures

KAUST Repository

Zong, Baoyu

2013-05-20

A novel approach to the fabrication of metal-cell-metal trilayer memory devices was demonstrated by using only two cycles of lithography and dry-etch procedures. The fabricated ultrahigh density crossbar devices can be scaled down to ≤70 nm in half-pitch without alignment issues. Depending on the different dry-etch mechanisms in transferring high and low density nanopatterns, suitable dry-etch angles and methods are studied for the transfer of high density nanopatterns. Some novel process methods have also been developed to eliminate the sidewall and other conversion obstacles for obtaining high density of uniform metallic nanopatterns. With these methods, ultrahigh density trilayer crossbar devices (∼2 × 1010 bit cm-2-kilobit electronic memory), which are composed of built-in practical magnetoresistive nanocells, have been achieved. This scalable process that we have developed provides the relevant industries with a cheap means to commercially fabricate three-dimensional high density metal-cell-metal nanodevices. © 2013 IOP Publishing Ltd.

The memory characteristics of submicron feature-size PZT capacitors with PtOx top electrode by using dry-etching

International Nuclear Information System (INIS)

Huang, C.-K.; Wang, C.-C.; Wu, T.-B.

2007-01-01

Dry etching and its effect on the characteristics of submicron feature-size PbZr 1-x Ti x O 3 (PZT) capacitors with PtO x top electrode were investigated. The photoresist (PR)-masked PtO x films were etched by an Ar/(20%)Cl 2 /O 2 helicon wave plasma. A fence-free pattern with a significantly high etch rate and sidewall slope was obtained by the addition of O 2 into the etching gas mixture, due to the chemical instability of PtO x and the formation of a PtO 2 passivation layer to suppress redeposition of the etch by-products on the etched surface. The patterned PtO x electrode can be further used as a hard mask for etching the PZT film, subsequently, with the gas mixture of Ar, CF 4 and O 2 . A high etching rate of PZT and a good etching selectivity to PtO x can be obtained at 30% O 2 addition into the Ar/(50%)CF 4 plasma. The etched capacitors have a steep, 72 0 , sidewall angle with a clean surface. Moreover, the addition of O 2 into the etching gas can well preserve the properties and the fatigue endurance of PtO x /PZT capacitors

Teste de microtração em esmalte de um sistema adesivo universal pela técnica etch-and-rinse e etch-and-dry

OpenAIRE

Peneque, Carolina Martins Santos

2014-01-01

Tese de mestrado, Medicina dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2014 Objetivo: Recorrendo ao teste de microtração, avaliar e comparar as forças adesivas em esmalte cortado de um sistema adesivo universal (Scotchbond Universal Adhesive, 3M ESPE, St. Paul, MN, USA) usado segundo as instruções do fabricante, nos modos etch-and-rinse e etch-and-dry. A hipótese nula testada é a de que não existem diferenças estatisticamente significativas nas forças de adesão ao esm...

Fabrication of Light Extraction Efficiency of Organic Light-Emitting Diodes with 3D Aspherical Microlens by Using Dry Etching Process

Directory of Open Access Journals (Sweden)

Y. C. Chen

2013-01-01

Full Text Available organic light-emitting diode (OLED can enable a greater artificial contrast ratio and viewing angle compared to liquid crystal display (LCD because OLED pixels directly emit light. There is a shortcoming that the internal quantum efficiency can reach values close to 100%, but about 80% light disperses because of the difference among the refractive indices of the substrate, anode, indium tin oxide (ITO film, and air. In this paper, three dimensions aspherical microlens arrays (3D A-MLAs with substrate modifications are developed to simulate the optical luminous field by using FRED software. This study modified parameters of 3D A-MLAs such as the diameter, fill-factor, aspect ratio, dry etching parameters, and electroforming rates of microlens to improve the extraction efficiency of the OLED. In dry etching, not only the aspect ratio with better extraction rate can be obtained by reactive ion etching (RIE dry etching, but also an undercutting phenomenon can be avoided. The dimensions of 3D A-MLAs can be accurately controlled in the electroforming process used to make a nickel-cobalt (Ni-Co metal mold to achieve the designed dimensions. According to the measured results, the average luminance efficacy of the OLEDs with 3D A-MLAs can be enhanced.

Effect of different air-drying time on the microleakage of single-step self-etch adhesives

OpenAIRE

Moosavi, Horieh; Forghani, Maryam; Managhebi, Esmatsadat

2013-01-01

Objectives This study evaluated the effect of three different air-drying times on microleakage of three self-etch adhesive systems. Materials and Methods Class I cavities were prepared for 108 extracted sound human premolars. The teeth were divided into three main groups based on three different adhesives: Opti Bond All in One (OBAO), Clearfil S3 Bond (CSB), Bond Force (BF). Each main group divided into three subgroups regarding the air-drying time: without application of air stream...

Uniformly thinned optical fibers produced via HF etching with spectral and microscopic verification.

Science.gov (United States)

Bal, Harpreet K; Brodzeli, Zourab; Dragomir, Nicoleta M; Collins, Stephen F; Sidiroglou, Fotios

2012-05-01

A method for producing uniformly thinned (etched) optical fibers is described, which can also be employed to etch optical fibers containing a Bragg grating (FBG) uniformly for evanescent-field-based sensing and other applications. Through a simple modification of this method, the fabrication of phase-shifted FBGs based on uneven etching is also shown. The critical role of how a fiber is secured is shown, and the success of the method is illustrated, by differential interference contrast microscopy images of uniformly etched FBGs. An etched FBG sensor for the monitoring of the refractive index of different glycerin solutions is demonstrated.

Effect of moisture and drying time on the bond strength of the one-step self-etching adhesive system

Directory of Open Access Journals (Sweden)

Yoon Lee

2012-08-01

Full Text Available Objectives To investigate the effect of dentin moisture degree and air-drying time on dentin-bond strength of two different one-step self-etching adhesive systems. Materials and Methods Twenty-four human third molars were used for microtensile bond strength testing of G-Bond and Clearfil S3 Bond. The dentin surface was either blot-dried or air-dried before applying these adhesive agents. After application of the adhesive agent, three different air drying times were evaluated: 1, 5, and 10 sec. Composite resin was build up to 4 mm thickness and light cured for 40 sec with 2 separate layers. Then the tooth was sectioned and trimmed to measure the microtensile bond strength using a universal testing machine. The measured bond strengths were analyzed with three-way ANOVA and regression analysis was done (p = 0.05. Results All three factors, materials, dentin wetness and air drying time, showed significant effect on the microtensile bond strength. Clearfil S3 Bond, dry dentin surface and 10 sec air drying time showed higher bond strength. Conclusions Within the limitation of this experiment, air drying time after the application of the one-step self-etching adhesive agent was the most significant factor affecting the bond strength, followed by the material difference and dentin moisture before applying the adhesive agent.

Fiber Bragg Grating Sensor for Detection of Nitrate Concentration in Water

Directory of Open Access Journals (Sweden)

A. S. LALASANGI

2011-02-01

Full Text Available The concentrations of chemical species in drinking water are of great interest. We demonstrated etched fiber Bragg grating (FBG as a concentration sensor for nitrate by analyzing the Bragg wavelength shift with concentration of chemical solution. The FBG is fabricated by phase mask technique on single mode Ge-B co-doped photosensitive fiber. Sensitivity of FBGs to the surrounding solution concentration can be enhanced by reducing diameter of the cladding with 40 % HF solution. The maximum sensitivity achieved is 1.322 ´ 10-3 nm/ppm. The overall shift of Bragg wavelength is of the order of 6.611 ´ 10-2 nm for 10 to 50 ppm concentration.

Dry etching of new phase-change material Al1.3Sb3Te in CF4/Ar plasma

International Nuclear Information System (INIS)

Zhang Xu; Rao Feng; Liu Bo; Peng Cheng; Zhou Xilin; Yao Dongning; Guo Xiaohui; Song Sannian; Wang Liangyong; Cheng Yan; Wu Liangcai; Song Zhitang; Feng Songlin

2012-01-01

The dry etching characteristic of Al 1.3 Sb 3 Te film was investigated by using a CF 4 /Ar gas mixture. The experimental control parameters were gas flow rate into the chamber, CF 4 /Ar ratio, the O 2 addition, the chamber background pressure, and the incident RF power applied to the lower electrode. The total flow rate was 50 sccm and the behavior of etch rate of Al 1.3 Sb 3 Te thin films was investigated as a function of the CF 4 /Ar ratio, the O 2 addition, the chamber background pressure, and the incident RF power. Then the parameters were optimized. The fast etch rate was up to 70.8 nm/min and a smooth surface was achieved using optimized etching parameters of CF 4 concentration of 4%, power of 300 W and pressure of 80 mTorr.

Comparison of damage introduced into GaN/AlGaN/GaN heterostructures using selective dry etch recipes

International Nuclear Information System (INIS)

Green, R T; Luxmoore, I J; Houston, P A; Ranalli, F; Wang, T; Parbrook, P J; Uren, M J; Wallis, D J; Martin, T

2009-01-01

A SiCl 4 /SF 6 dry etch plasma recipe is presented giving a selectivity of 14:1 between GaN and AlGaN. Using a leakage test structure, which enables bulk and surface leakage components to be identified independently, the optimized recipe is compared to an un-etched sample and devices recessed using a Cl 2 /Ar/O 2 -based plasma chemistry. Devices etched using the SiCl 4 /SF 6 recipe demonstrated reduced bulk and surface leakage currents when operated over a wide range of temperatures. Consequently the SiCl 4 /SF 6 recipe is identified as most suitable for the fabrication of gate recessed AlGaN/GaN HEMTs

Fiber Bragg Grating Sensor to Monitor Stress Kinetics in Drying Process of Commercial Latex Paints

Directory of Open Access Journals (Sweden)

Ivo de Lourenço

2010-05-01

Full Text Available In this paper, we report a study about the application of packaged fiber Bragg gratings used as strain sensors to monitor the stress kinetics during the drying process of commercial latex paints. Three stages of drying with distinct mechanical deformation and temporal behaviors were identified for the samples, with mechanical deformation from 15 μm to 21 μm in the longitudinal film dimension on time intervals from 370 to 600 minutes. Drying time tests based on human sense technique described by the Brazilian Technical Standards NBR 9558 were also done. The results obtained shows that human sense technique has a limited perception of the drying process and that the optical measurement system proposed can be used to characterize correctly the dry-through stage of paint. The influence of solvent (water addition in the drying process was also investigated. The paint was diluted with four parts paint and one part water (80% paint, and one part paint and one part water (50% paint. It was observed that the increase of the water ratio mixed into the paint decreases both the mechanical deformation magnitude and the paint dry-through time. Contraction of 5.2 μm and 10.4 μm were measured for concentrations of 50% and 80% of paint in the mixture, respectively. For both diluted paints the dry-through time was approximately 170 minutes less than undiluted paint. The optical technique proposed in this work can contribute to the development of new standards to specify the drying time of paint coatings.

Effect of air-drying time of single-application self-etch adhesives on dentin bond strength.

Science.gov (United States)

Chiba, Yasushi; Yamaguchi, Kanako; Miyazaki, Masashi; Tsubota, Keishi; Takamizawa, Toshiki; Moore, B Keith

2006-01-01

This study examined the effect of air-drying time of adhesives on the dentin bond strength of several single-application self-etch adhesive systems. The adhesive/resin composite combinations used were: Adper Prompt L-Pop/Filtek Z250 (AP), Clearfil Tri-S Bond/Clearfil AP-X (CT), Fluoro Bond Shake One/Beautifil (FB), G-Bond/Gradia Direct (GB) and One-Up Bond F Plus/Palfique Estelite (OF). Bovine mandibular incisors were mounted in self-curing resin and wet ground with #600 SiC to expose labial dentin. Adhesives were applied according to each manufacturer's instructions followed by air-drying time for 0 (without air-drying), 5 and 10 seconds. After light irradiation of the adhesives, the resin composites were condensed into a mold (phi4x2 mm) and polymerized. Ten samples per test group were stored in 37 degrees C distilled water for 24 hours; they were then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Tukey's HSD tests (alpha = 0.05) were done. FE-SEM observations of the resin/dentin interface were also conducted. Dentin bond strength varied with the different air drying times and ranged from 5.8 +/- 2.4 to 13.9 +/- 2.8 MPa for AP, 4.9 +/- 1.5 to 17.1 +/- 2.3 MPa for CT, 7.9 +/- 2.8 to 13.8 +/- 2.4 MPa for FB, 3.7 +/- 1.4 to 13.4 +/- 1.2 MPa for GB and 4.6 +/- 2.1 to 13.7 +/- 2.6 MPa for OF. With longer air drying of adhesives, no significant changes in bond strengths were found for the systems used except for OF. Significantly lower bond strengths were obtained for the 10-second air-drying group for OF. From FE-SEM observations, gaps between the cured adhesive and resin composites were observed for the specimens without the air drying of adhesives except for OF. The data suggests that, with four of the single-application self-etch adhesive systems, air drying is essential to obtain adequate dentin bond strengths, but increased drying time does not significantly influence bond strength. For the other system studied, the bond strength

Dry etch challenges for CD shrinkage in memory process

Science.gov (United States)

Matsushita, Takaya; Matsumoto, Takanori; Mukai, Hidefumi; Kyoh, Suigen; Hashimoto, Kohji

2015-03-01

Line pattern collapse attracts attention as a new problem of the L&S formation in sub-20nm H.P feature. Line pattern collapse that occurs in a slight non-uniformity of adjacent CD (Critical dimension) space using double patterning process has been studied with focus on micro-loading effect in Si etching. Bias RF pulsing plasma etching process using low duty cycle helped increase of selectivity Si to SiO2. In addition to the effect of Bias RF pulsing process, the thin mask obtained from improvement of selectivity has greatly suppressed micro-loading in Si etching. However it was found that micro-loading effect worsen again in sub-20nm space width. It has been confirmed that by using cycle etch process to remove deposition with CFx based etching micro-loading effect could be suppressed. Finally, Si etching process condition using combination of results above could provide finer line and space without "line pattern collapse" in sub-20nm.

Continuous liquid level monitoring sensor system using fiber Bragg grating

Science.gov (United States)

Sengupta, Dipankar; Kishore, Putha

2014-01-01

The design and packaging of simple, small, and low cost sensor heads, used for continuous liquid level measurement using uniformly thinned (etched) optical fiber Bragg grating (FBG) are proposed. The sensor system consists of only an FBG and a simple detection system. The sensitivity of sensor is found to be 23 pm/cm of water column pressure. A linear optical fiber edge filter is designed and developed for the conversion of Bragg wavelength shift to its equivalent intensity. The result shows that relative power measured by a photo detector is linearly proportional to the liquid level. The obtained sensitivity of the sensor is nearly -15 mV/cm.

Fiscal 2000 achievement report on the investigation of alternative gas system and process technologies for dry etching in electronic device manufacturing; 2000 nendo denshi device seizo process de shiyosuru etching gas no daitai gas system oyobi daitai process no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Efforts are made to develop technologies for saving PFC (perfluoro-compound) and conserving energy in semiconductor manufacturing processes, in particular, in the layer insulation film (SiO{sub 2}) dry etching process. Activities are conducted in the five fields of (1) research and development of technologies for reducing the amount of etching gas consumption, (2) development of a dry etching technology using alternative gas, (3) development of a dry etching technology using a low dielectric constant layer insulation film, (4) research and development of novel wiring structures and a method for fabricating the same, and (5) re-entrusted studies. Conducted in field (5) are studies of novel alternative gas - solid sources to substitute PFC, theory design technologies for low dielectric constant organic macromolecules, low dielectric constant material film fabrication by CVD (chemical vapor deposition), and technology for optical wiring inside chips. In field (2), studies are conducted of low GWP (global warming potential) alternative PFC gas aided etching and decomposition prevention technologies for reduction in PFC emissions, and it is made clear that C{sub 4}F{sub 6} performs excellently as an etchant. (NEDO)

Deeply-etched DBR mirrors for photonic integrated circuits and tunable lasers

NARCIS (Netherlands)

Docter, B.

2009-01-01

Deeply-etched Distributed Bragg Reflector (DBR) mirrors are a new versatile building block for Photonic Integrated Circuits that allows us to create more complex circuits for optical telecommunication applications. The DBR mirrors increase the device design flexibility because the mirrors can be

Growth of ZnO nanowire arrays directly onto Si via substrate topographical adjustments using both wet chemical and dry etching methods

Energy Technology Data Exchange (ETDEWEB)

Smith, Nathan A., E-mail: 523615@swansea.ac.uk [Centre for Nanohealth, Department of Physics, College of Science, University of Swansea, Singleton Park SA2 8PP United Kingdom (United Kingdom); Evans, Jon E.; Jones, Daniel R. [Multidisciplinary Nanotechnology Centre, College of Engineering, University of Swansea, Singleton Park, SA2 8PP United Kingdom (United Kingdom); Lord, Alex M. [Centre for Nanohealth, College of Engineering, University of Swansea, Singleton Park, SA2 8PP United Kingdom (United Kingdom); Wilks, S.P. [Centre for Nanohealth, Department of Physics, College of Science, University of Swansea, Singleton Park SA2 8PP United Kingdom (United Kingdom)

2015-03-15

Highlights: • Arrays of catalyst-free ZnO NWs have been grown by CVD without seed layers on Si. • Si surface topography was altered by substrate etching, resulting in NW growth. • XPS analysis shows growth is related to topography and not surface contamination. • Using e-beam lithography with etching, selective nanowire growth is demonstrated. • Electrical measurements on the arrays show improved conduction through the Si. - Abstract: Arrays of CVD catalyst-free ZnO nanowires have been successfully grown without the use of seed layers, using both wet chemical and dry plasma etching methods to alter surface topography. XPS analysis indicates that the NW growth cannot be attributed to a substrate surface chemistry and is therefore directly related to the substrate topography. These nanowires demonstrate structural and optical properties typical of CVD ZnO nanowires. Moreover, the NW arrays exhibit a degree of vertical alignment of less than 20° from the substrate normal. Electrical measurements suggest an improved conduction path through the substrate over seed layer grown nanowires. Furthermore, the etching technique was combined with e-beam lithography to produce high resolution selective area nanowire growth. The ability to pattern uniform nanowires using mature dry etch technology coupled with the increased charge transport through the substrate demonstrates the potential of this technique in the vertical integration of nanowire arrays.

Advanced dry etching studies for micro- and nano-systems

DEFF Research Database (Denmark)

Rasmussen, Kristian Hagsted

and even contaminate the surface with metal flakes after resist removal. Ion beam etching has also been used for etching of steel without any problems with redeposition. For steel the etch rate was low which reduced the selectivity to the photo resist. Sapphire, a crystal of aluminum oxide, has a very low....... However, just generating an oxygen plasma does not result in a controllable etch and may give rise to a poor surface for later use. It may be necessary to introduce other gases such as SF6 to reduce surface roughness. Roughness can also be introduced by the mask in the form of redeposition of material...

Effect of additive gases and injection methods on chemical dry etching of silicon nitride, silicon oxynitride, and silicon oxide layers in F2 remote plasmas

International Nuclear Information System (INIS)

Yun, Y. B.; Park, S. M.; Kim, D. J.; Lee, N.-E.; Kim, K. S.; Bae, G. H.

2007-01-01

The authors investigated the effects of various additive gases and different injection methods on the chemical dry etching of silicon nitride, silicon oxynitride, and silicon oxide layers in F 2 remote plasmas. N 2 and N 2 +O 2 gases in the F 2 /Ar/N 2 and F 2 /Ar/N 2 /O 2 remote plasmas effectively increased the etch rate of the layers. The addition of direct-injected NO gas increased the etch rates most significantly. NO radicals generated by the addition of N 2 and N 2 +O 2 or direct-injected NO molecules contributed to the effective removal of nitrogen and oxygen in the silicon nitride and oxide layers, by forming N 2 O and NO 2 by-products, respectively, and thereby enhancing SiF 4 formation. As a result of the effective removal of the oxygen, nitrogen, and silicon atoms in the layers, the chemical dry etch rates were enhanced significantly. The process regime for the etch rate enhancement of the layers was extended at elevated temperature

Improved photoluminescence efficiency in UV nanopillar light emitting diode structures by recovery of dry etching damage.

Science.gov (United States)

Jeon, Dae-Woo; Jang, Lee-Woon; Jeon, Ju-Won; Park, Jae-Woo; Song, Young Ho; Jeon, Seong-Ran; Ju, Jin-Woo; Baek, Jong Hyeob; Lee, In-Hwan

2013-05-01

In this study, we have fabricated 375-nm-wavelength InGaN/AlInGaN nanopillar light emitting diodes (LED) structures on c-plane sapphire. A uniform and highly vertical nanopillar structure was fabricated using self-organized Ni/SiO2 nano-size mask by dry etching method. To minimize the dry etching damage, the samples were subjected to high temperature annealing with subsequent chemical passivation in KOH solution. Prior to annealing and passivation the UV nanopillar LEDs showed the photoluminescence (PL) efficiency about 2.5 times higher than conventional UV LED structures which is attributed to better light extraction efficiency and possibly some improvement of internal quantum efficiency due to partially relieved strain. Annealing alone further increased the PL efficiency by about 4.5 times compared to the conventional UV LEDs, while KOH passivation led to the overall PL efficiency improvement by more than 7 times. Combined results of Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) suggest that annealing decreases the number of lattice defects and relieves the strain in the surface region of the nanopillars whereas KOH treatment removes the surface oxide from nanopillar surface.

ICP dry etching ITO to improve the performance of GaN-based LEDs

International Nuclear Information System (INIS)

Meng Lili; Chen Yixin; Ma Li; Liu Zike; Shen Guangdi

2011-01-01

In order to improve the light efficiency of the conventional GaN-based light-emitting diodes (LEDs), the indium tin oxide (ITO) film is introduced as the current spreading layer and the light anti-reflecting layer on the p-GaN surface. There is a big problem with the ITO thin film's corrosion during the electrode preparation. In this paper, at least, the edge of the ITO film was lateral corroded 3.5 μm width, i.e. 6.43%-1/3 of ITO film's area. An optimized simple process, i.e. inductively couple plasma (ICP), was introduced to solve this problem. The ICP process not only prevented the ITO film from lateral corrosion, but also improved the LED's light intensity and device performance. The edge of the ITO film by ICP dry etching is steep, and the areas of ITO film are whole. Compared with the chip by wet etching, the areas of light emission increase by 6.43% at least and the chip's lop values increase by 45.9% at most. (semiconductor devices)

Pulsed high-density plasmas for advanced dry etching processes

International Nuclear Information System (INIS)

Banna, Samer; Agarwal, Ankur; Cunge, Gilles; Darnon, Maxime; Pargon, Erwine; Joubert, Olivier

2012-01-01

Plasma etching processes at the 22 nm technology node and below will have to satisfy multiple stringent scaling requirements of microelectronics fabrication. To satisfy these requirements simultaneously, significant improvements in controlling key plasma parameters are essential. Pulsed plasmas exhibit considerable potential to meet the majority of the scaling challenges, while leveraging the broad expertise developed over the years in conventional continuous wave plasma processing. Comprehending the underlying physics and etching mechanisms in pulsed plasma operation is, however, a complex undertaking; hence the full potential of this strategy has not yet been realized. In this review paper, we first address the general potential of pulsed plasmas for plasma etching processes followed by the dynamics of pulsed plasmas in conventional high-density plasma reactors. The authors reviewed more than 30 years of academic research on pulsed plasmas for microelectronics processing, primarily for silicon and conductor etch applications, highlighting the potential benefits to date and challenges in extending the technology for mass-production. Schemes such as source pulsing, bias pulsing, synchronous pulsing, and others in conventional high-density plasma reactors used in the semiconductor industry have demonstrated greater flexibility in controlling critical plasma parameters such as ion and radical densities, ion energies, and electron temperature. Specifically, plasma pulsing allows for independent control of ion flux and neutral radicals flux to the wafer, which is key to eliminating several feature profile distortions at the nanometer scale. However, such flexibility might also introduce some difficulty in developing new etching processes based on pulsed plasmas. Therefore, the main characteristics of continuous wave plasmas and different pulsing schemes are compared to provide guidelines for implementing different schemes in advanced plasma etching processes based on

Low surface damage dry etched black silicon

Science.gov (United States)

Plakhotnyuk, Maksym M.; Gaudig, Maria; Davidsen, Rasmus Schmidt; Lindhard, Jonas Michael; Hirsch, Jens; Lausch, Dominik; Schmidt, Michael Stenbæk; Stamate, Eugen; Hansen, Ole

2017-10-01

Black silicon (bSi) is promising for integration into silicon solar cell fabrication flow due to its excellent light trapping and low reflectance, and a continuously improving passivation. However, intensive ion bombardment during the reactive ion etching used to fabricate bSi induces surface damage that causes significant recombination. Here, we present a process optimization strategy for bSi, where surface damage is reduced and surface passivation is improved while excellent light trapping and low reflectance are maintained. We demonstrate that reduction of the capacitively coupled plasma power, during reactive ion etching at non-cryogenic temperature (-20 °C), preserves the reflectivity below 1% and improves the effective minority carrier lifetime due to reduced ion energy. We investigate the effect of the etching process on the surface morphology, light trapping, reflectance, transmittance, and effective lifetime of bSi. Additional surface passivation using atomic layer deposition of Al2O3 significantly improves the effective lifetime. For n-type wafers, the lifetime reaches 12 ms for polished and 7.5 ms for bSi surfaces. For p-type wafers, the lifetime reaches 800 μs for both polished and bSi surfaces.

Modeling of block copolymer dry etching for directed self-assembly lithography

Science.gov (United States)

Belete, Zelalem; Baer, Eberhard; Erdmann, Andreas

2018-03-01

Directed self-assembly (DSA) of block copolymers (BCP) is a promising alternative technology to overcome the limits of patterning for the semiconductor industry. DSA exploits the self-assembling property of BCPs for nano-scale manufacturing and to repair defects in patterns created during photolithography. After self-assembly of BCPs, to transfer the created pattern to the underlying substrate, selective etching of PMMA (poly (methyl methacrylate)) to PS (polystyrene) is required. However, the etch process to transfer the self-assemble "fingerprint" DSA patterns to the underlying layer is still a challenge. Using combined experimental and modelling studies increases understanding of plasma interaction with BCP materials during the etch process and supports the development of selective process that form well-defined patterns. In this paper, a simple model based on a generic surface model has been developed and an investigation to understand the etch behavior of PS-b-PMMA for Ar, and Ar/O2 plasma chemistries has been conducted. The implemented model is calibrated for etch rates and etch profiles with literature data to extract parameters and conduct simulations. In order to understand the effect of the plasma on the block copolymers, first the etch model was calibrated for polystyrene (PS) and poly (methyl methacrylate) (PMMA) homopolymers. After calibration of the model with the homopolymers etch rate, a full Monte-Carlo simulation was conducted and simulation results are compared with the critical-dimension (CD) and selectivity of etch profile measurement. In addition, etch simulations for lamellae pattern have been demonstrated, using the implemented model.

HF-based clad etching of fibre Bragg grating and its utilization in ...

Indian Academy of Sciences (India)

2014-02-09

Feb 9, 2014 ... Abstract. This paper presents a fiber Bragg grating (FBG) based sensor to study the concentration of laser dye in dye–ethanol solution. The FBG used in this experiment is indigenously developed using 255 nm UV radiations from copper vapour laser. The cladding of the FBG was partially removed using ...

Fabrication of ultrahigh density metal-cell-metal crossbar memory devices with only two cycles of lithography and dry-etch procedures

KAUST Repository

Zong, Baoyu; Goh, J. Y.; Guo, Zaibing; Luo, Ping; Wang, Chenchen; Qiu, Jinjun; Ho, Pin; Chen, Yunjie; Zhang, Mingsheng; Han, Guchang

2013-01-01

A novel approach to the fabrication of metal-cell-metal trilayer memory devices was demonstrated by using only two cycles of lithography and dry-etch procedures. The fabricated ultrahigh density crossbar devices can be scaled down to ≤70 nm in half

Experimental and theoretical study of Bragg-Fresnel focalizing optical systems engraved on multi layers interferential mirrors adapted to X and X-UV fields; Etude experimentale et theorique d`optiques focalisantes de type Bragg-Fresnel gravees sur des miroirs interferentiels multicouches adaptes aux domaines X et X-UV

Energy Technology Data Exchange (ETDEWEB)

Idir, M.

1995-02-01

This work concerns the study of a particular type of X-ray focusing optics known as Bragg-Fresnel lenses, formed through ion-etching of multilayered structures. Using the Super-ACO (LURE/Orsay) synchrotron storage ring, we tested several Bragg-Fresnel lenses having either linear or elliptical geometries (producing a line or a point focus, respectively). Diffraction profiles were first obtained for the linear lenses ion-etched on W/Si multilayers of nano-metric period. The experimental results were compared with our theoretical predictions. We next proposed and tested a solution to the problem superposing the different diffraction orders in the focal plane, that of fabricating Bragg-Fresnel lenses with an off-axis configuration, first for the linear and then the elliptical geometry. An experimental application, for an off-axis elliptical lens produced a focused X-ray spot of 5 x 10 microns{sup 2} for the Super-ACO synchrotron source. The same lens also produced a 1/3-size X-ray image of a grid-like object at 1750 eV using the first and third diffraction orders. (author).

Cradle-to-gate life cycle assessment of the dry etching step in the manufacturing of photovoltaic cells

Directory of Open Access Journals (Sweden)

Otto Andersen

2014-11-01

Full Text Available A new photovoltaic silicon crystalline solar cell dry chemical etching process (DCEP is developed. It is an alternative to the current State-of-the-Art (SoA wet chemical etching process (WCEP, associated with relatively large environmental loadings in the form of high water consumption and emissions of greenhouse gases with high Global Warming Potential (GWP. In order to compare the environmental impacts of DCEP to the corresponding impacts from WCEP, a comparative attributional life cycle assessment (LCA is conducted. From the LCA it can be concluded that the DCEP will lead to 86% reduction in water consumption compared to WCEP (acidic, and 89% reduction compared to WCEP (alkaline. The emissions of greenhouse gases, as expressed by the GWP100 indicator of the etching step, are also reduced with 63% and 20% respectively, when compared with current SoA acidic and alkaline WCEP. The toxicity impacts are also assessed to be lower for the DCEP compared to WCEP technologies, although the uncertainty is relatively high for the applied toxicity indicators. All in all, DCEP can reduce the CO2eq emissions of solar photovoltaic systems production by 5-10%.

Analysis of InP-based single photon avalanche diodes based on a single recess-etching process

Science.gov (United States)

Lee, Kiwon

2018-04-01

Effects of the different etching techniques have been investigated by analyzing electrical and optical characteristics of two-types of single-diffused single photon avalanche diodes (SPADs). The fabricated two-types of SPADs have no diffusion depth variation by using a single diffusion process at the same time. The dry-etched SPADs show higher temperature dependence of a breakdown voltage, larger dark-count-rate (DCR), and lower photon-detection-efficiency (PDE) than those of the wet-etched SPADs due to plasma-induced damage of dry-etching process. The results show that the dry etching damages can more significantly affect the performance of the SPADs based on a single recess-etching process.

Inductively coupled plasma etching of III-V antimonides in BCl3/SiCl4 etch chemistry

International Nuclear Information System (INIS)

Swaminathan, K.; Janardhanan, P.E.; Sulima, O.V.

2008-01-01

Inductively coupled plasma etching of GaSb using BCl 3 /SiCl 4 etch chemistry has been investigated. The etch rates were studied as a function of bias power, inductively coupled plasma source power, plasma chemistry and chamber pressure. The etched surfaces remain smooth and stoichiometric over the entire range of plasma conditions investigated. The knowledge gained in etching GaSb was applied to etching AlGaAsSb and InGaAsSb in order to fabricate heterojunction phototransistors. As expected, InGaAsSb etch rate was much lower compared to the corresponding value for GaSb, mainly due to the relatively low volatility of indium chlorides. For a wide range of plasma conditions, the selectivity between GaSb and AlGaAsSb was close to unity, which is desirable for fabricating etched mirrors and gratings for Sb-based mid-infrared laser diodes. The surface roughness and the etch profile were examined for the etched GaSb, AlGaAsSb and InGaAsSb samples using scanning electron microscope. The high etch rates achieved (∼ 4 μm/min) facilitated deep etching of GaSb. A single layer, soft mask (AZ-4903 photoresist) was used to etch GaSb, with etch depth ∼ 90 μm. The deep dry etching of GaSb has many important applications including etching substrate windows for backside-illuminated photodetectors for the mid-infrared wavelength range

Low surface damage dry etched black silicon

DEFF Research Database (Denmark)

Plakhotnyuk, Maksym M.; Gaudig, Maria; Davidsen, Rasmus Schmidt

2017-01-01

Black silicon (bSi) is promising for integration into silicon solar cell fabrication flow due to its excellent light trapping and low reflectance, and a continuously improving passivation. However, intensive ion bombardment during the reactive ion etching used to fabricate bSi induces surface dam...

Photonic Hilbert transformers based on laterally apodized integrated waveguide Bragg gratings on a SOI wafer.

Science.gov (United States)

Bazargani, Hamed Pishvai; Burla, Maurizio; Chrostowski, Lukas; Azaña, José

2016-11-01

We experimentally demonstrate high-performance integer and fractional-order photonic Hilbert transformers based on laterally apodized Bragg gratings in a silicon-on-insulator technology platform. The sub-millimeter-long gratings have been fabricated using single-etch electron beam lithography, and the resulting HT devices offer operation bandwidths approaching the THz range, with time-bandwidth products between 10 and 20.

Experimental and theoretical study of Bragg-Fresnel focalizing optical systems engraved on multi layers interferential mirrors adapted to X and X-UV fields

International Nuclear Information System (INIS)

Idir, M.

1995-02-01

This work concerns the study of a particular type of X-ray focusing optics known as Bragg-Fresnel lenses, formed through ion-etching of multilayered structures. Using the Super-ACO (LURE/Orsay) synchrotron storage ring, we tested several Bragg-Fresnel lenses having either linear or elliptical geometries (producing a line or a point focus, respectively). Diffraction profiles were first obtained for the linear lenses ion-etched on W/Si multilayers of nano-metric period. The experimental results were compared with our theoretical predictions. We next proposed and tested a solution to the problem superposing the different diffraction orders in the focal plane, that of fabricating Bragg-Fresnel lenses with an off-axis configuration, first for the linear and then the elliptical geometry. An experimental application, for an off-axis elliptical lens produced a focused X-ray spot of 5 x 10 microns 2 for the Super-ACO synchrotron source. The same lens also produced a 1/3-size X-ray image of a grid-like object at 1750 eV using the first and third diffraction orders. (author)

Large-aperture focusing of x rays with micropore optics using dry etching of silicon wafers.

Science.gov (United States)

Ezoe, Yuichiro; Moriyama, Teppei; Ogawa, Tomohiro; Kakiuchi, Takuya; Mitsuishi, Ikuyuki; Mitsuda, Kazuhisa; Aoki, Tatsuhiko; Morishita, Kohei; Nakajima, Kazuo

2012-03-01

Large-aperture focusing of Al K(α) 1.49 keV x-ray photons using micropore optics made from a dry-etched 4 in. (100 mm) silicon wafer is demonstrated. Sidewalls of the micropores are smoothed with high-temperature annealing to work as x-ray mirrors. The wafer is bent to a spherical shape to collect parallel x rays into a focus. Our result supports that this new type of optics allows for the manufacturing of ultralight-weight and high-performance x-ray imaging optics with large apertures at low cost. © 2012 Optical Society of America

Refractive index and temperature sensitivity characteristics of a micro-slot fiber Bragg grating.

Science.gov (United States)

Saffari, Pouneh; Yan, Zhijun; Zhou, Kaiming; Zhang, Lin

2012-07-10

Fabrication and characterization of a UV inscribed fiber Bragg grating (FBG) with a micro-slot liquid core is presented. Femtosecond (fs) laser patterning/chemical etching technique was employed to engrave a micro-slot with dimensions of 5.74 μm(h)×125 μm(w)×1388.72 μm(l) across the whole grating. The device has been evaluated for refractive index (RI) and temperature sensitivities and exhibited distinctive thermal response and RI sensitivity beyond the detection limit of reported fiber gratings. This structure has not just been RI sensitive, but also maintained the robustness comparing with the bare core FBGs and long-period gratings with the partial cladding etched off.

Inductively coupled plasma etching of III-V antimonides in BCl{sub 3}/SiCl{sub 4} etch chemistry

Energy Technology Data Exchange (ETDEWEB)

Swaminathan, K. [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)], E-mail: swaminak@ece.osu.edu; Janardhanan, P.E.; Sulima, O.V. [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)

2008-10-01

Inductively coupled plasma etching of GaSb using BCl{sub 3}/SiCl{sub 4} etch chemistry has been investigated. The etch rates were studied as a function of bias power, inductively coupled plasma source power, plasma chemistry and chamber pressure. The etched surfaces remain smooth and stoichiometric over the entire range of plasma conditions investigated. The knowledge gained in etching GaSb was applied to etching AlGaAsSb and InGaAsSb in order to fabricate heterojunction phototransistors. As expected, InGaAsSb etch rate was much lower compared to the corresponding value for GaSb, mainly due to the relatively low volatility of indium chlorides. For a wide range of plasma conditions, the selectivity between GaSb and AlGaAsSb was close to unity, which is desirable for fabricating etched mirrors and gratings for Sb-based mid-infrared laser diodes. The surface roughness and the etch profile were examined for the etched GaSb, AlGaAsSb and InGaAsSb samples using scanning electron microscope. The high etch rates achieved ({approx} 4 {mu}m/min) facilitated deep etching of GaSb. A single layer, soft mask (AZ-4903 photoresist) was used to etch GaSb, with etch depth {approx} 90 {mu}m. The deep dry etching of GaSb has many important applications including etching substrate windows for backside-illuminated photodetectors for the mid-infrared wavelength range.

Dry-plasma-free chemical etch technique for variability reduction in multi-patterning (Conference Presentation)

Science.gov (United States)

Kal, Subhadeep; Mohanty, Nihar; Farrell, Richard A.; Franke, Elliott; Raley, Angelique; Thibaut, Sophie; Pereira, Cheryl; Pillai, Karthik; Ko, Akiteru; Mosden, Aelan; Biolsi, Peter

2017-04-01

Scaling beyond the 7nm technology node demands significant control over the variability down to a few angstroms, in order to achieve reasonable yield. For example, to meet the current scaling targets it is highly desirable to achieve sub 30nm pitch line/space features at back-end of the line (BEOL) or front end of line (FEOL); uniform and precise contact/hole patterning at middle of line (MOL). One of the quintessential requirements for such precise and possibly self-aligned patterning strategies is superior etch selectivity between the target films while other masks/films are exposed. The need to achieve high etch selectivity becomes more evident for unit process development at MOL and BEOL, as a result of low density films choices (compared to FEOL film choices) due to lower temperature budget. Low etch selectivity with conventional plasma and wet chemical etch techniques, causes significant gouging (un-intended etching of etch stop layer, as shown in Fig 1), high line edge roughness (LER)/line width roughness (LWR), non-uniformity, etc. In certain circumstances this may lead to added downstream process stochastics. Furthermore, conventional plasma etches may also have the added disadvantage of plasma VUV damage and corner rounding (Fig. 1). Finally, the above mentioned factors can potentially compromise edge placement error (EPE) and/or yield. Therefore a process flow enabled with extremely high selective etches inherent to film properties and/or etch chemistries is a significant advantage. To improve this etch selectivity for certain etch steps during a process flow, we have to implement alternate highly selective, plasma free techniques in conjunction with conventional plasma etches (Fig 2.). In this article, we will present our plasma free, chemical gas phase etch technique using chemistries that have high selectivity towards a spectrum of films owing to the reaction mechanism ( as shown Fig 1). Gas phase etches also help eliminate plasma damage to the

Improved response time of laser etched polymer optical fiber Bragg grating humidity sensor

OpenAIRE

Zhang, Wei; Chen, Xianfeng; Liu, Chen; Lu, Yuanfu; Cardoso, Marcos; Webb, David J.

2015-01-01

The humidity sensor made of polymer optical fiber Bragg grating (POFBG) responds to the water content change in fiber induced by the change of environmental condition. The response time strongly depends on fiber size as the water change is a diffusion process. The ultra short laser pulses have been providing an effective micro fabrication method to achieve spatial localized modification in materials. In this work we used the excimer laser to create different microstructures (slot, D-shape) in...

Single-crystal silicon trench etching for fabrication of highly integrated circuits

Science.gov (United States)

Engelhardt, Manfred

1991-03-01

The development of single crystal silicon trench etching for fabrication of memory cells in 4 16 and 64Mbit DRAMs is reviewed in this paper. A variety of both etch tools and process gases used for the process development is discussed since both equipment and etch chemistry had to be improved and changed respectively to meet the increasing requirements for high fidelity pattern transfer with increasing degree of integration. In additon to DRAM cell structures etch results for deep trench isolation in advanced bipolar ICs and ASICs are presented for these applications grooves were etched into silicon through a highly doped buried layer and at the borderline of adjacent p- and n-well areas respectively. Shallow trench etching of large and small exposed areas with identical etch rates is presented as an approach to replace standard LOCOS isolation by an advanced isolation technique. The etch profiles were investigated with SEM TEM and AES to get information on contathination and damage levels and on the mechanism leading to anisotropy in the dry etch process. Thermal wave measurements were performed on processed single crystal silicon substrates for a fast evaluation of the process with respect to plasma-induced substrate degradation. This useful technique allows an optimization ofthe etch process regarding high electrical performance of the fully processed memory chip. The benefits of the use of magnetic fields for the development of innovative single crystal silicon dry

Influence of warm air-drying on enamel bond strength and surface free-energy of self-etch adhesives.

Science.gov (United States)

Shiratsuchi, Koji; Tsujimoto, Akimasa; Takamizawa, Toshiki; Furuichi, Tetsuya; Tsubota, Keishi; Kurokawa, Hiroyasu; Miyazaki, Masashi

2013-08-01

We examined the effect of warm air-drying on the enamel bond strengths and the surface free-energy of three single-step self-etch adhesives. Bovine mandibular incisors were mounted in self-curing resin and then wet ground with #600 silicon carbide (SiC) paper. The adhesives were applied according to the instructions of the respective manufacturers and then dried in a stream of normal (23°C) or warm (37°C) air for 5, 10, and 20 s. After visible-light irradiation of the adhesives, resin composites were condensed into a mold and polymerized. Ten samples per test group were stored in distilled water at 37°C for 24 h and then the bond strengths were measured. The surface free-energies were determined by measuring the contact angles of three test liquids placed on the cured adhesives. The enamel bond strengths varied according to the air-drying time and ranged from 15.8 to 19.1 MPa. The trends for the bond strengths were different among the materials. The value of the γS⁺ component increased slightly when drying was performed with a stream of warm air, whereas that of the γS⁻ component decreased significantly. These data suggest that warm air-drying is essential to obtain adequate enamel bond strengths, although increasing the drying time did not significantly influence the bond strength. © 2013 Eur J Oral Sci.

Fabrication of high quality GaN nanopillar arrays by dry and wet chemical etching

OpenAIRE

Paramanik, Dipak; Motayed, Abhishek; King, Matthew; Ha, Jong-Yoon; Kryluk, Sergi; Davydov, Albert V.; Talin, Alec

2013-01-01

We study strain relaxation and surface damage of GaN nanopillar arrays fabricated using inductively coupled plasma (ICP) etching and post etch wet chemical treatment. We controlled the shape and surface damage of such nanopillar structures through selection of etching parameters. We compared different substrate temperatures and different chlorine-based etch chemistries to fabricate high quality GaN nanopillars. Room temperature photoluminescence and Raman scattering measurements were carried ...

Bragg scattering of electromagnetic waves by microwave-produced plasma layers

Science.gov (United States)

Kuo, S. P.; Zhang, Y. S.

1990-01-01

A set of parallel plasma layers is generated by two intersecting microwave pulses in a chamber containing dry air at a pressure comparable to the upper atmosphere. The dependencies of breakdown conditions on the pressure and pulse length are examined. The results are shown to be consistent with the appearance of tail erosion of the microwave pulse caused by air breakdown. A Bragg scattering experiment, using the plasma layers as a Bragg reflector, is then performed. Both time domain and frequency domain measurements of wave scattering are conducted. The experimental results are found to agree very well with the theory.

Fabrication of Fiber Bragg Grating Coating with TiO2 Nanostructured Metal Oxide for Refractive Index Sensor

Directory of Open Access Journals (Sweden)

Shaymaa Riyadh Tahhan

2017-01-01

Full Text Available To increase the sensitivity of biosensor a new approach using an optical fiber Bragg grating (FBG coated with a suitable nanostructured metal oxide (NMO is proposed which is costly effective compared to other biosensors. Bragg grating was written on a D-shaped optical fiber by phase mask method using a 248 nm KrF excimer laser for a 5 min exposure time producing a grating with a period of 528 nm. Titanium dioxide (TiO2 nanostructured metal oxide was coated over the fiber for the purpose of increasing its sensing area. The etched D-shaped FBG was then coated with 312 nm thick TiO2 nanostructured layer to ensure propagating the radiation modes within the core. The final structure was used to sense deionized water and saline. The etched D-shaped FBG original sensitivity before coating to air-deionized water and to air-saline was 0.314 nm/riu and 0.142 nm/riu, respectively. After coating the sensitivity became 1.257 nm/riu for air-deionized water and 0.857 nm/riu for air-saline.

Plasma Etching of Tapered Features in Silicon for MEMS and Wafer Level Packaging Applications

International Nuclear Information System (INIS)

Ngo, H-D; Hiess, Andre; Seidemann, Volker; Studzinski, Daniel; Lange, Martin; Leib, Juergen; Shariff, Dzafir; Ashraf, Huma; Steel, Mike; Atabo, Lilian; Reast, Jon

2006-01-01

This paper is a brief report of plasma etching as applied to pattern transfer in silicon. It will focus more on concept overview and strategies for etching of tapered features of interest for MEMS and Wafer Level Packaging (WLP). The basis of plasma etching, the dry etching technique, is explained and plasma configurations are described elsewhere. An important feature of plasma etching is the possibility to achieve etch anisotropy. The plasma etch process is extremely sensitive to many variables such as mask material, mask openings and more important the plasma parameters

Characteristics of the Fiber Laser Sensor System Based on Etched-Bragg Grating Sensing Probe for Determination of the Low Nitrate Concentration in Water.

Science.gov (United States)

Pham, Thanh Binh; Bui, Huy; Le, Huu Thang; Pham, Van Hoi

2016-12-22

The necessity of environmental protection has stimulated the development of many kinds of methods allowing the determination of different pollutants in the natural environment, including methods for determining nitrate in source water. In this paper, the characteristics of an etched fiber Bragg grating (e-FBG) sensing probe-which integrated in fiber laser structure-are studied by numerical simulation and experiment. The proposed sensor is demonstrated for determination of the low nitrate concentration in a water environment. Experimental results show that this sensor could determine nitrate in water samples at a low concentration range of 0-80 ppm with good repeatability, rapid response, and average sensitivity of 3.5 × 10 -3 nm/ppm with the detection limit of 3 ppm. The e-FBG sensing probe integrated in fiber laser demonstrates many advantages, such as a high resolution for wavelength shift identification, high optical signal-to-noise ratio (OSNR of 40 dB), narrow bandwidth of 0.02 nm that enhanced accuracy and precision of wavelength peak measurement, and capability for optical remote sensing. The obtained results suggested that the proposed e-FBG sensor has a large potential for the determination of low nitrate concentrations in water in outdoor field work.

Characteristics of the Fiber Laser Sensor System Based on Etched-Bragg Grating Sensing Probe for Determination of the Low Nitrate Concentration in Water

Directory of Open Access Journals (Sweden)

Thanh Binh Pham

2016-12-01

Full Text Available The necessity of environmental protection has stimulated the development of many kinds of methods allowing the determination of different pollutants in the natural environment, including methods for determining nitrate in source water. In this paper, the characteristics of an etched fiber Bragg grating (e-FBG sensing probe—which integrated in fiber laser structure—are studied by numerical simulation and experiment. The proposed sensor is demonstrated for determination of the low nitrate concentration in a water environment. Experimental results show that this sensor could determine nitrate in water samples at a low concentration range of 0–80 ppm with good repeatability, rapid response, and average sensitivity of 3.5 × 10−3 nm/ppm with the detection limit of 3 ppm. The e-FBG sensing probe integrated in fiber laser demonstrates many advantages, such as a high resolution for wavelength shift identification, high optical signal-to-noise ratio (OSNR of 40 dB, narrow bandwidth of 0.02 nm that enhanced accuracy and precision of wavelength peak measurement, and capability for optical remote sensing. The obtained results suggested that the proposed e-FBG sensor has a large potential for the determination of low nitrate concentrations in water in outdoor field work.

Dry Etching of Copper Phthalocyanine Thin Films: Effects on Morphology and Surface Stoichiometry

Directory of Open Access Journals (Sweden)

Michael J. Brett

2012-08-01

Full Text Available We investigate the evolution of copper phthalocyanine thin films as they are etched with argon plasma. Significant morphological changes occur as a result of the ion bombardment; a planar surface quickly becomes an array of nanopillars which are less than 20 nm in diameter. The changes in morphology are independent of plasma power, which controls the etch rate only. Analysis by X-ray photoelectron spectroscopy shows that surface concentrations of copper and oxygen increase with etch time, while carbon and nitrogen are depleted. Despite these changes in surface stoichiometry, we observe no effect on the work function. The absorbance and X-ray diffraction spectra show no changes other than the peaks diminishing with etch time. These findings have important implications for organic photovoltaic devices which seek nanopillar thin films of metal phthalocyanine materials as an optimal structure.

Monolithic mode-locked lasers with deeply dry etched Bragg mirror

DEFF Research Database (Denmark)

Larsson, David; Yvind, Kresten; Hvam, Jørn Märcher

Background: Semiconductor mode-locked lasers are attractive as components in futureultra high-speed telecommunication systems (160-640Gb/s); as picosecond pulse sources,clock-recovery devices and for demultiplexing in Optical Time Division Multiplexing(OTDM) systems. We have recently designed...... it possible to buy epitaxial wafers fromphotonic foundries as in the microelectronic industry.Design: The reflectivity spectrum from the total grating is calculated by matrixmultiplication of the individual periodic grating elements. The period of the grating,given by the mean effective index of the low....... The SiO2-film functions as a mask in the subsequent RIE of thesemiconductor (InP). We are now optimizing the semiconductor RIE to achieve 2 µmdeep waveguides and gratings with smooth vertical sidewalls and smooth bottom surface.This optimization involves optimizing the reaction chamber parameters: CH4/H2...

Dry etching of MgCaO gate dielectric and passivation layers on GaN

International Nuclear Information System (INIS)

Hlad, M.; Voss, L.; Gila, B.P.; Abernathy, C.R.; Pearton, S.J.; Ren, F.

2006-01-01

MgCaO films grown by rf plasma-assisted molecular beam epitaxy and capped with Sc 2 O 3 are promising candidates as surface passivation layers and gate dielectrics on GaN-based high electron mobility transistors (HEMTs) and metal-oxide semiconductor HEMTs (MOS-HEMTs), respectively. Two different plasma chemistries were examined for etching these thin films on GaN. Inductively coupled plasmas of CH 4 /H 2 /Ar produced etch rates only in the range 20-70 A/min, comparable to the Ar sputter rates under the same conditions. Similarly slow MgCaO etch rates (∼100 A/min) were obtained with Cl 2 /Ar discharges under the same conditions, but GaN showed rates almost an order of magnitude higher. The MgCaO removal rates are limited by the low volatilities of the respective etch products. The CH 4 /H 2 /Ar plasma chemistry produced a selectivity of around 2 for etching the MgCaO with respect to GaN

Dry etching of LaNiO3 thin films using inductively coupled plasma

International Nuclear Information System (INIS)

Kim, Gwan-Ha; Kim, Dong-Pyo; Kim, Kyoung-Tae; Kim, Chang-Il; Lee, Cheol-In; Kim, Tae-Hyung

2006-01-01

The etching characteristics of LaNiO 3 (LNO) thin films and SiO 2 in Cl 2 /Ar plasma were investigated. LNO etch rates decreased with increasing Cl 2 fraction in Ar plasma and the working pressure. Langmuir probe measurement showed a noticeable influence of Cl 2 /Ar mixing ratio on electron temperature, electron density, and ion current density. The modeling of volume kinetics for charged particles and OES measurements for neutral atoms indicated monotonous changes of both densities and fluxes of active species such as chlorine atoms and positive ions. The LNO etch rate behavior may be explained by physical mechanisms

Bragg Curve Spectroscopy

International Nuclear Information System (INIS)

Gruhn, C.R.

1981-05-01

An alternative utilization is presented for the gaseous ionization chamber in the detection of energetic heavy ions, which is called Bragg Curve Spectroscopy (BCS). Conceptually, BCS involves using the maximum data available from the Bragg curve of the stopping heavy ion (HI) for purposes of identifying the particle and measuring its energy. A detector has been designed that measures the Bragg curve with high precision. From the Bragg curve the range from the length of the track, the total energy from the integral of the specific ionization over the track, the dE/dx from the specific ionization at the beginning of the track, and the Bragg peak from the maximum of the specific ionization of the HI are determined. This last signal measures the atomic number, Z, of the HI unambiguously

Detection of Ammonia-Oxidizing Bacteria (AOB) Using a Porous Silicon Optical Biosensor Based on a Multilayered Double Bragg Mirror Structure.

Science.gov (United States)

Zhang, Hongyan; Lv, Jie; Jia, Zhenhong

2018-01-01

We successfully demonstrate a porous silicon (PS) double Bragg mirror by electrochemical etching at room temperature as a deoxyribonucleic acid (DNA) label-free biosensor for detecting ammonia-oxidizing bacteria (AOB). Compared to various other one-dimension photonic crystal configurations of PS, the double Bragg mirror structure is quite easy to prepare and exhibits interesting optical properties. The width of high reflectivity stop band of the PS double Bragg mirror is about 761 nm with a sharp and deep resonance peak at 1328 nm in the reflectance spectrum, which gives a high sensitivity and distinguishability for sensing performance. The detection sensitivity of such a double Bragg mirror structure is illustrated through the investigation of AOB DNA hybridization in the PS pores. The redshifts of the reflectance spectra show a good linear relationship with both complete complementary and partial complementary DNA. The lowest detection limit for complete complementary DNA is 27.1 nM and the detection limit of the biosensor for partial complementary DNA is 35.0 nM, which provides the feasibility and effectiveness for the detection of AOB in a real environment. The PS double Bragg mirror structure is attractive for widespread biosensing applications and provides great potential for the development of optical applications.

UV-assisted selective chemical etching of relief gratings in Er/Yb-codoped IOG1 phosphate glass

Energy Technology Data Exchange (ETDEWEB)

Pappas, C; Pissadakis, S [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vasilika Vouton, PO Box 1527, Heraklion 71 110, GREECE (Greece)

2007-04-15

The patterning of sub-micron periodicity Bragg reflectors in Er/Yb-codoped IOG1, phosphate glass is demonstrated. A high yield patterning technique is presented, wherein high volume damage is induced into the glass matrix by exposure to intense UV radiation, and subsequently a chemical development in a strong acid selectively etches the exposed areas. The grating reflectors were fabricated by employing an elliptical Talbot interferometer and the output of a 213nm, 150ps frequency quintupled Nd:YAG laser. The grating depth of the etched relief pattern in time was measured at fixed time intervals and the dependence is presented in upon the etching time and exposure conditions. The gratings fabricated are examined by atomic and scanning electron microscopy for revealing the topology of the relief structure. Gratings with period of the order of 500nm were fabricated, having a maximum depth of 60nm.

In vivo effect of a self-etching primer on dentin.

Science.gov (United States)

Milia, E; Lallai, M R; García-Godoy, F

1999-08-01

To determine the ultrastructural aspects of the dentin collagen area in the cavity preparation floor produced in vivo after phosphoric acid acid-etching or after using Clearfil Liner Bond 2 self-etching primer (LB2 Primer). Twenty-four non-carious third molars scheduled for extraction from young adult patients (16-30 years old) were used. Conventional Class I cavities (+/- 2 mm deep) were prepared on the occlusal surfaces of all teeth using a cylindrical diamond bur on a high-speed handpiece with copious water spray. To avoid dehydration of the dentin, the smear layer-covered dentin was briefly air-dried for 2 seconds. Cavities were assigned at random to the following groups: Group A: Dentin etched for 15 seconds with 34% phosphoric acid, rinsed for 20 seconds and then briefly air-dried for 2 seconds with oil-free compressed air leaving the surfaces slightly moist. Group B: LB2 Primer was applied to the cavity surfaces for 30 seconds and then briefly air-dried to remove the solvent. Group C: The untreated dentin smear layer was used as a control. In all three groups, the cavities were filled incrementally with a resin-based composite (APX), light curing every increment for 40 seconds. After 30 minutes, the teeth were extracted atraumatically and the samples immediately prepared for evaluation with the transmission electron microscope. The use of a self-etching primer did not produce significant morphological changes in the moist dentin substrate. Adverse morphological conditions where observed when there was an excess water on the dentin surface. Phosphoric acid altered the collagen more severely than the self-etching primer.

Regrowth of InP by MOVPE on dry-etched heterostructures of InP-GaInAsP

Energy Technology Data Exchange (ETDEWEB)

Catana, A. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland)); Broom, R.F. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland)); Germann, R. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland)); Roentgen, P. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland))

1993-04-01

The MOVPE growth behavior of InP on masked and dry-etched ridges in InP/InGaAsP heterostructures grown on (001)-oriented InP substrates has been studied by scanning electron and transmission electron microscopy. It is found that the orientation of the ridges is critical for obtaining good planarization. For ridges oriented along the 100 direction, the growth is uniform and defect-free, leasing to a plane surface. In the orthogonal 110 direction 60 twins are nucleated adjacent to the walls of the ridge. The resultant high density of (111)/(001) facets enhances the growth rate in these regions, leading to projecting walls at the sides of the ridge. (orig.)

Dry technologies for the production of crystalline silicon solar cells; Trockentechnologien zur Herstellung von kristallinen Siliziumsolarzellen

Energy Technology Data Exchange (ETDEWEB)

Rentsch, J.

2005-04-15

Within this work, dynamic plasma etching technologies for the industrial production of crystalline silicon solar cells has been investigated. The research activity can be separated into three major steps: the characterisation of the etching behaviour of a newly developed dynamic plasma etching system, the development and analysis of dry etching processes for solar cell production and the determination of the ecological and economical impacts of such a new technology compared to standard up to date technologies. The characterisation of the etching behaviour has been carried out for two different etching sources, a low frequency (110 kHz) and a microwave (2.45 GHz) plasma source. The parameter of interest was the delivered ion energy of each source mainly determining the reachable etch rate. The etch rate turned out to be the main most critical parameter concerning the reachable wafer throughput per hour. Other points of interest in characterisation of the etching system were the material of the transport carriers, the silicon load as well as the process temperatures. The development of different dry etching processes targets the design of a complete dry production process for crystalline silicon solar cells. Therefore etching processes for saw damage removal, texturing, edge isolation as well as etching of dielectric layers have been developed and optimised. The major benefits of a complete dry production process would be the reduction of handling steps in between process steps and therefore offers a large cost reduction potential. For multicrystalline silicon solar cells a cost reduction potential of 5 % compared to a standard wet chemical based reference process could be realized only including the dry etching of a phosphorus silicate glass layer after diffusion. Further reduction potential offers the implementation of a dry texturing process due to a significant efficiency increase. (orig.)

Dry etching of ferroelectric Bi4-xEuxTi3O12 (BET) thin films

International Nuclear Information System (INIS)

Lim, Kyu-Tae; Kim, Kyoung-Tae; Kim, Dong-Pyo; Kim, Chang-Il

2004-01-01

Bi 4-x Eu x Ti 3 O 12 (BET) thin films were etched by using a inductively coupled Cl 2 /Ar plasma. We obtained a maximum etch rate of 69 nm/min at a gas mixing ratio of Cl 2 (20 %)/Ar (80 %). This result suggests that an effective method for BET etching is chemically assisted physical etching. With increasing coil RF power, the plasma density increases so that the increased reactive free radicals and ions enhance the etch rates of BET, Pt, and SiO 2 . As the dc-bias voltage is increased, the increased ion energy leads to an increased etch rate of BET films. From X-ray photoelectron spectroscopy, the intensities of the Bi-O, the Eu-O, and the Ti-O peaks change with increasing Cl 2 concentration. For a pure Ar plasma, the peak associated with the oxygen-metal (O-M: TiO 2 , Bi 2 O 3 , Eu 2 O 3 ) bond seems to disappear while the pure oxygen peak does not appear. After the BET thin films is etched by using a Cl 2 /Ar plasma, the peak associated with the O-M bond increases slowly, but more quickly than the peak associated with pure oxygen atoms, due to a decrease in the Ar-ion bombardment. These results seem to indicate that Bi and Eu react little with Cl atoms and are removed predominantly by argon-ion bombardment. Also, Ti reacts little with Cl radicals and is mainly removed by chemically assisted physical etching.

Dry release of all-polymer structures

DEFF Research Database (Denmark)

Haefliger, D.; Nordstrøm, M.; Rasmussen, Peter Andreas

2005-01-01

We present a simple dry release technique which uses a thin fluorocarbon film for efficient removal of plastic microdevices from a mould or a handling substrate by reducing the adhesion between the two. This fluorocarbon film is deposited on the substrate in an advanced Si dry etch device utilisi...... 100% were demonstrated on wafer-scale. The fluorocarbon film showed excellent compatibility with metal etch processes and polymer baking and curing steps. It further facilitates demoulding of polydimethylsiloxane stamps suitable for soft-lithography....

Sensitive detection of C-reactive protein using optical fiber Bragg gratings.

Science.gov (United States)

Sridevi, S; Vasu, K S; Asokan, S; Sood, A K

2015-03-15

An accurate and highly sensitive sensor platform has been demonstrated for the detection of C-reactive protein (CRP) using optical fiber Bragg gratings (FBGs). The CRP detection has been carried out by monitoring the shift in Bragg wavelength (ΔλB) of an etched FBG (eFBG) coated with an anti-CRP antibody (aCRP)-graphene oxide (GO) complex. The complex is characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. A limit of detection of 0.01mg/L has been achieved with a linear range of detection from 0.01mg/L to 100mg/L which includes clinical range of CRP. The eFBG sensor coated with only aCRP (without GO) show much less sensitivity than that of aCRP-GO complex coated eFBG. The eFBG sensors show high specificity to CRP even in the presence of other interfering factors such as urea, creatinine and glucose. The affinity constant of ∼1.1×10(10)M(-1) has been extracted from the data of normalized shift (ΔλB/λB) as a function of CRP concentration. Copyright © 2014 Elsevier B.V. All rights reserved.

Shear Bond Strength of Saliva Contaminated and Re-etched All-in-One Adhesive to Enamel

Directory of Open Access Journals (Sweden)

M. Khoroushi

2008-12-01

Full Text Available Objective: The aim of this study was to investigate the effect of phosphoric acid re-etching of an enamel surface treated via a one-bottle adhesive system on shear bond strength between resin composite and the enamelsurface in different stages of adhesive application.Materials and Methods: Extracted intact premolars (n=84 were divided into sevengroups (n=12. In the control group 1, the adhesive i-Bond was used according to the manufacturer's instructions, with nocontamination. In groups 2 to 4, the conditioned and saliva, contaminated enamel was blot dried only, rinsed,and blot dried, rinsed blot dried and re-etched, respectively. In groups 5, 6and 7 cured adhesive was contaminated with saliva and then rinsed and blot-dried, blot dried only and rinsed, blot-dried and re-etched respectively. In groups 3, 4, 6 and 7 the adhesive was reapplied. Afterward, Z100 compos-ite cylinders were bonded to the enamel surfaces. The samples were thermocycled (5°C and 55°C, 30 s, dwelling time: 10 s, 500 cycles. Finally, the samples were sheared using Dartec testing machine and shear bond strength data were subjected to one-way ANOVA analysis and Tukey's HSD test.Results: There were statistically significant differences among groups 1 and 5-7. The samples in groups 1 and 4 demonstrated higher bond strengths than those in the other groups.Conclusion: Using phosphoric acid etching may be effective, only where contamination occurs prior to curing of the adhesive. After curing of the adhesive, none of the methods in this study would be preferred.

GaN MOSFET with Boron Trichloride-Based Dry Recess Process

International Nuclear Information System (INIS)

Jiang, Y; Wang, Q P; Tamai, K; Ao, J P; Ohno, Y; Miyashita, T; Motoyama, S; Wang, D J

2013-01-01

The dry recessed-gate GaN metal-oxide-semiconductor field-effect transistors (MOSFETs) on AlGaN/GaN heterostructure using boron trichloride (BCl 3 ) as etching gas were fabricated and characterized. Etching with different etching power was conducted. Devices with silicon tetrachloride (SiCl 4 ) etching gas were also prepared for comparison. Field-effect mobility and interface state density were extracted from current-voltage (I-V) characteristics. GaN MOSFETs on AlGaN/GaN heterostructure with BCl 3 based dry recess achieved a high maximum electron mobility of 141.5 cm 2 V −1 s −1 and a low interface state density.

Flux based modeling and simulation of dry etching for fabrication of silicon deep trench structures

Energy Technology Data Exchange (ETDEWEB)

Malik Rizwan [State Key Laboratory of Digital Manufacturing Equipment and technology, Huazhong University of Science and Technology, 1037 Luoyu road, Wuhan, China 43007 (China); Shi Tielin; Tang Zirong; Liu Shiyuan, E-mail: zirong@mail.hust.edu.cn, E-mail: rizwanmalik@smail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu road Wuhan, 430074 (China)

2011-02-01

Deep reactive ion etching (DRIE) process is a key growth for fabrication of micro-electromechanical system (MEMS) devices. Due to complexity of this process, including interaction of the process steps, full analytical modeling is complex. Plasma process holds deficiency of understanding because it is very easy to measure the results empirically. However, as device parameters shrink, this issue is more critical. In this paper, our process was modeled qualitatively based on 'High Density Plasma Etch Model'. Deep trench solutions of etch rate based on continuity equation were successfully generated first time through mathematical analysis. It was also proved that the product of fluorine and gas phase concentration in SF{sub 6} remains identical during both deposition and etching stages. The etching process was treated as a combination of isotropic, directional and angle-dependent component parts. It exploited a synergistic balance of chemical as well as physical etching for promoting silicon trenches and high aspect ratio structures. Simulations were performed for comprehensive analysis of fluxes coming towards the surface during chemical reaction of gas. It is observed that near the surface, the distribution of the arrival flux follows a cosine distribution. Our model is feasible to analyze various parameters like gas delivery, reactor volume and temperature that help to assert large scale effects and to optimize equipment design.

Studies of the confinement at laser-induced backside dry etching using infrared nanosecond laser pulses

Science.gov (United States)

Ehrhardt, M.; Lorenz, P.; Bayer, L.; Han, B.; Zimmer, K.

2018-01-01

In the present study, laser-induced backside etching of SiO2 at an interface to an organic material using laser pulses with a wavelength of λ = 1064 nm and a pulse length of τ = 7 ns have been performed in order to investigate selected processes involved in etching of the SiO2 at confined ablation conditions with wavelengths well below the band gap of SiO2. Therefore, in between the utilized metallic absorber layer and the SiO2 surface, a polymer interlayer with a thickness between 20 nm to 150 nm was placed with the aim, to separate the laser absorption process in the metallic absorber layer from the etching process of the SiO2 surface due to the provided organic interlayer. The influence of the confinement of the backside etching process was analyzed by the deposition of different thick polymer layers on top of the metallic absorber layer. In particular, it was found that the SiO2 etching depth decreases with higher polymer interlayer thickness. However, the etching depth increases with increasing the confinement layer thickness. SEM images of the laser processed areas show that the absorber and confinement layers are ruptured from the sample surface without showing melting, and suggesting a lift off process of these films. The driving force for the layers lift off and the etching of the SiO2 is probably the generated laser-induce plasma from the confined ablation that provides the pressure for lift off, the high temperatures and reactive organic species that can chemically attack the SiO2 surface at these conditions.

Improvement of soybean variety 'Bragg' through mutagenesis

Energy Technology Data Exchange (ETDEWEB)

Bhatnagar, P S; Prabhakar,; Tiwari, S P; Sandhu, J S [National Research Centre for Soybean, Indore (India)

1989-01-01

Full text: Variety 'Bragg' (Jackson x D49-2491) of soybean (Glycine max. (L.) Merrill) was found to be high yielding and widely adaptable throughout India. Its yield stability, however, is unsatisfactory, probably due to low germinability necessitating use of higher seed rate. With the main objective to rectify this defect, mutagenesis involving chemical as well as physical mutagens was used. Dry seeds were treated with EMS or MMS (0.2, 0.4 and 0.6%), or gamma rays (15, 20 and 25 kR) with and without additional exposure to UV (2 hrs at 260 nm) in 1982. In M{sub 2}, a mutation frequency ranging from 2.24 to 22.85% was observed. Screening of M{sub 2} and of subsequent generations yielded a broad spectrum of mutations. Some of the mutants are agronomically useful. Among them, mutant 'T{sub 2}14' resulting from 25 kR gamma rays + UV, was found to possess better germinability (+15%), earliness (5 days) and high yield during both rainy and post-rainy seasons in 1986 and 1987, when compared with the parent variety 'Bragg'. The mutant has smaller seed-size (TGW 125 g) than the parent (145 g). In soybean, large-seeded varieties were reported to have poorer seed germinability. Thus, the better germinability of the mutant might be related to its reduced seed size. Seeds of the mutant show a light brown colour of the hilum in contrast to the black hilum of 'Bragg'. In other characters the mutant is similar to 'Bragg'. The mutant should have potential for commercial cultivation in India. For confirmation of its agronomically superior performance, it is undergoing national evaluation in multilocational trials under 'All India Co-ordinated Research Project on Soybean (ICAR)'. The strain has been named 'NRC-2'. (author)

Improvement of soybean variety 'Bragg' through mutagenesis

International Nuclear Information System (INIS)

Bhatnagar, P.S.; Prabhakar; Tiwari, S.P.; Sandhu, J.S.

1989-01-01

Full text: Variety 'Bragg' (Jackson x D49-2491) of soybean (Glycine max. (L.) Merrill) was found to be high yielding and widely adaptable throughout India. Its yield stability, however, is unsatisfactory, probably due to low germinability necessitating use of higher seed rate. With the main objective to rectify this defect, mutagenesis involving chemical as well as physical mutagens was used. Dry seeds were treated with EMS or MMS (0.2, 0.4 and 0.6%), or gamma rays (15, 20 and 25 kR) with and without additional exposure to UV (2 hrs at 260 nm) in 1982. In M 2 , a mutation frequency ranging from 2.24 to 22.85% was observed. Screening of M 2 and of subsequent generations yielded a broad spectrum of mutations. Some of the mutants are agronomically useful. Among them, mutant 'T 2 14' resulting from 25 kR gamma rays + UV, was found to possess better germinability (+15%), earliness (5 days) and high yield during both rainy and post-rainy seasons in 1986 and 1987, when compared with the parent variety 'Bragg'. The mutant has smaller seed-size (TGW 125 g) than the parent (145 g). In soybean, large-seeded varieties were reported to have poorer seed germinability. Thus, the better germinability of the mutant might be related to its reduced seed size. Seeds of the mutant show a light brown colour of the hilum in contrast to the black hilum of 'Bragg'. In other characters the mutant is similar to 'Bragg'. The mutant should have potential for commercial cultivation in India. For confirmation of its agronomically superior performance, it is undergoing national evaluation in multilocational trials under 'All India Co-ordinated Research Project on Soybean (ICAR)'. The strain has been named 'NRC-2'. (author)

Plasma etching of polymers like SU8 and BCB

Science.gov (United States)

Mischke, Helge; Gruetzner, Gabi; Shaw, Mark

2003-01-01

Polymers with high viscosity, like SU8 and BCB, play a dominant role in MEMS application. Their behavior in a well defined etching plasma environment in a RIE mode was investigated. The 40.68 MHz driven bottom electrode generates higher etch rates combined with much lower bias voltages by a factor of ten or a higher efficiency of the plasma with lower damaging of the probe material. The goal was to obtain a well-defined process for the removal and structuring of SU8 and BCB using fluorine/oxygen chemistry, defined using variables like electron density and collision rate. The plasma parameters are measured and varied using a production proven technology called SEERS (Self Excited Electron Resonance Spectroscopy). Depending on application and on Polymer several metals are possible (e.g., gold, aluminum). The characteristic of SU8 and BCB was examined in the case of patterning by dry etching in a CF4/O2 chemistry. Etch profile and etch rate correlate surprisingly well with plasma parameters like electron density and electron collision rate, thus allowing to define to adjust etch structure in situ with the help of plasma parameters.

Effect of a Cooling Step Treatment on a High-Voltage GaN LED During ICP Dry Etching

Science.gov (United States)

Lin, Yen-Sheng; Hsiao, Sheng-Yu; Tseng, Chun-Lung; Shen, Ching-Hsing; Chiang, Jung-Sheng

2017-02-01

In this study, a lower dislocation density for a GaN surface and a reduced current path are observed at the interface of a SiO2 isolation sidewall, using high-resolution transmission electron microscopy. This is grown using a 3-min cooling step treatment during inductivity coupled plasma dry etching. The lower forward voltage is measured, the leakage current decreases from 53nA to 32nA, and the maximum output power increases from 354.8 W to 357.2 W for an input current of 30 mA. The microstructure and the optoelectronic properties of high-voltage light-emitting-diodes is proven to be affected by the cooling step treatment, which allows enough time to release the thermal energy of the SiO2 isolation well.

Nitride-based Schottky diodes and HFETs fabricated by photo-enhanced chemical wet etching

International Nuclear Information System (INIS)

Su, Y.K.; Chang, S.J.; Kuan, T.M.; Ko, C.H.; Webb, J.B.; Lan, W.H.; Cherng, Y.T.; Chen, S.C.

2004-01-01

Photo-enhanced chemical (PEC) wet etching technology was used to etch GaN and AlGaN epitaxial layers. It was found that the maximum etch rates were 510, 1960, 300, and 0 nm/mm for GaN, Al 0.175 Ga 0.825 N, Al 0.23 Ga 0.77 N, and Al 0.4 Ga 0.6 N, respectively. It was also found that we could achieve a high Al 0.175 Ga 0.825 N to GaN etch rate ratio of 12.6. Nitride-based Schottky diodes and heterostructure field effect transistors (HFETs) were also fabricated by PEC wet etching. It was found that we could achieve a saturated I D larger than 850 mA/mm and a maximum g m about 163 mS/mm from PEC wet etched HFET with a 0.5 μm gate length. Compared with dry etched devices, the leakage currents observed from the PEC wet etched devices were also found to be smaller

Suitability of N2 plasma for the RIE etching of thin Ag layers

International Nuclear Information System (INIS)

Hrkut, P.; Matay, L.; Kostic, I.; Bencurova, A.; Konecnikova, A.; Nemec, P.; Andok, R.; Hacsik, S.

2013-01-01

Silver layers of 48 nm thickness were evaporated using EB PVD on Si wafers. The masking resist layers were spin-coated and patterned by the EBDW lithography on the ZBA 21 (20 keV) (Carl-Zeiss, Jena; currently Vistec, Ltd.) variable shaped e-beam pattern generator in II SAS. In order to check the etching process in N 2 , we covered a part of the samples containing Ag with a layer of various resists. The samples were dried on a hot-plate and RIE etched in SCM 600 (1 Pa; 20 sccm; 500 W). After 8 minutes the non-masked Ag layer was completely etched away, what testified suitability of N 2 as an etching gas. Also the etch time of 4 minutes showed to be sufficient for etching through the Ag layer. In order to optimize the etching process it was necessary to estimate the etch-rate (E.R.) of suitable resist layers and of the silver layer. The (authors)

Bragg Curve, Biological Bragg Curve and Biological Issues in Space Radiation Protection with Shielding

Science.gov (United States)

Honglu, Wu; Cucinotta, F.A.; Durante, M.; Lin, Z.; Rusek, A.

2006-01-01

The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the major protection to astronauts from harmful exposure. Unlike low-LET gamma or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure. Since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak, the Bragg curve does not necessarily represent the biological damage along the particle traversal since biological effects are influenced by the track structure of both primary and secondary particles. Therefore, the biological Bragg curve is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. To achieve a Bragg curve distribution, we exposed cells to energetic heavy ions with the beam geometry parallel to a monolayer of fibroblasts. Qualitative analyses of gamma-H2AX fluorescence, a known marker of DSBs, indicated increased clustering of DNA damage before the Bragg peak, enhanced homogenous distribution at the peak, and provided visual evidence of high linear energy transfer (LET) particle traversal of cells beyond the Bragg peak. A quantitative biological response curve generated for micronuclei (MN) induction across the Bragg curve did not reveal an increased yield of MN at the location of the Bragg peak. However, the ratio of mono-to bi-nucleated cells, which indicates inhibition in cell progression, increased at the Bragg peak location. These results, along with other biological concerns, show that space radiation protection with shielding can be a complicated issue.

Etching Effect of an Atmospheric DC Arc Plasmatron

International Nuclear Information System (INIS)

Chun, Se Min; Kim, Ji Hun; Kang, In Je; Lee, Heon Ju

2010-01-01

Thermal plasmas (especially arc plasma) were extensively industrialized, principally by aeronautic sector. Cold plasma technologies have been developed in the microelectronics but their vacuum equipment limits their implantation. Plasmas used in dry etching, thin film deposition and surface treatment for display or semiconductor industries are operating at low pressures in very costly due to the use of vacuum equipment and vacuum components. Use of DC arc plasmatrons in welding, soldering, and cutting of metals is well known. A DC-arc plasmatron with high durability was reported to be a suitable device for etching silicon and photo-resist surfaces

Application of Fourier-Bessel technique for computing Eigen-states in a Bragg cylindrical space slot channel waveguide

Science.gov (United States)

Jafari, Seyed Hamed; Gauthier, Robert C.

2015-02-01

Maxwell's wave equations can be solved using different techniques in order to extract optical properties of a variety of dielectric structures. For structures that contain an extended axis which serve for the reference for cylindrical symmetry, we have shown that an expansion of the fields and inverse of the relative dielectric profile using a simplified and complete set of basis functions of Fourier-Bessel terms provide access to an eigenvalue formulation from which the eigen-states can be computed. We review the steps used to convert Maxwell's equation into an eigenvalue formulation, and then proceed to discuss several applications of the technique. For cylindrically symmetric structures, the computational technique provides a significantly reduced matrix order to be populated. New target structure for the presentation consists of cylindrical space slot channel waveguide in which the channel extends in azimuthal (ϕ) direction. The channel is provided by considering the etching of external side walls of "Bragg fiber". The configuration is similar to a structure that can support whispering-gallery modes, except that the modes highest field locations are within the ambient medium of the channel. Optical properties of this structure can be best examined through ?? field component which is discontinuous by ratio of relative dielectric constants when passing air-Bragg interfaces. The ability to select Bragg dielectric properties and to introduce non-uniformities in Bragg plane spacing provides access to tuning slot channel waveguide properties and design several novel configurations.

Metal-assisted etch combined with regularizing etch

Energy Technology Data Exchange (ETDEWEB)

Yim, Joanne; Miller, Jeff; Jura, Michael; Black, Marcie R.; Forziati, Joanne; Murphy, Brian; Magliozzi, Lauren

2018-03-06

In an aspect of the disclosure, a process for forming nanostructuring on a silicon-containing substrate is provided. The process comprises (a) performing metal-assisted chemical etching on the substrate, (b) performing a clean, including partial or total removal of the metal used to assist the chemical etch, and (c) performing an isotropic or substantially isotropic chemical etch subsequently to the metal-assisted chemical etch of step (a). In an alternative aspect of the disclosure, the process comprises (a) performing metal-assisted chemical etching on the substrate, (b) cleaning the substrate, including removal of some or all of the assisting metal, and (c) performing a chemical etch which results in regularized openings in the silicon substrate.

Axial contraction in etched optical fiber due to internal stress reduction.

Science.gov (United States)

Lim, Kok-Sing; Yang, Hang-Zhou; Chong, Wu-Yi; Cheong, Yew-Ken; Lim, Chin-Hong; Ali, Norfizah M; Ahmad, Harith

2013-02-11

When an optical fiber is dipped in an etching solution, the internal stress profile in the fiber varies with the fiber diameter. We observed a physical contraction as much as 0.2% in the fiber axial dimension when the fiber was reduced from its original diameter to ~6 µm through analysis using high resolution microscope images of the grating period of an etched FBG at different fiber diameters. This axial contraction is related to the varying axial stress profile in the fiber when the fiber diameter is reduced. On top of that, the refractive index of fiber core increases with reducing fiber diameter due to stress-optic effect. The calculated index increment is as much as 1.8 × 10(-3) at the center of fiber core after the diameter is reduced down to ~6 µm. In comparison with the conventional model that assumes constant grating period and neglects the variation in stress-induced index change in fiber core, our proposed model indicates a discrepancy as much as 3nm in Bragg wavelength at a fiber diameter of ~6 µm.

Performance improvements of binary diffractive structures via optimization of the photolithography and dry etch processes

Science.gov (United States)

Welch, Kevin; Leonard, Jerry; Jones, Richard D.

2010-08-01

Increasingly stringent requirements on the performance of diffractive optical elements (DOEs) used in wafer scanner illumination systems are driving continuous improvements in their associated manufacturing processes. Specifically, these processes are designed to improve the output pattern uniformity of off-axis illumination systems to minimize degradation in the ultimate imaging performance of a lithographic tool. In this paper, we discuss performance improvements in both photolithographic patterning and RIE etching of fused silica diffractive optical structures. In summary, optimized photolithographic processes were developed to increase critical dimension uniformity and featuresize linearity across the substrate. The photoresist film thickness was also optimized for integration with an improved etch process. This etch process was itself optimized for pattern transfer fidelity, sidewall profile (wall angle, trench bottom flatness), and across-wafer etch depth uniformity. Improvements observed with these processes on idealized test structures (for ease of analysis) led to their implementation in product flows, with comparable increases in performance and yield on customer designs.

A study on decontamination of TRU, Co, and Mo using plasma surface etching technique

International Nuclear Information System (INIS)

Seo, Y.D.; Kim, Y.S.; Paek, S.H.; Lee, K.H.; Jung, C.H.; Oh, W.Z.

2001-01-01

Recently dry decontamination/surface-cleaning technology using plasma etching has been focused in the nuclear industry. In this study, the applicability and the effectiveness of this new dry processing technique are experimentally investigated by examining the etching reaction of UO 2 , Co, and Mo in r.f. plasma with the etchant gas of CF 4 /O 2 mixture. UO 2 is chosen as a representing material for uranium and TRU (TRans-Uranic) compounds and metallic Co and Mo are selected because they are the principal contaminants in the spent nuclear components such as valves and pipes made of stainless steel or INCONEL. Results show that in all cases maximum etching rate is achieved when the mole fraction of O 2 to CF 4 /O 2 mixture gas is 20 %, regardless of temperature and r.f. power. (author)

Multiplexed FBG and etched fiber sensors for process and health monitoring of 2-&3-D RTM components

OpenAIRE

Keulen, Casey J.; Yıldız, Mehmet; Yildiz, Mehmet; Suleman, Afzal

2011-01-01

This paper presents research being conducted on the use of a combination of fiber optic sensors for process and health monitoring of resin transfer molded (RTM) composite structures. A laboratory scale RTM apparatus has been designed and built with the capability of visually monitoring the resin filling process and embedding fiber optic sensors into the composite. Fiber Bragg gratings (FBG) and etched fiber sensors (EFS) have been multiplexed and embedded in quasi-2-D panels and 3-D hollow se...

Introducing etch kernels for efficient pattern sampling and etch bias prediction

Science.gov (United States)

Weisbuch, François; Lutich, Andrey; Schatz, Jirka

2018-01-01

Successful patterning requires good control of the photolithography and etch processes. While compact litho models, mainly based on rigorous physics, can predict very well the contours printed in photoresist, pure empirical etch models are less accurate and more unstable. Compact etch models are based on geometrical kernels to compute the litho-etch biases that measure the distance between litho and etch contours. The definition of the kernels, as well as the choice of calibration patterns, is critical to get a robust etch model. This work proposes to define a set of independent and anisotropic etch kernels-"internal, external, curvature, Gaussian, z_profile"-designed to represent the finest details of the resist geometry to characterize precisely the etch bias at any point along a resist contour. By evaluating the etch kernels on various structures, it is possible to map their etch signatures in a multidimensional space and analyze them to find an optimal sampling of structures. The etch kernels evaluated on these structures were combined with experimental etch bias derived from scanning electron microscope contours to train artificial neural networks to predict etch bias. The method applied to contact and line/space layers shows an improvement in etch model prediction accuracy over standard etch model. This work emphasizes the importance of the etch kernel definition to characterize and predict complex etch effects.

Bragg grating rogue wave

Energy Technology Data Exchange (ETDEWEB)

Degasperis, Antonio [Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma (Italy); Wabnitz, Stefan, E-mail: stefan.wabnitz@unibs.it [Dipartimento di Ingegneria dell' Informazione, Università degli Studi di Brescia and INO-CNR, via Branze 38, 25123 Brescia (Italy); Aceves, Alejandro B. [Southern Methodist University, Dallas (United States)

2015-06-12

We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing may lead to extreme waves at extremely low powers.

A Nanoscale Plasma Etching Process for Pole Tip Recession of Perpendicular Recording Magnetic Head

OpenAIRE

LIU, Shoubin; HE, Dayao

2017-01-01

The pole tip of perpendicular recording head is constructed in a stacked structure with materials of NiCoFe, NiFe, Al2O3 and AlTiC. The surfaces of different materials are set at different heights below the air-bearing surface of slider. This paper presented a plasma dry etching process for Pole Tip Recession (PTR) based on an ion beam etching system. Ar and O2 mixed plasma at small incident angles have a high removal rate to the nonmagnetic material. It was utilised to etch the reference sur...

Switchable Bragg gratings

DEFF Research Database (Denmark)

Marckmann, Carl Johan

2003-01-01

Research Center (MIC) at the Technical University of Denmark. The Bragg gratings were fabricated at COM using UV irradiation of the planar waveguides using the phase mask method. The induction of a frozen-in DC electric field into the samples was performed by thermal poling of the Bragg gratings...... layers, it becam possible to investigate the symmetry properties of the third-order nonlinearities. Contrary to the expectations for an amorphous material, the measurements indicated an almost polarization independent third-order nonlinearity - the most probable explanation being electrostriction......The subject of this ph.d. thesis was the development of an electrically switchable Bragg grating made in an optical waveguide using thermal poling to be applied within optical telecommunication systems. The planar waveguides used in this thesis were fabricated at the Micro- and Nanotechnology...

Self-etch and etch-and-rinse adhesive systems in clinical dentistry.

Science.gov (United States)

Ozer, Fusun; Blatz, Markus B

2013-01-01

Current adhesive systems follow either an "etch-and-rinse" or "self-etch" approach, which differ in how they interact with natural tooth structures. Etch-and-rinse systems comprise phosphoric acid to pretreat the dental hard tissues before rinsing and subsequent application of an adhesive. Self-etch adhesives contain acidic monomers, which etch and prime the tooth simultaneously. Etch-and-rinse adhesives are offered as two- or three-step systems, depending on whether primer and bonding are separate or combined in a single bottle. Similarly, self-etch adhesives are available as one- or two-step systems. Both etch-and-rinse and self-etch systems form a hybrid layer as a result of resins impregnating the porous enamel or dentin. Despite current trends toward fewer and simpler clinical application steps, one-step dentin bonding systems exhibit bonding agent lower bond strengths and seem less predictable than multi-step etch-and-rinse and self-etch systems. The varying evidence available today suggests that the choice between etch-and-rinse and self-etch systems is often a matter of personal preference. In general, however, phosphoric acid creates a more pronounced and retentive etching pattern in enamel. Therefore, etch-and-rinse bonding systems are often preferred for indirect restorations and when large areas of enamel are still present. Conversely, self-etch adhesives provide superior and more predictable bond strength to dentin and are, consequently, recommended for direct composite resin restorations, especially when predominantly supported by dentin.

A Highly Sensitive Two-Dimensional Inclinometer Based on Two Etched Chirped-Fiber-Grating Arrays †

Science.gov (United States)

Chang, Hung-Ying; Chang, Yu-Chung; Liu, Wen-Fung

2017-01-01

We present a novel two-dimensional fiber-optic inclinometer with high sensitivity by crisscrossing two etched chirped fiber Bragg gratings (CFBG) arrays. Each array is composed of two symmetrically-arranged CFBGs. By etching away most of the claddings of the CFBGs to expose the evanescent wave, the reflection spectra are highly sensitive to the surrounding index change. When we immerse only part of the CFBG in liquid, the effective index difference induces a superposition peak in the refection spectrum. By interrogating the peak wavelengths of the CFBGs, we can deduce the tilt angle and direction simultaneously. The inclinometer has a resolution of 0.003° in tilt angle measurement and 0.00187 rad in tilt direction measurement. Due to the unique sensing mechanism, the sensor is temperature insensitive. This sensor can be useful in long term continuous monitoring of inclination or in real-time feedback control of tilt angles, especially in harsh environments with violent temperature variation. PMID:29244770

Bragg gratings in Topas

DEFF Research Database (Denmark)

Zhang, C.; Webb, D.J.; Kalli, K.

We report for the first time fibre Bragg grating inscription in microstructured optical fibre fabricated from Topas® cyclic olefin copolymer. The temperature sensitivity of the grating was studied revealing a positive Bragg wavelength shift of approximately 0.8 nmK-1,the largest sensitivity yet...

Iridium-coated micropore x-ray optics using dry etching of a silicon wafer and atomic layer deposition.

Science.gov (United States)

Ogawa, Tomohiro; Ezoe, Yuichiro; Moriyama, Teppei; Mitsuishi, Ikuyuki; Kakiuchi, Takuya; Ohashi, Takaya; Mitsuda, Kazuhisa; Putkonen, Matti

2013-08-20

To enhance x-ray reflectivity of silicon micropore optics using dry etching of silicon (111) wafers, iridium coating is tested by use of atomic layer deposition. An iridium layer is successfully formed on sidewalls of tiny micropores with a pore width of 20 μm and depth of 300 μm. The film thickness is ∼20  nm. An enhanced x-ray reflectivity compared to that of silicon is confirmed at Ti Kα 4.51 keV, for what we believe to be the first time, with this type of optics. Some discrepancies from a theoretical reflectivity curve of iridium-coated silicon are noticed at small incident angles <1.3°. When a geometrical shadowing effect due to occultation by a ridge existing on the sidewalls is taken into account, the observed reflectivity becomes well represented by the modified theoretical curve. An estimated surface micro roughness of ∼1  nm rms is consistent with atomic force microscope measurements of the sidewalls.

Atomic Layer Etching : What can we learn from Atomic Layer Deposition?

NARCIS (Netherlands)

Faraz, T.; Roozeboom, F.; Knoops, H.C.M.; Kessels, W.M.M.

2015-01-01

Current trends in semiconductor device manufacturing impose extremely stringent requirements on nanoscale processing techniques, both in terms of accurately controlling material properties and in terms of precisely controlling nanometer dimensions. To take nanostructuring by dry etching to the next

Atomic layer etching : what can we learn from atomic layer deposition?

NARCIS (Netherlands)

Faraz, T.; Roozeboom, F.; Knoops, H.C.M.; Kessels, W.M.M.

2015-01-01

Current trends in semiconductor device manufacturing impose extremely stringent requirements on nanoscale processing techniques, both in terms of accurately controlling material properties and in terms of precisely controlling nanometer dimensions. To take nanostructuring by dry etching to the next

Etch bias inversion during EUV mask ARC etch

Science.gov (United States)

Lajn, Alexander; Rolff, Haiko; Wistrom, Richard

2017-07-01

The introduction of EUV lithography to high volume manufacturing is now within reach for 7nm technology node and beyond (1), at least for some steps. The scheduling is in transition from long to mid-term. Thus, all contributors need to focus their efforts on the production requirements. For the photo mask industry, these requirements include the control of defectivity, CD performance and lifetime of their masks. The mask CD performance including CD uniformity, CD targeting, and CD linearity/ resolution, is predominantly determined by the photo resist performance and by the litho and etch processes. State-of-the-art chemically amplified resists exhibit an asymmetric resolution for directly and indirectly written features, which usually results in a similarly asymmetric resolution performance on the mask. This resolution gap may reach as high as multiple tens of nanometers on the mask level in dependence of the chosen processes. Depending on the printing requirements of the wafer process, a reduction or even an increase of this gap may be required. A potential way of tuning via the etch process, is to control the lateral CD contribution during etch. Aside from process tuning knobs like pressure, RF powers and gases, which usually also affect CD linearity and CD uniformity, the simplest knob is the etch time itself. An increased over etch time results in an increased CD contribution in the normal case. , We found that the etch CD contribution of ARC layer etch on EUV photo masks is reduced by longer over etch times. Moreover, this effect can be demonstrated to be present for different etch chambers and photo resists.

Optical fiber refractometer based on tapered tilted-fiber Bragg grating

Science.gov (United States)

Wang, Tao; Liu, Tiegen; Liu, Kun; Jiang, Junfeng; Yu, Zhe; Xue, Meng

2016-11-01

Tilted fiber Bragg gratings (TFBGs) have been demonstrated to be accurate refractometers as they couple light from the fiber core to the cladding. In our experiment, we changed the physical structure of the TFBGs to improve the refractive index sensing ability. One way is to stretch the grating section 5 mm longer. The result showed that not only the number of the cladding mode of the TFBG decreases but also the full width half-maximum (FWHM) of the cladding modes and core mode changes. The FWHM of the cladding mode of the tapered TFBG is more than twice than that of the original. However, the refractive index sensitivity of the tapered TFBG has no obvious improvement. Another way is to etch the grating section with 20% hydrofluoric acid solution. We find that the smaller the clad diameter, the higher the refractive index sensitivity of the TFBG.

Novel method of dual fiber Bragg gratings integrated in fiber ring laser for biochemical sensors

Science.gov (United States)

Bui, H.; Pham, T. B.; Nguyen, V. A.; Pham, V. D.; Do, T. C.; Nguyen, T. V.; Hoang, T. H. C.; Le, H. T.; Pham, V. H.

2018-05-01

Optical sensors have been shown to be very effective for measuring the toxic content in liquid and air environments. Optical sensors, which operate based on the wavelength shift of the optical signals, require an expensive spectrometer. In this paper, we propose a new configuration of the optical sensor device for measuring wavelength shift without using a spectrometer. This configuration has a large potential for application in biochemical sensing techniques, and comes with a low cost. This configuration uses dual fiber Bragg gratings (FBGs) integrated in a fiber ring laser structure of erbium-doped fiber, in which one FBG is used as a reference to sweep over the applicable spectrum of the etched-Bragg grating. The etched-FBG as a sensing probe is suitable for bio- and/or chemical sensors. The sensitivity and accuracy of the sensor system can be improved by the narrow linewidth of emission spectra from the laser, the best limit of detection of this sensor is 1.5  ×  10‑4 RIU (RIU: refractive index unit), as achieved by the optical sensor using a high resolution spectrometer. This sensor system has been experimentally investigated to detect different types of organic compounds, gasoline, mixing ratios of organic solvents in gasoline, and nitrate concentration in water samples. The experimental results show that this sensing method could determine different mixing ratios of organic solvents with good repeatability, high accuracy, and rapid response: e.g. for ethanol and/or methanol in gasoline RON 92 (RON: research octane number) of 0%–14% v/v, and nitrate in water samples at a low concentration range of 0–50 ppm. These results suggest that the proposed configuration can construct low-cost and accurate biochemical sensors.

Fabrication of porous silicon based tunable distributed Bragg reflectors by anodic etching of irradiated silicon

International Nuclear Information System (INIS)

Vendamani, V.S.; Dang, Z.Y.; Ramana, P.; Pathak, A.P.; Ravi Kanth Kumar, V.V.; Breese, M.B.H.; Nageswara Rao, S.V.S.

2015-01-01

Highlights: • Fabrication of tunable distributed Bragg reflectors (DBRs) by gamma/ion irradiation of Si and subsequent formation of porous silicon multilayers has been described. • The central wavelength and the width of the stop band are found to decrease with increase in irradiation fluence. • The Si samples irradiated with highest fluence of 2 × 10 13 ions/cm 2 (100 MeV Ag ions) and 60 kGy (gamma) showed a central reflection at λ = 476 nm and 544 nm respectively, in contrast to un-irradiated sample, where λ = 635 nm. • The observed changes in the central wavelengths are attributed to the density of defects generated by gamma and ion irradiation in c-Si. • This study is expected to provide useful information for fabricating tunable wave reflectors for optical communication and other device applications. - Abstract: We report a study on the fabrication of tunable distributed Bragg reflectors (DBRs) by gamma/ion irradiation of Si and subsequent formation of porous silicon multilayers. Porous Si multilayers with 50 bilayers were designed to achieve high intensity of reflection. The reflection spectra appear to have a broad continuous band between 400 and 800 nm with a distinct central wavelength corresponding to different wave reflectors. The central wavelength and the width of the stop band are found to decrease with increase in irradiation fluence. The Si samples irradiated with highest fluence of 2 × 10 13 ions/cm 2 (100 MeV Ag ions) and 60 kGy (gamma) showed a central reflection at λ = 476 nm and 544 nm respectively, in contrast to un-irradiated sample, where λ = 635 nm. The observed changes are attributed to the density of defects generated by gamma and ion irradiation in c-Si. These results suggest that the gamma irradiation is a convenient and alternative method to tune the central wavelength of reflection without creating high density of defects by high energy ion implantation. This study is expected to provide useful information for

Dry Etch Black Silicon with Low Surface Damage: Effect of Low Capacitively Coupled Plasma Power

DEFF Research Database (Denmark)

Iandolo, Beniamino; Plakhotnyuk, Maksym; Gaudig, Maria

2017-01-01

Black silicon fabricated by reactive ion etch (RIE) is promising for integration into silicon solar cells thanks to its excellent light trapping ability. However, intensive ion bombardment during the RIE induces surface damage, which results in enhanced surface recombination velocity. Here, we pr...... carrier lifetime thanks to reduced ion energy. Surface passivation using atomic layer deposition of Al2O3 improves the effective lifetime to 7.5 ms and 0.8 ms for black silicon n- and p-type wafers, respectively.......Black silicon fabricated by reactive ion etch (RIE) is promising for integration into silicon solar cells thanks to its excellent light trapping ability. However, intensive ion bombardment during the RIE induces surface damage, which results in enhanced surface recombination velocity. Here, we...... present a RIE optimization leading to reduced surface damage while retaining excellent light trapping and low reflectivity. In particular, we demonstrate that the reduction of the capacitively coupled power during reactive ion etching preserves a reflectance below 1% and improves the effective minority...

Reactive ion beam etching for microcavity surface emitting laser fabrication: technology and damage characterization

International Nuclear Information System (INIS)

Matsutani, A.; Tadokoro, T.; Koyama, F.; Iga, K.

1993-01-01

Reactive ion beam etching (RIBE) is an effective dry etching technique for the fabrication of micro-sized surface emitting (SE) lasers and optoelectronic devices. In this chapter, some etching characteristics for GaAs, InP and GaInAsP with a Cl 2 gas using an RIBE system are discussed. Micro-sized circular mesas including GaInAsP/InP multilayers with vertical sidewalls were fabricated. RIBE-induced damage in InP substrates was estimated by C-V and PL measurement. In addition, the removal of the induced damage by the second RIBE with different conditions for the InP wafer was proposed. The sidewall damage is characterized by photoluminescence emitted from the etched sidewall of a GaInAsP/InP DH wafer. (orig.)

Optimization of the etch-and-rinse technique: New perspectives to improve resin-dentin bonding and hybrid layer integrity by reducing residual water using dimethyl sulfoxide pretreatments.

Science.gov (United States)

Stape, Thiago Henrique Scarabello; Tjäderhane, Leo; Abuna, Gabriel; Sinhoreti, Mário Alexandre Coelho; Martins, Luís Roberto Marcondes; Tezvergil-Mutluay, Arzu

2018-04-13

To determine whether bonding effectiveness and hybrid layer integrity on acid-etched dehydrated dentin would be comparable to the conventional wet-bonding technique through new dentin biomodification approaches using dimethyl sulfoxide (DMSO). Etched dentin surfaces from extracted sound molars were randomly bonded in wet or dry conditions (30s air drying) with DMSO/ethanol or DMSO/H 2 O as pretreatments using a simplified (Scotchbond Universal Adhesive, 3M ESPE: SU) and a multi-step (Adper Scotchbond Multi-Purpose, 3M ESPE: SBMP) etch-and-rinse adhesives. Untreated dentin surfaces served as control. Bonded teeth (n=8) were stored in distilled water for 24h and sectioned into resin-dentin beams (0.8mm 2 ) for microtensile bond strength test and quantitative interfacial nanoleakage analysis (n=8) under SEM. Additional teeth (n=2) were prepared for micropermeability assessment by CFLSM under simulated pulpar pressure (20cm H 2 O) using 5mM fluorescein as a tracer. Microtensile data was analyzed by 3-way ANOVA followed by Tukey Test and nanoleakage by Kruskal-Wallis and Dunn-Bonferroni multiple comparison test (α=0.05). While dry-bonding of SBMP produced significantly lower bond strengths than wet-bonding (padhesives to demineralized air-dried dentin beyond conventional wet-bonding. Less porous resin-dentin interfaces with higher bond strengths on air-dried etched dentin were achieved; nonetheless, overall efficiency varied according to DMSO's co-solvent and adhesive type. DMSO pretreatments permit etched dentin to be air-dried before hybridization facilitating residual water removal and thus improving bonding effectiveness. This challenges the current paradigm of wet-bonding requirement for the etch-and-rinse approach creating new possibilities to enhance the clinical longevity of resin-dentin interfaces. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Two-year Randomized Clinical Trial of Self-etching Adhesives and Selective Enamel Etching.

Science.gov (United States)

Pena, C E; Rodrigues, J A; Ely, C; Giannini, M; Reis, A F

2016-01-01

The aim of this randomized, controlled prospective clinical trial was to evaluate the clinical effectiveness of restoring noncarious cervical lesions with two self-etching adhesive systems applied with or without selective enamel etching. A one-step self-etching adhesive (Xeno V(+)) and a two-step self-etching system (Clearfil SE Bond) were used. The effectiveness of phosphoric acid selective etching of enamel margins was also evaluated. Fifty-six cavities were restored with each adhesive system and divided into two subgroups (n=28; etch and non-etch). All 112 cavities were restored with the nanohybrid composite Esthet.X HD. The clinical effectiveness of restorations was recorded in terms of retention, marginal integrity, marginal staining, caries recurrence, and postoperative sensitivity after 3, 6, 12, 18, and 24 months (modified United States Public Health Service). The Friedman test detected significant differences only after 18 months for marginal staining in the groups Clearfil SE non-etch (p=0.009) and Xeno V(+) etch (p=0.004). One restoration was lost during the trial (Xeno V(+) etch; p>0.05). Although an increase in marginal staining was recorded for groups Clearfil SE non-etch and Xeno V(+) etch, the clinical effectiveness of restorations was considered acceptable for the single-step and two-step self-etching systems with or without selective enamel etching in this 24-month clinical trial.

Obtaining porous silicon suitable for sensor technology using MacEtch nonelectrolytic etching

Directory of Open Access Journals (Sweden)

Iatsunskyi I. R.

2013-12-01

Full Text Available The author suggests to use the etching method MacEtch (metal-assisted chemical etching for production of micro- and nanostructures of porous silicon. The paper presents research results on the morphology structures obtained at different parameters of deposition and etching processes. The research has shown that, depending on the parameters of deposition of silver particles and silicon wafers etching, the obtained surface morphology may be different. There may be both individual crater-like pores and developed porous or macroporous surface. These results indicate that the MacEtch etching is a promising method for obtaining micro-porous silicon nanostructures suitable for effective use in gas sensors and biological object sensors.

Bond strength of self-etch adhesives after saliva contamination at different application steps.

Science.gov (United States)

Cobanoglu, N; Unlu, N; Ozer, F F; Blatz, M B

2013-01-01

This study evaluated and compared the effect of saliva contamination and possible decontamination methods on bond strengths of two self-etching adhesive systems (Clearfil SE Bond [CSE], Optibond Solo Plus SE [OSE]). Flat occlusal dentin surfaces were created on 180 extracted human molar teeth. The two bonding systems and corresponding composite resins (Clearfil AP-X, Kerr Point 4) were bonded to the dentin under six surface conditions (n=15/group): group 1 (control): primer/bonding/composite; group 2: saliva/drying/primer/bonding/composite; group 3: primer/saliva/rinsing/drying/primer/bonding/composite; group 4: primer/saliva/rinsing/drying/bonding/composite; group 5: primer/bonding (cured)/saliva/rinsing/drying/primer/bonding/composite; group 6: primer/bonding (cured)/saliva/removing contaminated layer with a bur/rinsing/drying/primer/bonding/composite. Shear bond strength was tested after specimens were stored in distilled water at 37°C for 24 hours. One-way analysis of variance and Tukey post hoc tests were used for statistical analyses. For CSE, groups 2, 3, and 4 and for OSE, groups 6, 2, and 4 showed significantly lower bond strengths than the control group (pcontamination occurred after light polymerization of the bonding agent, repeating the bonding procedure recovered the bonding capacity of both self-etch adhesives. However, saliva contamination before or after primer application negatively affected their bond strength.

Impact of recess etching and surface treatments on ohmic contacts regrown by molecular-beam epitaxy for AlGaN/GaN high electron mobility transistors

Energy Technology Data Exchange (ETDEWEB)

Joglekar, S.; Azize, M.; Palacios, T. [Microsystems Technology Laboratories, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Beeler, M.; Monroy, E. [Université Grenoble-Alpes, 38000 Grenoble (France); CEA Grenoble, INAC-PHELIQS, 38000 Grenoble (France)

2016-07-25

Ohmic contacts fabricated by regrowth of n{sup +} GaN are favorable alternatives to metal-stack-based alloyed contacts in GaN-based high electron mobility transistors. In this paper, the influence of reactive ion dry etching prior to regrowth on the contact resistance in AlGaN/GaN devices is discussed. We demonstrate that the dry etch conditions modify the surface band bending, dangling bond density, and the sidewall depletion width, which influences the contact resistance of regrown contacts. The impact of chemical surface treatments performed prior to regrowth is also investigated. The sensitivity of the contact resistance to the surface treatments is found to depend upon the dangling bond density of the sidewall facets exposed after dry etching. A theoretical model has been developed in order to explain the observed trends.

Defect formation during chlorine-based dry etching and their effects on the electronic and structural properties of InP/InAsP quantum wells

Energy Technology Data Exchange (ETDEWEB)

Landesman, Jean-Pierre, E-mail: jean-pierre.landesman@univ-rennes1.fr [Institut de Physique de Rennes, CNRS-UMR 6251, Université Rennes 1, F-35042 Rennes (France); Jiménez, Juan; Torres, Alfredo [GdS Optronlab, Dpto. Fisica de la Materia Condensada, Universidad de Valladolid, 47011 Valladolid (Spain); Levallois, Christophe; Léger, Yoan; Beck, Alexandre [UMR FOTON, CNRS, INSA-Rennes, 20 avenue des buttes de Coësmes, F-35708 Rennes (France); Pommereau, Frédéric [III-V Lab, 1 Avenue Augustin Fresnel, RD128, F-91767 Palaiseau (France); Frigeri, Cesare [CNR-IMEM Istituto, Parco area delle Scienze 37/A, 43010 Parma (Italy); Rhallabi, Ahmed [Institut des Matériaux Jean-Rouxel, CNRS-UMR 6502, Université Nantes 1, F-44322 Nantes (France)

2016-07-15

The general objective is the investigation of the defects formed by dry etching tools such as those involved in the fabrication of photonic devices with III–V semiconductors. Emphasis is put on plasma exposures with chlorine-based chemistries. In addition to identifying these defects and describing their effects on the electro-optic and structural properties, the long-term target would be to predict the impact on the parameters of importance for photonic devices, and possibly include these predictions in their design. The work is first centered on explaining the experimental methodology. This methodology starts with the design and growth of a quantum well structure on indium phosphide, including ternary indium arsenide/phosphide quantum wells with graded arsenic/phosphor composition. These samples have then been characterized by luminescence methods (photo- and cathodoluminescence), high-resolution transmission electron microscopy, and secondary ion mass spectrometry. As one of the parameters of importance in this study, the authors have also included the doping level. The samples have been exposed to the etching plasmas for “short” durations that do not remove completely the quantum wells, but change their optical signature. No masking layer with lithographic features was involved as this work is purely oriented to study the interaction between the plasma and the samples. A significant difference in the luminescence spectra of the as-grown undoped and doped samples is observed. A mechanism describing the effect of the built-in electric field appearing as a consequence of the doping profile is proposed. This mechanism involves quantum confined Stark effect and electric-field induced carrier escape from the quantum wells. In the following part, the effects of exposure to various chlorine-based plasmas were explored. Differences are again observed between the undoped and doped samples, especially for chemistries containing silicon tetrachloride. Secondary ion

Carrier-lifetime-controlled selective etching process for semiconductors using photochemical etching

International Nuclear Information System (INIS)

Ashby, C.I.H.; Myers, D.R.

1992-01-01

This patent describes a process for selectively photochemically etching a semiconductor material. It comprises introducing at least one impurity into at least one selected region of a semiconductor material to be etched to increase a local impurity concentration in the at least one selected region relative to an impurity concentration in regions of the semiconductor material adjacent thereto, for reducing minority carrier lifetimes within the at least one selected region relative to the adjacent regions for thereby providing a photochemical etch-inhibiting mask at the at least one selected region; and etching the semiconductor material by subjecting the surface of the semiconductor material to a carrier-driven photochemical etching reaction for selectively etching the regions of the semiconductor material adjacent the at least one selected region having the increase impurity concentration; wherein the step of introducing at least one impurity is performed so as not to produce damage to the at least one selected region before any etching is performed

Black Silicon formation using dry etching for solar cells applications

International Nuclear Information System (INIS)

Murias, D.; Reyes-Betanzo, C.; Moreno, M.; Torres, A.; Itzmoyotl, A.; Ambrosio, R.; Soriano, M.; Lucas, J.; Cabarrocas, P. Roca i

2012-01-01

A study on the formation of Black Silicon on crystalline silicon surface using SF 6 /O 2 and SF 6 /O 2 /CH 4 based plasmas in a reactive ion etching (RIE) system is presented. The effect of the RF power, chamber pressure, process time, gas flow rates, and gas mixtures on the texture of silicon surface has been analyzed. Completely Black Silicon surfaces containing pyramid like structures have been obtained, using an optimized mask-free plasma process. Moreover, the Black Silicon surfaces have demonstrated average values of 1% and 4% for specular and diffuse reflectance respectively, feature that is suitable for the fabrication of low cost solar cells.

Etch Defect Characterization and Reduction in Hard-Mask-Based Al Interconnect Etching

International Nuclear Information System (INIS)

Lee, H.J.; Hung, C.L.; Leng, C.H.; Lian, N.T.; Young, L.W.

2009-01-01

This paper identifies the defect adders, for example, post hard-mask etch residue, post metal etch residue, and blocked etch metal island and investigates the removal characteristics of these defects within the oxide-masked Al etching process sequence. Post hard-mask etch residue containing C atom is related to the hardening of photoresist after the conventional post-RIE ashing at 275 degree C. An in situ O 2 -based plasma ashing on RIE etcher was developed to prevent the photoresist hardening from the high-ashing temperature; followed wet stripping could successfully eliminate such hardened polymeric residue. Post metal etch residue was caused from the attack of the Al sidewall by Cl atoms, and too much CHF 3 addition in the Al main etch step passivated the surface of Al resulting in poor capability to remove the Al-containing residue. The lower addition of CHF 3 in the Al main etch step would benefit from the residue removal. One possibility of blocked etch metal island creating was due to the micro masking formed on the opening of Ti N during the hard-mask patterning. We report that an additional Ti N surface pretreatment with the Ar/CHF 3 /N 2 plasmas could reduce the impact of the micro masking residues on blocked metal etch.

High-density plasma etching of III-nitrides: Process development, device applications and damage remediation

Science.gov (United States)

Singh, Rajwinder

Plasma-assisted etching is a key technology for III-nitride device fabrication. The inevitable etch damage resulting from energetic pattern transfer is a challenge that needs to be addressed in order to optimize device performance and reliability. This dissertation focuses on the development of a high-density inductively-coupled plasma (ICP) etch process for III-nitrides, the demonstration of its applicability to practical device fabrication using a custom built ICP reactor, and development of techniques for remediation of etch damage. A chlorine-based standard dry etch process has been developed and utilized in fabrication of a number of electronic and optoelectronic III-nitride devices. Annealing studies carried out at 700°C have yielded the important insight that the annealing time necessary for making good-quality metal contacts to etch processed n-GaN is very short (water, prior to metallization, removes some of the etch damage and is helpful in recovering contact quality. In-situ treatment consisting of a slow ramp-down of rf bias at the end of the etch is found to achieve the same effect as the ex-situ treatment. This insitu technique is significantly advantageous in a large-scale production environment because it eliminates a process step, particularly one involving treatment in hydrochloric acid. ICP equipment customization for scaling up the process to full 2-inch wafer size is described. Results on etching of state of the art 256 x 256 AlGaN focal plane arrays of ultraviolet photodetectors are reported, with excellent etch uniformity over the wafer area.

Modeling the characteristic etch morphologies along specific crystallographic orientations by anisotropic chemical etching

Directory of Open Access Journals (Sweden)

Kun-Dar Li

2018-02-01

Full Text Available To improve the advanced manufacturing technology for functional materials, a sophisticated control of chemical etching process is highly demanded, especially in the fields of environment and energy related applications. In this study, a phase-field-based model is utilized to investigate the etch morphologies influenced by the crystallographic characters during anisotropic chemical etching. Three types of etching modes are inspected theoretically, including the isotropic, and preferred oriented etchings. Owing to the specific etching behavior along the crystallographic directions, different characteristic surface structures are presented in the simulations, such as the pimple-like, pyramidal hillock and ridge-like morphologies. In addition, the processing parameters affecting the surface morphological formation and evolution are also examined systematically. According to the numerical results, the growth mechanism of surface morphology in a chemical etching is revealed distinctly. While the etching dynamics plays a dominant role on the surface formation, the characteristic surface morphologies corresponding to the preferred etching direction become more apparent. As the atomic diffusion turned into a determinative factor, a smoothened surface would appear, even under the anisotropic etching conditions. These simulation results provide fundamental information to enhance the development and application of anisotropic chemical etching techniques.

Modeling the characteristic etch morphologies along specific crystallographic orientations by anisotropic chemical etching

Science.gov (United States)

Li, Kun-Dar; Miao, Jin-Ru

2018-02-01

To improve the advanced manufacturing technology for functional materials, a sophisticated control of chemical etching process is highly demanded, especially in the fields of environment and energy related applications. In this study, a phase-field-based model is utilized to investigate the etch morphologies influenced by the crystallographic characters during anisotropic chemical etching. Three types of etching modes are inspected theoretically, including the isotropic, and preferred oriented etchings. Owing to the specific etching behavior along the crystallographic directions, different characteristic surface structures are presented in the simulations, such as the pimple-like, pyramidal hillock and ridge-like morphologies. In addition, the processing parameters affecting the surface morphological formation and evolution are also examined systematically. According to the numerical results, the growth mechanism of surface morphology in a chemical etching is revealed distinctly. While the etching dynamics plays a dominant role on the surface formation, the characteristic surface morphologies corresponding to the preferred etching direction become more apparent. As the atomic diffusion turned into a determinative factor, a smoothened surface would appear, even under the anisotropic etching conditions. These simulation results provide fundamental information to enhance the development and application of anisotropic chemical etching techniques.

Damage-Free Smooth-Sidewall InGaAs Nanopillar Array by Metal-Assisted Chemical Etching.

Science.gov (United States)

Kong, Lingyu; Song, Yi; Kim, Jeong Dong; Yu, Lan; Wasserman, Daniel; Chim, Wai Kin; Chiam, Sing Yang; Li, Xiuling

2017-10-24

Producing densely packed high aspect ratio In 0.53 Ga 0.47 As nanostructures without surface damage is critical for beyond Si-CMOS nanoelectronic and optoelectronic devices. However, conventional dry etching methods are known to produce irreversible damage to III-V compound semiconductors because of the inherent high-energy ion-driven process. In this work, we demonstrate the realization of ordered, uniform, array-based In 0.53 Ga 0.47 As pillars with diameters as small as 200 nm using the damage-free metal-assisted chemical etching (MacEtch) technology combined with the post-MacEtch digital etching smoothing. The etching mechanism of In x Ga 1-x As is explored through the characterization of pillar morphology and porosity as a function of etching condition and indium composition. The etching behavior of In 0.53 Ga 0.47 As, in contrast to higher bandgap semiconductors (e.g., Si or GaAs), can be interpreted by a Schottky barrier height model that dictates the etching mechanism constantly in the mass transport limited regime because of the low barrier height. A broader impact of this work relates to the complete elimination of surface roughness or porosity related defects, which can be prevalent byproducts of MacEtch, by post-MacEtch digital etching. Side-by-side comparison of the midgap interface state density and flat-band capacitance hysteresis of both the unprocessed planar and MacEtched pillar In 0.53 Ga 0.47 As metal-oxide-semiconductor capacitors further confirms that the surface of the resultant pillars is as smooth and defect-free as before etching. MacEtch combined with digital etching offers a simple, room-temperature, and low-cost method for the formation of high-quality In 0.53 Ga 0.47 As nanostructures that will potentially enable large-volume production of In 0.53 Ga 0.47 As-based devices including three-dimensional transistors and high-efficiency infrared photodetectors.

Bragg diffraction of fermions at optical potentials

International Nuclear Information System (INIS)

Deh, Benjamin

2008-01-01

This thesis describes the Bragg diffraction of ultracold fermions at an optical potential. A moving optical lattice was created, by overlaying two slightly detuned lasers. Atoms can be diffracted at this lattice if the detuning fulfills the Bragg condition for resting atoms. This Bragg diffraction is analyzed systematically in this thesis. To this end Rabi oscillations between the diffraction states were driven, as well in the weakly interacting Bragg regime, as in the strongly interacting Kapitza-Dirac regime. Simulations, based on a driven two-, respectively multilevel-system describe the observed effects rather well. Furthermore, the temporal evolution of the diffracted states in the magnetic trapping potential was studied. The anharmonicity of the trap in use and the scattering cross section for p-wave collisions in a 6 Li system was determined from the movement of these states. Moreover the momentum distribution of the fermions was measured with Bragg spectroscopy and first signs of Fermi degeneracy were found. Finally an interferometer with fermions was build, exhibiting a coherence time of more than 100 μs. With this, the possibility for measurement and manipulation of ultracold fermions with Bragg diffraction could bee shown. (orig.)

Ultrafast Optical Signal Processing with Bragg Structures

Directory of Open Access Journals (Sweden)

Yikun Liu

2017-05-01

Full Text Available The phase, amplitude, speed, and polarization, in addition to many other properties of light, can be modulated by photonic Bragg structures. In conjunction with nonlinearity and quantum effects, a variety of ensuing micro- or nano-photonic applications can be realized. This paper reviews various optical phenomena in several exemplary 1D Bragg gratings. Important examples are resonantly absorbing photonic structures, chirped Bragg grating, and cholesteric liquid crystals; their unique operation capabilities and key issues are considered in detail. These Bragg structures are expected to be used in wide-spread applications involving light field modulations, especially in the rapidly advancing field of ultrafast optical signal processing.

A neural network for the Bragg synthetic curves recognition.; Una red neuronal para el reconocimiento de curvas de Bragg sinteticas

Energy Technology Data Exchange (ETDEWEB)

Reynoso V, M R; Vega C, J J; Fernandez A, J; Belmont M, E; Policroniades R, R; Moreno B, E [Instituto Nacional de Investigaciones Nucleares, Salazar, Edo. de Mexico. (Mexico)

1997-12-31

A ionization chamber was employed named Bragg curve spectroscopy. The Bragg peak amplitude is a monotone growing function of Z, which permits to identify elements through their measurement. A better technique for this measurement is to improve the use of neural networks with the purpose of the identification of the Bragg curve. (Author).

Polymer optical fiber bragg grating sensors

DEFF Research Database (Denmark)

Stefani, Alessio; Yuan, Scott Wu; Andresen, Søren

2010-01-01

Fiber-optical accelerometers based on polymer optical fiber Bragg gratings are reported. We have written fiber Bragg gratings for 1550 nm and 850 nm operations, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

Silicon germanium as a novel mask for silicon deep reactive ion etching

KAUST Repository

Serry, Mohamed Y.

2013-10-01

This paper reports on the use of p-type polycrystalline silicon germanium (poly-Si1-xGex) thin films as a new masking material for the cryogenic deep reactive ion etching (DRIE) of silicon. We investigated the etching behavior of various poly-Si1-xGex:B (0Etching selectivity for silicon, silicon oxide, and photoresist was determined at different etching temperatures, ICP and RF powers, and SF6 to O2 ratios. The study demonstrates that the etching selectivity of the SiGe mask for silicon depends strongly on three factors: Ge content; boron concentration; and etching temperature. Compared to conventional SiO2 and SiN masks, the proposed SiGe masking material exhibited several advantages, including high etching selectivity to silicon (>1:800). Furthermore, the SiGe mask was etched in SF6/O2 plasma at temperatures ≥ - 80°C and at rates exceeding 8 μm/min (i.e., more than 37 times faster than SiO2 or SiN masks). Because of the chemical and thermodynamic stability of the SiGe film as well as the electronic properties of the mask, it was possible to deposit the proposed film at CMOS backend compatible temperatures. The paper also confirms that the mask can easily be dry-removed after the process with high etching-rate by controlling the ICP and RF power and the SF6 to O2 ratios, and without affecting the underlying silicon substrate. Using low ICP and RF power, elevated temperatures (i.e., > - 80°C), and an adjusted O2:SF6 ratio (i.e., ~6%), we were able to etch away the SiGe mask without adversely affecting the final profile. Ultimately, we were able to develop deep silicon- trenches with high aspect ratio etching straight profiles. © 1992-2012 IEEE.

Influence of Pre-etching Times on Fatigue Strength of Self-etch Adhesives to Enamel.

Science.gov (United States)

Takamizawa, Toshiki; Barkmeier, Wayne W; Tsujimoto, Akimasa; Endo, Hajime; Tsuchiya, Kenji; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

To use shear bond strength (SBS) and shear fatigue strength (SFS) testing to determine the influence of phosphoric acid pre-etching times prior to application of self-etch adhesives on enamel bonding. Two single-step self-etch universal adhesives (Prime&Bond Elect and Scotchbond Universal), a conventional single-step self-etch adhesive (G-ӕnial Bond), and a conventional two-step self-etch adhesive (OptiBond XTR) were used. The SBS and SFS were obtained with phosphoric acid pre-etching for 3, 10, or 15 s prior to application of the adhesives, and without pre-etching (0 s) as a control. A staircase method was used to determine the SFS with 10 Hz frequency for 50,000 cycles or until failure occurred. The mean demineralization depth for each treated enamel surface was also measured using a profilometer. For all the adhesives, the groups with pre-etching showed significantly higher SBS and SFS than groups without pre-etching. However, there was no significant difference in SBS and SFS among groups with > 3 s of preetching. In addition, although the groups with pre-etching showed significantly deeper demineralization depths than groups without pre-etching, there was no significant difference in depth among groups with > 3 s of pre-etching. Three seconds of phosphoric acid pre-etching prior to application of self-etch adhesive can enhance enamel bonding effectiveness.

Self-etching adhesive on intact enamel, with and without pre-etching.

Science.gov (United States)

Devarasa, G M; Subba Reddy, V V; Chaitra, N L; Swarna, Y M

2012-05-01

Bond strengths of composite resin to enamel using self-etch adhesive (SEA) Clearfil SE bond system on intact enamel and enamel pre-etched with phosphoric acid were compared. The objective was to determine if the pre-etching would increase the bond strengths of the SEA systems to intact enamel and to evaluate the effect of pre-etching on bond formation of self-etch adhesives on intact enamel. Labial surfaces of 40 caries free permanent upper central and lateral incisors were cleaned, sectioned of their roots. All specimens were mounted on acrylic block and divided randomly into four groups. In two groups the application of self-etch adhesive, Clearfil SE bond was carried as per manufacturer's instructions, composite cylinders were built, whereas in the other two groups, 37% phosphoric acid etching was done before the application of self-etching adhesives. Then the resin tags were analyzed using scanning electron microscope and shear bond strength was measured using Instron universal testing machine. When phosphoric acid was used, there was significant increase in the depth of penetration of resin tags and in the Shear Bond Strength of composite to enamel. The results indicate that out of both treatment groups, pre-etching the intact enamel with 37% phosphoric acid resulted in formation of longer resin tags and higher depth of penetration of resin tags of the Clearfil SE bond, and attaining higher bond strength of the Clearfil SE bond to intact enamel. Copyright © 2011 Wiley Periodicals, Inc.

Fundamental losses in planar Bragg waveguides

NARCIS (Netherlands)

Vinogradov, A. V.; Mitrofanov, A. N.; Popov, A. V.; Fedin, M. A.

2007-01-01

This paper considers a planar Bragg waveguide. The guided modes and their dissipation due to the fundamental absorption are described. In the interacting-wave approximation, an analytical relation between the characteristics of the modes and parameters of the Bragg-waveguide geometry was

Study of Thermal Electrical Modified Etching for Glass and Its Application in Structure Etching

Directory of Open Access Journals (Sweden)

Zhan Zhan

2017-02-01

Full Text Available In this work, an accelerating etching method for glass named thermal electrical modified etching (TEM etching is investigated. Based on the identification of the effect in anodic bonding, a novel method for glass structure micromachining is proposed using TEM etching. To validate the method, TEM-etched glasses are prepared and their morphology is tested, revealing the feasibility of the new method for micro/nano structure micromachining. Furthermore, two kinds of edge effect in the TEM and etching processes are analyzed. Additionally, a parameter study of TEM etching involving transferred charge, applied pressure, and etching roughness is conducted to evaluate this method. The study shows that TEM etching is a promising manufacture method for glass with low process temperature, three-dimensional self-control ability, and low equipment requirement.

Fibre Bragg grating for flood embankment monitoring

Science.gov (United States)

Markowski, Konrad; Nevar, Stanislau; Dworzanski, Adam; Hackiewicz, Krzysztof; Jedrzejewski, Kazimierz

2014-11-01

In this article we present the preliminary studies for the flood embankment monitoring system based on the fibre Bragg gratings. The idea of the system is presented. The Bragg resonance shift is transformed to the change of the power detected by the standard InGaAs photodiode. The discrimination of the received power was executed by another fibre Bragg grating with different parameters. The project of the fully functional system is presented as well.

Low-loss slot waveguides with silicon (111 surfaces realized using anisotropic wet etching

Directory of Open Access Journals (Sweden)

Kapil Debnath

2016-11-01

Full Text Available We demonstrate low-loss slot waveguides on silicon-on-insulator (SOI platform. Waveguides oriented along the (11-2 direction on the Si (110 plane were first fabricated by a standard e-beam lithography and dry etching process. A TMAH based anisotropic wet etching technique was then used to remove any residual side wall roughness. Using this fabrication technique propagation loss as low as 3.7dB/cm was realized in silicon slot waveguide for wavelengths near 1550nm. We also realized low propagation loss of 1dB/cm for silicon strip waveguides.

Self-aligned mask renewal for anisotropically etched circular micro- and nanostructures

International Nuclear Information System (INIS)

Kaspar, Peter; Jäckel, Heinz; Holzapfel, Sebastian; Windhab, Erich J

2011-01-01

The top–down fabrication of high aspect ratio circular micro- and nanostructures in silicon nitride is presented. A new method is introduced to increase the aspect ratio of anisotropically etched holes by a factor of more than two with respect to the results obtained from an established dry-etching process. The method is based on the renewal of an etching mask after a first etching step has been completed. Mask renewal is done by line-of-sight deposition of a masking layer on the surface of the sample, which is mounted at an angle with respect to the deposition direction. No additional alignment step is required. The proof of principle is performed for silicon nitride etching through a mask of titanium, but the method has great potential to be applicable to a wide variety of substrate–mask combinations and to find entrance into various engineering fields. Two specific applications are highlighted. Firstly, a thick silicon nitride hardmask is used for the fabrication of deeply etched photonic crystal holes in indium phosphide (InP). For holes of 280 nm diameter, a record aspect ratio of 20 and an overall selectivity of 28.5 between a positive-tone resist layer and InP are reported. Secondly, the use of perforated silicon nitride membranes for droplet formation for applications in food engineering or pharmaceutics is addressed. Preliminary results show a potential for the self-aligned mask renewal method to exceed state-of-the-art membrane quality in terms of pore size, aspect ratio and membrane stability.

Silicon etch process

International Nuclear Information System (INIS)

Day, D.J.; White, J.C.

1984-01-01

A silicon etch process wherein an area of silicon crystal surface is passivated by radiation damage and non-planar structure produced by subsequent anisotropic etching. The surface may be passivated by exposure to an energetic particle flux - for example an ion beam from an arsenic, boron, phosphorus, silicon or hydrogen source, or an electron beam. Radiation damage may be used for pattern definition and/or as an etch stop. Ethylenediamine pyrocatechol or aqueous potassium hydroxide anisotropic etchants may be used. The radiation damage may be removed after etching by thermal annealing. (author)

A nontransferring dry adhesive with hierarchical polymer nanohairs.

Science.gov (United States)

Jeong, Hoon Eui; Lee, Jin-Kwan; Kim, Hong Nam; Moon, Sang Heup; Suh, Kahp Y

2009-04-07

We present a simple yet robust method for fabricating angled, hierarchically patterned high-aspect-ratio polymer nanohairs to generate directionally sensitive dry adhesives. The slanted polymeric nanostructures were molded from an etched polySi substrate containing slanted nanoholes. An angled etching technique was developed to fabricate slanted nanoholes with flat tips by inserting an etch-stop layer of silicon dioxide. This unique etching method was equipped with a Faraday cage system to control the ion-incident angles in the conventional plasma etching system. The polymeric nanohairs were fabricated with tailored leaning angles, sizes, tip shapes, and hierarchical structures. As a result of controlled leaning angle and bulged flat top of the nanohairs, the replicated, slanted nanohairs showed excellent directional adhesion, exhibiting strong shear attachment (approximately 26 N/cm(2) in maximum) in the angled direction and easy detachment (approximately 2.2 N/cm(2)) in the opposite direction, with a hysteresis value of approximately 10. In addition to single scale nanohairs, monolithic, micro-nanoscale combined hierarchical hairs were also fabricated by using a 2-step UV-assisted molding technique. These hierarchical nanoscale patterns maintained their adhesive force even on a rough surface (roughness <20 microm) because of an increase in the contact area by the enhanced height of hierarchy, whereas simple nanohairs lost their adhesion strength. To demonstrate the potential applications of the adhesive patch, the dry adhesive was used to transport a large-area glass (47.5 x 37.5 cm(2), second-generation TFT-LCD glass), which could replace the current electrostatic transport/holding system with further optimization.

A nontransferring dry adhesive with hierarchical polymer nanohairs

KAUST Repository

Jeong, H. E.

2009-03-20

We present a simple yet robust method for fabricating angled, hierarchically patterned high-aspect-ratio polymer nanohairs to generate directionally sensitive dry adhesives. The slanted polymeric nanostructures were molded from an etched polySi substrate containing slanted nanoholes. An angled etching technique was developed to fabricate slanted nanoholes with flat tips by inserting an etch-stop layer of silicon dioxide. This unique etching method was equipped with a Faraday cage system to control the ion-incident angles in the conventional plasma etching system. The polymeric nanohairs were fabricated with tailored leaning angles, sizes, tip shapes, and hierarchical structures. As a result of controlled leaning angle and bulged flat top of the nanohairs, the replicated, slanted nanohairs showed excellent directional adhesion, exhibiting strong shear attachment (approximately 26 N/cm(2) in maximum) in the angled direction and easy detachment (approximately 2.2 N/cm(2)) in the opposite direction, with a hysteresis value of approximately 10. In addition to single scale nanohairs, monolithic, micro-nanoscale combined hierarchical hairs were also fabricated by using a 2-step UV-assisted molding technique. These hierarchical nanoscale patterns maintained their adhesive force even on a rough surface (roughness <20 microm) because of an increase in the contact area by the enhanced height of hierarchy, whereas simple nanohairs lost their adhesion strength. To demonstrate the potential applications of the adhesive patch, the dry adhesive was used to transport a large-area glass (47.5 x 37.5 cm(2), second-generation TFT-LCD glass), which could replace the current electrostatic transport/holding system with further optimization.

Preparation and analysis of amorphous carbon films deposited from (C{sub 6}H{sub 12})/Ar/He chemistry for application as the dry etch hard mask in the semiconductor manufacturing process

Energy Technology Data Exchange (ETDEWEB)

Lee, Seungmoo [Department of Materials Science and Engineering, Korea University, Seoul, 136-701 (Korea, Republic of); TC Technology Team, Samsung Electronics Co. Ltd., Gyeounggi-Do, 446-711 (Korea, Republic of); Won, Jaihyung; Choi, Jongsik [TC Technology Team, Samsung Electronics Co. Ltd., Gyeounggi-Do, 446-711 (Korea, Republic of); Jang, Samseok [Department of Materials Science and Engineering, Korea University, Seoul, 136-701 (Korea, Republic of); Jee, Yeonhong; Lee, Hyeondeok [TC Technology Team, Samsung Electronics Co. Ltd., Gyeounggi-Do, 446-711 (Korea, Republic of); Byun, Dongjin, E-mail: dbyun@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul, 136-701 (Korea, Republic of)

2011-08-01

Amorphous carbon layers (ACL) were deposited on Si (100) wafers by plasma enhanced chemical vapor deposition (PECVD) by using 1-hexene (C{sub 6}H{sub 12}) as a carbon source for dry etch hard mask of semiconductor devices manufacturing process. The deposition characteristics and film properties were investigated by means of ellipsometry, Raman spectroscopy, X-ray photo electron spectroscopy (XPS) and stress analysis. Hardness, Young's modulus, and surface roughness of ACL deposited at 550 deg. C were investigated by using nano-indentation and AFM. The deposition rate was decreased from 5050 A/min to 2160 A/min, and dry etch rate was decreased from 2090 A/min to 1770 A/min, and extinction coefficient was increased from 0.1 to 0.5. Raman analysis revealed a higher shift of the G-peak and a lower shift of the D-peak and the increase of I(D)/I(G) ratio as the deposition temperature was increased from 350 deg. C to 550 deg. C. XPS results of ACL deposited at 550 deg. C revealed a carbon 1s binding energy of 284.4 eV. The compressive film stress was decreased from 2.95 GPa to 1.28 GPa with increasing deposition temperature. The hardness and Young's modulus of ACL deposited at 550 deg. C were 5.8 GPa and 48.7 GPa respectively. The surface roughness RMS of ACL deposited at 550 deg. C was 2.24 A, and that after cleaning in diluted HF solution (H{sub 2}O:HF = 200:1), SC1 (NH{sub 4}OH:H{sub 2}O{sub 2}:H{sub 2}O = 1:4:20) solution, and sulfuric acid solution (H{sub 2}SO{sub 4}:H{sub 2}O{sub 2} = 6:1) was 2.28 A, 2.30 A and 7.34 A, respectively. The removal amount of ACL deposited at 550 deg. C in diluted HF solution, SC1 solution and sulfuric acid solution was 6 A, 36 A and 110 A, respectively. These results demonstrated the viability of ACL deposited by PECVD from C{sub 6}H{sub 12} at 550 deg. C for application as the dry etch hard mask in fabrication of semiconductor devices.

Influence of different pre-etching times on fatigue strength of self-etch adhesives to dentin.

Science.gov (United States)

Takamizawa, Toshiki; Barkmeier, Wayne W; Tsujimoto, Akimasa; Suzuki, Takayuki; Scheidel, Donal D; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

2016-04-01

The purpose of this study was to use shear bond strength (SBS) and shear fatigue strength (SFS) testing to determine the influence on dentin bonding of phosphoric acid pre-etching times before the application of self-etch adhesives. Two single-step self-etch universal adhesives [Prime & Bond Elect (EL) and Scotchbond Universal (SU)], a conventional single-step self-etch adhesive [G-aenial Bond (GB)], and a two-step self-etch adhesive [OptiBond XTR (OX)] were used. The SBS and SFS values were obtained with phosphoric acid pre-etching times of 3, 10, or 15 s before application of the adhesives, and for a control without pre-etching. For groups with 3 s of pre-etching, SU and EL showed higher SBS values than control groups. No significant difference was observed for GB among the 3 s, 10 s, and control groups, but the 15 s pre-etching group showed significantly lower SBS and SFS values than the control group. No significant difference was found for OX among the pre-etching groups. Reducing phosphoric acid pre-etching time can minimize the adverse effect on dentin bonding durability for the conventional self-etch adhesives. Furthermore, a short phosphoric acid pre-etching time enhances the dentin bonding performance of universal adhesives. © 2016 Eur J Oral Sci.

Bragg-Fresnel optics: New field of applications

Energy Technology Data Exchange (ETDEWEB)

Snigirev, A. [ESRF, Grenoble (France)

1997-02-01

Bragg-Fresnel Optics shows excellent compatibility with the third generation synchrotron radiation sources such as ESRF and is capable of obtaining monochromatic submicron focal spots with 10{sup 8}-10{sup 9} photons/sec in an energy bandwidth of 10{sup -4}-10{sup -6} and in a photon energy range between 2-100 keV. New types of Bragg-Fresnel lenses like modified, ion implanted, bent and acoustically modulated were tested. Microprobe techniques like microdiffraction and microfluorescence based on Bragg-Fresnel optics were realised at the ESRF beamlines. Excellent parameters of the X-ray beam at the ESRF in terms of low emittance and quite small angular source size allow for Bragg-Fresnel optics to occupy new fields of applications such as high resolution diffraction, holography, interferometry and phase contrast imaging.

Nanostructuring of Mo/Si multilayers by means of reactive ion etching using a three-level mask

International Nuclear Information System (INIS)

Dreeskornfeld, L.; Haindl, G.; Kleineberg, U.; Heinzmann, U.; Shi, F.; Volland, B.; Rangelow, I.W.; Majkova, E.; Luby, S.; Kostic,; Matay, L.; Hrkut, P.; Hudek, P.; Lee, H.-Y.

2004-01-01

Recently, Mo/Si multilayer reflectors have been gaining industry interest as a promising choice for the next generation extreme ultraviolet mask material for printing sub 70 nm feature size devices. A reactive ion etching system with optimized hardware using CHF 3 /Ar process regime shows the capability for highly anisotropic etching of sub congruent with 400 nm feature sizes in Mo/Si test multilayers with ten periods and a bilayer thickness of 7.8 nm which were prepared by e-beam evaporation. A three-level-mask technique consisting of a top resist mask layer poly-methyl-meth-acrylate, a middle hard amorphous Si mask layer and a bottom-level polyimide layer is used to create the etch mask. The etch characteristics of the polyimide film is shown to be one of the major factors determining the success of the described multilayer etching process. The developed etching technology demonstrates superior process performance without facets, excellent uniformity and good profile control. No contamination, degeneration or defect generation in the unetched multilayer structure could be detected. This non-conventional process results in minimum deposition during the etching thus eliminating the need for a dry or wet cleaning. Sidewall angles in Mo/Si multilayers of 85 deg. , without undercut, bowing and ripples resulting in smooth sidewalls are achieved

Optical Effects Accompanying the Dynamical Bragg Diffraction in Linear 1D Photonic Crystals Based on Porous Silicon

Directory of Open Access Journals (Sweden)

Anton Maydykovskiy

2014-10-01

Full Text Available We survey our recent results on the observation and studies of the effects accompanying the dynamical Bragg diffraction in one-dimensional photonic crystals (PhC. Contrary to the kinematic Bragg diffraction, the dynamical one considers a continuous interaction between the waves travelling within a spatially-periodic structure and is the most pronounced in the so called Laue geometry, leading to a number of exciting phenomena. In the described experiments, we study the PhC based on porous silicon or porous quartz, made by the electrochemical etching of crystalline silicon with the consequent thermal annealing. Importantly, these PhC are approximately hundreds of microns thick and contain a few hundreds of periods, so that the experiments in the Laue diffraction scheme are available. We discuss the effect of the temporal splitting of femtosecond laser pulses and show that the effect is quite sensitive to the polarization and the phase of a femtosecond laser pulse. We also show the experimental realization of the Pendular effect in porous quartz PhC and demonstrate the experimental conditions for the total spatial switching of the output radiation between the transmitted and diffracted directions. All described effects are of high interest for the control over the light propagation based on PhC structures.

Quadrilateral Micro-Hole Array Machining on Invar Thin Film: Wet Etching and Electrochemical Fusion Machining

Directory of Open Access Journals (Sweden)

Woong-Kirl Choi

2018-01-01

Full Text Available Ultra-precision products which contain a micro-hole array have recently shown remarkable demand growth in many fields, especially in the semiconductor and display industries. Photoresist etching and electrochemical machining are widely known as precision methods for machining micro-holes with no residual stress and lower surface roughness on the fabricated products. The Invar shadow masks used for organic light-emitting diodes (OLEDs contain numerous micro-holes and are currently machined by a photoresist etching method. However, this method has several problems, such as uncontrollable hole machining accuracy, non-etched areas, and overcutting. To solve these problems, a machining method that combines photoresist etching and electrochemical machining can be applied. In this study, negative photoresist with a quadrilateral hole array pattern was dry coated onto 30-µm-thick Invar thin film, and then exposure and development were carried out. After that, photoresist single-side wet etching and a fusion method of wet etching-electrochemical machining were used to machine micro-holes on the Invar. The hole machining geometry, surface quality, and overcutting characteristics of the methods were studied. Wet etching and electrochemical fusion machining can improve the accuracy and surface quality. The overcutting phenomenon can also be controlled by the fusion machining. Experimental results show that the proposed method is promising for the fabrication of Invar film shadow masks.

Bragg reflection program

International Nuclear Information System (INIS)

Lynn, J.W.

This user's guide to the Bragg Reflection Program (BRP) is in the nature of an informal report. The general purpose of BRP is to scan a series of Bragg reflections automatically in order to obtain profiles and integrated intensities. The program is used in conjunction with the SUPERVISOR and READ packages, and the procedures for using it are similar to those for the Triple-Axis Control program. All the general features of the system, SUPERVISOR and READ packages as described in the Spectrometer Control Systems User's Guide are preserved. The presentation assumes that the reader is familiar with these. Sections are given on the READ package, execution and use, error messages, and output. A few sample problems are shown. (1 figure) (U.S.)

Evaluation of different polymers for fast neutron personnel dosimetry using electrochemical etching

International Nuclear Information System (INIS)

Gammage, R.B.; Cotter, S.J.

1977-01-01

There is considerable optimism for the enhancement by electrochemical etching of fast neutron-induced recoil tracks in polycarbonate for the purpose of personnel dosimetry. The threshold energy, however, is rather high. A desirable improvement would be to lower this energy below 1 MeV. With this objective in mind, we have commenced an investigation of cellulose acetate, triacetate, and acetobutyrate in addition to polycarbonate. These cellulose derivatives are chemically more reactive and physically weaker than polycarbonate. It might, therefore, be possible to initiate the electrochemical amplification at the sites of shorter recoil atom damage tracks than is possible with polycarbonate. Some characteristics important for electrochemically etching in aqueous electrolytes are listed. Chemical etching is combined with treeing, an electrical breakdown process that starts when the dielectric strength is exceeded. These mechanical and electrical properties pertain to the dry plastics. The absorption of water molecules and electrolyte ions will cause these values to be reduced. Results and conclusions of the study are presented

Cascaded Bragg scattering in fiber optics.

Science.gov (United States)

Xu, Y Q; Erkintalo, M; Genty, G; Murdoch, S G

2013-01-15

We report on a theoretical and experimental study of cascaded Bragg scattering in fiber optics. We show that the usual energy-momentum conservation of Bragg scattering can be considerably relaxed via cascade-induced phase-matching. Experimentally we demonstrate frequency translation over six- and 11-fold cascades, in excellent agreement with derived phase-matching conditions.

Etching of fused silica fiber by metallic laser-induced backside wet etching technique

Energy Technology Data Exchange (ETDEWEB)

Vass, Cs., E-mail: vasscsaba@physx.u-szeged.hu [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Kiss, B.; Kopniczky, J.; Hopp, B. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary)

2013-08-01

The tip of multimode fused silica fiber (core diameter: 550 μm) was etched by metallic laser-induced backside wet etching (M-LIBWE) method. Frequency doubled, Q-switched Nd:YAG laser (λ = 532 nm; τ{sub FWHM} = 8 ns) was used as laser source. The laser beam was coupled into the fiber by a fused silica lens with a focal length of 1500 mm. The other tip of the fiber was dipped into liquid gallium metallic absorber. The etching threshold fluence was measured to be 475 mJ/cm{sup 2}, while the highest fluence, which resulted etching without breaking the fiber, was 1060 mJ/cm{sup 2}. The progress of etching was followed by optical microscopy, and the etch rate was measured to be between 20 and 37 nm/pulse depending on the applied laser energy. The surface morphologies of the etched tips were studied by scanning electron microscopy. A possible application of the structured fibers was also tested.

Etching of fused silica fiber by metallic laser-induced backside wet etching technique

International Nuclear Information System (INIS)

Vass, Cs.; Kiss, B.; Kopniczky, J.; Hopp, B.

2013-01-01

The tip of multimode fused silica fiber (core diameter: 550 μm) was etched by metallic laser-induced backside wet etching (M-LIBWE) method. Frequency doubled, Q-switched Nd:YAG laser (λ = 532 nm; τ FWHM = 8 ns) was used as laser source. The laser beam was coupled into the fiber by a fused silica lens with a focal length of 1500 mm. The other tip of the fiber was dipped into liquid gallium metallic absorber. The etching threshold fluence was measured to be 475 mJ/cm 2 , while the highest fluence, which resulted etching without breaking the fiber, was 1060 mJ/cm 2 . The progress of etching was followed by optical microscopy, and the etch rate was measured to be between 20 and 37 nm/pulse depending on the applied laser energy. The surface morphologies of the etched tips were studied by scanning electron microscopy. A possible application of the structured fibers was also tested.

Plasma etching of patterned tungsten

International Nuclear Information System (INIS)

Franssila, S.

1993-01-01

Plasma etching of tungsten is discussed from the viewpoint of thin film structure and integrated circuit process engineering. The emphasis is on patterned tungsten etching for silicon device and X-ray mask fabrication. After introducing tungsten etch chemistries and mechanisms, microstructural aspects of tungsten films (crystal structure, grain size, film density, defects, impurities) in relation to etching are discussed. Approaches to etch process optimization are presented, and the current state-of-the-art of patterned tungsten etching is reviewed. (orig.)

Optical Fiber Thermometer Based on Fiber Bragg Gratings

Science.gov (United States)

Rosli, Ekbal Bin; Mohd. Noor, Uzer

2018-03-01

Fiber Bragg grating has generated much interest in use as sensors to measure strain, temperature, and other physical parameters. It also the most common component used to develop this sensor with the advantages of simple, intrinsic sensing elements, electrically passive operation, EMI immunity, high sensitivity, compact size and potentially low cost [6]. This paper reports the design of an optical fiber thermometer based on fiber Bragg gratings. The system was developed for detecting temperature and strain by monitoring the shift of Bragg wavelength. The shifting of Bragg wavelength is used to indicate the temperature and strain due to the change in the surrounding temperature and strain. When the temperature and strain reach the exact wavelength level of the system, the temperature and strain value will display on the Arduino liquid crystal display (LCD). The optical fiber will provide the broadband light source and after passing the FBG the Bragg wavelength into the optical spectrum analyzer (OSA). The system is based on FBG as a physical quantity sensor. The temperatures measured is taken from the water bath and that of the strain is provided by amount of slotted mass used. The outcome of this project is to characterize the Bragg wavelength shifting from the fiber Bragg grating output. As the conclusion, this project provides an efficient optical fiber thermometer in measuring temperature and strain in order to replace the use of conventional electrical instruments.

Precise in situ etch depth control of multilayered III−V semiconductor samples with reflectance anisotropy spectroscopy (RAS equipment

Directory of Open Access Journals (Sweden)

Ann-Kathrin Kleinschmidt

2016-11-01

Full Text Available Reflectance anisotropy spectroscopy (RAS equipment is applied to monitor dry-etch processes (here specifically reactive ion etching (RIE of monocrystalline multilayered III–V semiconductors in situ. The related accuracy of etch depth control is better than 16 nm. Comparison with results of secondary ion mass spectrometry (SIMS reveals a deviation of only about 4 nm in optimal cases. To illustrate the applicability of the reported method in every day settings for the first time the highly etch depth sensitive lithographic process to form a film lens on the waveguide ridge of a broad area laser (BAL is presented. This example elucidates the benefits of the method in semiconductor device fabrication and also suggests how to fulfill design requirements for the sample in order to make RAS control possible.

Self-etching ceramic primer versus hydrofluoric acid etching: Etching efficacy and bonding performance.

Science.gov (United States)

El-Damanhoury, Hatem M; Gaintantzopoulou, Maria D

2018-01-01

This study assessed the effect of pretreatment of hybrid and glass ceramics using a self-etching primer on the shear bond strength (SBS) and surface topography, in comparison to pretreatment with hydrofluoric acid and silane. 40 rectangular discs from each ceramic material (IPS e.max CAD;EM, Vita Mark II;VM, Vita Enamic;VE), were equally divided (n=10) and assigned to one of four surface pretreatment methods; etching with 4.8% hydrofluoric acid followed by Monobond plus (HFMP), Monobond etch & prime (Ivoclar Vivadent) (MEP), No treatment (NT) as negative control and Monobond plus (Ivoclar Vivadent) with no etching (MP) as positive control. SBS of resin cement (Multilink-N, Ivoclar Vivadent) to ceramic surfaces was tested following a standard protocol. Surface roughness was evaluated using an Atomic force microscope (AFM). Surface topography and elemental analysis were analyzed using SEM/EDX. Data were analyzed with two-way analysis of variance (ANOVA) and post-hoc Bonferroni test at a significance level of α=0.05. Pretreatment with HFMP resulted in higher SBS and increased surface roughness in comparison to MEP and MP. Regardless the method of surface pretreatment, the mean SBS values of EM ceramic was significantly higher (pceramics for resin-luting cementation. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

A neural network for the Bragg synthetic curves recognition

International Nuclear Information System (INIS)

Reynoso V, M.R.; Vega C, J.J.; Fernandez A, J.; Belmont M, E.; Policroniades R, R.; Moreno B, E.

1996-01-01

A ionization chamber was employed named Bragg curve spectroscopy. The Bragg peak amplitude is a monotone growing function of Z, which permits to identify elements through their measurement. A better technique for this measurement is to improve the use of neural networks with the purpose of the identification of the Bragg curve. (Author)

A study on etching of UO2, Co, and Mo surface with R.F. plasma using CF4 and O2

International Nuclear Information System (INIS)

Kim, Yong Soo; Seo, Yong Dae

2003-01-01

Recently dry decontamination/surface-cleaning technology using plasma etching has been focused in the nuclear industry. In this study, the applicability of this new dry processing technique are experimentally investigated by examining the etching reaction of UO 2 , Co, and Mo in r.f. plasma with the etchant gas of CF 4 /O 2 mixture. UO 2 is chosen as a representing material for uranium and TRU (TRans-Uranic) compounds while metallic Co and Mo are selected because they are the principal contaminants in the used metallic nuclear components such as valves and pipes made of stainless steel or Inconel. Results show that in all cases maximum etching rate is achieved when the mole fraction of O 2 in CF 4 /O 2 mixture gas is 20%, regardless of temperature and r.f. power. In case of UO 2 , the highest etching reaction rate is greater than 1000 monolayers/min. at 370 .deg. C under 150 W r.f. power which is equivalent to 0.4 μm/min. As for Co, etching reaction begins to take place significantly when the temperature exceeds 350 .deg. C. Maximum etching rate achieved at 380 .deg. C is 0.06 μm/min. Mo etching reaction takes place vigorously even at relatively low temperature and the reaction rate increases drastically with increasing temperature. Highest etching rate at 380 .deg. C is 1.9 μm /min. According to OES (Optical Emission Spectroscopy) and AES (Auger Electron Spectroscopy) analysis, primary reaction seems to be a fluorination reaction, but carbonyl compound formation reaction may assist the dominant reaction, especially in case of Co and Mo. Through this basic study, the feasibility and the applicability of plasma decontamination technique are demonstrated

Effect of pre-etching on sealing ability of two current self-etching adhesives

Directory of Open Access Journals (Sweden)

K Khosravi

2005-05-01

Full Text Available Background: We evaluated the effect of phosphoric acid etching on microleakage of two current self-etching adhesives on enamel margins in comparison to a conventional total- etch system. Methods: Sixty buccal class V cavities were made at the cemento-enamel junction with beveled enamel margins of extracted human premolar teeth and randomly divided into five groups (12 specimens in each group. Group 1 was applying with Clearfil SE bond, Group 2 with 35% phosphoric acid etching of enamel margins plus Clearfil SE bond, Group3 with I bond, Group 4 with 35% phosphoric acid etching of enamel margins plus I bond and Group5 with Scotchbond multi-purpose. All groups restored with a composite resins. After 24 hours storage with 100% humidity, the samples were thermocycled, immersed in a dye solution and sectioned buccoligually and enamel margins microleakage were evaluated on a scale of 0 to 2. Results: The differences between Groups 1 & 3 and Groups 3 & 4 were significant (P<0.05 but no significant differences between Groups1 & 2 or 1 & 5 were observed. Conclusion: The findings suggest that all-in-one adhesive systems need pre-etching enamel margins with phosphoric acid for effectively seal. Key words: Self-Etching Adhesives, Microleakage, Enamel, Total-Etch system

MEMS Bragg grating force sensor

DEFF Research Database (Denmark)

Reck, Kasper; Thomsen, Erik Vilain; Hansen, Ole

2011-01-01

We present modeling, design, fabrication and characterization of a new type of all-optical frequency modulated MEMS force sensor based on a mechanically amplified double clamped waveguide beam structure with integrated Bragg grating. The sensor is ideally suited for force measurements in harsh...... environments and for remote and distributed sensing and has a measured sensitivity of -14 nm/N, which is several times higher than what is obtained in conventional fiber Bragg grating force sensors. © 2011 Optical Society of America....

Controlled ion track etching

Science.gov (United States)

George, J.; Irkens, M.; Neumann, S.; Scherer, U. W.; Srivastava, A.; Sinha, D.; Fink, D.

2006-03-01

It is a common practice since long to follow the ion track-etching process in thin foils via conductometry, i.e . by measurement of the electrical current which passes through the etched track, once the track breakthrough condition has been achieved. The major disadvantage of this approach, namely the absence of any major detectable signal before breakthrough, can be avoided by examining the track-etching process capacitively. This method allows one to define precisely not only the breakthrough point before it is reached, but also the length of any non-transient track. Combining both capacitive and conductive etching allows one to control the etching process perfectly. Examples and possible applications are given.

InGaN multiple-quantum-well epifilms on GaN-sillicon substrates for microcavities and surface-emitting lasers

International Nuclear Information System (INIS)

Lee, June Key; Cho, Hoon; Kim, Bok Hee; Park, Si Hyun; Gu, Erdan; Watson, Ian; Dawson, Martin

2006-01-01

We report the processing of InGaN/GaN epifilms on GaN-silicon substrates. High-quality InGaN/GaN multi-quantum wells (MQWs) were grown on GaN-silicon substrates, and their membranes were successfully fabricated using a selective wet etching of silicon followed by a dry etching of the AlGaN buffer layer. With atomic force microscope (AFM) measurements and photoluminescence (PL) measurements, we investigated the physical and the optical properties of the InGaN/GaN MQWs membranes. On the InGaN/GaN MQW membranes, dielectric distributed Bragg reflector (DBRs) were successfully deposited, which give, new possibilities for use in GaN microcavity and surface-emitting laser fabrication.

More vertical etch profile using a Faraday cage in plasma etching

Science.gov (United States)

Cho, Byeong-Ok; Hwang, Sung-Wook; Ryu, Jung-Hyun; Moon, Sang Heup

1999-05-01

Scanning electron microscope images of sidewalls obtained by plasma etching of an SiO2 film with and without a Faraday cage have been compared. When the substrate film is etched in the Faraday cage, faceting is effectively suppressed and the etch profile becomes more vertical regardless of the process conditions. This is because the electric potential in the cage is nearly uniform and therefore distortion of the electric field at the convex corner of a microfeature is prevented. The most vertical etch profile is obtained when the cage is used in fluorocarbon plasmas, where faceting is further suppressed due to the decrease in the chemical sputtering yield and the increase in the radical/ion flux on the substrate.

Anisotropic etching of silicon for application in micro machine using plasma of SF6/CH4/O2/Ar and SF6/CF4/O2/Ar

International Nuclear Information System (INIS)

Reyes B, C.; Moshkalyov, S.A.; Swart, J.W.

2004-01-01

We investigated the reactive ion etching of silicon using SF 6 /CH 4 (CF 4 )/O 2 /Ar gas mixtures containing fluorine for MEMS applications. Etch rates and anisotropy of etch profiles were examined as a function of gas composition, material of electrode, and RF power. Etch depths were measured using a profilometers, and etch profiles were analyzed by scanning electron microscope. As a mask material, an aluminium film deposited by evaporation, was used. High anisotropy of etching of 0.95 was achieved at etch depths up to 20-30 micrometers and etch rates of approximately 0.3-0.6 μm/min. Highly anisotropic etching is based on a mechanism that enhance the ion bombarding and protects the sidewalls due to polymerization and/or oxidation mechanisms in order to avoid the lateral etch. However, under the anisotropic etching conditions, considerable damages of the etched surfaces (roughness formation), were observed. After etching experiments, wet / dry cleaning procedures were applied to remove surface residues resulting from the reactive ion etching and to improve the etched surface morphology. (Author)

Device fabrication by plasma etching

International Nuclear Information System (INIS)

Mogab, C.J.

1980-01-01

Plasma etching as applied to many of the materials encountered in the fabrication of LSI's is complicated by loading effect-the dependence of etch rate on the integrated surface area to be etched. This problem is alleviated by appropriate choice of etchant and etching conditions. Appropriate choice of system parameters, generally most concerned with the inherent lifetime of etchant species, may also result in improvement of etch rate uniformity on a wafer-by-wafer basis

ICP etching for InAs-based InAs/GaAsSb superlattice long wavelength infrared detectors

Science.gov (United States)

Huang, Min; Chen, Jianxin; Xu, Jiajia; Wang, Fangfang; Xu, Zhicheng; He, Li

2018-05-01

In this work, we study and report the dry etching processes for InAs-based InAs/GaAsSb strain-free superlattice long wavelength infrared (LWIR) detectors. The proper etching parameters were first obtained through the parametric studies of Inductively Coupled Plasma (ICP) etching of both InAs and GaSb bulk materials in Cl2/N2 plasmas. Then an InAs-based InAs/GaAsSb superlattice LWIR detector with PπN structure was fabricated by using the optimized etching parameters. At 80 K, the detector exhibits a 100% cut-off wavelength of 12 μm and a responsivity of 1.5 A/W. Moreover, the dark current density of the device under a bias of -200 mV reaches 5.5 × 10-4 A/cm2, and the R0A is 15 Ω cm2. Our results pave the way towards InAs-based superlattice LWIR detectors with better performances.

Fabrication of combined-scale nano- and microfluidic polymer systems using a multilevel dry etching, electroplating and molding process

DEFF Research Database (Denmark)

Tanzi, Simone; Østergaard, Peter Friis; Matteucci, Marco

2012-01-01

Microfabricated single-cell capture and DNA stretching devices have been produced by injection molding. The fabrication scheme employed deep reactive ion etching in a silicon substrate, electroplating in nickel and molding in cyclic olefin polymer. This work proposes technical solutions to fabric......Microfabricated single-cell capture and DNA stretching devices have been produced by injection molding. The fabrication scheme employed deep reactive ion etching in a silicon substrate, electroplating in nickel and molding in cyclic olefin polymer. This work proposes technical solutions...

Frequency shift of the Bragg and Non-Bragg backscattering from periodic water wave

Science.gov (United States)

Wen, Biyang; Li, Ke

2016-08-01

Doppler effect is used to measure the relative speed of a moving target with respect to the radar, and is also used to interpret the frequency shift of the backscattering from the ocean wave according to the water-wave phase velocity. The widely known relationship between the Doppler shift and the water-wave phase velocity was deduced from the scattering measurements data collected from actual sea surface, and has not been verified under man-made conditions. Here we show that this ob- served frequency shift of the scattering data from the Bragg and Non-Bragg water wave is not the Doppler shift corresponding to the water-wave phase velocity as commonly believed, but is the water-wave frequency and its integral multiple frequency. The power spectrum of the backscatter from the periodic water wave consists of serials discrete peaks, which is equally spaced by water wave frequency. Only when the water-wave length is the integer multiples of the Bragg wave, and the radar range resolution is infinite, does the frequency shift of the backscattering mathematically equal the Doppler shift according to the water-wave phase velocity.

Ga+ focused-ion-beam implantation-induced masking for H2 etching of ZnO films

International Nuclear Information System (INIS)

Fang, Hsin-Chiao; Huang, Jun-Han; Chu, Wen-Huei; Liu, Chuan-Pu

2010-01-01

Gallium implantation of ZnO by a focused-ion beam is used to create a mask for ZnO dry etching with hydrogen. Effects of Ga + fluence on the etch stop properties and the associated mechanisms are investigated. The fluence of 2.8 x 10 16 cm -2 is determined to be optimum to render the best mask quality. While lower fluences would cause less etching selectivity, higher fluences would cause erosion of the surface and particles to be precipitated on the surface after H 2 treatment at high temperature. In contrast to the commonly adopted gallium oxide formation on Si, transmission electron microscopy analysis reveals that, for the fluences ≤ 2.8 x 10 16 cm -2 , Ga + ions are incorporated as dopants into ZnO without any second phases or precipitates, indicating the Ga-doped ZnO layer behaves as a mask for H 2 etching due to the higher electronegativity of Ga + towards oxygen. However, for the fluences ≥ 4.6 x 10 16 cm -2 , the surface particles are responsible for the etch stop and are identified as ZnGa 2 O 4 . We finally demonstrate a complicated pattern of 'NCKU' on ZnO by using this technique. The study not only helps clarify the related mechanisms, but also suggests a feasible extension of the etch stop process that can be applied to more functional material.

A volatile-solvent gas fiber sensor based on polyaniline film coated on superstructure fiber Bragg gratings

International Nuclear Information System (INIS)

Ai, L; Chen, T C; Su, W K; Mau, J C; Liu, W F

2008-01-01

A fiber sensor based on a polyaniline (PANI) film that is coated on the surface of an etched superstructure fiber grating to detect volatile solvent vapors is experimentally demonstrated. This sensing mechanism is based on the interaction of the testing gas with the polyaniline coating film, which changes the film index, resulting in a shift in the Bragg wavelength. The sensitivity of this sensor to ammonia (NH 3 ) gas is about 0.073 pm ppm −1 , which depends on the optical characteristics of the fiber grating, the diameter of the fiber cladding and the constituents of the sensing film. Methanol concentrations can also be measured using this sensing scheme. The sensitivity of this sensor must be improved to provide a simple, reliable, repeatable and non-destructive method for sensing various chemical gases. (technical design note)

Comparison of Self-Etch Primers with Conventional Acid Etching System on Orthodontic Brackets

Science.gov (United States)

Zope, Amit; Zope-Khalekar, Yogita; Chitko, Shrikant S.; Kerudi, Veerendra V.; Patil, Harshal Ashok; Jaltare, Pratik; Dolas, Siddhesh G

2016-01-01

Introduction The self-etching primer system consists of etchant and primer dispersed in a single unit. The etching and priming are merged as a single step leading to fewer stages in bonding procedure and reduction in the number of steps that also reduces the chance of introduction of error, resulting in saving time for the clinician. It also results in smaller extent of enamel decalcification. Aim To compare the Shear Bond Strength (SBS) of orthodontic bracket bonded with Self-Etch Primers (SEP) and conventional acid etching system and to study the surface appearance of teeth after debonding; etching with conventional acid etch and self-etch priming, using stereomicroscope. Materials and Methods Five Groups (n=20) were created randomly from a total of 100 extracted premolars. In a control Group A, etching of enamel was done with 37% phosphoric acid and bonding of stainless steel brackets with Transbond XT (3M Unitek, Monrovia, California). Enamel conditioning in left over four Groups was done with self-etching primers and adhesives as follows: Group B-Transbond Plus (3M Unitek), Group C Xeno V+ (Dentsply), Group D-G-Bond (GC), Group E-One-Coat (Coltene). The Adhesive Remnant Index (ARI) score was also evaluated. Additionally, the surface roughness using profilometer were observed. Results Mean SBS of Group A was 18.26±7.5MPa, Group B was 10.93±4.02MPa, Group C was 6.88±2.91MPa while of Group D was 7.78±4.13MPa and Group E was 10.39±5.22MPa respectively. In conventional group ARI scores shows that over half of the adhesive was remaining on the surface of tooth (score 1 to 3). In self-etching primer groups ARI scores show that there was no or minor amount of adhesive remaining on the surface of tooth (score 4 and 5). SEP produces a lesser surface roughness on the enamel than conventional etching. However, statistical analysis shows significant correlation (pbracket bonding after enamel conditioning with any of the SEPs tested. The SEPs used in Groups C (Xeno V

Shear bond strength of self-etch adhesives to enamel with additional phosphoric acid etching.

Science.gov (United States)

Lührs, Anne-Katrin; Guhr, Silke; Schilke, Reinhard; Borchers, Lothar; Geurtsen, Werner; Günay, Hüsamettin

2008-01-01

This study evaluated the shear bond strength of self-etch adhesives to enamel and the effect of additional phosphoric acid etching. Seventy sound human molars were randomly divided into three test groups and one control group. The enamel surfaces of the control group (n=10) were treated with Syntac Classic (SC). Each test group was subdivided into two groups (each n=10). In half of each test group, ground enamel surfaces were coated with the self-etch adhesives AdheSe (ADH), Xeno III (XE) or Futurabond NR (FNR). In the remaining half of each test group, an additional phosphoric acid etching of the enamel surface was performed prior to applying the adhesives. The shear bond strength was measured with a universal testing machine at a crosshead speed of 1 mm/minute after storing the samples in distilled water at 37 degrees C for 24 hours. Fracture modes were determined by SEM examination. For statistical analysis, one-way ANOVA and the two-sided Dunnett Test were used (p>0.05). Additional phosphoric etching significantly increased the shear bond strength of all the examined self-etch adhesives (padhesive fractures. For all the self-etch adhesives, a slight increase in mixed fractures occurred after conditioning with phosphoric acid. An additional phosphoric acid etching of enamel should be considered when using self-etch adhesives. More clinical studies are needed to evaluate the long-term success of the examined adhesives.

Dimensional crossover in Bragg scattering from an optical lattice

International Nuclear Information System (INIS)

Slama, S.; Cube, C. von; Ludewig, A.; Kohler, M.; Zimmermann, C.; Courteille, Ph.W.

2005-01-01

We study Bragg scattering at one-dimensional (1D) optical lattices. Cold atoms are confined by the optical dipole force at the antinodes of a standing wave generated inside a laser-driven high-finesse cavity. The atoms arrange themselves into a chain of pancake-shaped layers located at the antinodes of the standing wave. Laser light incident on this chain is partially Bragg reflected. We observe an angular dependence of this Bragg reflection which is different from what is known from crystalline solids. In solids, the scattering layers can be taken to be infinitely spread (three-dimensional limit). This is not generally true for an optical lattice consistent of a 1D linear chain of pointlike scattering sites. By an explicit structure factor calculation, we derive a generalized Bragg condition, which is valid in the intermediate regime. This enables us to determine the aspect ratio of the atomic lattice from the angular dependance of the Bragg scattered light

In vitro bonding effectiveness of three different one-step self-etch adhesives with additional enamel etching.

Science.gov (United States)

Batra, Charu; Nagpal, Rajni; Tyagi, Shashi Prabha; Singh, Udai Pratap; Manuja, Naveen

2014-08-01

To evaluate the effect of additional enamel etching on the shear bond strength of three self-etch adhesives. Class II box type cavities were made on extracted human molars. Teeth were randomly divided into one control group of etch and rinse adhesive and three test groups of self-etch adhesives (Clearfil S3 Bond, Futurabond NR, Xeno V). The teeth in the control group (n = 10) were treated with Adper™ Single Bond 2. The three test groups were further divided into two subgroups (n = 10): (i) self-etch adhesive was applied as per the manufacturer's instructions; (ii) additional etching of enamel surfaces was done prior to the application of self-etch adhesives. All cavities were restored with Filtek Z250. After thermocycling, shear bond strength was evaluated using a Universal testing machine. Data were analyzed using anova independent sample's 't' test and Dunnett's test. The failure modes were evaluated with a stereomicroscope at a magnification of 10×. Additional phosphoric acid etching of the enamel surface prior to the application of the adhesive system significantly increased the shear bond strength of all the examined self-etch adhesives. Additional phosphoric acid etching of enamel surface significantly improved the shear bond strength. © 2013 Wiley Publishing Asia Pty Ltd.

Thermodynamics of nuclear track chemical etching

Science.gov (United States)

Rana, Mukhtar Ahmed

2018-05-01

This is a brief paper with new and useful scientific information on nuclear track chemical etching. Nuclear track etching is described here by using basic concepts of thermodynamics. Enthalpy, entropy and free energy parameters are considered for the nuclear track etching. The free energy of etching is determined using etching experiments of fission fragment tracks in CR-39. Relationship between the free energy and the etching temperature is explored and is found to be approximately linear. The above relationship is discussed. A simple enthalpy-entropy model of chemical etching is presented. Experimental and computational results presented here are of fundamental interest in nuclear track detection methodology.

High-density plasma etching characteristics of indium-gallium-zinc oxide thin films in CF4/Ar plasma

International Nuclear Information System (INIS)

Joo, Young-Hee; Kim, Chang-Il

2015-01-01

We investigated the etching process of indium-gallium-zinc oxide (IGZO) thin films in an inductively coupled plasma system. The dry etching characteristics of the IGZO thin films were studied by varying the CF 4 /Ar gas mixing ratio, RF power, DC-bias voltage, and process pressure. We determined the following optimized process conditions: an RF power of 700 W, a DC-bias voltage of − 150 V, and a process pressure of 2 Pa. A maximum etch rate of 25.63 nm/min for the IGZO thin films was achieved in a plasma with CF 4 /Ar(= 25:75), and the selectivity of IGZO to Al and TiN was found to be 1.3 and 0.7, respectively. We determined the ionic composition of the CF 4 /Ar plasma using optical emission spectroscopy. Analysis of chemical reactions at the IGZO thin film surfaces was performed using X-ray photoelectron spectroscopy. - Highlights: • IGZO thin film was etched by CF 4 /Ar plasma as a function of gas mixing ratio. • IGZO bonds were broken Ar + sputtering and then reacted with the C-F x radicals. • The physical sputtering is dominant in etch control compared with chemical etching

III-Nitride Blue Laser Diode with Photoelectrochemically Etched Current Aperture

Science.gov (United States)

Megalini, Ludovico

Group III-nitride is a remarkable material system to make highly efficient and high-power optoelectronics and electronic devices because of the unique electrical, physical, chemical and structural properties it offers. In particular, InGaN-based blue Laser Diodes (LDs) have been successfully employed in a variety of applications ranging from biomedical and military devices to scientific instrumentation and consumer electronics. Recently their use in highly efficient Solid State Lighting (SSL) has been proposed because of their superior beam quality and higher efficiency at high input power density. Tremendous advances in research of GaN semi-polar and non-polar crystallographic planes have led both LEDs and LDs grown on these non-basal planes to rival with, and with the promise to outperform, their equivalent c-plane counterparts. However, still many issues need to be addressed, both related to material growth and device fabrication, including a lack of conventional wet etching techniques. GaN and its alloys with InN and AlN have proven resistant essentially to all known standard wet etching techniques, and the predominant etching methods rely on chlorine-based dry etching (RIE). These introduce sub-surface damage which can degrade the electrical properties of the epitaxial structure and reduce the reliability and lifetime of the final device. Such reasons and the limited effectiveness of passivation techniques have so far suggested to etch the LD ridges before the active region, although it is well-known that this can badly affect the device performance, especially in narrow stripe width LDs, because the gain guiding obtained in the planar configuration is weak and the low index step and high lateral current leakage result in devices with threshold current density higher than devices whose ridge is etched beyond the active region. Moreover, undercut etching of III-nitride layers has proven even more challenging, with limitations in control of the lateral etch

Optical fibre Bragg gratings at harmonics of the Bragg wavelength and their sensing properties

International Nuclear Information System (INIS)

Collins, Stephen F; Sidiroglou, Fotios; Bal, Harpreet K; Baxter, Greg W; Wade, Scott A

2013-01-01

Spectral features in optical fibre Bragg gratings (FBGs) at various harmonics of the Bragg wavelength arise due to saturation of the writing process. Additionally, phase-mask-produced FBGs possess a complex refractive index pattern, producing an extra periodicity equal to the phase-mask periodicity that supplements the desired periodicity of half that of the phase-mask, as shown via differential interference contrast microscopy. Some spectral peaks or dips occur as doublets with a wavelength spacing that depends upon fibre alignment relative to the phase mask. These spectral properties are of importance, as they allow the realization of alternative FBG sensors of various measurands. (paper)

Microdosimetry for a carbon ion beam using track-etched detectors

International Nuclear Information System (INIS)

Ambrozova, I.; Ploc, O.; Davidkova, M.; Vondracek, V.; Sefl, M.; Stepan, V.; Pachnerova Brabcova, K.; Incerti, S.

2015-01-01

Track-etched detectors (TED) have been used as linear energy transfer (LET) spectrometers in heavy ion beams for many years. LET spectra and depth -dose distribution of a carbon ion beam were measured behind polymethylmethacrylate degraders at Heavy Ion Medical Accelerator in Chiba, Japan. The measurements were performed along monoenergetic beam with energy 290 MeV u -1 in different positions: (1) at beam extraction area, (2) at beginning, (3) maximum and (4) behind the Bragg peak region (0, 117, 147 and 151 mm of water-equivalent depth, respectively). The LET spectra inside and outside of the primary ion beam have been evaluated. TED record only heavy charged particles with LET above 8 -10 keV μm -1 , while electrons and ions with lower LET are not detected. The Geant4 simulation toolkit version 4.9.6.P01 has been used to estimate the contribution of non-detected particles to absorbed dose. Presented results demonstrate the applicability of TED for microdosimetry measurements in therapeutic carbon ion beams. (authors)

Surface etching technologies for monocrystalline silicon wafer solar cells

Science.gov (United States)

Tang, Muzhi

With more than 200 GW of accumulated installations in 2015, photovoltaics (PV) has become an important green energy harvesting method. The PV market is dominated by solar cells made from crystalline silicon wafers. The engineering of the wafer surfaces is critical to the solar cell cost reduction and performance enhancement. Therefore, this thesis focuses on the development of surface etching technologies for monocrystalline silicon wafer solar cells. It aims to develop a more efficient alkaline texturing method and more effective surface cleaning processes. Firstly, a rapid, isopropanol alcohol free texturing method is successfully demonstrated to shorten the process time and reduce the consumption of chemicals. This method utilizes the special chemical properties of triethylamine, which can form Si-N bonds with wafer surface atoms. Secondly, a room-temperature anisotropic emitter etch-back process is developed to improve the n+ emitter passivation. Using this method, 19.0% efficient screen-printed aluminium back surface field solar cells are developed that show an efficiency gain of 0.15% (absolute) compared with conventionally made solar cells. Finally, state-of-the-art silicon surface passivation results are achieved using hydrogen plasma etching as a dry alternative to the classical hydrofluoric acid wet-chemical process. The effective native oxide removal and the hydrogenation of the silicon surface are shown to be the reasons for the excellent level of surface passivation achieved with this novel method.

Determination of etching parameters for pulsed XeF2 etching of silicon using chamber pressure data

Science.gov (United States)

Sarkar, Dipta; Baboly, M. G.; Elahi, M. M.; Abbas, K.; Butner, J.; Piñon, D.; Ward, T. L.; Hieber, Tyler; Schuberth, Austin; Leseman, Z. C.

2018-04-01

A technique is presented for determination of the depletion of the etchant, etched depth, and instantaneous etch rate for Si etching with XeF2 in a pulsed etching system in real time. The only experimental data required is the pressure data collected temporally. Coupling the pressure data with the knowledge of the chemical reactions allows for the determination of the etching parameters of interest. Using this technique, it is revealed that pulsed etching processes are nonlinear, with the initial etch rate being the highest and monotonically decreasing as the etchant is depleted. With the pulsed etching system introduced in this paper, the highest instantaneous etch rate of silicon was recorded to be 19.5 µm min-1 for an initial pressure of 1.2 Torr for XeF2. Additionally, the same data is used to determine the rate constant for the reaction of XeF2 with Si; the reaction is determined to be second order in nature. The effect of varying the exposed surface area of Si as well as the effect that pressure has on the instantaneous etch rate as a function of time is shown applying the same technique. As a proof of concept, an AlN resonator is released using XeF2 pulses to remove a sacrificial poly-Si layer.

Development of etched nuclear tracks

International Nuclear Information System (INIS)

Somogyi, G.

1980-01-01

The theoretical description of the evolution of etched tracks in solid state nuclear track detectors is considered for different initial conditions, for the cases of constant and varying track etch rates, isotropic and anisotropic bulk etching as well as for thick and thin detectors. It is summarized how one can calculate the main parameters of etch-pit geometry, the track length, the axes of a surface track opening, track profile and track contour. The application of the theory of etch-track evolution is demonstrated with selected practical problems. Attention is paid to certain questions related to the determination of unknown track parameters and calculation of surface track sizes. Finally, the theory is extended to the description of the perforation and etch-hole evolution process in thin detectors, which is of particular interest for track radiography and nuclear filter production. (orig.)

Development of etched nuclear tracks

International Nuclear Information System (INIS)

Somogyi, G.

1979-01-01

The theoretical description of the evolution of etched tracks in solid state nuclear track detectors is considered for different initial conditions, for the cases of constant and varying track etch rates, isotopic and unisotropic bulk etching as well as for thick and thin detectors. It is summarized how the main parameters of etch-pit geometry, the track length, the axes of a surface track opening, the track profile and the track contour can be calculated. The application of the theory of etch-track evolution is demonstrated with selected practical problems. Attention is paid to certain questions related to the determination of unknown track parameters and calculation of surface track sizes. Finally, the theory is extended to the description of the perforation and etch-hole evolution process in thin detectors, which is of particular interest for track radiography and nuclear filter production. (author)

An etching mask and a method to produce an etching mask

DEFF Research Database (Denmark)

2016-01-01

The present invention relates to an etching mask comprising silicon containing block copolymers produced by self-assembly techniques onto silicon or graphene substrate. Through the use of the etching mask, nanostructures having long linear features having sub-10 nm width can be produced....

COMPOSITE RESIN BOND STRENGTH TO ETCHED DENTINWITH ONE SELF PRIMING ADHESIVE

Directory of Open Access Journals (Sweden)

P SAMIMI

2002-09-01

Full Text Available Introduction. The purpose of this study was to compare shear bond strength of composite resins to etched dentin in both dry and wet dentin surface with active and inactive application of a single-bottle adhesive resin (Single Bond, 3M Dental products. Methods. Fourthy four intact human extracted molars and premolars teeth were selected. The facial surfaces of the teeth were grounded with diamond bur to expose dentin. Then specimens were divided into four groups of 11 numbers (9 Molars and 2 Premolars. All the samples were etched with Phosphoric Acid Gel 35% and then rinsed for 10 seconds. The following stages were carried out for each group: Group I (Active-Dry: After rinsing, air drying of dentin surface for 15 seconds, active priming of adhesive resin for 15 seconds, air drying for 5 seconds, the adhesive resin layer was light cured for 10 seconds. Group III (Inactive-Dry:After rinsing, air drying of dentin surface for 15 seconds, adhesive resin was applied and air dryied for 5 seconds, the adhesive layer was light cured for 10 seconds. Group III (Active-Wet:After rinsing, removal of excess water of dentin surface with a cotton roll, active priming of adhesive resin for 15 seconds and air drying for 5 seconds, the adhesive layer was light cured for 10 seconds. Group IV (Inactive-Wet:After rinsing, removal of excess water of dentin surface with a cotton roll, the adhesive resin was applied and air dryied for 5 seconds and then cured for 10 seconds. After adhesive resin application, composite resin (Z250, 3M Dental products was applied on prepared surface with cylindrical molds (with internal diameter of 2.8mm, & height of 5mm and light-cured for 100 seconds (5x20s. The samples were then thermocycled. They were located in 6±3c water .temperature for 10 seconds and then 15 seconds in inviromental temperature, 10s in 55±3c water temperature and then were located at room temperature for 15s. This test was repeated for 100s. All of the specimens

Effect of collagen fibrils removal on shear bond strength of total etch and self etch adhesive systems

Directory of Open Access Journals (Sweden)

Pishevar L.

2009-12-01

Full Text Available "nBackground and Aim: Sodium hypochlorite can remove the organic phase of the demineralized dentin and it produces direct resin bonding with hydroxyapatite crystals. Therefore, the hydrolytic degradation of collagen fibrils which might affect the bonding durability is removed. The aim of this study was to evaluate the effect of collagen fibrils removal by 10% NaOCl on dentin shear bond strength of two total etch and self etch adhesive systems."nMaterials and Methods: Sixty extracted human premolar teeth were used in this study. Buccal surface of teeth were grounded until dentin was exposed. Then teeth were divided into four groups. According to dentin surface treatment, experimental groups were as follows: Group I: Single Bond (3M according to manufacture instruction, Group II: 10% NaOCl+Single bond (3M, Group III: Clearfil SE Bond (Kuraray according to manufacture instruction, and Group IV: Clearfil SE Bond primer. After that, the specimens were immersed in 50% acetone solution for removing extra monomer. Then the specimens were rinsed and dried. 10% NaOCl was applied and finally adhesive was used. Then composite was bonded to the treated surfaces using a 4 2 mm cylindrical plastic mold. Specimens were thermocycled for 500 cycles (5-55ºC. A shear load was employed by a universal testing machine with a cross head speed of 1mm/min. The data were analyzed for statistical significance with One-way ANOVA, Two-way ANOVA and Tukey HSD post-hoc tests."nResults: The mean shear bond strengths of groups were as follows: Single Bond=16.8±4.2, Clearfil SE Bond=23.7±4.07, Single Bond+NaOCl=10.5±4.34, Clearfil SE Bond+NaOCl=23.3±3.65 MPa. Statistical analysis revealed that using 10% NaOCl significantly decreased the shear bond strength in Single Bond group (P=0.00, but caused no significant difference in the shear bond strength in Clearfil SE Bond group (P=0.99."nConclusion: Based on the results of this study, NaOCl treatment did not improve the bond

High-density plasma etching characteristics of indium-gallium-zinc oxide thin films in CF{sub 4}/Ar plasma

Energy Technology Data Exchange (ETDEWEB)

Joo, Young-Hee; Kim, Chang-Il

2015-05-29

We investigated the etching process of indium-gallium-zinc oxide (IGZO) thin films in an inductively coupled plasma system. The dry etching characteristics of the IGZO thin films were studied by varying the CF{sub 4}/Ar gas mixing ratio, RF power, DC-bias voltage, and process pressure. We determined the following optimized process conditions: an RF power of 700 W, a DC-bias voltage of − 150 V, and a process pressure of 2 Pa. A maximum etch rate of 25.63 nm/min for the IGZO thin films was achieved in a plasma with CF{sub 4}/Ar(= 25:75), and the selectivity of IGZO to Al and TiN was found to be 1.3 and 0.7, respectively. We determined the ionic composition of the CF{sub 4}/Ar plasma using optical emission spectroscopy. Analysis of chemical reactions at the IGZO thin film surfaces was performed using X-ray photoelectron spectroscopy. - Highlights: • IGZO thin film was etched by CF{sub 4}/Ar plasma as a function of gas mixing ratio. • IGZO bonds were broken Ar{sup +} sputtering and then reacted with the C-F{sub x} radicals. • The physical sputtering is dominant in etch control compared with chemical etching.

A novel deep reactive ion etched (DRIE) glass micro-model for two-phase flow experiments.

Science.gov (United States)

Karadimitriou, N K; Joekar-Niasar, V; Hassanizadeh, S M; Kleingeld, P J; Pyrak-Nolte, L J

2012-09-21

In the last few decades, micro-models have become popular experimental tools for two-phase flow studies. In this work, the design and fabrication of an innovative, elongated, glass-etched micro-model with dimensions of 5 × 35 mm(2) and constant depth of 43 microns is described. This is the first time that a micro-model with such depth and dimensions has been etched in glass by using a dry etching technique. The micro-model was visualized by a novel setup that allowed us to monitor and record the distribution of fluids throughout the length of the micro-model continuously. Quasi-static drainage experiments were conducted in order to obtain equilibrium data points that relate capillary pressure to phase saturation. By measuring the flow rate of water through the flow network for known pressure gradients, the intrinsic permeability of the micro-model's flow network was also calculated. The experimental results were used to calibrate a pore-network model and test its validity. Finally, we show that glass-etched micro-models can be valuable tools in single and/or multi-phase flow studies and their applications.

Process for etching zirconium metallic objects

International Nuclear Information System (INIS)

Panson, A.J.

1988-01-01

In a process for etching of zirconium metallic articles formed from zirconium or a zirconium alloy, wherein the zirconium metallic article is contacted with an aqueous hydrofluoric acid-nitric acid etching bath having an initial ratio of hydrofluoric acid to nitric acid and an initial concentration of hydrofluoric and nitric acids, the improvement, is described comprising: after etching of zirconium metallic articles in the bath for a period of time such that the etching rate has diminished from an initial rate to a lesser rate, adding hydrofluoric acid and nitric acid to the exhausted bath to adjust the concentration and ratio of hydrofluoric acid to nitric acid therein to a value substantially that of the initial concentration and ratio and thereby regenerate the etching solution without removal of dissolved zirconium therefrom; and etching further zirconium metallic articles in the regenerated etching bath

Simultaneous measurement of magnetic field and temperature based on an etched TCFMI cascaded with an FBG

Science.gov (United States)

Yan, Guofeng; Zhang, Liang; He, Sailing

2016-04-01

In this paper, a dual-parameter measurement scheme based on an etched thin core fiber modal interferometer (TCMI) cascaded with a fiber Bragg grating (FBG) is proposed and experimentally demonstrated for simultaneous measurement of magnetic field and temperature. The magnetic field and temperature responses of the packaged TCFMI were first investigated, which showed that the magnetic field sensitivity could be highly enhanced by decreasing of the TCF diameter and the temperature-cross sensitivities were up to 3-7 Oe/°C at 1550 nm. Then, the theoretical analysis and experimental demonstration of the proposed dual-parameter sensing scheme were conducted. Experimental results show that, the reflection of the FBG has a magnetic field intensity and temperature sensitivities of -0.017 dB/Oe and 0.133 dB/°C, respectively, while the Bragg wavelength of the FBG is insensitive to magnetic field and has a temperature sensitivity of 13.23 pm/°C. Thus by using the sensing matrix method, the intensity of the magnetic field and the temperature variance can be measured, which enables magnetic field sensing under strict temperature environments. In the on-off time response test, the fabricated sensor exhibited high repeatability and short response time of ∼19.4 s. Meanwhile the reflective sensing probe type is more compact and practical for applications in hard-to-reach conditions.

Comparison of shear bond strength between unfilled resin to dry enamel and dentin bonding to moist and dry enamel

Directory of Open Access Journals (Sweden)

Yasini E.

2005-05-01

Full Text Available Statement of Problem: The use of dentine bondings on enamel and dentin in total etch protocols has recently become popular. Unfilled resin is hydrophobic and dentin bonding is hydrophilic in nature. This chemical difference could be effective in enamel bonding process. Purpose: The aim of this study was to compare the shear bond strength of unfilled resin to dry enamel and dentin bonding to dry and moist enamel. Materials and Methods: In this experimental study, a total of 30 incisor teeth were used. The specimens were randomly assigned to three groups of 10. 37% phosphoric acid etchant was applied to the enamel surfaces in each group for 15 seconds, rinsed with water for 20 seconds and dried for 20 seconds with compressed air in groups one and two. After conditioning, group 1 received unfilled resin (Margin Bond, Colten and group 2 received dentin bonding (Single Bond, 3M and in group 3 after conditioning and rinsing with water, a layer of dentin bonding (Single Bond was applied on wet enamel. The enamel and dentin bonding were light cured for 20 seconds. A ring mold 3.5 mm in diameter and 2 mm height was placed over the specimens to receive the composite filling material (Z100, 3M. The composite was cured for 40 seconds. The specimens were thermocycled and shear bond strengths were determined using an Instron Universal Testing Machine. The findings were analyzed by ANOVA One-Way and Tukey HSD tests. Results: Shear bond strength of dentin bonding to dry enamel was significantly less than unfilled resin to dry enamel (P<0.05. There was no significant difference between the bond strength of dentin bonding to moist and dry enamel. In addition bond strength of dentin bonding to wet enamel was not significantly different from unfilled resin to dry enamel. Conclusion: Based on the findings of this study, it is suggested that enamel surface should remain slightly moist after etching before bonding with single bond but when using unfilled resin, the

Bond strength of a pit-and-fissure sealant associated to etch-and-rinse and self-etching adhesive systems to saliva-contaminated enamel: individual vs. simultaneous light curing.

Science.gov (United States)

Gomes-Silva, Jaciara Miranda; Torres, Carolina Paes; Contente, Marta Maria Martins Giamatei; Oliveira, Maria Angélica Hueb de Menezes; Palma-Dibb, Regina Guenka; Borsatto, Maria Cristina

2008-01-01

This study evaluated in vitro the shear bond strength (SBS) of a resin-based pit-and-fissure sealant [Fluroshield (F), Dentsply/Caulk] associated with either an etch-and-rinse [Adper Single Bond 2 (SB), 3M/ESPE] or a self-etching adhesive system [Clearfil S3 Bond (S3), Kuraray Co., Ltd.] to saliva-contaminated enamel, comparing two curing protocols: individual light curing of the adhesive system and the sealant or simultaneous curing of both materials. Mesial and distal enamel surfaces from 45 sound third molars were randomly assigned to 6 groups (n=15), according to the bonding technique: I - F was applied to 37% phosphoric acid etched enamel. The other groups were contaminated with fresh human saliva (0.01 mL; 10 s) after acid etching: II - SB and F were light cured separately; III - SB and F were light cured together; IV - S3 and F were light cured separately; V - S3 and F were light cured simultaneously; VI - F was applied to saliva-contaminated, acid-etched enamel without an intermediate bonding agent layer. SBS was tested to failure in a universal testing machine at 0.5 mm/min. Data were analyzed by one-way ANOVA and Fisher's test (alpha=0.05).The debonded specimens were examined with a stereomicroscope to assess the failure modes. Three representative specimens from each group were observed under scanning electron microscopy for a qualitative analysis. Mean SBS in MPa were: I-12.28 (+/-4.29); II-8.57 (+/-3.19); III-7.97 (+/-2.16); IV-12.56 (+/-3.11); V-11.45 (+/-3.77); and VI-7.47 (+/-1.99). In conclusion, individual or simultaneous curing of the intermediate bonding agent layer and the resin sealant did not seem to affect bond strength to saliva-contaminated enamel. S3/F presented significantly higher SBS than the that of the groups treated with SB etch-and-rinse adhesive system and similar SBS to that of the control group, in which the sealant was applied under ideal dry, noncontaminated conditions.

Transmission-enabled fiber Fabry-Perot cavity based on a deeply etched slotted micromirror.

Science.gov (United States)

Othman, Muhammad A; Sabry, Yasser M; Sadek, Mohamed; Nassar, Ismail M; Khalil, Diaa A

2018-06-01

In this work, we report the analysis, fabrication, and characterization of an optical cavity built using a Bragg-coated fiber (BCF) mirror and a metal-coated microelectromechanical systems (MEMS) slotted micromirror, where the latter allows transmission output from the cavity. Theoretical modeling, using Fourier optics analysis for the cavity response based on tracing the propagation of light back and forth between the mirrors, is presented. Detailed simulation analysis is carried out for the spectral response of the cavity under different design conditions. MEMS chips of the slotted micromirror are fabricated using deep reactive ion etching of a silicon-on-insulator substrate with different device-etching depths of 150 μm and 80 μm with aluminum and gold metal coating, respectively. The cavity is characterized as an optical filter using a BCF with reflectivity that is larger than 95% in a 300 nm range across the E-band and the L-band. Versatile filter characteristics were obtained for different values of the MEMS micromirror slit width and cavity length. A free spectral range (FSR) of about 33 nm and a quality factor of about 196 were obtained for a 5.5 μm width aluminum slit, while an FSR of about 148 nm and a quality factor of about 148 were obtained for a 1.5 μm width gold slit. The presented structure opens the door for wide spectral response transmission-type MEMS filters.

Single-Run Single-Mask Inductively-Coupled-Plasma Reactive-Ion-Etching Process for Fabricating Suspended High-Aspect-Ratio Microstructures

Science.gov (United States)

Yang, Yao-Joe; Kuo, Wen-Cheng; Fan, Kuang-Chao

2006-01-01

In this work, we present a single-run single-mask (SRM) process for fabricating suspended high-aspect-ratio structures on standard silicon wafers using an inductively coupled plasma-reactive ion etching (ICP-RIE) etcher. This process eliminates extra fabrication steps which are required for structure release after trench etching. Released microstructures with 120 μm thickness are obtained by this process. The corresponding maximum aspect ratio of the trench is 28. The SRM process is an extended version of the standard process proposed by BOSCH GmbH (BOSCH process). The first step of the SRM process is a standard BOSCH process for trench etching, then a polymer layer is deposited on trench sidewalls as a protective layer for the subsequent structure-releasing step. The structure is released by dry isotropic etching after the polymer layer on the trench floor is removed. All the steps can be integrated into a single-run ICP process. Also, only one mask is required. Therefore, the process complexity and fabrication cost can be effectively reduced. Discussions on each SRM step and considerations for avoiding undesired etching of the silicon structures during the release process are also presented.

Effects of gas-flow structures on radical and etch-product density distributions on wafers in magnetomicrowave plasma etching reactors

International Nuclear Information System (INIS)

Ikegawa, Masato; Kobayashi, Jun'ichi; Fukuyama, Ryoji

2001-01-01

To achieve high etch rate, uniformity, good selectivity, and etch profile control across large diameter wafers, the distributions of ions, radicals, and etch products in magnetomicrowave high-etch-rate plasma etching reactors must be accurately controlled. In this work the effects of chamber heights, a focus ring around the wafer, and gas supply structures (or gas flow structures) on the radicals and etch products flux distribution onto the wafer were examined using the direct simulation Monte Carlo method and used to determine the optimal reactor geometry. The pressure uniformity on the wafer was less than ±1% when the chamber height was taller than 60 mm. The focus ring around the wafer produced uniform radical and etch-product fluxes but increased the etch-product flux on the wafer. A downward-flow gas-supply structure (type II) produced a more uniform radical distribution than that produced by a radial gas-supply structure (type I). The impact flow of the type II structure removed etch products from the wafer effectively and produced a uniform etch-product distribution even without the focus ring. Thus the downward-flow gas-supply structure (type II) was adopted in the design for the second-generation of a magnetomicrowave plasma etching reactor with a higher etching rate

Dynamic strain measurement of hydraulic system pipeline using fibre Bragg grating sensors

Directory of Open Access Journals (Sweden)

Qiang Wang

2016-04-01

Full Text Available Fatigue failure is a serious problem in hydraulic piping systems installed in the machinery and equipment working in harsh operational conditions. To alleviate this problem, health monitoring of pipes can be conducted by measuring and analysing vibration-induced strain. Fibre Bragg grating is considered as a promising sensing approach for dynamic load monitoring. In this article, dynamic strain measurements based on fibre Bragg grating sensors for small-bore metal pipes have been investigated. The quasi-distributed strain sensing of fibre Bragg grating sensors is introduced. Two comparison experiments were carried out under vibration and impact loads among the methods of electrical strain gauge, piezoelectric accelerometer and fibre Bragg grating sensor. Experimental results indicate that fibre Bragg grating sensor possesses an outstanding ability to resist electromagnetic interference compared with strain gauge. The natural frequency measurement results, captured by fibre Bragg grating sensor, agree well with the modal analysis results obtained from finite element analysis. In addition, the attached fibre Bragg grating sensor brings a smaller impact on the dynamic characteristics of the measured pipe than the accelerometer due to its small size and lightweight. Fibre Bragg grating sensors have great potential for the quasi-distributed measurement of dynamic strain for the dynamic characteristic research and health monitoring of hydraulic system pipeline.

The etching behaviour of silicon carbide compacts

International Nuclear Information System (INIS)

Jepps, N.W.; Page, T.F.

1981-01-01

A series of microstructural investigations has been undertaken in order to explore the reliability of particular etches in revealing microstructural detail in silicon carbide compacts. A series of specimens has been etched and examined following complete prior microstructural characterization by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffractometry techniques. In particular, the sensitivity of both a molten salt (KOH/KNO 3 ) etch and a commonly-used oxidizing electrolytic 'colour' etch to crystal purity, crystallographic orientation and polytypic structure has been established. The molten salt etch was found to be sensitive to grain boundaries and stacking disorder while the electrolytic etch was found to be primarily sensitive to local purity and crystallographic orientation. Neither etch appeared intrinsically polytype sensitive. Specifically, for the 'colour' etch, the p- or n-type character of impure regions appears critical in controlling etching behaviour; p-type impurities inhibiting, and n-type impurities enhancing, oxidation. The need to interpret etching behaviour in a manner consistent with the results obtained by a variety of other microstructural techniques will be emphasized. (author)

Laser sensor with Bragg gratings of fiber optics to physics parameter measuring

International Nuclear Information System (INIS)

Vazquez, R.; Garcia, C.; May, M.; Camas, J.

2009-01-01

We present the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980nm, an 4.23 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength increases their temperature which can be used as a sensor element. The laser generation thus shows that the Bragg grating is increasing their temperature. We used a Peltier cell for to change gradually the temperature. (Author)

Corrugated grating on organic multilayer Bragg reflector

Science.gov (United States)

Jaquet, Sylvain; Scharf, Toralf; Herzig, Hans Peter

2007-08-01

Polymeric multilayer Bragg structures are combined with diffractive gratings to produce artificial visual color effects. A particular effect is expected due to the angular reflection dependence of the multilayer Bragg structure and the dispersion caused by the grating. The combined effects can also be used to design particular filter functions and various resonant structures. The multilayer Bragg structure is fabricated by spin-coating of two different low-cost polymer materials in solution on a cleaned glass substrate. These polymers have a refractive index difference of about 0.15 and permit multilayer coatings without interlayer problems. Master gratings of different periods are realized by laser beam interference and replicated gratings are superimposed on the multilayer structure by soft embossing in a UV curing glue. The fabrication process requires only polymer materials. The obtained devices are stable and robust. Angular dependent reflection spectrums for the visible are measured. These results show that it is possible to obtain unexpected reflection effects. A rich variety of color spectra can be generated, which is not possible with a single grating. This can be explained by the coupling of transmission of grating orders and the Bragg reflection band. A simple model permits to explain some of the spectral vs angular dependence of reflected light.

Etching characteristics of a CR-39 track detector at room temperature in different etching solutions

International Nuclear Information System (INIS)

Dajko, G.

1991-01-01

Investigations were carried out to discover how the etching characteristics of CR-39 detectors change with varying conditions of the etching process. Measurements were made at room temperature in pure NaOH and KOH solutions; in different alcoholic KOH solutions (PEW solution, i.e. potassium hydroxide, ethyl alcohol, water); and in NaOH and KOH solutions containing different additives. The bulk etching rate of the detector (V B ) and the V (= V T /V B ) function, i.e. track to bulk etch rates ratio, for 6.1 MeV α-particles, were measured systematically. (author)

Atomic Layer Etching of Silicon to Solve ARDE-Selectivity-Profile-Uniformity Trade-Offs

Science.gov (United States)

Wang, Mingmei; Ranjan, Alok; Ventzek, Peter; Koshiishi, Akira

2014-10-01

With shrinking critical dimensions, dry etch faces more and more challenges. Minimizing each of aspect ratio dependent etching (ARDE), bowing, undercut, selectivity, and within die uniformly across a wafer are met by trading off one requirement against another. At the root of the problem is that roles radical flux, ion flux and ion energy play may be both good and bad. Increasing one parameter helps meeting one requirement but hinders meeting the other. Self-limiting processes like atomic layer etching (ALE) promise a way to escape the problem of balancing trade-offs. ALE was realized in the mid-1990s but the industrial implementation has been slow. In recent years interest in ALE has revived. We present how ARDE, bowing/selectivity trade-offs may be overcome by varying radical/ion ratio, byproduct re-deposition. We overcome many of the practical implementation issues associated with ALE by precise passivation process control. The Monte Carlo Feature Profile Model (MCFPM) is used to illustrate realistic scenarios built around an Ar/Cl2 chemistry driven etch of Si masked by SiO2. We demonstrate that ALE can achieve zero ARDE and infinite selectivity. Profile control depends on careful management of the ion energies and angles. For ALE to be realized in production environment, tight control of IAD is a necessary. Experimental results are compared with simulation results to provide context to the work.

Etching in microsystem technology

CERN Document Server

Kohler, Michael

2008-01-01

Microcomponents and microdevices are increasingly finding application in everyday life. The specific functions of all modern microdevices depend strongly on the selection and combination of the materials used in their construction, i.e., the chemical and physical solid-state properties of these materials, and their treatment. The precise patterning of various materials, which is normally performed by lithographic etching processes, is a prerequisite for the fabrication of microdevices.The microtechnical etching of functional patterns is a multidisciplinary area, the basis for the etching p

Etching conditions and shape of tracks

International Nuclear Information System (INIS)

Kudo, Shuichi

1979-01-01

The etching effect of hydrogen fluoride (HF) solution of 5%, 10%, 20% and 46% was investigated, using the perlite dug out at Wada-toge, Japan. They were studied by the progressive etching at 30 deg C, after the perlite was subjected to thermal neutron irradiation for 8 hours in the research reactor of the Institute for Atomic Energy of St. Paul (Rikkyo) University. Observation was performed mainly by replica, and false tracks, which are difficult to be judged whether they are the tracks or not, didn't appear as far as this experiment was concerned. Measurements of etch-pits and track density were carried out. The results of these investigations were considered and analyzed to describe them in five sections. The conclusions are as follows: (1) Regarding the ease of etch-pit observation and the adjustment of etching time, etching with 5% HF solution is most advantageous among four solutions of 5, 10, 20 and 46% HF. (2) The measurement of track density is more affected by the difference in counting criteria than the difference in etching conditions. The data on the size of etch-pits are required to discuss the problems of track density and counting efficiency. (3) If linear tracks are to be observed using hydrogen fluoride, it is necessary to investigate the etching characteristics with the solution of lower concentration. (Wakatsuki, Y.)

Influence of optical fiber location behind an apodized phase mask on Bragg grating reflection efficiencies at Bragg wavelength and its harmonics

Science.gov (United States)

Osuch, Tomasz; Jaroszewicz, Zbigniew

2017-01-01

An apodized fiber Bragg grating formation using a phase mask with variable duty cycle is numerically analyzed. In particular, an impact of position of an optical fiber behind the phase mask with Gaussian apodization profile on Bragg grating reflection efficiencies at Bragg wavelength and its harmonics is extensively studied. It is shown that reflection efficiency of each harmonic strongly depends on the optical fiber location with respect to the adjacent Talbot planes during the grating inscription. An analytical formula for calculation such periodical changes of reflection strength is proposed. It is also proved, that the smaller optical fiber diameter the higher fluctuations of reflectivity for particular harmonic occur. Results presented for such general case (i.e. phase mask with variable duty cycle with all non-zero diffraction orders) directly correspond to less complex structures, such as uniform phase masks and those with variable groove depth. They are also useful in optimization of Bragg wavelength and harmonic reflection efficiencies as well as in deep understanding of apodized FBG formation using aforementioned phase masks.

Silicon graphene Bragg gratings.

Science.gov (United States)

Capmany, José; Domenech, David; Muñoz, Pascual

2014-03-10

We propose the use of interleaved graphene sections on top of a silicon waveguide to implement tunable Bragg gratings. The filter central wavelength and bandwidth can be controlled changing the chemical potential of the graphene sections. Apodization techniques are also presented.

Comparison of enamel bond fatigue durability between universal adhesives and two-step self-etch adhesives: Effect of phosphoric acid pre-etching.

Science.gov (United States)

Suda, Shunichi; Tsujimoto, Akimasa; Barkmeier, Wayne W; Nojiri, Kie; Nagura, Yuko; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

2018-03-30

The effect of phosphoric acid pre-etching on enamel bond fatigue durability of universal adhesives and two-step self-etch adhesives was investigated. Four universal adhesives and three two-step self-etch adhesives were used. The initial shear bond strengths and shear fatigue strengths to enamel with and without phosphoric acid pre-etching using the adhesives were determined. SEM observations were also conducted. Phosphoric acid pre-etching of enamel was found to increase the bond fatigue durability of universal adhesives, but its effect on two-step self-etch adhesives was material-dependent. In addition, some universal adhesives with phosphoric acid pre-etching showed similar bond fatigue durability to the two-step self-etch adhesives, although the bond fatigue durability of universal adhesives in self-etch mode was lower than that of the two-step self-etch adhesives. Phosphoric acid pre-etching enhances enamel bond fatigue durability of universal adhesives, but the effect of phosphoric acid pre-etching on the bond fatigue durability of two-step self-etch adhesives was material-dependent.

Effect of etching on bonding of a self-etch adhesive to dentine affected by amelogenesis imperfecta.

Science.gov (United States)

Epasinghe, Don Jeevanie; Yiu, Cynthia Kar Yung

2018-02-01

Dentine affected by amelogenesis imperfecta (AI) is histologically altered due to loss of hypoplastic enamel and becomes hypermineralized. In the present study, we examined the effect of additional acid etching on microtensile bond strength of a self-etch adhesive to AI-affected dentine. Flat coronal dentine obtained from extracted AI-affected and non-carious permanent molars were allocated to two groups: (a) Clearfil SE Bond (control); and (b) Clearfil SE Bond and additional etching with 34% phosphoric acid for 15 seconds. The bonded teeth were sectioned into .8-mm 2 beams for microtensile bond strength testing, and stressed to failure under tension. The bond strength data were analyzed using two-way analysis of variance (dentine type and etching step) and Student-Newman-Keuls multiple comparison test (P<.05). Representative fractured beams from each group were examined under scanning electron microscopy. Both factors, dentine substrate (P<.001) and etching step (P<.05), and their interactions (P<.001), were statistically significant. Additional etching had an adverse effect on the bond strength of Clearfil SE Bond to normal dentine (P<.005), and no significant improvement was found for AI-affected dentine (P=.479). Additional acid etching does not improve the bond strength of a self-etch adhesive to AI-affected dentine. © 2017 John Wiley & Sons Australia, Ltd.

All-Silica Hollow-Core Microstructured Bragg Fibers for Biosensor Application

DEFF Research Database (Denmark)

Passaro, Davide; Foroni, Matteo; Poli, Federica

2008-01-01

The possibility to exploit all-silica hollow-core-microstructured Bragg fibers to realize a biosensor useful to detect the DNA hybridization process has been investigated. A Bragg fiber recently fabricated has been considered for the analysis performed by means of a full-vector modal solver based...... layer on the inner surface of the fiber holes can modify the fundamental mode properties. The numerical analysis results have successfully demonstrated the DNA bio-sensor feasibility in hollow-core Bragg fibers....

FY 1999 report on the results of the R and D of the substituting gas system and the substituting process of the etching gas used in the electronic device production process; 1999 nendo denshi device seizo process de shiyosuru etching gas no daitai gas system oyobi daitai process no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

As to the dry etching process and the wiring process where PFC gas and electric power are required most in the electronic device production process, an investigational study was conducted with the aim of PFC saving and energy saving, and the FY 1999 results were summed up. In the study, high efficiency etching process analysis equipment was developed, and three kinds of PFC gas quantitative analysis method were comparatively studied. Relating to the substitution of global environmental warming gas, it was found that C{sub x}F{sub y} type gas was effective which includes no oxygen, has a lot of carbon element numbers, and has double unsaturated bond. Further, in the study of the technology of PFC decomposition by plasma, it was indicated that PFC of 98.7% at maximum in exhaust gas could be removed on ideal conditions. In the dry etching technology by non-PFC gas of the organic insulating film, it was found out that NH{sub 3} base gas is more excellent in both shape and speed of etching than the existing O{sub 2} base one. As to the future wiring technology, new concepts of the optical wiring inside chip, etc. were proposed. (NEDO)

X-ray diffraction at Bragg angles around π/2

International Nuclear Information System (INIS)

Mayolo, C.M.G. de.

1991-01-01

X-ray diffraction at Bragg angles around π/2 is studied from the theoretical and experimental points of view. The proposed corrections to the dynamical theory in the θ β ≅ π/2 cases, has been reviewed showing the equivalence between two formalisms leading to a corrected expression for the dependence of the angular parameter y with the angle of incidence. An expression for y valid in the conventional and θ β ≅ π/2 cases has been obtained. A general expression for Bragg law and for energy resolution after a Bragg diffraction was also deduced. (author)

Flexible Bragg reflection waveguide devices fabricated on a plastic substrate

Science.gov (United States)

Kim, Kyung-Jo; Yi, Jeong-Ah; Oh, Min-Cheol; Noh, Young-Ouk; Lee, Hyung-Jong

2007-09-01

Bragg reflecting waveguide devices are fabricated on a flexible substrate by using a post lift-off process in order to provide highly uniform grating patterns on a wide range. In this process, the flexible substrate spin-coated on silicon wafer is released after the final fabrication process of chip dicing. The fabricated flexible Bragg reflector shows very sharp transmission spectrum with 3-dB bandwidth of 0.1 nm and 10-dB bandwidth of 0.4 nm, which proves the Bragg reflector has excellent uniformity. To achieve athermal operation of the flexible Bragg reflector, thermal expansion property of the plastic substrate is controlled by the thickness of two polymer materials constructing the plastic substrate. The flexible substrate with 0.7-μm SU-8 layers sandwiching 100-μm NOA61 layer provides an optimized thermal expansion property to compensate the thermo-optic effect of the waveguide made of ZPU polymer. The temperature dependence of the Bragg reflector is decreased to -0.011 nm/°C through the incorporation of the plastic substrate.

Four-year water degradation of a total-etch and two self-etching adhesives bonded to dentin

NARCIS (Netherlands)

Abdalla, A.I.; Feilzer, A.J.

2008-01-01

Objectives: To evaluate effect of direct and indirect water storage on the microtensile dentin bond strength of one total-etch and two self-etching adhesives. Methods: The adhesive materials were: one total-etch adhesive; ‘Admira Bond’ and two selfetch adhesives; ‘Clearfil SE Bond’ and ‘Hybrid

Inductively coupled plasma etching of GaAs low loss waveguides for a traveling waveguide polarization converter, using chlorine chemistry

Science.gov (United States)

Lu, J.; Meng, X.; Springthorpe, A. J.; Shepherd, F. R.; Poirier, M.

2004-05-01

A traveling waveguide polarization converter [M. Poirier et al.] has been developed, which involves long, low loss, weakly confined waveguides etched in GaAs (epitaxially grown by molecular beam epitaxy), with electroplated ``T electrodes'' distributed along the etched floor adjacent to the ridge walls, and airbridge interconnect metallization. This article describes the development of the waveguide fabrication, based on inductively coupled plasma (ICP) etching of GaAs using Cl2 chemistry; the special processes required to fabricate the electrodes and metallization [X. Meng et al.], and the device characteristics [M. Poirier et al.], are described elsewhere. The required waveguide has dimensions nominally 4 μm wide and 2.1 μm deep, with dimensional tolerances ~0.1 μm across the wafer and wafer to wafer. A vertical etch profile with very smooth sidewalls and floors is required to enable the plated metal electrodes to be fabricated within 0.1 μm of the ridge. The ridges were fabricated using Cl2 ICP etching and a photoresist mask patterned with an I-line stepper; He backside cooling, combined with an electrostatic chuck, was employed to ensure good heat transfer to prevent resist reticulation. The experimental results showed that the ridge profile is very sensitive to ICP power and platen rf power. High ICP power and low platen power tend to result in more isotropic etching, whereas increasing platen power increases the photoresist etch rate, which causes rougher ridge sidewalls. No strong dependence of GaAs etch rate and ridge profile were observed with small changes in process temperature (chuck temperature). However, when the chuck temperature was decreased from 25 to 0 °C, etch uniformity across a 3 in. wafer improved from 6% to 3%. Photoresist and polymer residues present after the ICP etch were removed using a combination of wet and dry processes. .

Inductively coupled plasma etching of GaAs low loss waveguides for a traveling waveguide polarization converter, using chlorine chemistry

International Nuclear Information System (INIS)

Lu, J.; Meng, X.; SpringThorpe, A.J.; Shepherd, F.R.; Poirier, M.

2004-01-01

A traveling waveguide polarization converter [M. Poirier et al.] has been developed, which involves long, low loss, weakly confined waveguides etched in GaAs (epitaxially grown by molecular beam epitaxy), with electroplated 'T electrodes' distributed along the etched floor adjacent to the ridge walls, and airbridge interconnect metallization. This article describes the development of the waveguide fabrication, based on inductively coupled plasma (ICP) etching of GaAs using Cl 2 chemistry; the special processes required to fabricate the electrodes and metallization [X. Meng et al.], and the device characteristics [M. Poirier et al.], are described elsewhere. The required waveguide has dimensions nominally 4 μm wide and 2.1 μm deep, with dimensional tolerances ∼0.1 μm across the wafer and wafer to wafer. A vertical etch profile with very smooth sidewalls and floors is required to enable the plated metal electrodes to be fabricated within 0.1 μm of the ridge. The ridges were fabricated using Cl 2 ICP etching and a photoresist mask patterned with an I-line stepper; He backside cooling, combined with an electrostatic chuck, was employed to ensure good heat transfer to prevent resist reticulation. The experimental results showed that the ridge profile is very sensitive to ICP power and platen rf power. High ICP power and low platen power tend to result in more isotropic etching, whereas increasing platen power increases the photoresist etch rate, which causes rougher ridge sidewalls. No strong dependence of GaAs etch rate and ridge profile were observed with small changes in process temperature (chuck temperature). However, when the chuck temperature was decreased from 25 to 0 deg. C, etch uniformity across a 3 in. wafer improved from 6% to 3%. Photoresist and polymer residues present after the ICP etch were removed using a combination of wet and dry processes

Nanoporous distributed Bragg reflectors on free-standing nonpolar m-plane GaN

Science.gov (United States)

Mishkat-Ul-Masabih, Saadat; Luk, Ting Shan; Rishinaramangalam, Ashwin; Monavarian, Morteza; Nami, Mohsen; Feezell, Daniel

2018-01-01

We report the fabrication of m-plane nanoporous distributed Bragg reflectors (DBRs) on free-standing GaN substrates. The DBRs consist of 15 pairs of alternating undoped and highly doped n-type ([Si] = ˜3.7 × 1019 cm-3) GaN. Electrochemical (EC) etching was performed to convert the highly doped regions into a porous material, consequently reducing the effective refractive index of the layers. We demonstrate a DBR with peak reflectance greater than 98% at 450 nm with a stopband width of ˜72 nm. The polarization ratio of an incident polarized light source remains identical after reflection from the DBR, verifying that there is no drop in the polarization ratio due to the interfaces between the porous layers. We also quantify the porosity under various EC bias conditions for layers with different doping concentrations. The bias voltage controls the average pore diameter, while the pore density is primarily determined by the doping concentration. The results show that nanoporous DBRs on nonpolar free-standing GaN are promising candidates for high-reflectance, lattice-matched DBR mirrors for GaN-based resonant cavity devices.

Can previous acid etching increase the bond strength of a self-etching primer adhesive to enamel?

Directory of Open Access Journals (Sweden)

Ana Paula Morales Cobra Carvalho

2009-06-01

Full Text Available Because a greater research effort has been directed to analyzing the adhesive effectiveness of self etch primers to dentin, the aim of this study was to evaluate, by microtensile testing, the bond strength to enamel of a composite resin combined with a conventional adhesive system or with a self-etching primer adhesive, used according to its original prescription or used with previous acid etching. Thirty bovine teeth were divided into 3 groups with 10 teeth each (n= 10. In one of the groups, a self-etching primer (Clearfil SE Bond - Kuraray was applied in accordance with the manufacturer's instructions and, in the other, it was applied after previous acid etching. In the third group, a conventional adhesive system (Scotchbond Multipurpose Plus - 3M-ESPE was applied in accordance with the manufacturer's instructions. The results obtained by analysis of variance revealed significant differences between the adhesive systems (F = 22.31. The self-etching primer (Clearfil SE Bond presented lower enamel bond strength values than the conventional adhesive system (Scotchbond Multipurpose Plus (m = 39.70 ± 7.07 MPa both when used according to the original prescription (m = 27.81 ± 2.64 MPa and with previous acid etching (m = 25.08 ± 4.92 MPa.

Fabrication et applications des reseaux de Bragg ultra-longs

Science.gov (United States)

Gagne, Mathieu

This thesis presents the principal accomplishments realized during the PhD project. The thesis is presented by publication format and is a collection of four published articles having fiber Bragg gratings as a central theme. First achieved in 1978, UV writing of fiber Bragg gratings is nowadays a common and mature technology being present in both industry and academia. The property of reflecting light guided by optical fibers lead to diverse applications in telecommunication, lasers as well as several types of sensors. The conventional fabrication technique is generally based on the use of generally expensive phase masks which determine the obtained characteristics of the fiber Bragg grating. The fiber being photosensitive at those wavelengths, a periodic pattern can be written into it. The maximal length, the period, the chirp, the index contrast and the apodisation are all characteristics that depend on the phase mask. The first objective of the research project is to be able to go beyond this strong dependance on the phase mask without deteriorating grating quality. This is what really sets apart the technique presented in this thesis from other long fiber Bragg grating fabrication techniques available in the literature. The fundamental approach to obtain ultra long fiber Bragg gratings of arbitrary profile is to replace the scheme of scanning a UV beam across a phase mask to expose a fixed fiber by a scheme where the UV beam and phase mask are fixed and where the fiber is moving instead. To obtain a periodic index variation, the interference pattern itself must be synchronized with the moving fiber. Two variations of this scheme were implanted: the first one using electro-optical phase modulator placed in each arm of a Talbot interferometer and the second one using a phase mask mounted on a piezo electric actuator. A new scheme that imparts fine movements of the interferometer is also implemented for the first time and showed to be essential to achieve high

Plasma etching of electrospun polymeric nanofibres

Energy Technology Data Exchange (ETDEWEB)

Verdonck, Patrick [LSI-PSI-EPUSP, Av. Prof. Luciano Gualberto trav 3, 158, 05508-900 Sao Paulo, SP (Brazil)]. E-mail: verdonck@imec.be; Braga Caliope, Priscila [LSI-PSI-EPUSP, Av. Prof. Luciano Gualberto trav 3, 158, 05508-900 Sao Paulo, SP (Brazil); Moral Hernandez, Emilio del [LSI-PSI-EPUSP, Av. Prof. Luciano Gualberto trav 3, 158, 05508-900 Sao Paulo, SP (Brazil); Silva, Ana Neilde R. da [LSI-PSI-EPUSP, Av. Prof. Luciano Gualberto trav 3, 158, 05508-900 Sao Paulo, SP (Brazil); FATEC-SP, Pca Fernando Prestes, 30 Sao Paulo, SP (Brazil)

2006-10-25

Electrospun polymeric nanofibres have several applications because of their high surface area to volume and high length to diameter ratios. This paper investigates the influence of plasma etching on these fibres and the etching mechanisms. For the characterization, SEM analysis was performed to determine the forms and shapes of the fibres and SEM photos were analysed by the technique of mathematical morphology, in order to determine the area on the sample occupied by the fibres and the frequency distribution of the nanofibre diameters. The results showed that the oxygen plasma etches the nanofibres much faster when ion bombardment is present. The form of the fibres is not altered by the etching, indicating the possibility of transport of oxygen atoms over the fibre surface. The most frequent diameter, somewhat surprisingly, is not significantly dependent on the etching process, and remains of the order of 80 nm, indicating that fibres with smaller diameters are etched at high rates.

Longevity of Self-etch Dentin Bonding Adhesives Compared to Etch-and-rinse Dentin Bonding Adhesives: A Systematic Review.

Science.gov (United States)

Masarwa, Nader; Mohamed, Ahmed; Abou-Rabii, Iyad; Abu Zaghlan, Rawan; Steier, Liviu

2016-06-01

A systematic review and meta-analysis were performed to compare longevity of Self-Etch Dentin Bonding Adhesives to Etch-and-Rinse Dentin Bonding Adhesives. The following databases were searched for PubMed, MEDLINE, Web of Science, CINAHL, the Cochrane Library complemented by a manual search of the Journal of Adhesive Dentistry. The MESH keywords used were: "etch and rinse," "total etch," "self-etch," "dentin bonding agent," "bond durability," and "bond degradation." Included were in-vitro experimental studies performed on human dental tissues of sound tooth structure origin. The examined Self-Etch Bonds were of two subtypes; Two Steps and One Step Self-Etch Bonds, while Etch-and-Rinse Bonds were of two subtypes; Two Steps and Three Steps. The included studies measured micro tensile bond strength (μTBs) to evaluate bond strength and possible longevity of both types of dental adhesives at different times. The selected studies depended on water storage as the aging technique. Statistical analysis was performed for outcome measurements compared at 24 h, 3 months, 6 months and 12 months of water storage. After 24 hours (p-value = 0.051), 3 months (p-value = 0.756), 6 months (p-value=0.267), 12 months (p-value=0.785) of water storage self-etch adhesives showed lower μTBs when compared to the etch-and-rinse adhesives, but the comparisons were statistically insignificant. In this study, longevity of Dentin Bonds was related to the measured μTBs. Although Etch-and-Rinse bonds showed higher values at all times, the meta-analysis found no difference in longevity of the two types of bonds at the examined aging times. Copyright © 2016 Elsevier Inc. All rights reserved.

Bragg polaritons in a ZnSe-based unfolded microcavity at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Sebald, K.; Rahman, SK. S.; Cornelius, M.; Kaya, T.; Gutowski, J. [Semiconductor Optics, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany); Klein, T.; Gust, A.; Hommel, D. [Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen, 28334 Bremen (Germany); Klembt, S. [Institut Néel, Université Grenoble Alpes and CNRS, B.P. 166, 38042 Grenoble (France)

2016-03-21

In this contribution, we present strong coupling of ZnSe quantum well excitons to Bragg modes resulting in the formation of Bragg polariton eigenstates, characterized by a small effective mass in comparison to a conventional microcavity. We observe an anticrossing of the excitonic and the photonic component in our sample being a clear signature for the strong-coupling regime. The anticrossing is investigated by changing the detuning between the excitonic components and the Bragg mode. We find anticrossings between the first Bragg mode and the heavy- as well as light-hole exciton, respectively, resulting in three polariton branches. The observed Bragg-polariton branches are in good agreement with theoretical calculations. The strong indication for the existence of strong coupling is traceable up to a temperature of 200 K, with a Rabi-splitting energy of 24 meV and 13 meV for the Bragg mode with the heavy- and light-hole exciton, respectively. These findings demonstrate the advantages of this sample configuration for ZnSe-based devices for the strong coupling regime.

Comparison of enamel bond fatigue durability of universal adhesives and two-step self-etch adhesives in self-etch mode.

Science.gov (United States)

Tsujimoto, Akimasa; Barkmeier, Wayne W; Hosoya, Yumiko; Nojiri, Kie; Nagura, Yuko; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

2017-10-01

To comparatively evaluate universal adhesives and two-step self-etch adhesives for enamel bond fatigue durability in self-etch mode. Three universal adhesives (Clearfil Universal Bond; G-Premio Bond; Scotchbond Universal Adhesive) and three two-step self-etch adhesives (Clearfil SE Bond; Clearfil SE Bond 2; OptiBond XTR) were used. The initial shear bond strength and shear fatigue strength of the adhesive to enamel in self-etch mode were determined. The initial shear bond strengths of the universal adhesives to enamel in self-etch mode was significantly lower than those of two-step self-etch adhesives and initial shear bond strengths were not influenced by type of adhesive in each adhesive category. The shear fatigue strengths of universal adhesives to enamel in self-etch mode were significantly lower than that of Clearfil SE Bond and Clearfil SE Bond 2, but similar to that OptiBond XTR. Unlike two-step self-etch adhesives, the initial shear bond strength and shear fatigue strength of universal adhesives to enamel in self-etch mode was not influenced by the type of adhesive. This laboratory study showed that the enamel bond fatigue durability of universal adhesives was lower than Clearfil SE Bond and Clearfil SE Bond 2, similar to Optibond XTR, and was not influenced by type of adhesive, unlike two-step self-etch adhesives.

Etching Behavior of Aluminum Alloy Extrusions

Science.gov (United States)

Zhu, Hanliang

2014-11-01

The etching treatment is an important process step in influencing the surface quality of anodized aluminum alloy extrusions. The aim of etching is to produce a homogeneously matte surface. However, in the etching process, further surface imperfections can be generated on the extrusion surface due to uneven materials loss from different microstructural components. These surface imperfections formed prior to anodizing can significantly influence the surface quality of the final anodized extrusion products. In this article, various factors that influence the materials loss during alkaline etching of aluminum alloy extrusions are investigated. The influencing variables considered include etching process parameters, Fe-rich particles, Mg-Si precipitates, and extrusion profiles. This study provides a basis for improving the surface quality in industrial extrusion products by optimizing various process parameters.

Effect of Phosphoric Acid Pre-etching on Fatigue Limits of Self-etching Adhesives.

Science.gov (United States)

Takamizawa, T; Barkmeier, W W; Tsujimoto, A; Scheidel, D D; Erickson, R L; Latta, M A; Miyazaki, M

2015-01-01

The purpose of this study was to use shear bond strength (SBS) and shear fatigue limit (SFL) testing to determine the effect of phosphoric acid pre-etching of enamel and dentin prior to application of self-etch adhesives for bonding resin composite to these substrates. Three self-etch adhesives--1) G- ænial Bond (GC Corporation, Tokyo, Japan); 2) OptiBond XTR (Kerr Corp, Orange, CA, USA); and 3) Scotchbond Universal (3M ESPE Dental Products, St Paul, MN, USA)--were used to bond Z100 Restorative resin composite to enamel and dentin surfaces. A stainless-steel metal ring with an inner diameter of 2.4 mm was used to bond the resin composite to flat-ground (4000 grit) tooth surfaces for determination of both SBS and SFL. Fifteen specimens each were used to determine initial SBS to human enamel/dentin, with and without pre-etching with a 35% phosphoric acid (Ultra-Etch, Ultradent Products Inc, South Jordan, UT, USA) for 15 seconds prior to the application of the adhesives. A staircase method of fatigue testing (25 specimens for each test) was then used to determine the SFL of resin composite bonded to enamel/dentin using a frequency of 10 Hz for 50,000 cycles or until failure occurred. A two-way analysis of variance and Tukey post hoc test were used for analysis of SBS data, and a modified t-test with Bonferroni correction was used for the SFL data. Scanning electron microscopy was used to examine the area of the bonded restorative/tooth interface. For all three adhesive systems, phosphoric acid pre-etching of enamel demonstrated significantly higher (padhesives clearly demonstrated different tendencies between enamel and dentin. The effect of using phosphoric acid, prior to the application of the self-etching adhesives, on SBS and SFL was dependent on the adhesive material and tooth substrate and should be carefully considered in clinical situations.

Birefringence Bragg Binary (3B) grating, quasi-Bragg grating and immersion gratings

Science.gov (United States)

Ebizuka, Noboru; Morita, Shin-ya; Yamagata, Yutaka; Sasaki, Minoru; Bianco, Andorea; Tanabe, Ayano; Hashimoto, Nobuyuki; Hirahara, Yasuhiro; Aoki, Wako

2014-07-01

A volume phase holographic (VPH) grating achieves high angular dispersion and very high diffraction efficiency for the first diffraction order and for S or P polarization. However the VPH grating could not achieve high diffraction efficiency for non-polarized light at a large diffraction angle because properties of diffraction efficiencies for S and P polarizations are different. Furthermore diffraction efficiency of the VPH grating extinguishes toward a higher diffraction order. A birefringence binary Bragg (3B) grating is a thick transmission grating with optically anisotropic material such as lithium niobate or liquid crystal. The 3B grating achieves diffraction efficiency up to 100% for non-polarized light by tuning of refractive indices for S and P polarizations, even in higher diffraction orders. We fabricated 3B grating with liquid crystal and evaluated the performance of the liquid crystal grating. A quasi-Bragg (QB) grating, which consists long rectangle mirrors aligned in parallel precisely such as a window shade, also achieves high diffraction efficiency toward higher orders. We fabricated QB grating by laminating of silica glass substrates and glued by pressure fusion of gold films. A quasi-Bragg immersion (QBI) grating has smooth mirror hypotenuse and reflector array inside the hypotenuse, instead of step-like grooves of a conventional immersion grating. An incident beam of the QBI grating reflects obliquely at a reflector, then reflects vertically at the mirror surface and reflects again at the same reflector. We are going to fabricate QBI gratings by laminating of mirror plates as similar to fabrication of the QB grating. We will also fabricate silicon and germanium immersion gratings with conventional step-like grooves by means of the latest diamond machining methods. We introduce characteristics and performance of these gratings.

Fabrication and Optical Characterization of Silicon Nanostructure Arrays by Laser Interference Lithography and Metal-Assisted Chemical Etching

Directory of Open Access Journals (Sweden)

P. Heydari

2014-10-01

Full Text Available In this paper metal-assisted chemical etching has been applied to pattern porous silicon regions and silicon nanohole arrays in submicron period simply by using positive photoresist as a mask layer. In order to define silicon nanostructures, Metal-assisted chemical etching (MaCE was carried out with silver catalyst. Provided solution (or materiel in combination with laser interference lithography (LIL fabricated different reproducible pillars, holes and rhomboidal structures. As a result, Submicron patterning of porous areas and nanohole arrays on Si substrate with a minimum feature size of 600nm was achieved. Measured reflection spectra of the samples present different optical characteristics which is dependent on the shape, thickness of metal catalyst and periodicity of the structure. These structures can be designed to reach a photonic bandgap in special range or antireflection layer in energy harvesting applications. The resulted reflection spectra of applied method are comparable to conventional expensive and complicated dry etching techniques.

The Effect of Phosphoric Acid Pre-etching Times on Bonding Performance and Surface Free Energy with Single-step Self-etch Adhesives.

Science.gov (United States)

Tsujimoto, A; Barkmeier, W W; Takamizawa, T; Latta, M A; Miyazaki, M

2016-01-01

The purpose of this study was to evaluate the effect of phosphoric acid pre-etching times on shear bond strength (SBS) and surface free energy (SFE) with single-step self-etch adhesives. The three single-step self-etch adhesives used were: 1) Scotchbond Universal Adhesive (3M ESPE), 2) Clearfil tri-S Bond (Kuraray Noritake Dental), and 3) G-Bond Plus (GC). Two no pre-etching groups, 1) untreated enamel and 2) enamel surfaces after ultrasonic cleaning with distilled water for 30 seconds to remove the smear layer, were prepared. There were four pre-etching groups: 1) enamel surfaces were pre-etched with phosphoric acid (Etchant, 3M ESPE) for 3 seconds, 2) enamel surfaces were pre-etched for 5 seconds, 3) enamel surfaces were pre-etched for 10 seconds, and 4) enamel surfaces were pre-etched for 15 seconds. Resin composite was bonded to the treated enamel surface to determine SBS. The SFEs of treated enamel surfaces were determined by measuring the contact angles of three test liquids. Scanning electron microscopy was used to examine the enamel surfaces and enamel-adhesive interface. The specimens with phosphoric acid pre-etching showed significantly higher SBS and SFEs than the specimens without phosphoric acid pre-etching regardless of the adhesive system used. SBS and SFEs did not increase for phosphoric acid pre-etching times over 3 seconds. There were no significant differences in SBS and SFEs between the specimens with and without a smear layer. The data suggest that phosphoric acid pre-etching of ground enamel improves the bonding performance of single-step self-etch adhesives, but these bonding properties do not increase for phosphoric acid pre-etching times over 3 seconds.

Development of variable-magnification X-ray Bragg optics.

Science.gov (United States)

Hirano, Keiichi; Yamashita, Yoshiki; Takahashi, Yumiko; Sugiyama, Hiroshi

2015-07-01

A novel X-ray Bragg optics is proposed for variable-magnification of an X-ray beam. This X-ray Bragg optics is composed of two magnifiers in a crossed arrangement, and the magnification factor, M, is controlled through the azimuth angle of each magnifier. The basic properties of the X-ray optics such as the magnification factor, image transformation matrix and intrinsic acceptance angle are described based on the dynamical theory of X-ray diffraction. The feasibility of the variable-magnification X-ray Bragg optics was verified at the vertical-wiggler beamline BL-14B of the Photon Factory. For X-ray Bragg magnifiers, Si(220) crystals with an asymmetric angle of 14° were used. The magnification factor was calculated to be tunable between 0.1 and 10.0 at a wavelength of 0.112 nm. At various magnification factors (M ≥ 1.0), X-ray images of a nylon mesh were observed with an air-cooled X-ray CCD camera. Image deformation caused by the optics could be corrected by using a 2 × 2 transformation matrix and bilinear interpolation method. Not only absorption-contrast but also edge-contrast due to Fresnel diffraction was observed in the magnified images.

Copper-assisted, anti-reflection etching of silicon surfaces

Science.gov (United States)

Toor, Fatima; Branz, Howard

2014-08-26

A method (300) for etching a silicon surface (116) to reduce reflectivity. The method (300) includes electroless deposition of copper nanoparticles about 20 nanometers in size on the silicon surface (116), with a particle-to-particle spacing of 3 to 8 nanometers. The method (300) includes positioning (310) the substrate (112) with a silicon surface (116) into a vessel (122). The vessel (122) is filled (340) with a volume of an etching solution (124) so as to cover the silicon surface (116). The etching solution (124) includes an oxidant-etchant solution (146), e.g., an aqueous solution of hydrofluoric acid and hydrogen peroxide. The silicon surface (116) is etched (350) by agitating the etching solution (124) with, for example, ultrasonic agitation, and the etching may include heating (360) the etching solution (124) and directing light (365) onto the silicon surface (116). During the etching, copper nanoparticles enhance or drive the etching process.

Excitation of surface electromagnetic waves in a graphene-based Bragg grating.

Science.gov (United States)

Sreekanth, Kandammathe Valiyaveedu; Zeng, Shuwen; Shang, Jingzhi; Yong, Ken-Tye; Yu, Ting

2012-01-01

Here, we report the fabrication of a graphene-based Bragg grating (one-dimensional photonic crystal) and experimentally demonstrate the excitation of surface electromagnetic waves in the periodic structure using prism coupling technique. Surface electromagnetic waves are non-radiative electromagnetic modes that appear on the surface of semi-infinite 1D photonic crystal. In order to fabricate the graphene-based Bragg grating, alternating layers of high (graphene) and low (PMMA) refractive index materials have been used. The reflectivity plot shows a deepest, narrow dip after total internal reflection angle corresponds to the surface electromagnetic mode propagating at the Bragg grating/air boundary. The proposed graphene based Bragg grating can find a variety of potential surface electromagnetic wave applications such as sensors, fluorescence emission enhancement, modulators, etc.

Plasma etching: Yesterday, today, and tomorrow

Energy Technology Data Exchange (ETDEWEB)

Donnelly, Vincent M.; Kornblit, Avinoam [Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204 (United States)

2013-09-15

The field of plasma etching is reviewed. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as the mid 1960s and more widely in the early 1970s, in an effort to reduce liquid waste disposal in manufacturing and achieve selectivities that were difficult to obtain with wet chemistry. Quickly, the ability to anisotropically etch silicon, aluminum, and silicon dioxide in plasmas became the breakthrough that allowed the features in integrated circuits to continue to shrink over the next 40 years. Some of this early history is reviewed, and a discussion of the evolution in plasma reactor design is included. Some basic principles related to plasma etching such as evaporation rates and Langmuir–Hinshelwood adsorption are introduced. Etching mechanisms of selected materials, silicon, silicon dioxide, and low dielectric-constant materials are discussed in detail. A detailed treatment is presented of applications in current silicon integrated circuit fabrication. Finally, some predictions are offered for future needs and advances in plasma etching for silicon and nonsilicon-based devices.

Plasma etching: Yesterday, today, and tomorrow

International Nuclear Information System (INIS)

Donnelly, Vincent M.; Kornblit, Avinoam

2013-01-01

The field of plasma etching is reviewed. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as the mid 1960s and more widely in the early 1970s, in an effort to reduce liquid waste disposal in manufacturing and achieve selectivities that were difficult to obtain with wet chemistry. Quickly, the ability to anisotropically etch silicon, aluminum, and silicon dioxide in plasmas became the breakthrough that allowed the features in integrated circuits to continue to shrink over the next 40 years. Some of this early history is reviewed, and a discussion of the evolution in plasma reactor design is included. Some basic principles related to plasma etching such as evaporation rates and Langmuir–Hinshelwood adsorption are introduced. Etching mechanisms of selected materials, silicon, silicon dioxide, and low dielectric-constant materials are discussed in detail. A detailed treatment is presented of applications in current silicon integrated circuit fabrication. Finally, some predictions are offered for future needs and advances in plasma etching for silicon and nonsilicon-based devices

[Evaluation of shear bond strengths of self-etching and total-etching dental adhesives to enamel and dentin].

Science.gov (United States)

Yu, Ling; Liu, Jing-Ming; Wang, Xiao-Yan; Gao, Xue-Jun

2009-03-01

To evaluate the shear bond strengths of four dental adhesives in vitro. The facial surfaces of 20 human maxillary incisors were prepared to expose fresh enamel and randomly divided into four groups, in each group 5 teeth were bonded with one adhesives: group A (Clearfil Protect Bond, self-etching two steps), group B (Adper( Prompt, self-etching one step), group C (SwissTEC SL Bond, total-etching two steps), group D (Single Bond, total-etching two steps). Shear bond strengths were determined using an universal testing machine after being stored in distilled water for 24 h at 37 degrees C. The bond strengths to enamel and dentin were (25.33 +/- 2.84) and (26.07 +/- 5.56) MPa in group A, (17.08 +/- 5.13) and (17.93 +/- 4.70) MPa in group B, (33.14 +/- 6.05) and (41.92 +/- 6.25) MPa in group C, (22.51 +/- 6.25) and (21.45 +/- 7.34) MPa in group D. Group C showed the highest and group B the lowest shear bond strength to enamel and dentin among the four groups. The two-step self-etching adhesive showed comparable shear bond strength to some of the total-etching adhesives and higher shear bond strength than one-step self-etching adhesive.

Optical fibre Bragg grating recorded in TOPAS cyclic olefin copolymer

DEFF Research Database (Denmark)

Johnson, I.P.; Yuan, Scott Wu; Stefani, Alessio

2011-01-01

A report is presented on the inscription of a fibre Bragg grating into a microstructured polymer optical fibre fabricated from TOPAS cyclic olefin copolymer. This material offers two important advantages over poly (methyl methacrylate), which up to now has formed the basis for polymer fibre Bragg...

Novel thermal annealing methodology for permanent tuning polymer optical fiber Bragg gratings to longer wavelengths.

Science.gov (United States)

Pospori, A; Marques, C A F; Sagias, G; Lamela-Rivera, H; Webb, D J

2018-01-22

The Bragg wavelength of a polymer optical fiber Bragg grating can be permanently shifted by utilizing the thermal annealing method. In all the reported fiber annealing cases, the authors were able to tune the Bragg wavelength only to shorter wavelengths, since the polymer fiber shrinks in length during the annealing process. This article demonstrates a novel thermal annealing methodology for permanently tuning polymer optical fiber Bragg gratings to any desirable spectral position, including longer wavelengths. Stretching the polymer optical fiber during the annealing process, the period of Bragg grating, which is directly related with the Bragg wavelength, can become permanently longer. The methodology presented in this article can be used to multiplex polymer optical fiber Bragg gratings at any desirable spectral position utilizing only one phase-mask for their photo-inscription, reducing thus their fabrication cost in an industrial setting.

High-density plasma-induced etch damage of wafer-bonded AlGaInP/mirror/Si light-emitting diodes

CERN Document Server

Wuu, D S; Huang, S H; Chung, C R

2002-01-01

Dry etch of wafer-bonded AlGaInP/mirror/Si light-emitting diodes (LEDs) with planar electrodes was performed by high-density plasma using an inductively coupled plasma (ICP) etcher. The etching characteristics were investigated by varying process parameters such as Cl sub 2 /N sub 2 gas combination, chamber pressure, ICP power and substrate-bias power. The corresponding plasma properties (ion flux and dc bias), in situ measured by a Langmuir probe, show a strong relationship to the etch results. With a moderate etch rate of 1.3 mu m/min, a near vertical and smooth sidewall profile can be achieved under a Cl sub 2 /(Cl sub 2 +N sub 2) gas mixture of 0.5, ICP power of 800 W, substrate-bias power of 100 W, and chamber pressure of 0.67 Pa. Quantitative analysis of the plasma-induced damage was attempted to provide a means to study the mechanism of leakage current and brightness with various dc bias voltages (-110 to -328 V) and plasma duration (3-5 min) on the wafer-bonded LEDs. It is found that the reverse leaka...

Bragg gratings: Optical microchip sensors

Science.gov (United States)

Watts, Sam

2010-07-01

A direct UV writing technique that can create multiple Bragg gratings and waveguides in a planar silica-on-silicon chip is enabling sensing applications ranging from individual disposable sensors for biotechnology through to multiplexed sensor networks in pharmaceutical manufacturing.

Zeonex Microstructured Polymer Optical Fibre Bragg Grating Sensor

DEFF Research Database (Denmark)

Woyessa, Getinet; Fasano, Andrea; Markos, Christos

2016-01-01

We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time.......We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time....

Long-term bond strength of adhesive systems applied to etched and deproteinized dentin

Directory of Open Access Journals (Sweden)

Ninoshka Uceda-Gómez

2007-12-01

Full Text Available The aim of this study was to evaluate the early and 12-month bond strength of two adhesive systems (Single Bond-SB and One Step-OS applied to demineralized dentin (WH and demineralized/NaOCl-treated dentin (H. Twenty flat dentin surfaces were exposed, etched, rinsed and slightly dried. For the H groups, a solution of 10% NaOCl was applied for 60 s, rinsed (15 s and slightly dried. The adhesives were applied according to the manufacturer's instructions and composite resin crowns were incrementally constructed. After 24 h (water-37ºC, the specimens was sectioned in order to obtain resin-dentin sticks (0.8 mm². The specimens were tested in microtensile (0.5 mm/min immediately (IM or after 12 months of water storage (12M. The data (MPa were subjected to ANOVA and Tukey's test (a=0.05. Only the main factors adhesive and time were significant (p=0.004 and p=0.003, respectively. SB (42.3±9.1 showed higher bond strengths than OS (33.6±11.6. The mean bond strength for IM-group (42.5±8.7 was statistically superior to 12M (33.3±11.8. The use of 10% NaOCl, after acid etching, did not improve the immediate and the long-term resin-dentin bond strength.

Laterally coupled distributed feedback lasers emitting at 2 μm with quantum dash active region and high-duty-cycle etched semiconductor gratings

Science.gov (United States)

Papatryfonos, Konstantinos; Saladukha, Dzianis; Merghem, Kamel; Joshi, Siddharth; Lelarge, Francois; Bouchoule, Sophie; Kazazis, Dimitrios; Guilet, Stephane; Le Gratiet, Luc; Ochalski, Tomasz J.; Huyet, Guillaume; Martinez, Anthony; Ramdane, Abderrahim

2017-02-01

Single-mode diode lasers on an InP(001) substrate have been developed using InAs/In0.53Ga0.47As quantum dash (Qdash) active regions and etched lateral Bragg gratings. The lasers have been designed to operate at wavelengths near 2 μm and exhibit a threshold current of 65 mA for a 600 μm long cavity, and a room temperature continuous wave output power per facet >5 mW. Using our novel growth approach based on the low ternary In0.53Ga0.47As barriers, we also demonstrate ridge-waveguide lasers emitting up to 2.1 μm and underline the possibilities for further pushing the emission wavelength out towards longer wavelengths with this material system. By introducing experimentally the concept of high-duty-cycle lateral Bragg gratings, a side mode suppression ratio of >37 dB has been achieved, owing to an appreciably increased grating coupling coefficient of κ ˜ 40 cm-1. These laterally coupled distributed feedback (LC-DFB) lasers combine the advantage of high and well-controlled coupling coefficients achieved in conventional DFB lasers, with the regrowth-free fabrication process of lateral gratings, and exhibit substantially lower optical losses compared to the conventional metal-based LC-DFB lasers.

The chemical and electrochemical anisotropic etching of silicon

International Nuclear Information System (INIS)

Dixon, E.

1997-06-01

The success of silicon IC technology in producing a wide variety of microstructures relies heavily on the orientation dependant etching observed for silicon in alkaline media. Despite the rapid growth of this industry, the chemical and electrochemical mechanisms by which anisotropic etching occurs remain poorly understood. The most common etchant systems in use are ethylenediamine-pyrocatechol-water (EPW) and potassium hydroxide-isopropanol-water (KOH-IPA), and whilst these systems are highly plane selective they each have distinct disadvantages. The occurrence of inhomogeneities such as micropyramids and pits on the surface of etched substrates is a particularly disadvantageous characteristic of many alkaline etching systems. A complete understanding of the chemical and electrochemical anisotropic etching mechanisms is essential in order to obtain more reproducible etching, improved etch rate ratios and the development of more reliable etching baths. Wet chemical etching experiments to evaluate the etching rates for the different alkali metal cations have shown that similar etch rates are observed for LiOH, NaOH and KOH but those of RbOH and CsOH are significantly lower. The presence of impurities was shown to worsen the etched wafer's surface finish obtained in these etching baths. Additives have been shown to dramatically improve the surface finish with the presence of IPA in conjunction with etchant oxygenation virtually eliminating all surface defects. Electrochemical experiments were used to assess the electrochemical behaviour of Si p-(100) in of a wide variety of etchants and variations were seen according to the etchant used. A.C impedance spectroscopy showed a variation in the flat-band potential (V FB ) according to alkali metal hydroxide etchant used. These trends were similarly observed in the presence of isopropanol. Oxygenation was observed to reproducibly alter the flat-band potentials. A.c impedance spectroscopic studies additionally confirmed the

Plasma etching of niobium-SiO/sub x/ layers

International Nuclear Information System (INIS)

Schelle, D.; Tiller, H.J.

1986-01-01

CF 4 -plasma etching of niobium and SiO/sub x/ layers has been investigated in a r.f. diode reactor. Etch rates increase linearly with increasing power density and also increase with pressure. The etch rate ratio can be changed using different etch gases or operating in different plasma modes (PE or IEPE). Changing from the ion enhanced plasma etching mode (IEPE) to plasma etching mode (PE) the etch rate ratio is changing by a factor of ten. On the basis of etch rate dependences on process parametes and thermodynamic data it has been suggested the generation of fluorine radicals as the rate limiting step. A general etching model has been proposed, which explains qualitatively and quantitatively (on account of data from literature) the measured results. (author)

Optical single sideband modulation radio over fiber system by using a fiber-Bragg-grating-based acousto-optic filter

Science.gov (United States)

Gao, Song; Pei, Li; Li, Zhuoxuan; Liu, Chao; Wang, Yiqun; Weng, Sijun

2013-03-01

An optical single sideband (OSSB) modulation radio over a fiber system, by using an acousto-optic filter (AOF), is proposed and demonstrated. In the AOF, a uniform fiber Bragg grating is etched and modulated by an axially propagating acoustic wave. Due to the acousto-optic superlattice modulation, two secondary reflection peaks, centered on the primary reflection peak, are generated. In the scheme, an optical double-sideband signal passes though the AOF to realize OSSB modulation. Because the reflect depth of the primary peak is much deeper than those of the secondary peaks, the carrier experiences higher attenuation than the upper sideband, which means the carrier-to-sideband ratio (CSR) can be optimized at the same time. We demonstrate this scheme via simulations, and successfully reduce the CSR from 9.73 to 2.9 dB. As a result, the receiving sensitivity improved from -23.43 to -31.18 dBm at BER of 10-9 with 30 km long SMF.

Evaluation of Pentafluoroethane and 1,1-Difluoroethane for a Dielectric Etch Application in an Inductively Coupled Plasma Etch Tool

Science.gov (United States)

Karecki, Simon; Chatterjee, Ritwik; Pruette, Laura; Reif, Rafael; Sparks, Terry; Beu, Laurie; Vartanian, Victor

2000-07-01

In this work, a combination of two hydrofluorocarbon compounds, pentafluoroethane (FC-125, C2HF5) and 1,1-difluoroethane (FC-152a, CF2H-CH3), was evaluated as a potential replacement for perfluorocompounds in dielectric etch applications. A high aspect ratio oxide via etch was used as the test vehicle for this study, which was conducted in a commercial inductively coupled high density plasma etch tool. Both process and emissions data were collected and compared to those provided by a process utilizing a standard perfluorinated etch chemistry (C2F6). Global warming (CF4, C2F6, CHF3) and hygroscopic gas (HF, SiF4) emissions were characterized using Fourier transform infrared (FTIR) spectroscopy. FC-125/FC-152a was found to produce significant reductions in global warming emissions, on the order of 68 to 76% relative to the reference process. Although etch stopping, caused by a high degree of polymer deposition inside the etched features, was observed, process data otherwise appeared promising for an initial study, with good resist selectivity and etch rates being achieved.

Guiding Properties of Silica/Air Hollow-Core Bragg Fibers

DEFF Research Database (Denmark)

Foroni, Matteo; Passaro, Davide; Poli, Federica

2008-01-01

The guiding properties of realistic silica/air hollow-core Bragg fibers have been investigated by calculating the dispersion curves, the confinement loss spectrum and the field distribution of the guided modes through a full-vector modal solver based on the finite element method. In particular, t...... the different possible applications, the feasibility of a DNA bio-sensor based on a hollow-core Bragg fiber has been demonstrated....

Bragg solitons in systems with separated nonuniform Bragg grating and nonlinearity

Science.gov (United States)

Ahmed, Tanvir; Atai, Javid

2017-09-01

The existence and stability of quiescent Bragg grating solitons are systematically investigated in a dual-core fiber, where one of the cores is uniform and has Kerr nonlinearity while the other one is linear and incorporates a Bragg grating with dispersive reflectivity. Three spectral gaps are identified in the system, in which both lower and upper band gaps overlap with one branch of the continuous spectrum; therefore, these are not genuine band gaps. However, the central band gap is a genuine band gap. Soliton solutions are found in the lower and upper gaps only. It is found that in certain parameter ranges, the solitons develop side lobes. To analyze the side lobes, we have derived exact analytical expressions for the tails of solitons that are in excellent agreement with the numerical solutions. We have analyzed the stability of solitons in the system by means of systematic numerical simulations. We have found vast stable regions in the upper and lower gaps. The effect and interplay of dispersive reflectivity, the group velocity difference, and the grating-induced coupling on the stability of solitons are investigated. A key finding is that a stronger grating-induced coupling coefficient counteracts the stabilization effect of dispersive reflectivity.

Bio-inspired nanobowl/nanoball structures fabricated via solvent etching/swelling on nanosphere assembly patterns

Energy Technology Data Exchange (ETDEWEB)

Chang, Wan-Yi; Liu, Pang-Hsin; Wu, You [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 811, Taiwan, ROC (China); Chung, Yi-Chang, E-mail: ycchung@nuk.edu.tw [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 811, Taiwan, ROC (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC (China)

2014-11-03

Ordered self-assembled nanopatterns have attracted much attention for their ability to mimic moth-eye structures and display unique optical properties. In the study, emulsifier-free emulsion polymerization was performed to prepare polystyrene nanospheres with uniform size distribution. Various hydrophilic monomers were added to copolymerize with styrene, including 2-hydroxyethyl methacrylate, acrylic acid, and methyl acrylic acid, respectively, to enhance the self-assembling ability of nanospheres. The nanosphere suspension was injected into an air–water interface to self-assemble a nanosphere array, and then the resulting photonic crystal film was deposited on a substrate using a scooping transfer technique. The layer-by-layer scooping transfer technique can be applied to produce 2D and 3D assembled nanosphere layers on an area as large as a 4-inch wafer. The pattern of the 2D nanosphere array was attached to a UV-curable precursor surface and then encapsulated and transferred to the crosslinked resin after UV irradiation. The sample was then immersed into some solvents which could partially swell the resin surface to produce nanoball structures or etch the surface to generate nanobowl structures. The size of the as-prepared polystyrene spheres was about 360 nm, while the feature size of the nanoballs was about 230 nm after undergoing acetonitrile swelling. The facile and inexpensive technique can be applied to produce ordered nanoball patterns for various applications, such as optical coatings, superhydrophobic coatings, biophotosensors, antireflection films, dry adhesives, and so on. - Highlights: • We prepared core-shell PS nanosphere suspensions with narrow-size-distribution. • We employed a scooping technique to fabricate large-area nanosphere monolayers. • Swelling by acetonitrile formed nanoballs on a UV resin/nanosphere laminated layer. • Etching by toluene produced nanobowl on the UV resin/nanosphere laminated layer. • The parted nanoball

Pemodelan Tapis Fabry-perot pada Serat Optik dengan Menggunakan Fiber Bragg Grating

OpenAIRE

Pramuliawati, Septi; ', Saktioto; ', Defrianto

2015-01-01

Fabry-perot filter was successfully developed by a uniform Fiber Bragg Grating in fiber optic. A characterization of Bragg Grating was analyzed by using computational model with second-order of Transfer Matrix Method based on Coupled Mode Theory. The reflectivity, length of grating, and bandwidth were parametrics to determine the performance of single Bragg Grating. The transmission spectrum showed the longer grating is designed, the larger the reflectivity was produced, so that the transmiss...

Kinetics of varnish long-term drying process monitored by a heterogeneous optical sensor system

International Nuclear Information System (INIS)

Saccon, F A M; De Oliveira, F M D R; Ribas, M O; Zambianchi, P Jr; Muller, M; Fabris, J L

2013-01-01

The drying process of an acrylic varnish film was monitored over 24 h by a heterogeneous optical sensor system. The system employs a fibre optic transducer based on Bragg gratings and optical coherence tomography, operating respectively around 1.55 and 1.3 µm. The sensor is able to provide information about the temporal evolution of temperature, mechanical deformation, thickness and average refractive index of the coating during the drying process. Resolutions for these optically measured parameters are 0.05 °C (temperature), 0.5 µε (strain), 1.5 µm (thickness) and 0.004 (refractive index). Besides, the sensor can detect the growth of a surface dry skin and supply information about the film bulk uniformity. A model for the mass loss of solvent as the drying process evolves is also discussed. (paper)

Deep Reactive Ion Etching (DRIE) of High Aspect Ratio SiC Microstructures using a Time-Multiplexed Etch-Passivate Process

Science.gov (United States)

Evans, Laura J.; Beheim, Glenn M.

2006-01-01

High aspect ratio silicon carbide (SiC) microstructures are needed for microengines and other harsh environment micro-electro-mechanical systems (MEMS). Previously, deep reactive ion etching (DRIE) of low aspect ratio (AR less than or = 1) deep (greater than 100 micron) trenches in SiC has been reported. However, existing DRIE processes for SiC are not well-suited for definition of high aspect ratio features because such simple etch-only processes provide insufficient control over sidewall roughness and slope. Therefore, we have investigated the use of a time-multiplexed etch-passivate (TMEP) process, which alternates etching with polymer passivation of the etch sidewalls. An optimized TMEP process was used to etch high aspect ratio (AR greater than 5) deep (less than 100 micron) trenches in 6H-SiC. Power MEMS structures (micro turbine blades) in 6H-SiC were also fabricated.

Silicon germanium mask for deep silicon etching

KAUST Repository

Serry, Mohamed

2014-07-29

Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

Silicon germanium mask for deep silicon etching

KAUST Repository

Serry, Mohamed; Rubin, Andrew; Refaat, Mohamed; Sedky, Sherif; Abdo, Mohammad

2014-01-01

Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

Morphological Evaluation of the Adhesive/Enamel interfaces of Two-step Self-etching Adhesives and Multimode One-bottle Self-etching Adhesives.

Science.gov (United States)

Sato, Takaaki; Takagaki, Tomohiro; Matsui, Naoko; Hamba, Hidenori; Sadr, Alireza; Nikaido, Toru; Tagami, Junji

To evaluate the acid-base resistant zone (ABRZ) at the adhesive/enamel interface of self-etching adhesives with or without prior phosphoric acid etching. Four adhesives were used in 8 groups: Clearfil SE Bond (SEB), Optibond XTR (XTR), Scotchbond Universal Adhesive (SBU), and Clearfil BOND SE ONE (ONE) without prior phosphoric-acid etching, and each adhesive with phosphoric acid etching for 10 s (P-SEB, P-XTR, P-SBU and P-ONE, respectively). After application of self-etching adhesives on ground enamel surfaces of human teeth, a flowable composite was placed. For observation of the acid-base resistant zone (ABRZ), the bonded interface was exposed to demineralizing solution (pH 4.5) for 4.5 h, followed by 5% NaOCl with ultrasonication for 20 min. After the acid-base challenge, morphological attributes of the interface were observed using SEM. ABRZ formation was confirmed in all groups. The funnel-shaped erosion beneath the interface was present in SBU and ONE, where nearly 10 to 15 μm of enamel was dissolved. With phosphoric acid etching, the ABRZs were obviously thicker compared with no phosphoric acid etching. Enamel beneath the bonding interface was more susceptible to acid dissolution in SBU and ONE. In the case of the one-bottle self-etching adhesives and universal adhesives that intrinsically have higher pH values, enamel etching should be recommended to improve the interfacial quality.

Optical diagnostics for plasma etching

NARCIS (Netherlands)

Bisschops, T.H.J.; Kroesen, G.M.W.; Veldhuizen, van E.M.; de Zeeuw, C.J.H.; Timmermans, C.J.

1985-01-01

Several optical diagnostics were used to det. plasma properties and etch rates in an single wafer etch reactor. Results of UV-visible spectroscopy and IR absorption spectroscopy, indicating different mol. species and their densities are presented. The construction of an interferometer to det. the

Quasi-Bragg diffraction of atoms

NARCIS (Netherlands)

Domen, K.F.E.M.; Jansen, M.A.H.M.; Leeuwen, van K.A.H.

2006-01-01

We report on a novel atomic beamsplitter. It combines the advantages of Bragg scattering (transfer possible into a single, very high diffraction order due to adiabatic conservation of ‘transverse kinetic energy’) with the convenience of tuning the splitting angle simply by adjusting a magnetic

Physicochemical characteristics of PFC surfactants for dry decontamination

Energy Technology Data Exchange (ETDEWEB)

Oh, Won Jin; Lee, Chi Woo [Korea University, Seoul (Korea)

2001-04-01

Even the trace amount of the used nuclear fuels of high radioactivity are hazardous to the earth and humans. Perfluorocarbons and perfluorocarbon surfactants are emerging to be efficient chemicals in the dry decontamination process of the used fuels of high radioactivity. The theme was undertaken to increase the knowledge on perfluorocarbon surfactants to develop the perfluorocarbon system in the dry decontamination process in Korea. Several cationic and anionic pfc surfactants were synthesized. Effects of pfc surfactants on electrochemical etching of silicon were investigated to form porous silicons. Forces were measured between silicon surfaces and AFM tip in the absence and presence of pfc surfactants. 7 refs., 10 figs. (Author)

Crystal growth vs. conventional acid etching: A comparative evaluation of etch patterns, penetration depths, and bond strengths

Directory of Open Access Journals (Sweden)

Devanna Raghu

2008-01-01

Full Text Available The present study was undertaken to investigate the effect on enamel surface, penetration depth, and bond strength produced by 37% phosphoric acid and 20% sulfated polyacrylic acid as etching agents for direct bonding. Eighty teeth were used to study the efficacy of the etching agents on the enamel surface, penetration depth, and tensile bond strength. It was determined from the present study that a 30 sec application of 20% sulfated polyacrylic acid produced comparable etching topography with that of 37% phosphoric acid applied for 30 sec. The 37% phosphoric acid dissolves enamel to a greater extent than does the 20% sulfated polyacrylic acid. Instron Universal testing machine was used to evaluate the bond strengths of the two etching agents. Twenty percent sulfated polyacrylic acid provided adequate tensile bond strength. It was ascertained that crystal growth can be an alternative to conventional phosphoric acid etching as it dissolves lesser enamel and provides adequate tensile bond strength.

Bulk and track etching of PET studied by spectrophotometer

International Nuclear Information System (INIS)

Zhu, Z.Y.; Duan, J.L.; Maekawa, Y.; Koshikawa, H.; Yoshida, M.

2004-01-01

UV-VIS spectra of poly(ethylene terephthalate) (PET) solutions formed by etching PET in NaOH solution were analyzed with respect to the etching time. A linear relationship between absorptions centered at 4.45 and 5.11 eV with weight loss of PET in NaOH solution was established. The relation was applied to study the influence of UV light illumination on bulk etching of PET and to evaluate pore size of etched-through tracks. It is found that bulk etching of PET can be greatly enhanced by UV illumination in air in the wavelength range around 313 nm. A surface area of about 350 nm in thickness shows a 23 times increase in bulk-etching rate after illuminated for 6 h. The phenomenon is attributed to the oxygen-assisted photo-degradation through generating of new photo-unstable species. The enhancement in bulk etching was immediately reduced as the etching proceeds below the surface with an exponential decay constant of about 1.5 μm -1 . Etching of Xe ion irradiated PET films gives extra etching products with similar chemical structure as revealed by spectrophotometer measurements. Quantitative analysis of etching products from latent tracks implies that pores of about 14.6 nm in radius are formed after etching in 0.74 N NaOH at 40 deg. C for 35 min, which is in agreement with the conductometric measurement

Bragg diffraction of fermions at optical potentials; Braggbeugung von Fermionen an optischen Potentialen

Energy Technology Data Exchange (ETDEWEB)

Deh, Benjamin

2008-10-27

This thesis describes the Bragg diffraction of ultracold fermions at an optical potential. A moving optical lattice was created, by overlaying two slightly detuned lasers. Atoms can be diffracted at this lattice if the detuning fulfills the Bragg condition for resting atoms. This Bragg diffraction is analyzed systematically in this thesis. To this end Rabi oscillations between the diffraction states were driven, as well in the weakly interacting Bragg regime, as in the strongly interacting Kapitza-Dirac regime. Simulations, based on a driven two-, respectively multilevel-system describe the observed effects rather well. Furthermore, the temporal evolution of the diffracted states in the magnetic trapping potential was studied. The anharmonicity of the trap in use and the scattering cross section for p-wave collisions in a {sup 6}Li system was determined from the movement of these states. Moreover the momentum distribution of the fermions was measured with Bragg spectroscopy and first signs of Fermi degeneracy were found. Finally an interferometer with fermions was build, exhibiting a coherence time of more than 100 {mu}s. With this, the possibility for measurement and manipulation of ultracold fermions with Bragg diffraction could bee shown. (orig.)

An In Vitro Evaluation of Leakage of Two Etch and Rinse and Two Self-Etch Adhesives after Thermocycling

Science.gov (United States)

Geerts, Sabine; Bolette, Amandine; Seidel, Laurence; Guéders, Audrey

2012-01-01

Our experiment evaluated the microleakage in resin composite restorations bonded to dental tissues with different adhesive systems. 40 class V cavities were prepared on the facial and lingual surfaces of each tooth with coronal margins in enamel and apical margins in cementum (root dentin). The teeth were restored with Z100 resin composite bonded with different adhesive systems: Scotchbond Multipurpose (SBMP), a 3-step Etch and Rinse adhesive, Adper Scotchbond 1 XT (SB1), a 2-step Etch and Rinse adhesive, AdheSE One (ADSE-1), a 1-step Self-Etch adhesive, and AdheSE (ADSE), a 2-step Self-Etch adhesive. Teeth were thermocycled and immersed in 50% silver nitrate solution. When both interfaces were considered, SBMP has exhibited significantly less microleakage than other adhesive systems (resp., for SB1, ADSE-1 and ADSE, P = 0.0007, P adhesives, microleakage was found greater at enamel than at dentin interfaces (for ADSE, P = 0.024 and for ADSE-1, P adhesive systems, there was no significant difference between enamel and dentin interfaces; (3) SBMP was found significantly better than other adhesives both at enamel and dentin interfaces. In our experiment Etch and Rinse adhesives remain better than Self-Etch adhesives at enamel interface. In addition, there was no statistical difference between 1-step (ADSE-1) and 2-step (ADSE) Self-Etch adhesives. PMID:22675358

Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

DEFF Research Database (Denmark)

Min, Rui; Marques, Carlos; Bang, Ole

2018-01-01

We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different...

Design and UV writing of advanced Bragg gratings in optical fibers

DEFF Research Database (Denmark)

Plougmann, Nikolai

2004-01-01

: · Development of a novel polarization control method for UV writing of advanced Bragg gratings with arbitrary refractive index modulation profile including multiple pi-phase shifts. · Development of a novel efficient technique for Bragg grating design which allows calculating an index modulation profile...

Comparative evaluation of self-etching primers and phosphoric acid effectiveness on composite to enamel bond: an in vitro study.

Science.gov (United States)

Patil, Basanagouda S; Rao, Bk Raghavendra; Sharathchandra, Sm; Hegde, Reshma; Kumar, G Vinay

2013-09-01

The aim of the present study was to investigate the effectiveness of the one total-etch self-priming adhesive, one two-step self-etching primer adhesive, and one 'all-in-one' self-etching adhesive system on the adhesion of a resin composite to enamel. Thirty-six freshly extracted human mandibular molars were selected for this study. A fat area about 5 mm in diameter was created on the exposed mesial surface of enamel of each tooth by moist grinding with 320, 420 and 600 grit silicon carbide paper. Twelve teeth were randomly assigned into three groups. In group 1, Adper Easy One (3M ESPE), a one step self-etching primer adhesive was applied and light curing unit for 10 seconds. In group 2, Adper SE Plus, a two-step self-etching primer with bottle A containing the aqueous primer and bottle B containing the acidic adhesive was applied and light cured for 10 seconds. Group 3 (control)-etchant 37% phosphoric acid is applied to the surface for 15 seconds and rinsed with water and air dried and adhesive (single bond 2) is applied to the surface and tube is placed and light cured for 20 seconds. Composite material (Z350) was placed in the tube and light cured for 40 seconds in all the groups. Bond strength testing was done using universal testing machine at the enamel-composite interface. The debonded enamel surface was evaluated in stereomicroscope to assess the cohesive, adhesive or mixed fracture. Data was statistically analyzed by one way analysis of variance (ANOVA). Group 1 performed least among all groups with a mean score of 19.46 MPa. Group 2 had a mean score of 25.67 MPa. Group 3 had a mean score of 27.16 MPa. Under the conditions of this in vitro study, the bond strength values of the two-step self-etching primer systems tested were similar to the total-etch. And, one step self-etching primers have lower bond strength compared to the total-etch.

Influence of Non-uniform Temperature Field on Spectra of Fibre Bragg Grating

International Nuclear Information System (INIS)

Yan, Zhou; Xing-Fang, He; Xiao-Yong, Fang; Jie, Yuan; Li-Qun, Yin; Mao-Sheng, Cao

2009-01-01

We simulate the spectrum characteristics of fibre Bragg grating (FBG) with non-uniform temperature using the transmission matrix method, and the results are analysed. It is found that firstly the modulated coefficient of average refractive index is a very important parameter that influences the spectrum characteristic of the fibre Bragg grating, and secondly the spectrum curves are different in different temperature fields at the same parameter. Hence, we can determine the metrical temperature by analysing the spectrum of fibre Bragg grating

Fabrication of biomimetic dry-adhesion structures through nanosphere lithography

Science.gov (United States)

Kuo, P. C.; Chang, N. W.; Suen, Y.; Yang, S. Y.

2018-03-01

Components with surface nanostructures suitable for biomimetic dry adhesion have a great potential in applications such as gecko tape, climbing robots, and skin patches. In this study, a nanosphere lithography technique with self-assembly nanospheres was developed to achieve effective and efficient fabrication of dry-adhesion structures. Self-assembled monolayer nanospheres with high regularity were obtained through tilted dip-coating. Reactive-ion etching of the self-assembled nanospheres was used to fabricate nanostructures of different shapes and aspect ratios by varying the etching time. Thereafter, nickel molds with inverse nanostructures were replicated using the electroforming process. Polydimethylsiloxane (PDMS) nanostructures were fabricated through a gas-assisted hot-embossing method. The pulling test was performed to measure the shear adhesion on the glass substrate of a sample, and the static contact angle was measured to verify the hydrophobic property of the structure. The enhancement of the structure indicates that the adhesion force increased from 1.2 to 4.05 N/cm2 and the contact angle increased from 118.6° to 135.2°. This columnar structure can effectively enhance the adhesion ability of PDMS, demonstrating the potential of using nanosphere lithography for the fabrication of adhesive structures.

Reactive ion etching of microphotonic structures

International Nuclear Information System (INIS)

Du, J.; Glasscock, J.; Vanajek, J.; Savvides, N.

2004-01-01

Full text: Fabrication of microphotonic structures such as planar waveguides and other periodic structures based on silicon technology has become increasingly important due to the potential for integration of planar optical devices. We have fabricated various periodic microstructures on silicon wafers using standard optical lithography and reactive ion etching (RIE). For optical applications the surface roughness and the sidewall angle or steepness of microstructures are the most critical factors. In particular, sidewall roughness of the etched waveguide core accounts for most of the optical propagation loss. We show that by varying the main RIE parameters such as gas pressure, RF power and CF 4 /Ar/O 2 gas composition it is possible to produce microstructures with near-vertical sidewalls and very smooth surfaces. In addition to plasma etching conditions, poor edge quality of the mask often causes sidewall roughness. We employed Ni/Cr metal masks in these experiments for deep etching, and used Ar + ion milling instead of wet chemical etching to open the mask. This improves the edge quality of the mask and ultimately results in smooth sidewalls

A comparison of orthodontic bracket shear bond strength on enamel deproteinized by 5.25% sodium hypochlorite using total etch and self-etch primer

Science.gov (United States)

Ongkowidjaja, F.; Soegiharto, B. M.; Purbiati, M.

2017-08-01

The shear bond strength (SBS) can be increased by removing protein pellicles from the enamel surface by deproteinization using 5.25% sodium hypochlorite (NaOCl). The SBS of a self-etch primer is lower than that of a total etch primer; nonetheless, it prevents white spot lesions. This study aimed to assess the SBS of the Anyetch (AE) total etch primer and FL-Bond II Shofu (FL) self-etch primer after enamel deproteinization using 5.25% NaOCl. Forty eight human maxillary first premolars were extracted, cleaned, and divided into four groups. In group A, brackets were bonded to the enamel without deproteinization before etching (A1: 10 teeth using total etch primer (AE); A2: 10 teeth using self-etch primer (FL)). In group B, brackets were bonded to the enamel after deproteinization with 5.25% NaOCl before etching (B1: 10 teeth using total etch primer (AE); B2: 10 teeth using self-etch primer (FL)). Brackets were bonded using Transbond XT, stored in artificial saliva for 24 h at 37°C, mounted on acrylic cylinders, and debonded using a Shimadzu AG-5000 universal testing machine. There were no significant differences in SBS between the total etch (AE) groups (p > 0.05) and between the self-etch (FL) groups (p > 0.05). There were significant differences in SBS between groups A and B. The mean SBS for groups A1, A2, B1, and B2 was 12.91±3.99, 4.46±2.47, 13.06±3.66, and 3.62±2.36 MPa, respectively. Deproteinization using NaOCl did not affect the SBS of the total etch primer (AE) group; it reduced the SBS of the self-etch primer (FL) group, but not with a statistically significant difference.

SU-8 etching in inductively coupled oxygen plasma

DEFF Research Database (Denmark)

Rasmussen, Kristian Hagsted; Keller, Stephan Sylvest; Jensen, Flemming

2013-01-01

Structuring or removal of the epoxy based, photo sensitive polymer SU-8 by inductively coupled plasma reactive ion etching (ICP-RIE) was investigated as a function of plasma chemistry, bias power, temperature, and pressure. In a pure oxygen plasma, surface accumulation of antimony from the photo......-initiator introduced severe roughness and reduced etch rate significantly. Addition of SF6 to the plasma chemistry reduced the antimony surface concentration with lower roughness and higher etch rate as an outcome. Furthermore the etch anisotropy could be tuned by controlling the bias power. Etch rates up to 800 nm...

A novel method for length of chirped fiber Bragg grating sensor

Science.gov (United States)

Li, Zhenwei; Wei, Peng; Liu, Taolin

2018-03-01

Length of chirped fiber Bragg grating sensor is very important for detonation velocity. Different from other ways, we proposed a novel method based on the optical frequency domain reflection theory to measure the length of chirped fiber grating sensor in non-contact condition. This method adopts a tunable laser source to provide wavelength scanning laser, which covers the Full Width at Half Maximum of spectrum of the chirped fiber Bragg grating sensor. A Michelson interferometer is used to produce optical interference signal. Finally, the grating's length is attainable by distance domain signal. In theory, length resolution of chirped fiber Bragg grating sensor could be 0.02 mm. We perform a series of length measurement experiments for chirped fiber grating sensor, including comparison experiments with hot-tip method. And the experiment results show that the novel method could accurately measure the length of chirped fiber Bragg grating sensors, and the length differences between the optical frequency domain reflection method and the hot-tip probe method are very small.

Bragg-edge neutron transmission strain tomography for in situ loadings

Energy Technology Data Exchange (ETDEWEB)

Wensrich, C.M., E-mail: christopher.wensrich@newcastle.edu.au [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Hendriks, J.N.; Gregg, A. [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Meylan, M.H. [School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308 (Australia); Luzin, V. [Bragg Institute, Australian Nuclear Science and Technology Organisation (ANSTO), Kirrawee, NSW 2232 (Australia); Tremsin, A.S. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2016-09-15

An approach for tomographic reconstruction of three-dimensional strain distributions from Bragg-edge neutron transmission strain images is outlined and investigated. This algorithm is based on the link between Bragg-edge strain measurements and the Longitudinal Ray Transform, which has been shown to be sensitive only to boundary displacement. By exploiting this observation we provide a method for reconstructing boundary displacement from sets of Bragg-edge strain images. In the case where these displacements are strictly the result of externally applied tractions, corresponding internal strain fields can then be found through traditional linear-static finite element methods. This approach is tested on synthetic data in two-dimensions, where the rate of convergence in the presence of measurement noise and beam attenuation is examined.

Performance of a universal adhesive on etched and non-etched surfaces: Do the results match the expectations?

Energy Technology Data Exchange (ETDEWEB)

Grégoire, Geneviève, E-mail: genevieve.gregoire@univ-tlse3.fr [Department of Biomaterials, Faculty of Odontology, University Toulouse III, 31062 Toulouse (France); Sharrock, Patrick, E-mail: patrick.sharrock@gmail.com [CNRS UMR 5302, University Toulouse III, Mines-Albi, 81013 Albi (France); Prigent, Yann, E-mail: prigent@chimie.ups-tlse.fr [Institut de Chimie de Toulouse (ICT) – FR 2599, Faculté des Sciences et de l' Ingénierie, University Toulouse III, 31062 Toulouse (France)

2016-09-01

A universal adhesive was applied to human dentin in both the etched and rinsed state and the normal non etched state, to compare the resulting properties and detect any significant differences. The study focused on observations of the hybrid layer by scanning electron microscopy and on fluid permeation measurements as a function of time. Spectroscopic characterizations included infrared and differential calorimetric curves of the samples. The results obtained show non-statistically significant fluid permeability between the two sample types. Both the etched and rinsed samples and the non-etched ones showed similar homogeneous hybrid layers that reduced the fluid flow, and corresponded to well spread polymer coatings. The infrared results illustrated the spectra obtained on going from the outside adhesive layer to the inside portion of the dentin-polymer interface and did not reveal any intermediate zone resembling demineralized collagen that would be water saturated and not infiltrated with adhesive. The Differential Scanning Calorimetry (DSC) curves corresponded to the curves obtained with ethanol wet bonding in that free water (melting at 0 °C) was removed by the universal adhesive, and that no collagen melting was observed for the non-etched samples. The Diffusion-Ordered Spectroscopy Nuclear Magnetic Resonance (DOSY NMR) spectrum of the virgin adhesive showed the presence of water and ethanol solvents and indicated that several monomer or prepolymer molecules were present with multiple acrylic functional groups with diffusion coefficients related to molecular weights. Overall, the results show that universal adhesive can be used in the milder self-etch mode and that more aggressive etch and rinse procedure can be reserved for the occasions with sclerotic dentin or enamel regions more difficult to treat.

Performance of a universal adhesive on etched and non-etched surfaces: Do the results match the expectations?

International Nuclear Information System (INIS)

Grégoire, Geneviève; Sharrock, Patrick; Prigent, Yann

2016-01-01

A universal adhesive was applied to human dentin in both the etched and rinsed state and the normal non etched state, to compare the resulting properties and detect any significant differences. The study focused on observations of the hybrid layer by scanning electron microscopy and on fluid permeation measurements as a function of time. Spectroscopic characterizations included infrared and differential calorimetric curves of the samples. The results obtained show non-statistically significant fluid permeability between the two sample types. Both the etched and rinsed samples and the non-etched ones showed similar homogeneous hybrid layers that reduced the fluid flow, and corresponded to well spread polymer coatings. The infrared results illustrated the spectra obtained on going from the outside adhesive layer to the inside portion of the dentin-polymer interface and did not reveal any intermediate zone resembling demineralized collagen that would be water saturated and not infiltrated with adhesive. The Differential Scanning Calorimetry (DSC) curves corresponded to the curves obtained with ethanol wet bonding in that free water (melting at 0 °C) was removed by the universal adhesive, and that no collagen melting was observed for the non-etched samples. The Diffusion-Ordered Spectroscopy Nuclear Magnetic Resonance (DOSY NMR) spectrum of the virgin adhesive showed the presence of water and ethanol solvents and indicated that several monomer or prepolymer molecules were present with multiple acrylic functional groups with diffusion coefficients related to molecular weights. Overall, the results show that universal adhesive can be used in the milder self-etch mode and that more aggressive etch and rinse procedure can be reserved for the occasions with sclerotic dentin or enamel regions more difficult to treat.

Modeling of the angular dependence of plasma etching

International Nuclear Information System (INIS)

Guo Wei; Sawin, Herbert H.

2009-01-01

An understanding of the angular dependence of etching yield is essential to investigate the origins of sidewall roughness during plasma etching. In this article the angular dependence of polysilicon etching in Cl 2 plasma was modeled as a combination of individual angular-dependent etching yields for ion-initiated processes including physical sputtering, ion-induced etching, vacancy generation, and removal. The modeled etching yield exhibited a maximum at ∼60 degree sign off-normal ion angle at low flux ratio, indicative of physical sputtering. It transformed to the angular dependence of ion-induced etching with the increase in the neutral-to-ion flux ratio. Good agreement between the modeling and the experiments was achieved for various flux ratios and ion energies. The variation of etching yield in response to the ion angle was incorporated in the three-dimensional profile simulation and qualitative agreement was obtained. The surface composition was calculated and compared to x-ray photoelectron spectroscopy (XPS) analysis. The modeling indicated a Cl areal density of 3x10 15 atoms/cm 2 on the surface that is close to the value determined by the XPS analysis. The response of Cl fraction to ion energy and flux ratio was modeled and correlated with the etching yields. The complete mixing-layer kinetics model with the angular dependence effect will be used for quantitative surface roughening analysis using a profile simulator in future work.

Response of fiber Bragg gratings to longitudinal ultrasonic waves.

Science.gov (United States)

Minardo, Aldo; Cusano, Andrea; Bernini, Romeo; Zeni, Luigi; Giordano, Michele

2005-02-01

In the last years, fiber optic sensors have been widely exploited for several sensing applications, including static and dynamic strain measurements up to acoustic detection. Among these, fiber Bragg grating sensors have been indicated as the ideal candidate for practical structural health monitoring in light of their unique advantages over conventional sensing devices. Although this class of sensors has been successfully tested for static and low-frequency measurements, the identification of sensor performances for high-frequency detection, including acoustic emission and ultrasonic investigations, is required. To this aim, the analysis of feasibilty on the use of fiber Bragg grating sensors as ultrasonic detectors has been carried out. In particular, the response of fiber Bragg gratings subjected to the longitudinal ultrasonic (US) field has been theoretically and numerically investigated. Ultrasonic field interaction has been modeled, taking into account the direct deformation of the grating pitch combined with changes in local refractive index due to the elasto-optic effect. Numerical results, obtained for both uniform and Gaussian-apodized fiber Bragg gratings, show that the grating spectrum is strongly influenced by the US field in terms of shape and central wavelength. In particular, a key parameter affecting the grating response is the ratio between the US wavelength and the grating length. Normal operation characterized by changes in wavelength of undistorted Bragg peak is possible only for US wavelengths longer than the grating length. For US wavelengths approaching the grating length, the wavelength change is accompanied by subpeaks formation and main peak amplitude modulation. This effect can be attributed to the nonuniformity of the US perturbation along the grating length. At very high US frequencies, the grating is not sensitive any longer. The results of this analysis provide useful tools for the design of grating-based ultrasound sensors for

Influence of Etching Protocol and Silane Treatment with a Universal Adhesive on Lithium Disilicate Bond Strength.

Science.gov (United States)

Kalavacharla, V K; Lawson, N C; Ramp, L C; Burgess, J O

2015-01-01

To measure the effects of hydrofluoric acid (HF) etching and silane prior to the application of a universal adhesive on the bond strength between lithium disilicate and a resin. Sixty blocks of lithium disilicate (e.max CAD, Ivoclar Vivadent) were sectioned into coupons and polished. Specimens were divided into six groups (n=10) based on surface pretreatments, as follows: 1) no treatment (control); 2) 5% HF etch for 20 seconds (5HF); 3) 9.5% HF etch for 60 seconds (9.5HF); 4) silane with no HF (S); 5) 5% HF for 20 seconds + silane (5HFS); and 6) 9.5% HF for 60 seconds + silane (9.5HFS). All etching was followed by rinsing, and all silane was applied in one coat for 20 seconds and then dried. The universal adhesive (Scotchbond Universal, 3M ESPE) was applied onto the pretreated ceramic surface, air thinned, and light cured for 10 seconds. A 1.5-mm-diameter plastic tube filled with Z100 composite (3M ESPE) was applied over the bonded ceramic surface and light cured for 20 seconds on all four sides. The specimens were thermocycled for 10,000 cycles (5°C-50°C/15 s dwell time). Specimens were loaded until failure using a universal testing machine at a crosshead speed of 1 mm/min. The peak failure load was used to calculate the shear bond strength. Scanning electron microscopy images were taken of representative e.max specimens from each group. A two-way analysis of variance (ANOVA) determined that there were significant differences between HF etching, silane treatment, and the interaction between HF and silane treatment (puniversal adhesive.

Effects of the Addictives on Etching Characteristics of Aluminum Foil

Energy Technology Data Exchange (ETDEWEB)

Kim, S.K.; Jang, J.M.; Chi, C.S. [Kookmin University, Seoul (Korea); Shin, D.C. [Sungnam Polytechnic, Sungnam (Korea); Lee, J.H.; Oh, H.J. [Hanseo University, Seosan (Korea)

2001-01-01

The effects of additives in the HCI etching solution on etching behaviors of aluminium foil as dielectric film for electrolytic capacitors were investigated. The etch pits formed in 1M hydrochloric acid containing ethylene glycol as an additive contain more fine and homogeneous etch tunnels compared to thoese in 1 M hydrochloric acid only, which led to the increase in the effective internal surface area of aluminum foil. After anodizing of aluminum foil etched in etching solutions, the LCR meter results have shown that the capacitance of dielectric film etched in hydrochloric acid with ethylene glycol was increased remarkably compared to that etched in hydrochloric acid only. (author). 21 refs., 10 figs.

High mobility bottom gate InGaZnO thin film transistors with SiOx etch stopper

Science.gov (United States)

Kim, Minkyu; Jeong, Jong Han; Lee, Hun Jung; Ahn, Tae Kyung; Shin, Hyun Soo; Park, Jin-Seong; Jeong, Jae Kyeong; Mo, Yeon-Gon; Kim, Hye Dong

2007-05-01

The authors report on the fabrication of thin film transistors (TFTs), which use an amorphous indium gallium zinc oxide (a-IGZO) channel, by rf sputtering at room temperature and for which the channel length and width are patterned by photolithography and dry etching. To prevent plasma damage to the active channel, a 100-nm-thick SiOx layer deposited by plasma enhanced chemical vapor deposition was adopted as an etch stopper structure. The a-IGZO TFT (W /L=10μm/50μm) fabricated on glass exhibited a high field-effect mobility of 35.8cm2/Vs, a subthreshold gate swing value of 0.59V/decade, a thrseshold voltage of 5.9V, and an Ion/off ratio of 4.9×106, which is acceptable for use as the switching transistor of an active-matrix TFT backplane.

Ion-beam etching of ramps in thin film heterostructures

International Nuclear Information System (INIS)

Mozhaev, P. B.; Mozhaeva, Ju. E.; Komissinskii, P. V.

2002-01-01

Ion-beam patterning of thin films and heterostructures is one of the most common processes of fabrication of thin film devices and structures. 'Directed' nature of ion-beam etching provides a possibility to form certain profiles on the films surface, like shallow ramps, when etching is performed at some inclination angle. A simple geometrical model is presented, describing the formation of a ramp as a shadow of the mask on the film surface. Good agreement with the experiment can be obtained if the mask etching is taken into account. The etching at the opposite direction ('high-angle etching') also can be satisfactory described by the model. The profile of the slope - positive or negative curvature, pits near the end of the ramp - is discussed as a function of the etch rate dependence on the incidence angle. Such etch rate dependences for some often used materials were measured. An area of instability of the resulting ramp shape is found for the 'high-angle etching'. The model is compared with the experimental data reported by other groups. Finally ion-beam etching of a rotating sample at non-normal incidence is discussed, the results are compared with experimental data. (Authors)

Stereotactic Bragg peak proton radiosurgery method

International Nuclear Information System (INIS)

Kjellberg, R.N.

1979-01-01

A brief description of the technical aspects of a stereotactic Bragg peak proton radiosurgical method for the head is presented. The preparatory radiographic studies are outlined and the stereotactic instrument and positioning of the patient are described. The instrument is so calibrated that after corrections for soft tissue and bone thickness, the Bragg peak superimposes upon the intracranial target. The head is rotated at specific intervals to allow predetermined portals of access for the beam path, all of which converge on the intracranial target. Normally, portals are arranged to oppose and overlap from both sides of the head. Using a number of beams (in sequence) on both sides of the head, the target dose is far greater than the path dose. The procedure normally takes 3/2-2 hours, following which the patient can walk away. (Auth./C.F.)

Micromorphological characterization of adhesive interface of sound dentin and total-etch and self-etch adhesives.

Science.gov (United States)

Drobac, Milan; Stojanac, Igor; Ramić, Bojana; Premović, Milica; Petrović, Ljubomir

2015-01-01

The ultimate goal in restorative dentistry has always been to achieve strong and permanent bond between the dental tissues and filling materials. It is not easy to achieve this task because the bonding process is different for enamel and dentin-dentin is more humid and more organic than enamel. It is moisture and organic nature of dentin that make this hard tissue very complex to achieve adhesive bond. One of the first and most widely used tools for examining the adhesive bond between hard dental tissues and composite restorative materials is scanning electron microscopy. The aim of this study was scanning electron microscopy analyzes the interfacial micro morphology of total-etch and self-etch adhesives. Micro morphological characteristics of interface between total-etch adhesive (Prime & Bond NT) in combination with the corresponding composite (Ceram X Mono) were compared with those of self-etching adhesive (AdheSE One) in, combination with the corresponding composite (Tetric EvoCeram). The specimens were observed under 1000 x magnification of scanning electron microscopy (JEOL, JSM-6460 Low Vacuum). Measurement of the thickness of the hybrid layer of the examined com posite systems was performed with the software of the device used (NIH Image Analyser). Micromorphological analysis of interface showed that the hybrid layer in sound dentin was well formed, its average thickness being 2.68 microm, with a large number of resin tags and a large amount of lateral branches for specimens with a composite system Prime & Bond NT-Ceram X Mono. However, the specimens' with composite systems Adhese One-Tetric EvoCeram did not show the presence of hybrid layer and the resin tags were poorly represented. The results of this study suggest that total-etch adhesives bond better with sound dentin than self-etch adhesive.

Polymer Optical Fibre Bragg Grating Humidity Sensor at 100ºC

DEFF Research Database (Denmark)

Woyessa, Getinet; Fasano, Andrea; Markos, Christos

2016-01-01

We have demonstrated a polymer optical fibre Bragg grating humidity sensor that can be operated up to 100ºC. The sensor has been fabricated from a polycarbonate (PC) microstructured polymer optical fibre Bragg grating (mPOFBG). PC mPOFBG gave a relative humidity (RH) sensitivity of 6.95±0.83 pm...

Directional Etching of Silicon by Silver Nanostructures

Science.gov (United States)

Sharma, Pradeep; Wang, Yuh-Lin

2011-02-01

We report directional etching of nanostructures (nanochannels and nanotrenches) into the Si(100) substrates in aqueous HF and H2O2 solution by lithographically defined Ag patterns (nanoparticles, nanorods, and nanorings). The Effect of Ag/Si interface oxide on the directional etching has been studied by etching Ag/SiOx/Si samples of known interface oxide thickness. Based on high resolution transmission electron microscopy (HRTEM) imaging and TEM-energy dispersive X-ray (EDX) spectra of the Ag/Si interfaces, we propose that maintenance of the sub-nanometer oxide at the Ag/Si interfaces and Ag-Si interaction are the key factors which regulate the directional etching of Si.

Capturing reflected cladding modes from a fiber Bragg grating with a double-clad fiber coupler.

Science.gov (United States)

Baiad, Mohamad Diaa; Gagné, Mathieu; Lemire-Renaud, Simon; De Montigny, Etienne; Madore, Wendy-Julie; Godbout, Nicolas; Boudoux, Caroline; Kashyap, Raman

2013-03-25

We present a novel measurement scheme using a double-clad fiber coupler (DCFC) and a fiber Bragg grating (FBG) to resolve cladding modes. Direct measurement of the optical spectra and power in the cladding modes is obtained through the use of a specially designed DCFC spliced to a highly reflective FBG written into slightly etched standard photosensitive single mode fiber to match the inner cladding diameter of the DCFC. The DCFC is made by tapering and fusing two double-clad fibers (DCF) together. The device is capable of capturing backward propagating low and high order cladding modes simply and efficiently. Also, we demonstrate the capability of such a device to measure the surrounding refractive index (SRI) with an extremely high sensitivity of 69.769 ± 0.035 μW/RIU and a resolution of 1.433 × 10(-5) ± 8 × 10(-9) RIU between 1.37 and 1.45 RIU. The device provides a large SRI operating range from 1.30 to 1.45 RIU with sufficient discrimination for all individual captured cladding modes. The proposed scheme can be adapted to many different types of bend, temperature, refractive index and other evanescent wave based sensors.

Increased interference fringe visibility from the post-fabrication heat treatment of a perfect crystal silicon neutron interferometer

Science.gov (United States)

Heacock, B.; Arif, M.; Cory, D. G.; Gnaeupel-Herold, T.; Haun, R.; Huber, M. G.; Jamer, M. E.; Nsofini, J.; Pushin, D. A.; Sarenac, D.; Taminiau, I.; Young, A. R.

2018-02-01

We find that annealing a previously chemically etched interferometer at 800 °C dramatically increased the interference fringe visibility from 23% to 90%. The Bragg plane misalignments were also measured before and after annealing using neutron rocking curves, showing that Bragg plane alignment was improved across the interferometer after annealing. This suggests that current interferometers with low fringe visibility may be salvageable and that annealing may become an important step in the fabrication process of future neutron interferometers, leading to less need for chemical etching and larger more exotic neutron interferometers.

Shear bond strength of orthodontic brackets after acid-etched and erbium-doped yttrium aluminum garnet laser-etched

Directory of Open Access Journals (Sweden)

Shiva Alavi

2014-01-01

Full Text Available Background: Laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. The purpose of this study was to compare the shear bond strength (SBS and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (Er:YAG laser. Materials and Methods: In this experimental in vitro study, buccal surfaces of 15 non-carious human premolars were divided into mesial and distal regions. Randomly, one of the regions was etched with 37% phosphoric acid for 15 s and another region irradiated with Er:YAG laser at 100 mJ energy and 20 Hz frequency for 20 s. Stainless steel brackets were then bonded using Transbond XT, following which all the samples were stored in distilled water for 24 h and then subjected to 500 thermal cycles. SBS was tested by a chisel edge, mounted on the crosshead of universal testing machine. After debonding, the teeth were examined under Χ10 magnification and adhesive remnant index (ARI score determined. SBS and ARI scores of the two groups were then compared using t-test and Mann-Whitney U test. Significant level was set at P < 0.05. Results: The mean SBS of the laser group (16.61 ± 7.7 MPa was not significantly different from that of the acid-etched group (18.86 ± 6.09 MPa (P = 0.41. There was no significant difference in the ARI scores between two groups (P = 0.08. However, in the laser group, more adhesive remained on the brackets, which is not suitable for orthodontic purposes. Conclusion: Laser etching at 100 mJ energy produced bond strength similar to acid etching. Therefore, Er:YAG laser may be an alternative method for conventional acid-etching.

Optimization of silver-assisted nano-pillar etching process in silicon

Science.gov (United States)

Azhari, Ayu Wazira; Sopian, Kamaruzzaman; Desa, Mohd Khairunaz Mat; Zaidi, Saleem H.

2015-12-01

In this study, a respond surface methodology (RSM) model is developed using three-level Box-Behnken experimental design (BBD) technique. This model is developed to investigate the influence of metal-assisted chemical etching (MACE) process variables on the nanopillars profiles created in single crystalline silicon (Si) substrate. Design-Expert® software (version 7.1) is employed in formulating the RSM model based on five critical process variables: (A) concentration of silver (Ag), (B) concentration of hydrofluoric acid (HF), (C) concentration of hydrogen peroxide (H2O2), (D) deposition time, and (E) etching time. This model is supported by data from 46 experimental configurations. Etched profiles as a function of lateral etching rate, vertical etching rate, height, size and separation between the Si trenches and etching uniformity are characterized using field emission scanning electron microscope (FE-SEM). A quadratic regression model is developed to correlate critical process variables and is validated using the analysis of variance (ANOVA) methodology. The model exhibits near-linear dependence of lateral and vertical etching rates on both the H2O2 concentration and etching time. The predicted model is in good agreement with the experimental data where R2 is equal to 0.80 and 0.67 for the etching rate and lateral etching respectively. The optimized result shows minimum lateral etching with the average pore size of about 69 nm while the maximum etching rate is estimated at around 360 nm/min. The model demonstrates that the etching process uniformity is not influenced by either the etchant concentration or the etching time. This lack of uniformity could be attributed to the surface condition of the wafer. Optimization of the process parameters show adequate accuracy of the model with acceptable percentage errors of 6%, 59%, 1.8%, 38% and 61% for determination of the height, separation, size, the pore size and the etching rate respectively.

Temperature dependence of active photonic band gap in bragg-spaced quantum wells

Energy Technology Data Exchange (ETDEWEB)

Hu Zhiqiang; Wang Tao; Yu Chunchao; Xu Wei, E-mail: huzhiqianghzq@163.com [Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China)

2011-02-01

A novel all-optical polarization switch of active photonic band gap structure based on non-resonant optical Stark effect bragg-spaced quantum wells was investigated and it could be compatible with the optical communication system. The theory is based on InGaAsP/InP Bragg-spaced quantum wells (BSQWs). Mainly through the design of the InGaAsP well layer component and InP barrier thickness to make the quantum-period cycle meet the bragg condition and the bragg frequency is equal to re-hole exciton resonance frequency. When a spectrally narrow control pulse is tuned within the forbidden gap, such BSQWs have been shown to exhibit large optical nonlinearities and ps recovery times, which can form T hz switch. However, the exciton binding energy of InGaAsP will be automatically separate at room temperature, so the effect of all-optical polarization switching of active photonic band gap bragg structure quantum wells can only be studied at low temperature. By a large number of experiments, we tested part of the material parameters of BSQWs in the temperature range 10-300K. On this basis, the InGaAsP and InP refractive index changes with wavelength, InP thermal expansion coefficient are studied and a relationship equation is established. Experimental results show that the bragg reflection spectra with temperature mainly is effected by InP refractive index changes with temperature. Our theoretical study and experiment are an instruction as a reference in the designs and experiments of future practical optical switches.

Temperature dependence of active photonic band gap in bragg-spaced quantum wells

International Nuclear Information System (INIS)

Hu Zhiqiang; Wang Tao; Yu Chunchao; Xu Wei

2011-01-01

A novel all-optical polarization switch of active photonic band gap structure based on non-resonant optical Stark effect bragg-spaced quantum wells was investigated and it could be compatible with the optical communication system. The theory is based on InGaAsP/InP Bragg-spaced quantum wells (BSQWs). Mainly through the design of the InGaAsP well layer component and InP barrier thickness to make the quantum-period cycle meet the bragg condition and the bragg frequency is equal to re-hole exciton resonance frequency. When a spectrally narrow control pulse is tuned within the forbidden gap, such BSQWs have been shown to exhibit large optical nonlinearities and ps recovery times, which can form T hz switch. However, the exciton binding energy of InGaAsP will be automatically separate at room temperature, so the effect of all-optical polarization switching of active photonic band gap bragg structure quantum wells can only be studied at low temperature. By a large number of experiments, we tested part of the material parameters of BSQWs in the temperature range 10-300K. On this basis, the InGaAsP and InP refractive index changes with wavelength, InP thermal expansion coefficient are studied and a relationship equation is established. Experimental results show that the bragg reflection spectra with temperature mainly is effected by InP refractive index changes with temperature. Our theoretical study and experiment are an instruction as a reference in the designs and experiments of future practical optical switches.

Influence factors on etching rate of PET nuclear pore membrane

International Nuclear Information System (INIS)

Zuo Zhenzhong; Wu Zhendong; Liang Haiying; Ju Wei; Chen Dongfeng; Fu Yuanyong; Qu Guopu

2014-01-01

Background: The nuclear pore membrane is a kind of liquid filtration material manufactured by irradiation and chemical etching. Various conditions in etch process have a great influence on etch rate. Purpose: The influence factors of concentration and temperature of etch solution and the irradiation energy of heavy ions on etch rate was studied. Methods: Four layers of PET (polyethylene terephthalate) films were stacked together and were irradiated with 140-MeV 32 S ions at room temperature under vacuum conditions. Utilizing conductivity measurement technique, the electrical current changes through the u:radiated PET film were monitored during etching, from which the breakthrough time and therefore the track etching rate was calculated. Results: The results show that there is an exponential correlation between etch rate and temperature, and a linear correlation between etch rate and concentration. The track etching rate increases linearly with energy loss rate. Empirical formula for the bulk etching rate as a function of etchant concentration and temperature was also established via fitting of measurements. Conclusion: It is concluded that by using 1.6-MeV·u -1 32 S ions, PET nuclear pore membrane with cylindrical pore shape can be prepared at 85℃ with etchant concentration of l mol·L -1 . (authors)

Energy dispersive X-ray fluorescence analysis with Bragg polarized Mo radiation. Energiedispersive Roentgenfluoreszenzanalyse mit Bragg-polarisierter Mo Strahlung

Energy Technology Data Exchange (ETDEWEB)

Gloeckl, H

1983-01-01

The aim of introducing energy dispersive analysis into X-ray fluorescence analysis is to suppress background from the Bremsstrahlung spectrum and the characteristic radiation without an undue reduction of the signal. The variant under consideration uses linearly polarization radiation obtained after a Bragg reflection,under delta = 90/sup 0/. In an introductory part, Bragg reflection, fluorescence and strong radiation are considered quantitatively with respect to counting statistics and detection limits. In the experimental part two combinations are describe, of a Ta crystal with a Cr tube and of a Mo crystal with a Mo tube. Details of adjustment, sample preparation and calibration and detection limits are given. The pros and cons of the Ta/Cr and the Mo/Mo are contrasted and proposals for further improvements are given.

Optimization of silver-assisted nano-pillar etching process in silicon

International Nuclear Information System (INIS)

Azhari, Ayu Wazira; Sopian, Kamaruzzaman; Desa, Mohd Khairunaz Mat; Zaidi, Saleem H.

2015-01-01

Graphical abstract: - Highlights: • Statistical analysis for synthesis of nano-pillar in crystalline Si substrates is presented. • Model is in good agreement with experimental for the etching rate and lateral etching respectively. • Optimum values for all parameters in fabrication of nanostructured Si are attained. - Abstract: In this study, a respond surface methodology (RSM) model is developed using three-level Box–Behnken experimental design (BBD) technique. This model is developed to investigate the influence of metal-assisted chemical etching (MACE) process variables on the nanopillars profiles created in single crystalline silicon (Si) substrate. Design-Expert ® software (version 7.1) is employed in formulating the RSM model based on five critical process variables: (A) concentration of silver (Ag), (B) concentration of hydrofluoric acid (HF), (C) concentration of hydrogen peroxide (H 2 O 2 ), (D) deposition time, and (E) etching time. This model is supported by data from 46 experimental configurations. Etched profiles as a function of lateral etching rate, vertical etching rate, height, size and separation between the Si trenches and etching uniformity are characterized using field emission scanning electron microscope (FE-SEM). A quadratic regression model is developed to correlate critical process variables and is validated using the analysis of variance (ANOVA) methodology. The model exhibits near-linear dependence of lateral and vertical etching rates on both the H 2 O 2 concentration and etching time. The predicted model is in good agreement with the experimental data where R 2 is equal to 0.80 and 0.67 for the etching rate and lateral etching respectively. The optimized result shows minimum lateral etching with the average pore size of about 69 nm while the maximum etching rate is estimated at around 360 nm/min. The model demonstrates that the etching process uniformity is not influenced by either the etchant concentration or the etching time

Optimization of silver-assisted nano-pillar etching process in silicon

Energy Technology Data Exchange (ETDEWEB)

Azhari, Ayu Wazira, E-mail: ayuwazira@unimap.edu.my [Solar Energy Research Institute, Universiti Kebangsaan Malaysia, Bangi, Selangor 43650 (Malaysia); School of Environmental Engineering, Universiti Malaysia Perlis, 01000, Kangar, Perlis (Malaysia); Sopian, Kamaruzzaman [Solar Energy Research Institute, Universiti Kebangsaan Malaysia, Bangi, Selangor 43650 (Malaysia); Desa, Mohd Khairunaz Mat [School of Electrical and Electronic Engineering, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, 14300 (Malaysia); Zaidi, Saleem H. [Solar Energy Research Institute, Universiti Kebangsaan Malaysia, Bangi, Selangor 43650 (Malaysia)

2015-12-01

Graphical abstract: - Highlights: • Statistical analysis for synthesis of nano-pillar in crystalline Si substrates is presented. • Model is in good agreement with experimental for the etching rate and lateral etching respectively. • Optimum values for all parameters in fabrication of nanostructured Si are attained. - Abstract: In this study, a respond surface methodology (RSM) model is developed using three-level Box–Behnken experimental design (BBD) technique. This model is developed to investigate the influence of metal-assisted chemical etching (MACE) process variables on the nanopillars profiles created in single crystalline silicon (Si) substrate. Design-Expert{sup ®} software (version 7.1) is employed in formulating the RSM model based on five critical process variables: (A) concentration of silver (Ag), (B) concentration of hydrofluoric acid (HF), (C) concentration of hydrogen peroxide (H{sub 2}O{sub 2}), (D) deposition time, and (E) etching time. This model is supported by data from 46 experimental configurations. Etched profiles as a function of lateral etching rate, vertical etching rate, height, size and separation between the Si trenches and etching uniformity are characterized using field emission scanning electron microscope (FE-SEM). A quadratic regression model is developed to correlate critical process variables and is validated using the analysis of variance (ANOVA) methodology. The model exhibits near-linear dependence of lateral and vertical etching rates on both the H{sub 2}O{sub 2} concentration and etching time. The predicted model is in good agreement with the experimental data where R{sup 2} is equal to 0.80 and 0.67 for the etching rate and lateral etching respectively. The optimized result shows minimum lateral etching with the average pore size of about 69 nm while the maximum etching rate is estimated at around 360 nm/min. The model demonstrates that the etching process uniformity is not influenced by either the etchant

Linear and circular polarized tunable slow light in Bragg-spaced graphene layers

Energy Technology Data Exchange (ETDEWEB)

Liu, Jiang-Tao, E-mail: jtliu@semi.ac.cn [Nanoscale Science and Technology Laboratory, Institute for Advanced Study, Nanchang University, Nanchang 330031 (China); Department of Physics, Nanchang University, Nanchang 330031 (China); Liu, Nian-Hua [Nanoscale Science and Technology Laboratory, Institute for Advanced Study, Nanchang University, Nanchang 330031 (China); Department of Physics, Nanchang University, Nanchang 330031 (China); Wang, Hai [Department of Physics, Capital Normal University, Beijing 100037 (China); Wang, Tong-Biao [Department of Physics, Nanchang University, Nanchang 330031 (China); Li, Xiao-Jing [College of Physics and Energy, Fujian Normal University, Fuzhou 350007 (China)

2014-11-01

The light pulse delay in Bragg-spaced graphene layers (BSGs) combined with a magnetic field is investigated theoretically. BSGs can slow down the group velocity of light more effectively than traditional Bragg-spaced quantum wells due to the large binding energy and strong dipole oscillator strength of the magnetic-exciton of graphene. The group velocity can be tuned by varying the pulse frequency, the Bragg frequency, and the magnetic field. Especially, by tuning the occupation number of the Landau level the group velocity in BSGs shows strong tunable circular dichroism. Our findings could have applications in photonic integrated circuits and quantum computation.

Semiconductor structure and recess formation etch technique

Energy Technology Data Exchange (ETDEWEB)

Lu, Bin; Sun, Min; Palacios, Tomas Apostol

2017-02-14

A semiconductor structure has a first layer that includes a first semiconductor material and a second layer that includes a second semiconductor material. The first semiconductor material is selectively etchable over the second semiconductor material using a first etching process. The first layer is disposed over the second layer. A recess is disposed at least in the first layer. Also described is a method of forming a semiconductor structure that includes a recess. The method includes etching a region in a first layer using a first etching process. The first layer includes a first semiconductor material. The first etching process stops at a second layer beneath the first layer. The second layer includes a second semiconductor material.

System Construction for the Measurement of Bragg Grating Characteristics in Optical Fibers

Science.gov (United States)

West, Douglas P.

1995-01-01

Bragg gratings are used to measure strain in optical fibers. To measure strain they are sometimes used as a smart structure. They must be characterized after they are written to determine their spectral response. This paper deals with the test setup to characterize Bragg grating spectral responses.Bragg gratings are a photo-induced phenomena in optical fibers. The gratings can be used to measure strain by measuring the shift in wavelength. They placed the fibers into a smart structure to measure the stress and strain produced on support columns placed in bridges. As the cable is subjected to strain the grating causes a shift to a longer wavelength if the fiber is stretched and a shift to a shorter wavelength shift if the fiber is compacted. Our applications involve using the fibers to measure stress and strain on airborne systems. There are many ways to write Bragg gratings into optical fibers. Our focus is on side writing the grating. Our capabilities are limited in the production rate of the gratings. The Bragg grating is written into a fiber and becomes a permanent fixture. We are writing the grating to be centered at 1300 nm because that is the standard phase mask wavelength.

Rare-earth-ion-doped ultra-narrow-linewidth lasers on a silicon chip and applications to intra-laser-cavity optical sensing

NARCIS (Netherlands)

Bernhardi, Edward; de Ridder, R.M.; Worhoff, Kerstin; Pollnau, Markus

We report on diode-pumped distributed-feedback (DFB) and distributed-Bragg-reflector (DBR) channel waveguide lasers in Er-doped and Yb-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into

3D memory: etch is the new litho

Science.gov (United States)

Petti, Christopher

2018-03-01

This paper discusses the process challenges and limitations for 3D NAND processes, focusing on vertical 3D architectures. The effect of deep memory hole etches on die cost is calculated, with die cost showing a minimum at a given number of layers because of aspect-ratio dependent etch effects. Techniques to mitigate these etch effects are summarized, as are other etch issues, such as bowing and twisting. Metal replacement gate processes and their challenges are also described. Lastly, future directions of vertical 3D NAND technologies are explored.

Fiber-optical accelerometers based on polymer optical fiber Bragg gratings

DEFF Research Database (Denmark)

Yuan, Scott Wu; Stefani, Alessio; Bang, Ole

2010-01-01

Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer.......Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

Infinitely high etch selectivity during CH4/H2/Ar inductively coupled plasma (ICP) etching of indium tin oxide (ITO) with photoresist mask

International Nuclear Information System (INIS)

Kim, D.Y.; Ko, J.H.; Park, M.S.; Lee, N.-E.

2008-01-01

Under certain conditions during ITO etching using CH 4 /H 2 /Ar inductively coupled plasmas, the etch rate selectivity of ITO to photoresist (PR) was infinitely high because the ITO films continued to be etched, but a net deposition of the α-C:H layer occurred on the top of the PR. Analyses of plasmas and etched ITO surfaces suggested that the continued consumption of the carbon and hydrogen in the deposited α-C:H layer by their chemical reaction with In and Sn atoms in the ITO resulting in the generation of volatile metal-organic etch products and by the ion-enhanced removal of the α-C:H layer presumably play important roles in determining the ITO etch rate and selectivity

UV writing of advanced Bragg gratings in optical waveguides

DEFF Research Database (Denmark)

Jensen, Jesper Bo Damm

2002-01-01

of the novel polarization control method for UV writing of Bragg gratings with advanced apodization profiles including phase shifts. The principle of the polarization control method relies on a spatial separation of the s- and p-polarized components of a linearly polarized UV beam corresponding to half......, Technical University of Denmark. During fabrication the planar waveguides were annealed in an oxygen rich atmosphere. This reduces the photosensitivity to a negligible level and Bragg gratings cannot be written within reasonable time unless the waveguides are sensitized by deuterium loading. Samples were...

Spatially-Resolved Ion Trajectory Measurements During Cl2 Reactive Ion Beam Etching and Ar Ion Beam Etching

International Nuclear Information System (INIS)

Vawter, G. Allen; Woodworth, Joseph R.; Zubrzycki, Walter J.

1999-01-01

The angle of ion incidence at the etched wafer location during RIBE and IBE using Cl 2 , Ar and O 2 ion beams has been characterized using an ion energy and angle analyzer. Effects of beam current and accelerator grid bias on beam divergence and the spatial uniformity of the spread of incident angles are measured. It is observed that increased total beam current can lead to reduced current density at the sample stage due to enhanced beam divergence at high currents. Results are related to preferred etch system design for uniform high-aspect-ratio etching across semiconductor wafers

High mobility bottom gate InGaZnO thin film transistors with SiOx etch stopper

International Nuclear Information System (INIS)

Kim, Minkyu; Jeong, Jong Han; Lee, Hun Jung; Ahn, Tae Kyung; Shin, Hyun Soo; Park, Jin-Seong; Jeong, Jae Kyeong; Mo, Yeon-Gon; Kim, Hye Dong

2007-01-01

The authors report on the fabrication of thin film transistors (TFTs), which use an amorphous indium gallium zinc oxide (a-IGZO) channel, by rf sputtering at room temperature and for which the channel length and width are patterned by photolithography and dry etching. To prevent plasma damage to the active channel, a 100-nm-thick SiO x layer deposited by plasma enhanced chemical vapor deposition was adopted as an etch stopper structure. The a-IGZO TFT (W/L=10 μm/50 μm) fabricated on glass exhibited a high field-effect mobility of 35.8 cm 2 /V s, a subthreshold gate swing value of 0.59 V/decade, a thrseshold voltage of 5.9 V, and an I on/off ratio of 4.9x10 6 , which is acceptable for use as the switching transistor of an active-matrix TFT backplane

A magnetically tunable non-Bragg defect mode in a corrugated waveguide filled with liquid crystals

Science.gov (United States)

Zhang, Lu; Fan, Ya-Xian; Liu, Huan; Han, Xu; Lu, Wen-Qiang; Tao, Zhi-Yong

2018-04-01

A magnetically tunable, non-Bragg defect mode (NBDM) was created in the terahertz frequency range by inserting a defect in the middle of a periodically corrugated waveguide filled with liquid crystals (LCs). In the periodic waveguide, non-Bragg gaps beyond the Bragg ones, which appear in the transmission spectra, are created by different transverse mode resonances. The transmission spectra of the waveguide containing a defect showed that a defect mode was present inside the non-Bragg gap. The NBDM has quite different features compared to the Bragg defect mode, which includes more complex, high-order guided wave modes. In our study, we filled the corrugated waveguide with LCs to realize the tunability of the NBDM. The simulated results showed that the NBDM in a corrugated waveguide filled with LCs can be used in filters, sensors, switches, and other terahertz integrated devices.

Si etching with reactive neutral beams of very low energy

Energy Technology Data Exchange (ETDEWEB)

Hara, Yasuhiro [Organization for Research and Development of Innovative Science and Technology, Kansai University, 3-3-35 Yamate-chou, Suita, Osaka 565-0871 (Japan); Hamagaki, Manabu; Mise, Takaya [RIKEN, 2-1, Hirosawa, Wako, Saitama 351-0198 (Japan); Iwata, Naotaka; Hara, Tamio [Toyota Technological Institute, 2-12-1 Hisakata, Tenpaku-ku, Nagoya 468-8511 (Japan)

2014-12-14

A Si etching process has been investigated with reactive neutral beams (NBs) extracted using a low acceleration voltage of less than 100 V from CF{sub 4} and Ar mixed plasmas. The etched Si profile shows that the etching process is predominantly anisotropic. The reactive NB has a constant Si etching rate in the acceleration voltage range from 20 V to 80 V. It is considered that low-energy NBs can trigger Si etching because F radicals adsorb onto the Si surface and weaken Si–Si bonds. The etching rate per unit beam flux is 33 times higher than that with Ar NB. These results show that the low-energy reactive NB is useful for damage-free high speed Si etching.

Plasma/Neutral-Beam Etching Apparatus

Science.gov (United States)

Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

1989-01-01

Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

Interrogation of weak Bragg grating sensors based on dual-wavelength differential detection.

Science.gov (United States)

Cheng, Rui; Xia, Li

2016-11-15

It is shown that for weak Bragg gratings the logarithmic ratio of reflected intensities at any two wavelengths within the spectrum follows a linear relationship with the Bragg wavelength shift, with a slope proportional to their wavelength spacing. This finding is exploited to develop a flexible, efficient, and cheap interrogation solution of weak fiber Bragg grating (FBGs), especially ultra-short FBGs, in distributed sensing based on dual-wavelength differential detection. The concept is experimentally studied in both single and distributed sensing systems with ultra-short FBG sensors. The work may form the basis of new and promising FBG interrogation techniques based on detecting discrete rather than continuous spectra.

Ionoacoustic characterization of the proton Bragg peak with submillimeter accuracy

Energy Technology Data Exchange (ETDEWEB)

Assmann, W., E-mail: walter.assmann@lmu.de; Reinhardt, S.; Lehrack, S.; Edlich, A.; Thirolf, P. G.; Parodi, K. [Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748 (Germany); Kellnberger, S.; Omar, M.; Ntziachristos, V. [Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstrasse 1, Neuherberg 85764 (Germany); Moser, M.; Dollinger, G. [Institute for Applied Physics and Measurement Technology, Universität der Bundeswehr, Werner-Heisenberg-Weg 39, Neubiberg 85577 (Germany)

2015-02-15

Purpose: Range verification in ion beam therapy relies to date on nuclear imaging techniques which require complex and costly detector systems. A different approach is the detection of thermoacoustic signals that are generated due to localized energy loss of ion beams in tissue (ionoacoustics). Aim of this work was to study experimentally the achievable position resolution of ionoacoustics under idealized conditions using high frequency ultrasonic transducers and a specifically selected probing beam. Methods: A water phantom was irradiated by a pulsed 20 MeV proton beam with varying pulse intensity and length. The acoustic signal of single proton pulses was measured by different PZT-based ultrasound detectors (3.5 and 10 MHz central frequencies). The proton dose distribution in water was calculated by Geant4 and used as input for simulation of the generated acoustic wave by the matlab toolbox k-WAVE. Results: In measurements from this study, a clear signal of the Bragg peak was observed for an energy deposition as low as 10{sup 12} eV. The signal amplitude showed a linear increase with particle number per pulse and thus, dose. Bragg peak position measurements were reproducible within ±30 μm and agreed with Geant4 simulations to better than 100 μm. The ionoacoustic signal pattern allowed for a detailed analysis of the Bragg peak and could be well reproduced by k-WAVE simulations. Conclusions: The authors have studied the ionoacoustic signal of the Bragg peak in experiments using a 20 MeV proton beam with its correspondingly localized energy deposition, demonstrating submillimeter position resolution and providing a deep insight in the correlation between the acoustic signal and Bragg peak shape. These results, together with earlier experiments and new simulations (including the results in this study) at higher energies, suggest ionoacoustics as a technique for range verification in particle therapy at locations, where the tumor can be localized by ultrasound

Mirror and Bragg reflections of neutrons at a nuclear resonance: [Final technical report

International Nuclear Information System (INIS)

Batigun, C.M.; Brugger, R.M.

1987-01-01

These experiments have observed the mirror reflection and Bragg diffraction of neutrons at the energy of a low lying nuclear resonance of 115 In. The reflector was a mirror of In metal with the resonance at 1.457 eV. The mirror reflection for different angles of incidence has been measured and sets of data showing the relative reflectivities have been obtained. For the Bragg diffraction, the crystal was a wafer of InP and several examples of Bragg reflections near 1.455 eV were measured. 4 refs., 12 figs

Colagem ortodôntica em esmalte com presença ou ausência de contaminação salivar: é necessário o uso de adesivo auto-condicionante ou de adesivo hidrofílico? Orthodontic bonding in dry and saliva contaminated enamel: is a self-etching primer or a moisture-insensitive primer necessary?

Directory of Open Access Journals (Sweden)

Cristiane Becher Rosa

2008-06-01

Full Text Available OBJETIVO: o objetivo deste trabalho foi avaliar a resistência ao cisalhamento da colagem ortodôntica de um adesivo hidrofílico (Transbond Moisture-Insensitive Primer, 3M Unitek, Monrovia, Califórnia, de um adesivo auto-condicionante (Transbond Self-Etching Primer, 3M Unitek, Monrovia, Califórnia, e sem uso de adesivo, em superfícies de esmalte secas ou contaminadas por saliva. METODOLOGIA: incisivos bovinos (60 foram divididos em 6 grupos: (1 controle sem contaminação salivar (sem adesivo, (2 controle com contaminação salivar (sem adesivo, (3 adesivo auto-condicionante sem contaminação salivar, (4 adesivo auto-condicionante com contaminação salivar antes do adesivo, (5 adesivo hidrofílico sem contaminação salivar e (6 adesivo hidrofílico com contaminação salivar antes do adesivo. Braquetes metálicos foram colados com compósito (Transbond XT, 3M Unitek, Monrovia, Califórnia. Após a colagem, os corpos-de prova foram armazenados a 37±1ºC em ambiente úmido até a realização do teste de cisalhamento. Diferença estatística foi determinada com valor de probabilidade de 0,05 ou menos (p AIM: The purpose of this study was to evaluate the shear bond strength of orthodontic bonding with the use of a hydrophilic primer (Transbond Moisture-Insensitive Primer, 3M Unitek, Monrovia, Calif., a self-etching primer (Transbond Plus Self-etching Primer, 3M Unitek, Monrovia, Calif. and without primer application, in dry and saliva contaminated enamel surfaces. METHODS: Bovine incisors (60 were divided into 6 groups: (1 uncontaminated control (no primer, (2 control with saliva contamination (no primer, (3 uncontaminated self-etching primer, (4 saliva contamination before self-etching primer, (5 uncontaminated hydrophilic primer and (6 saliva contamination before hydrophilic primer. Stainless steel brackets were bonded with composite resin (Transbond XT, 3M Unitek, Monrovia, Calif.. After bonding, all samples were stored at 37±1°C in a

Performance of a new one-step multi-mode adhesive on etched vs non-etched enamel on bond strength and interfacial morphology.

Science.gov (United States)

de Goes, Mario Fernando; Shinohara, Mirela Sanae; Freitas, Marcela Santiago

2014-06-01

To compare microtensile bond strength (μTBS) and interfacial morphology of a new one-step multimode adhesive with a two-step self-etching adhesive and two etch-and-rinse adhesives systems on enamel. Thirty human third molars were sectioned to obtain two enamel fragments. For μTBS, 48 enamel surfaces were ground using 600-grit SiC paper and randomly assigned into 6 groups (n = 8): nonetched Scotchbond Universal [SBU]; etched SBU [SBU-et]; non-etched Clearfil SE Bond [CSE]; etched CSE [CSE-et]; Scotchbond Multi-PURPOSE [SBMP]; Excite [EX]. The etched specimens were conditioned with 37% phosphoric acid for 30 s, each adhesive system was applied according to manufacturers' instructions, and composite resin blocks (Filtek Supreme Plus, 3M ESPE) were incrementally built up. Specimens were sectioned into beams with a cross-sectional area of 0.8-mm2 and tested under tension (1 mm/min). The data were analyzed with oneway ANOVA and Fisher's PLSD (α = 0.05). For interface analysis, two samples from each group were embedded in epoxy resin, polished, and then observed using scanning electron microscopy (SEM). The μTBS values (in MPa) and the standard deviations were: SBU = 27.4 (8.5); SBU-et = 33.6 (9.3); CSE = 28.5 (8.3); CSE-et = 34.2 (9.0); SBMP = 30.4 (11.0); EX = 23.3 (8.2). CSE-et and SBU-et presented the highest bond strength values, followed by SBMP, CSE, and SBU which did not differ significantly from each other. EX showed the statistically significantly lowest bond strength values. SEM images of interfaces from etched samples showed long adhesive-resin tags penetrating into demineralized enamel. Preliminary etching of enamel significantly increased bond strength for the new one-step multimode adhesive SBU and two-step self-etching adhesive CSE.

Comparative study of resist stabilization techniques for metal etch processing

Science.gov (United States)

Becker, Gerry; Ross, Matthew F.; Wong, Selmer S.; Minter, Jason P.; Marlowe, Trey; Livesay, William R.

1999-06-01

This study investigates resist stabilization techniques as they are applied to a metal etch application. The techniques that are compared are conventional deep-UV/thermal stabilization, or UV bake, and electron beam stabilization. The electron beam tool use din this study, an ElectronCure system from AlliedSignal Inc., ELectron Vision Group, utilizes a flood electron source and a non-thermal process. These stabilization techniques are compared with respect to a metal etch process. In this study, two types of resist are considered for stabilization and etch: a g/i-line resist, Shipley SPR-3012, and an advanced i-line, Shipley SPR 955- Cm. For each of these resist the effects of stabilization on resist features are evaluated by post-stabilization SEM analysis. Etch selectivity in all cases is evaluated by using a timed metal etch, and measuring resists remaining relative to total metal thickness etched. Etch selectivity is presented as a function of stabilization condition. Analyses of the effects of the type of stabilization on this method of selectivity measurement are also presented. SEM analysis was also performed on the features after a compete etch process, and is detailed as a function of stabilization condition. Post-etch cleaning is also an important factor impacted by pre-etch resist stabilization. Results of post- etch cleaning are presented for both stabilization methods. SEM inspection is also detailed for the metal features after resist removal processing.

Effects of etching time on enamel bond strengths.

Science.gov (United States)

Triolo, P T; Swift, E J; Mudgil, A; Levine, A

1993-12-01

This study evaluated the effects of etching time on bond strengths of composite to enamel. Proximal surfaces of extracted molars were etched with either a conventional etchant (35% phosphoric acid) or one of two dentin/enamel conditioners, 10% maleic acid (Scotchbond Multi-Purpose Etchant), or a solution of oxalic acid, aluminum nitrate, and glycine (Gluma 1 & 2 Conditioner). Each agent was applied for 15, 30, or 60 seconds. Specimens etched with 35% phosphoric acid had the highest mean bond strengths at each etching time. At the manufacturer's recommended application times, the other two agents gave significantly lower shear bond strengths than phosphoric acid.

High-Density Plasma-Induced Etch Damage of GaN

International Nuclear Information System (INIS)

Baca, A.G.; Han, J.; Lester, L.F.; Pearton, S.J.; Ren, F.; Shul, R.J.; Willison, C.G.; Zhang, L.; Zolper, J.C.

1999-01-01

Anisotropic, smooth etching of the group-III nitrides has been reported at relatively high rates in high-density plasma etch systems. However, such etch results are often obtained under high de-bias and/or high plasma flux conditions where plasma induced damage can be significant. Despite the fact that the group-III nitrides have higher bonding energies than more conventional III-V compounds, plasma-induced etch damage is still a concern. Attempts to minimize such damage by reducing the ion energy or increasing the chemical activity in the plasma often result in a loss of etch rate or anisotropy which significantly limits critical dimensions and reduces the utility of the process for device applications requiring vertical etch profiles. It is therefore necessary to develop plasma etch processes which couple anisotropy for critical dimension and sidewall profile control and high etch rates with low-damage for optimum device performance. In this study we report changes in sheet resistance and contact resistance for n- and p-type GaN samples exposed to an Ar inductively coupled plasma (ICP). In general, plasma-induced damage was more sensitive to ion bombardment energies as compared to plasma flux. In addition, p-GaN was typically more sensitive to plasma-induced damage as compared to n-GaN

Particle precipitation in connection with KOH etching of silicon

DEFF Research Database (Denmark)

Nielsen, Christian Bergenstof; Christensen, Carsten; Pedersen, Casper

2004-01-01

This paper considers the precipitation of iron oxide particles in connection with the KOH etching of cavities in silicon wafers. The findings presented in this paper suggest that the source to the particles is the KOH pellets used for making the etching solution. Experiments show that the precipi......This paper considers the precipitation of iron oxide particles in connection with the KOH etching of cavities in silicon wafers. The findings presented in this paper suggest that the source to the particles is the KOH pellets used for making the etching solution. Experiments show...... that the precipitation is independent of KOH etching time, but that the amount of deposited material varies with dopant type and dopant concentration. The experiments also suggest that the precipitation occurs when the silicon wafers are removed from the KOH etching solution and not during the etching procedure. When...... not removed, the iron oxide particles cause etch pits on the Si surface when later processed and exposed to phosphoric acid. It has been found that the particles can be removed in an HCl solution, but not completely in an H2SO4- H2O2 solution. The paper discusses the involved precipitation mechanism in terms...

Influence of water storage on fatigue strength of self-etch adhesives.

Science.gov (United States)

Takamizawa, Toshiki; Barkmeier, Wayne W; Tsujimoto, Akimasa; Scheidel, Donal D; Watanabe, Hidehiko; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

2015-12-01

The purpose of this study was to determine enamel and dentin bond durability after long-term water storage using self-etch adhesives. Two single step self-etch adhesives (SU, Scotchbond Universal and GB, G-ӕnial Bond) and a two-step self-etch adhesive (OX, OptiBond XTR) were used. The shear bond strength (SBS) and shear fatigue strength (FS) of the enamel and dentin were obtained with and without phosphoric acid pre-etching prior to application of the adhesives. The specimens were stored in distilled water at 37 °C for 24 h, 6 months, and one year. A staircase method was used to determine the FS using a frequency of 10 Hz for 50,000 cycles or until failure occurred. The SBS and FS of enamel bonds were significantly higher with pre-etching, when compared to no pre-etching for the same water storage period. The FS of dentin bonds with pre-etching tended to decrease relative to no pre-etching at the same storage period. For the one year storage period, SU and GB with pre-etching showed significantly lower FS values than the groups without pre-etching. The influence of water storage on FS of the self-etch adhesives was dependent on the adhesive material, storage period and phosphoric acid pre-etching of the bonding site. Phosphoric acid pre-etching of enamel improves the effectiveness of self-etch adhesive systems. Inadvertent contact of phosphoric acid on dentin appears to reduce the ability of self-etch adhesives to effectively bond resin composite materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mode splitting effect in FEMs with oversized Bragg resonators

Energy Technology Data Exchange (ETDEWEB)

Peskov, N. Yu.; Sergeev, A. S. [Institute of Applied Physics Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Kaminsky, A. K.; Perelstein, E. A.; Sedykh, S. N. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Kuzikov, S. V. [Institute of Applied Physics Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Nizhegorodsky State University, Nizhny Novgorod (Russian Federation)

2016-07-15

Splitting of the fundamental mode in an oversized Bragg resonator with a step of the corrugation phase, which operates over the feedback loop involving the waveguide waves of different transverse structures, was found to be the result of mutual influence of the neighboring zones of the Bragg scattering. Theoretical description of this effect was developed within the framework of the advanced (four-wave) coupled-wave approach. It is shown that mode splitting reduces the selective properties, restricts the output power, and decreases the stability of the narrow-band operating regime in the free-electron maser (FEM) oscillators based on such resonators. The results of the theoretical analysis were confirmed by 3D simulations and “cold” microwave tests. Experimental data on Bragg resonators with different parameters in a 30-GHz FEM are presented. The possibility of reducing the mode splitting by profiling the corrugation parameters is shown. The use of the mode splitting effect for the output power enhancement by passive compression of the double-frequency pulse generated in the FEM with such a resonator is discussed.

Features of copper etching in chlorine-argon plasma

International Nuclear Information System (INIS)

Efremov, A.M.; Svettsov, V.I.

1995-01-01

Chlorine mixtures with inert gases including argon exhibit promise as plasma feed gases for etching metals and semiconductors in the microelectronics industry. It was shown that even strong dilution of reactive gas with an inert gas (up to 80-90% of the latter) has virtually no effect in decreasing the rate of plasma etching of materials such as silicon and gallium arsenide, compared to etching in pure chlorine. The principal reactive species responsible for etching these substrates are chlorine atoms therefore, a possible explanation of the effect is an increase in the rate of bulk generation of chlorine atoms in the presence of argon. In this work the authors studied the influence of argon on the rate of copper etching in chlorine, because copper, unlike the above substrates, reacts effectively not only with the atoms but with the ground-state molecules of chlorine

Chromatic X-ray magnifying method and apparatus by Bragg reflective planes on the surface of Abbe sphere

Science.gov (United States)

Thoe, Robert S.

1991-01-01

Method and apparatus for producing sharp, chromatic, magnified images of X-ray emitting objects, are provided. The apparatus, which constitutes an X-ray microscope or telescope, comprises a connected collection of Bragg reflecting planes, comprised of either a bent crystal or a synthetic multilayer structure, disposed on and adjacent to a locus determined by a spherical surface. The individual Bragg planes are spatially oriented to Bragg reflect radiation from the object location toward the image location. This is accomplished by making the Bragg planes spatially coincident with the surfaces of either a nested series of prolate ellipsoids of revolution, or a nested series of spheres. The spacing between the Bragg reflecting planes can be tailored to control the wavelengths and the amount of the X-radiation that is Bragg reflected to form the X-ray image.

Neutron dosimetry using electrochemical etching

International Nuclear Information System (INIS)

Su, S.J.; Stillwagon, G.B.; Morgan, K.Z.

1977-01-01

Registration of α-tracks and fast-neutron-induced recoils tracks by the electrochemical etching technique as applied to sensitive polymer foils (e.g., polycarbonate) provides a simple, sensitive and inexpensive means of fast neutron personnel dosimetry as well as a valuable research tool for microdosimetry. When tracks were amplified by our electrochemical technique and the etching results compared with conventional etching technique a striking difference was noted. The electrochemically etched tracks were of much larger diameter (approx. 100 μm) and gave superior contrast. Two optical devices--the transparency projector and microfiche reader--were adapted to facilitate counting of the tracks appearing on our polycarbonate foils. The projector produced a magnification of 14X for a screen to projector distance of 5.0 meter and read's magnification was 50X. A Poisson distribution was determined for the number of tracks located in a particular area of the foil and experimentally verified by random counting of quarter sections of the microfiche reader screen. Finally, in an effort to determine dose equivalent (rem), a conversion factor is being determined by finding the sensitivity response (tracks/neutron) of recoil particle induced tracks as a function of monoenergetic fast neutrons and comparing results with those obtained by others

PROTECTIVE COATINGS OF FIBER BRAGG GRATING FOR MINIMIZING OF MECHANICAL IMPACT ON ITS WAVELENGTH CHARACTERISTICS

Directory of Open Access Journals (Sweden)

A. S. Munko

2015-03-01

Full Text Available The paper deals with the scheme for the study of the Bragg wavelength shift dependence on the applied tensile force. Samples of fiber Bragg gratings with different coatings have been studied: the restored acrylate coating, the heatshrinkable fusion splice protection sleeve without metal rod, the heat-shrinkable fusion splice protection sleeve with a metal rod, the metal capillary, polyvinylchloride tube. For different coatings of diffractive structure, dependences of wavelength shift for the Bragg grating resonance have been obtained on the tensile strength applied to the ends of an optical fiber. It was determined that the studied FBG coatings give the possibility to reduce the mechanical impact on the Bragg wavelength shift for 1.1-15 times as compared to an uncoated waveguide. The most effective version of coated fiber Bragg grating is the heatshrinkable fusion splice protection sleeve with a metal rod. When the force (equal to 6 N is applied to the 100 mm optical fiber area with the inscribed diffractive structure, the Bragg wavelength shift is 7.5 nm for the unprotected sample and 0.5 nm for the one coated with the heat-shrinkable fusion splice protection sleeve.

Electronegativity-dependent tin etching from thin films

Energy Technology Data Exchange (ETDEWEB)

Pachecka, M., E-mail: m.pachecka@utwente.nl; Sturm, J. M.; Kruijs, R. W. E. van de; Lee, C. J.; Bijkerk, F. [Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, Drienerlolaan 5, Enschede (Netherlands)

2016-07-15

The influence of a thin film substrate material on the etching of a thin layer of deposited tin (Sn) by hydrogen radicals was studied. The amount of remaining Sn was quantified for materials that cover a range of electronegativities. We show that, for metals, etching depends on the relative electronegativity of the surface material and Sn. Tin is chemically etched from surfaces with an electronegativity smaller than Sn, while incomplete Sn etching is observed for materials with an electronegativity larger than Sn. Furthermore, the amount of remaining Sn increases as the electronegativity of the surface material increases. We speculate, that, due to Fermi level differences in the material’s electronic structure, the energy of the two conduction bands shift such that the availability of electrons for binding with hydrogen is significantly reduced.

Methods of removal of defects arising at liquid etching of polycrystalline silicon

Directory of Open Access Journals (Sweden)

Ivanchykou A. E.

2008-02-01

Full Text Available The paper presents a model of generation of defects having the form of spots on the surface of the polycrystalline silicon during processing of semiconductor wafers with hydrofluoric acid based etchant, and a model of removal of such defects in chemical solutions. The authors investigate how the centrifuge speed during drying and the relief of structures, produced on the plate, effect the number of defects. It is shown that there is a possibility to remove defects by chemical treatment in the peroxide-ammonia solutions (PAS and also by sequence of chemical cleaning in Karo mixture, SiO2 etching and treatment in PAS.

In vitro evaluation of microleakage around orthodontic brackets using laser etching and Acid etching methods.

Directory of Open Access Journals (Sweden)

Mohammad Hossein Toodehzaeim

2014-06-01

Full Text Available path of microleakage between the enamel and adhesive potentially allows microbial ingress that may consequently cause enamel decalcification. The aim of this study was to compare microleakage of brackets bonded either by laser or acid etching techniques.The specimens were 33 extracted premolars that were divided into three groups as the acid etching group (group 1, laser etching with Er:YAG at 100 mJ and 15 Hz for 15s (group 2, and laser etching with Er:YAG at 140 mJ and 15 Hz for 15s (group 3. After photo polymerization, the teeth were subjected to 500 thermal cycles. Then the specimens were sealed with nail varnish, stained with 2% methylen blue for 24hs, sectioned, and examined under a stereomicroscope. They were scored for marginal microleakage that occurred between the adhesive-enamel and bracket-adhesive interfaces from the occlusal and gingival margins. Data were analyzed with the Kruskal- Wallis test.For the adhesive-enamel and bracket-adhesive surfaces, significant differences were not observed between the three groups.According to this study, the Er:YAG laser with 1.5 and 2.1 watt settings may be used as an adjunctive for preparing the surface for orthodontic bracket bonding.

Security System Responsive to Optical Fiber Having Bragg Grating

Science.gov (United States)

Gary, Charles K. (Inventor); Ozcan, Meric (Inventor)

1997-01-01

An optically responsive electronic lock is disclosed comprising an optical fiber serving as a key and having Bragg gratings placed therein. Further, an identification system is disclosed which has the optical fiber serving as means for tagging and identifying an object. The key or tagged object is inserted into a respective receptacle and the Bragg gratings cause the optical fiber to reflect a predetermined frequency spectra pattern of incident light which is detected by a decoder and compared against a predetermined spectrum to determine if an electrical signal is generated to either operate the lock or light a display of an authentication panel.

Influence of copper foil polycrystalline structure on graphene anisotropic etching

Energy Technology Data Exchange (ETDEWEB)

Sharma, Kamal P. [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Mahyavanshi, Rakesh D. [Department of Physical Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Kalita, Golap, E-mail: kalita.golap@nitech.ac.jp [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Department of Physical Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Tanemura, Masaki [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Department of Physical Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

2017-01-30

Graphical abstract: Hexagonal hole formation with anisotropic etching independent of the stripes and wrinkles in the synthesized graphene. We also observed variation in etched pattern of the graphene depending on the base Cu grain orientations, attributing to difference in nucleation and growth process. - Highlights: • Reveal the influence of copper polycrystalline structure on anisotropic etching of graphene. • Hexagonal hole formation with etching is observed to be independent of stripes and wrinkles in graphene. • Variation in etched pattern of graphene depending on the base Cu grain is confirmed. • This finding will help to understand the nature of microscopic etched pattern in graphene. - Abstract: Anisotropic etching of graphene and other two dimensional materials is an important tool to understand the growth process as well as enabling fabrication of various well-defined structures. Here, we reveal the influence of copper foil polycrystalline structure on anisotropic etching process of as-synthesized graphene. Graphene crystals were synthesized on the polycrystalline Cu foil by a low-pressure chemical vapor deposition (LPCVD) system. Microscopic analysis shows difference in shape, size and stripes alignment of graphene crystals with dissimilar nucleation within closure vicinity of neighboring Cu grains. Post-growth etching of such graphene crystals also significantly affected by the crystallographic nature of Cu grains as observed by the field emission scanning electron microscope (FE-SEM) and electron back scattered diffraction (EBSD) analysis. Hexagonal hole formation with anisotropic etching is observed to be independent of the stripes and wrinkles in the synthesized graphene. We also observed variation in etched pattern of the graphene depending on the base Cu grain orientations, attributing to difference in nucleation and growth process. The findings can facilitate to understand the nature of microscopic etched pattern depending on metal

Influence of copper foil polycrystalline structure on graphene anisotropic etching

International Nuclear Information System (INIS)

Sharma, Kamal P.; Mahyavanshi, Rakesh D.; Kalita, Golap; Tanemura, Masaki

2017-01-01

Graphical abstract: Hexagonal hole formation with anisotropic etching independent of the stripes and wrinkles in the synthesized graphene. We also observed variation in etched pattern of the graphene depending on the base Cu grain orientations, attributing to difference in nucleation and growth process. - Highlights: • Reveal the influence of copper polycrystalline structure on anisotropic etching of graphene. • Hexagonal hole formation with etching is observed to be independent of stripes and wrinkles in graphene. • Variation in etched pattern of graphene depending on the base Cu grain is confirmed. • This finding will help to understand the nature of microscopic etched pattern in graphene. - Abstract: Anisotropic etching of graphene and other two dimensional materials is an important tool to understand the growth process as well as enabling fabrication of various well-defined structures. Here, we reveal the influence of copper foil polycrystalline structure on anisotropic etching process of as-synthesized graphene. Graphene crystals were synthesized on the polycrystalline Cu foil by a low-pressure chemical vapor deposition (LPCVD) system. Microscopic analysis shows difference in shape, size and stripes alignment of graphene crystals with dissimilar nucleation within closure vicinity of neighboring Cu grains. Post-growth etching of such graphene crystals also significantly affected by the crystallographic nature of Cu grains as observed by the field emission scanning electron microscope (FE-SEM) and electron back scattered diffraction (EBSD) analysis. Hexagonal hole formation with anisotropic etching is observed to be independent of the stripes and wrinkles in the synthesized graphene. We also observed variation in etched pattern of the graphene depending on the base Cu grain orientations, attributing to difference in nucleation and growth process. The findings can facilitate to understand the nature of microscopic etched pattern depending on metal

Photonic jet μ-etching: from static to dynamic process

Science.gov (United States)

Abdurrochman, A.; Lecler, S.; Zelgowski, J.; Mermet, F.; Fontaine, J.; Tumbelaka, B. Y.

2017-05-01

Photonic jet etching is a direct-laser etching method applying photonic jet phenomenon to concentrate the laser beam onto the proceeded material. We call photonic jet the phenomenon of the localized sub-wavelength propagative beam generated at the shadow-side surfaces of micro-scale dielectric cylinders or spheres, when they are illuminated by an electromagnetic plane-wave or laser beam. This concentration has made possible the laser to yield sub-μ etching marks, despite the laser was a near-infrared with nano-second pulses sources. We will present these achievements from the beginning when some spherical glasses were used for static etching to dynamic etching using an optical fiber with a semi-elliptical tip.

Fabrication of locally micro-structured fiber Bragg gratings by fs-laser machining

Science.gov (United States)

Dutz, Franz J.; Stephan, Valentin; Marchi, Gabriele; Koch, Alexander W.; Roths, Johannes; Huber, Heinz P.

2018-06-01

Here, we describe a method for producing locally micro-structured fiber Bragg gratings (LMFGB) by fs-laser machining. This technique enables the precise and reproducible ablation of cladding material to create circumferential grooves inside the claddings of optical fibers. From initial ablation experiments we acquired optimized process parameters. The fabricated grooves were located in the middle of uniform type I fiber Bragg gratings. LMFBGs with four different groove widths of 48, 85, 135 and 205 μ { {m}} were produced. The grooves exhibited constant depths of about 30 μ {m} and steep sidewall angles. With the combination of micro-structures and fiber Bragg gratings, fiber optic sensor elements with enhanced functionalities can be achieved.

Uniform Fiber Bragg Grating modeling and simulation used matrix transfer method

OpenAIRE

IKHLEF, Abdallah; HEDARA, Rachida; CHIKH-BLED, Mohamed

2012-01-01

This paper presents the modeling and simulation of an optical fiber Bragg grating for maximum reflectivity, minimum side lobe. Gating length represents as one of the critical parameters in contributing to a high performance fiber Bragg grating. The reflection spectra and side lobes strength were analyzed with different lengths .The side lobes have been suppressed using raised cosine apodization while maintaining the peak reflectivity. Such simulations are based on ...

Nuclear Bragg diffraction using synchrotron radiation

International Nuclear Information System (INIS)

Rueffer, R.; Gerdau, E.; Grote, M.; Hollatz, R.; Roehlsberger, R.; Rueter, H.D.; Sturhahn, W.

1990-01-01

Nuclear Bragg diffraction with synchrotron radiation as source will become a powerful new X-ray source in the A-region. This source exceeds by now the brilliance of conventional Moessbauer sources giving hyperfine spectroscopy further momentum. As examples applications to yttrium iron garnet (YIG) and iron borate will be discussed. (author)

Development of deep silicon plasma etching for 3D integration technology

Directory of Open Access Journals (Sweden)

Golishnikov А. А.

2014-02-01

Full Text Available Plasma etch process for thought-silicon via (TSV formation is one of the most important technological operations in the field of metal connections creation between stacked circuits in 3D assemble technology. TSV formation strongly depends on parameters such as Si-wafer thickness, aspect ratio, type of metallization material, etc. The authors investigate deep silicon plasma etch process for formation of TSV with controllable profile. The influence of process parameters on plasma etch rate, silicon etch selectivity to photoresist and the structure profile are researched in this paper. Technology with etch and passivation steps alternation was used as a method of deep silicon plasma etching. Experimental tool «Platrane-100» with high-density plasma reactor based on high-frequency ion source with transformer coupled plasma was used for deep silicon plasma etching. As actuation gases for deep silicon etching were chosen the following gases: SF6 was used for the etch stage and CHF3 was applied on the polymerization stage. As a result of research, the deep plasma etch process has been developed with the following parameters: silicon etch rate 6 µm/min, selectivity to photoresist 60 and structure profile 90±2°. This process provides formation of TSV 370 µm deep and about 120 µm in diameter.

Etching of enamel for direct bonding with a thulium fiber laser

Science.gov (United States)

Kabaş Sarp, Ayşe S.; Gülsoy, Murat

2011-03-01

Background: Laser etching of enamel for direct bonding can decrease the risk of surface enamel loss and demineralization which are the adverse effects of acid etching technique. However, in excess of +5.5°C can cause irreversible pulpal responses. In this study, a 1940- nm Thulium Fiber Laser in CW mode was used for laser etching. Aim: Determination of the suitable Laser parameters of enamel surface etching for direct bonding of ceramic brackets and keeping that intrapulpal temperature changes below the threshold value. Material and Method: Polycrystalline ceramic orthodontic brackets were bonded on bovine teeth by using 2 different kinds of etching techniques: Acid and Laser Etching. In addition to these 3 etched groups, there was also a group which was bonded without etching. Brackets were debonded with a material testing machine. Breaking time and the load at the breaking point were measured. Intrapulpal temperature changes were recorded by a K-type Thermocouple. For all laser groups, intrapulpal temperature rise was below the threshold value of 5.5°C. Results and Conclusion: Acid-etched group ( 11.73 MPa) significantly required more debonding force than 3- second- irradiated ( 5.03 MPa) and non-etched groups ( 3.4 MPa) but the results of acid etched group and 4- second- irradiated group (7.5 MPa) showed no significant difference. Moreover, 4- second irradiated group was over the minimum acceptable value for clinical use. Also, 3- second lasing caused a significant reduction in time according to acid-etch group. As a result, 1940- nm laser irradiation is a promising method for laser etching.

Development and application of the electrochemical etching technique. Annual progress report

International Nuclear Information System (INIS)

1979-08-01

This report documents advances in the development and application of the electrochemical etching technique for thermal and epithermal neutron dosimetry as well as track geometry determinations. The bulk and track etching rates were studied by evaluating the track geometry during electrochemical etching. The foil surface removed versus etching time for two different etchants at 1000 V, 2 kHz, and 22 0 C were studied. Results indicated that the bulk etching rates were constant for the two etchants, i.e. 45% KOH and 45% KOH mixed with an equal volume of C 2 H 5 OH 5 and were equal to 0.20 +- 0.14 μm/hr and 2.7 +- 0.27 μm/hr from each side of the foil. The track etching rate (as contrasted with the bulk etching rate) can be determined by the microscope focus at various depths. The increase of track depth values as a function of etching time for the two etchants are plotted. The track cone angles were determined and found to be much larger for electrochemically etched polycarbonate foils than for most plastics etched with passive chemical techniques

Ultra-large bandwidth hollow-core guiding in all-silica bragg fibers with nano-supports

DEFF Research Database (Denmark)

Vienne, Guillaume; Xu, Yong; Jakobsen, Christian

2004-01-01

We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in t...... in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m....

Singular Sheet Etching of Graphene with Oxygen Plasma

Institute of Scientific and Technical Information of China (English)

Haider Al-Mumen; Fubo Rao; Wen Li; Lixin Dong

2014-01-01

This paper reports a simple and controllable post-synthesis method for engineering the number of graphene layers based on oxygen plasma etching. Singular sheet etching(SSE) of graphene was achieved with the optimum process duration of 38 seconds. As a demonstration of this SSE process, monolayer graphene films were produced from bilayer graphenes. Experimental investigations verified that the oxygen plasma etching removes a single layer graphene sheet in an anisotropic fashion rather than anisotropic mode. In addition,etching via the oxygen plasma at the ground electrodes introduced fewer defects to the bottom graphene layer compared with the conventional oxygen reactive ion etching using the powered electrodes. Such defects can further be reduced with an effective annealing treatment in an argon environment at 900-1000?C. These results demonstrate that our developed SSE method has enabled a microelectronics manufacturing compatible way for single sheet precision subtraction of graphene layers and a potential technique for producing large size graphenes with high yield from multilayer graphite materials.

Singular Sheet Etching of Graphene with Oxygen Plasma

Institute of Scientific and Technical Information of China (English)

Haider Al-Mumen; Fubo Rao; Wen Li; Lixin Dong

2014-01-01

This paper reports a simple and controllable post-synthesis method for engineering the number of graphene layers based on oxygen plasma etching. Singular sheet etching (SSE) of graphene was achieved with the optimum process duration of 38 seconds. As a demonstration of this SSE process, monolayer graphene films were produced from bilayer graphenes. Experimental investigations verified that the oxygen plasma etching removes a single layer graphene sheet in an anisotropic fashion rather than anisotropic mode. In addition, etching via the oxygen plasma at the ground electrodes introduced fewer defects to the bottom graphene layer compared with the conventional oxygen reactive ion etching using the powered electrodes. Such defects can further be reduced with an effective annealing treatment in an argon environment at 900-1000◦C. These results demonstrate that our developed SSE method has enabled a microelectronics manufacturing compatible way for single sheet precision subtraction of graphene layers and a potential technique for producing large size graphenes with high yield from multilayer graphite materials.

Optical-fiber strain sensors with asymmetric etched structures.

Science.gov (United States)

Vaziri, M; Chen, C L

1993-11-01

Optical-fiber strain gauges with asymmetric etched structures have been analyzed, fabricated, and tested. These sensors are very sensitive with a gauge factor as high as 170 and a flat frequency response to at least 2.7 kHz. The gauge factor depends on the asymmetry of the etched structures and the number of etched sections. To understand the physical principles involved, researchers have used structural analysis programs based on a finite-element method to analyze fibers with asymmetric etched structures under tensile stress. The results show that lateral bends are induced on the etched fibers when they are stretched axially. To relate the lateral bending to the optical attenuation, we have also employed a ray-tracing technique to investigate the dependence of the attenuation on the structural deformation. Based on the structural analysis and the ray-tracing study parameters affecting the sensitivity have been studied. These results agree with the results of experimental investigations.

Effects of mask imperfections on InP etching profiles

International Nuclear Information System (INIS)

Huo, D.T.C.; Yan, M.F.; Wynn, J.D.; Wilt, D.P.

1990-01-01

The authors have demonstrated that the quality of etch masks has a significant effect on the InP etching profiles. In particular, the authors have shown that mask imperfections can cause defective etching profiles, such as vertical sidewalls and extra mask undercutting in InP. The authors also discovered that the geometry of these defective profiles is determined by the orientation of the substrate relative to the direction of the mask imperfections. Along a left-angle 110 right-angle line mask defect, the downward etching process changes the left-angle 110 right-angle v-grooves to vertical sidewalls without extra undercutting. For v-grooves aligned along the left-angle 110 right-angle direction, defects on the mask give a significant extra undercutting without changing the etching profile

Induction of Micronuclei in Human Fibroblasts across the Bragg Curve of Energetic Si and Fe Ions

Science.gov (United States)

Wu, H.; Rusek, A.; Hada, M.

2006-01-01

The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the major protection to astronauts from harmful exposure. Unlike low-LET gamma or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure. Since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak, the Bragg curve does not necessarily represent the biological damage along the particle traversal since biological effects are influenced by the track structure of both primary and secondary particles. Therefore, the biological Bragg curve is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. We studied micronuclei (MN) induction across the Bragg curve of Si and Fe ions at incident energies of 300 MeV/nucleon and 1 GeV/nucleon. A quantitative biological response curve did not reveal an increased yield of MN at the location of the Bragg peak. However, the ratio of mono- to bi-nucleated cells, which indicates inhibition in cell progression, increased at the Bragg peak location. These results confirm the hypothesis that severely damaged cells at the Bragg peak are likely to go through reproduction death.

The mechanism of selective corrugation removal by KOH anisotropic wet etching

International Nuclear Information System (INIS)

Shikida, M; Inagaki, N; Sasaki, H; Amakawa, H; Fukuzawa, K; Sato, K

2010-01-01

The mechanism of selective corrugation removal by anisotropic wet etching—which reduces a periodic corrugation, called 'scalloping', formed on the sidewalls of microstructures by the Bosch process in deep reactive-ion etching (D-RIE)—was investigated. In particular, the corrugation-removal mechanism was analyzed by using the etching rate distribution pattern, and two equations for predicting the corrugation-removal time by the etching were derived. A Si{1 0 0} wafer was first etched by D-RIE at a depth of 29.4 µm (60 cycles) to form the corrugation on the sidewall surface. The height and pitch of the corrugation were 196 and 494 nm, respectively. Selective removal of the corrugation by using 50% KOH (40 °C) was experimentally tried. The corrugation formed on Si{1 0 0} sidewall surfaces was gradually reduced in size as the etching progressed, and it was completely removed after 5 min of etching. Similarly, the corrugation formed on a Si{1 1 0} sidewall surface was also selectively removed by KOH etching (etching time: 3 min). The roughness value of the sidewall surface was reduced from 17.6 nm to a few nanometers by the etching. These results confirm that the corrugation-removal mechanism using anisotropic wet etching can be explained in terms of the distribution pattern of etching rate

Variation of Bragg curve characteristic induced by changing the position of inhomogeneous material: Geant4 simulation study

Energy Technology Data Exchange (ETDEWEB)

Park, So-Hyun; Jung, Won-Gyun; Suh, Tae-Suk [Catholic University, Seoul (Korea, Republic of); Jang, Hong-Seok; Choi, Byeong-Oak [Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Rah, Jeong-Eun; Park, Sun-Gyong; Lee, Se-Byeong [National Cancer Center, Ilsan (Korea, Republic of)

2011-02-15

When proton beam passes through the human body, the stopping power and the depth-dose distribution of the proton are influenced by the relative location among adjacent materials or the difference in material conditions. Our study demonstrates the effect of inhomogeneous materials placed in the Plateau and Bragg peak regions of the Bragg curve in water. We evaluated the Bragg peak position, range, penumbra and integrated doses by using the Geant4 simulation toolkit. The positions of inhomogeneities were selected as the proximal 36% and 50% points of the maximum dose, which indicates the location at entrance regions of the Plateau and the Bragg peak, respectively. Bone (density {rho} = 1.85 g/cm{sup 3}) and adipose tissue (density {rho} = 0.92 g/cm{sup 3}) were selected as inhomogeneous materials. The thickness of each material was varied by 0.1 cm between 0.1 cm and 1.0 cm. In addition, the initial energy of the proton beam was changed in 30 MeV steps between 108 MeV and 220 MeV. The effects of inhomogeneous conditions were performed for various parameters: Bragg peak position, range, penumbra width, full width at half maximum and dose of Bragg curve. A dose perturbation was observed in the region of the Bragg peak and inhomogeneous material, especially, When the bone equivalent material was inserted within the Bragg curve. However, there were no significant variations in the other parameters, except for the dose perturbation depending on the inserted location of each material. This study shows the characteristic changes in the Bragg curve due to inhomogeneous materials.

Bragg peak proton beam treatment of arteriovenous malformations of the brain

International Nuclear Information System (INIS)

Kjellberg, R.N.; Poletti, C.E.; Roberson, G.H.; Adams, R.D.

1978-01-01

This report describes 27 patients treated for arteriovenous malformations of the brain by the Bragg Peak proton beam method during the past 12 years. The authors are led to a measure of confidence that Bragg Peak proton therapy can be provided without lethal risk attributed to the procedure. In 21 patients no neurological change has occurred, two patients experienced neurological improvement and four have developed new neurological abnormalities considered complications of the therapy. (Auth.)

Three-dimensional Bragg diffraction in growth-disordered opals

Science.gov (United States)

Baryshev, A. V.; Kaplyanskii, Alexander A.; Kosobukin, Vladimir A.; Limonov, M. F.; Samusev, K. B.; Usvyat, D. E.

2003-06-01

After artificial opals as well as opal-based infilled and inverted composites are considered to be promising representatives of photonic crystal materials. Earlier, photonic stop gaps in opals were studied mainly in transmission or specular reflection geometries corresponding to "one-dimensional" Bragg diffraction. On the contrary, this work was aimed at observing the typical patterns of optical Bragg diffraction in which phenomenon opal crystal structure acts as a three-dimensional diffraction grating. Although our experiments were performed for artificial opals possessing unavoidable imperfections a well-pronounced diffraction peaks were observed characteristic of a crystal structure. Each of the diffraction maxima reveals a photonic stop gap in the specified direction, while the spectral width of the peak is a measure of the photonic stop gap width.

Characterization of Crystallographic Structures Using Bragg-Edge Neutron Imaging at the Spallation Neutron Source

Directory of Open Access Journals (Sweden)

Gian Song

2017-12-01

Full Text Available Over the past decade, wavelength-dependent neutron radiography, also known as Bragg-edge imaging, has been employed as a non-destructive bulk characterization method due to its sensitivity to coherent elastic neutron scattering that is associated with crystalline structures. Several analysis approaches have been developed to quantitatively determine crystalline orientation, lattice strain, and phase distribution. In this study, we report a systematic investigation of the crystal structures of metallic materials (such as selected textureless powder samples and additively manufactured (AM Inconel 718 samples, using Bragg-edge imaging at the Oak Ridge National Laboratory (ORNL Spallation Neutron Source (SNS. Firstly, we have implemented a phenomenological Gaussian-based fitting in a Python-based computer called iBeatles. Secondly, we have developed a model-based approach to analyze Bragg-edge transmission spectra, which allows quantitative determination of the crystallographic attributes. Moreover, neutron diffraction measurements were carried out to validate the Bragg-edge analytical methods. These results demonstrate that the microstructural complexity (in this case, texture plays a key role in determining the crystallographic parameters (lattice constant or interplanar spacing, which implies that the Bragg-edge image analysis methods must be carefully selected based on the material structures.

Site-controlled fabrication of silicon nanotips by indentation-induced selective etching

Science.gov (United States)

Jin, Chenning; Yu, Bingjun; Liu, Xiaoxiao; Xiao, Chen; Wang, Hongbo; Jiang, Shulan; Wu, Jiang; Liu, Huiyun; Qian, Linmao

2017-12-01

In the present study, the indentation-induced selective etching approach is proposed to fabricate site-controlled pyramidal nanotips on Si(100) surface. Without any masks, the site-controlled nanofabrication can be realized by nanoindentation and post etching in potassium hydroxide (KOH) solution. The effect of indentation force and etching time on the formation of pyramidal nanotips was investigated. It is found that the height and radius of the pyramidal nanotips increase with the indentation force or etching time, while long-time etching can lead to the collapse of the tips. The formation of pyramidal tips is ascribed to the anisotropic etching of silicon and etching stop of (111) crystal planes in KOH aqueous solution. The capability of this fabrication method was further demonstrated by producing various tip arrays on silicon surface by selective etching of the site-controlled indent patterns, and the maximum height difference of these tips is less than 10 nm. The indentation-induced selective etching provides a new strategy to fabricate well site-controlled tip arrays for multi-probe SPM system, Si nanostructure-based sensors and high-quality information storage.

Fluorocarbon based atomic layer etching of Si_3N_4 and etching selectivity of SiO_2 over Si_3N_4

International Nuclear Information System (INIS)

Li, Chen; Metzler, Dominik; Oehrlein, Gottlieb S.; Lai, Chiukin Steven; Hudson, Eric A.

2016-01-01

Angstrom-level plasma etching precision is required for semiconductor manufacturing of sub-10 nm critical dimension features. Atomic layer etching (ALE), achieved by a series of self-limited cycles, can precisely control etching depths by limiting the amount of chemical reactant available at the surface. Recently, SiO_2 ALE has been achieved by deposition of a thin (several Angstroms) reactive fluorocarbon (FC) layer on the material surface using controlled FC precursor flow and subsequent low energy Ar"+ ion bombardment in a cyclic fashion. Low energy ion bombardment is used to remove the FC layer along with a limited amount of SiO_2 from the surface. In the present article, the authors describe controlled etching of Si_3N_4 and SiO_2 layers of one to several Angstroms using this cyclic ALE approach. Si_3N_4 etching and etching selectivity of SiO_2 over Si_3N_4 were studied and evaluated with regard to the dependence on maximum ion energy, etching step length (ESL), FC surface coverage, and precursor selection. Surface chemistries of Si_3N_4 were investigated by x-ray photoelectron spectroscopy (XPS) after vacuum transfer at each stage of the ALE process. Since Si_3N_4 has a lower physical sputtering energy threshold than SiO_2, Si_3N_4 physical sputtering can take place after removal of chemical etchant at the end of each cycle for relatively high ion energies. Si_3N_4 to SiO_2 ALE etching selectivity was observed for these FC depleted conditions. By optimization of the ALE process parameters, e.g., low ion energies, short ESLs, and/or high FC film deposition per cycle, highly selective SiO_2 to Si_3N_4 etching can be achieved for FC accumulation conditions, where FC can be selectively accumulated on Si_3N_4 surfaces. This highly selective etching is explained by a lower carbon consumption of Si_3N_4 as compared to SiO_2. The comparison of C_4F_8 and CHF_3 only showed a difference in etching selectivity for FC depleted conditions. For FC accumulation conditions

Microfiber Bragg grating hydrogen sensor base on co-sputtered Pd/Ni composite film

Science.gov (United States)

Wang, Gaopeng; Yang, Minghong; Dai, Jixiang; Cheng, Cheng; Yuan, Yinqian

2015-07-01

A novel hydrogen sensor based on Pd/Ni co-sputtered coating on micro fiber Bragg grating (MFBG) is proposed and experimentally demonstrated. The microfiber is stretched uniformly and the Bragg grating is directly inscribed on the microfiber without hydrogen loading using 193 nm ArF excimer laser and a phase mask. Palladium and nickel coatings are co-sputtered on the micro fiber Bragg grating for hydrogen sensing. The MFBG hydrogen sensors are characterized concerning their response to the hydrogen, ambient temperature and ambient refractive index, respectively. The performance of the proposed MFBG hydrogen sensor is obviously enhanced, especially when compared to standard FBG hydrogen sensors.

Etching patterns on the micro‐ and nanoscale

DEFF Research Database (Denmark)

Michael-Lindhard, Jonas; Herstrøm, Berit; Stöhr, Frederik

2014-01-01

‐ray beam down to a spot size of some 100 nm, the sidewalls of the cavities etched down to 300 μm into a silicon wafer must be perfectly straight and normal to the surface and have minimum roughness.The range of possible applications of the silicon etches is greatly extended if combined with electroplating...... and polymer injection molding. High precision patterns of, for instance microfluidic devices, are etched intosilicon which is then electroplated with nickel that will serve as a stamp in the polymer injection molding tool where thousands of devices may be replicated. In addition to silicon and its derived...

Plasma etching a ceramic composite. [evaluating microstructure

Science.gov (United States)

Hull, David R.; Leonhardt, Todd A.; Sanders, William A.

1992-01-01

Plasma etching is found to be a superior metallographic technique for evaluating the microstructure of a ceramic matrix composite. The ceramic composite studied is composed of silicon carbide whiskers (SiC(sub W)) in a matrix of silicon nitride (Si3N4), glass, and pores. All four constituents are important in evaluating the microstructure of the composite. Conventionally prepared samples, both as-polished or polished and etched with molten salt, do not allow all four constituents to be observed in one specimen. As-polished specimens allow examination of the glass phase and porosity, while molten salt etching reveals the Si3N4 grain size by removing the glass phase. However, the latter obscures the porosity. Neither technique allows the SiC(sub W) to be distinguished from the Si3N4. Plasma etching with CF4 + 4 percent O2 selectively attacks the Si3N4 grains, leaving SiC(sub W) and glass in relief, while not disturbing the pores. An artifact of the plasma etching reaction is the deposition of a thin layer of carbon on Si3N4, allowing Si3N4 grains to be distinguished from SiC(sub W) by back scattered electron imaging.

Etch characteristics of BCB film using inductively coupled plasma

International Nuclear Information System (INIS)

Kang, Pil Seung; Kim, Dong Pyo; Kim, Kyoung Tae; Kim, Chang Il; Kim, Sang Gi

2003-01-01

The etching characteristics and mechanism of BCB thin films were investigated as a function of CF 4 /O 2 mixing ratio in ICP system. Maximum etch rate of 830 nm/min is obtained at the mixture of O 2 /CF 4 (=80%/20%). OES actinometry results showed that volume density of oxygen atoms fallows the same extreme behavior with the BCB etch rate, while the density of fluorine atoms changes monotonously. Therefore chemical destruction of BCB by oxygen atoms was proposed as the dominant etch mechanism. XPS analysis showed that the addition of CF 4 to O 2 helps to volatilize silicon atoms containing in BCB but leads to the formation of F-containing polymer layer. The profile of etched BCB film was close to 90 .deg. and the surface was clean

Developments regarding the Bragg rule for stopping power and critical examination of its application to water

International Nuclear Information System (INIS)

Kamaratos, E.

1983-01-01

A critical comparison is made of various experimental findings regarding the Bragg additivity rule for stopping power. It appears that deviations from the Bragg additivity rule reported a long time ago and ascribed to chemical binding effects and phase effects are real, despite even recent statements of the contrary. Nevertheless, when the Bragg rule is applied to water, critical examination of very recent experimental results for the stopping power in the gaseous state of water, hydrogen and oxygen in this work suggest that the reported deviations from the Bragg additivity rule for the stopping power of gaseous water may be the result of experimental error. (orig.)

No-waiting dentine self-etch concept-Merit or hype.

Science.gov (United States)

Huang, Xue-Qing; Pucci, César R; Luo, Tao; Breschi, Lorenzo; Pashley, David H; Niu, Li-Na; Tay, Franklin R

2017-07-01

A recently-launched universal adhesive, G-Premio Bond, provides clinicians with the alternative to use the self-etch technique for bonding to dentine without waiting for the adhesive to interact with the bonding substrate (no-waiting self-etch; Japanese brochure), or after leaving the adhesive undisturbed for 10s (10-s self-etch; international brochure). The present study was performed to examine in vitro performance of this new universal adhesive bonded to human coronal dentine using the two alternative self-etch modes. One hundred and ten specimens were bonded using two self-etch application modes and examined with or without thermomechanical cycling (10,000 thermal cycles and 240,000 mechanical cycles) to simulate one year of intraoral functioning. The bonded specimens were sectioned for microtensile bond testing, ultrastructural and nanoleakage examination using transmission electron microscopy. Changes in the composition of mineralised dentine after adhesive application were examined using Fourier transform infrared spectroscopy. Both reduced application time and thermomechanical cycling resulted in significantly lower bond strengths, thinner hybrid layers, and significantly more extensive nanoleakage after thermomechanical cycling. Using the conventional 10-s application time improved bonding performance when compared with the no-waiting self-etch technique. Nevertheless, nanoleakage was generally extensive under all testing parameters employed for examining the adhesive. Although sufficient bond strength to dentine may be achieved using the present universal adhesive in the no-waiting self-etch mode that does not require clinicians to wait prior to polymerisation of the adhesive, this self-etch concept requires further technological refinement before it can be recommended as a clinical technique. Although the surge for cutting application time to increase user friendliness remains the most frequently sought conduit for advancement of dentine bonding

Synchrotron radiation focusing by a Bragg--Fresnel lens

International Nuclear Information System (INIS)

Aristov, V.V.; Basov, Y.A.; Snigirev, A.A.

1989-01-01

Since the discovery of x rays and until the present time the possibilities of their controlling and focusing have been widely discussed. In the hard spectrum region (λ∼1 A) the main focusing schemes are the following: geometrical focusing based on incoherent interaction of wave packets reflected by different regions of bending crystals and coherent (dynamic) focusing performed at the cost of the effect of refraction index angular dispersion near the exact Bragg angle value -θ B . A main disadvantage of geometrical focusing is low spatial resolution (∼0.1 mm) and temperature stability. In the case of coherent focusing a main disadvantage is a narrow angular aperture (∼10 sec. of arc) at spatial resolution (∼1--10 μm). Recently, advances in the development of diffraction physics and microstructuring technology open up possibilities for fabricating effective focusing x-ray optical elements---Bragg--Fresnel lenses (BFL)---with high spatial resolution (∼0.1 μm) at a wide angular aperture and high temperature stability. The present paper describes the main principles of Bragg--Fresnel optics (BFO). It presents the results on the synchrotron experiment and on observation of focusing. In this work the peculiarities of BFL diffraction contrast formation are investigated and image transmission using a BFL is performed. Possibilities of developing x-ray optical schemes of ultrahigh resolution on the basis of BFL elements are also discussed

What's new in dentine bonding? Self-etch adhesives.

Science.gov (United States)

Burke, F J Trevor

2004-12-01

Bonding to dentine is an integral part of contemporary restorative dentistry, but early systems were not user-friendly. The introduction of new systems which have a reduced number of steps--the self-etch adhesives--could therefore be an advantage to clinicians, provided that they are as effective as previous adhesives. These new self-etch materials appear to form hybrid layers as did the previous generation of materials. However, there is a need for further clinical research on these new materials. Advantages of self-etch systems include, no need to etch and rinse, reduced post-operative sensitivity and low technique sensitivity. Disadvantages include, the inhibition of set of self- or dual-cure resin materials and the need to roughen untreated enamel surfaces prior to bonding.

Etching radical controlled gas chopped deep reactive ion etching

Science.gov (United States)

Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

2013-10-01

A method for silicon micromachining techniques based on high aspect ratio reactive ion etching with gas chopping has been developed capable of producing essentially scallop-free, smooth, sidewall surfaces. The method uses precisely controlled, alternated (or chopped) gas flow of the etching and deposition gas precursors to produce a controllable sidewall passivation capable of high anisotropy. The dynamic control of sidewall passivation is achieved by carefully controlling fluorine radical presence with moderator gasses, such as CH.sub.4 and controlling the passivation rate and stoichiometry using a CF.sub.2 source. In this manner, sidewall polymer deposition thicknesses are very well controlled, reducing sidewall ripples to very small levels. By combining inductively coupled plasmas with controlled fluorocarbon chemistry, good control of vertical structures with very low sidewall roughness may be produced. Results show silicon features with an aspect ratio of 20:1 for 10 nm features with applicability to nano-applications in the sub-50 nm regime. By comparison, previous traditional gas chopping techniques have produced rippled or scalloped sidewalls in a range of 50 to 100 nm roughness.

Technique for etching monolayer and multilayer materials

Science.gov (United States)

Bouet, Nathalie C. D.; Conley, Raymond P.; Divan, Ralu; Macrander, Albert

2015-10-06

A process is disclosed for sectioning by etching of monolayers and multilayers using an RIE technique with fluorine-based chemistry. In one embodiment, the process uses Reactive Ion Etching (RIE) alone or in combination with Inductively Coupled Plasma (ICP) using fluorine-based chemistry alone and using sufficient power to provide high ion energy to increase the etching rate and to obtain deeper anisotropic etching. In a second embodiment, a process is provided for sectioning of WSi.sub.2/Si multilayers using RIE in combination with ICP using a combination of fluorine-based and chlorine-based chemistries and using RF power and ICP power. According to the second embodiment, a high level of vertical anisotropy is achieved by a ratio of three gases; namely, CHF.sub.3, Cl.sub.2, and O.sub.2 with RF and ICP. Additionally, in conjunction with the second embodiment, a passivation layer can be formed on the surface of the multilayer which aids in anisotropic profile generation.

Premonochromator characteristics of Si and Ge crystals for nuclear Bragg scattering

International Nuclear Information System (INIS)

Harami, Taikan

1990-07-01

The use of monochromator plays an important role as monochromatizing the photon from a facility having an electron storage ring to a narrow band width about the wavelength determined by the Bragg condition. This paper describes the dynamical diffraction formulae and collects the characteristics data of premonochromators of Si and Ge crystals for nuclear Bragg scattering. The numerical studies show the following data. (1) Reflectivity, Bragg reflection width, energy resolution and integral reflecting power for the various reflections of Si and Ge crystals at the photon with the resonance excitation energy of the Moessbauer nuclei of 181 Tm(6.21 keV), 169 Tm(8.42 keV), 57 Fe(14.41 keV), 119 Sn(23.87 keV) and 238 U(44.70 keV). (2) Tables of susceptibilities and figures of rocking curves for the various reflections of Si and Ge crystals. (author)

Polymer waveguide Bragg grating Fabry–Perot filter using a nanoimprinting technique

International Nuclear Information System (INIS)

Binfeng, Yun; Guohua, Hu; Yiping, Cui

2014-01-01

A narrow band waveguide Fabry–Perot filter at 1550 nm, which is composed of two polymer waveguide Bragg gratings as reflectors, is presented. By using conventional lithography, a low-loss polymer channel waveguide was fabricated, and the submicron Bragg grating structure was transferred onto the waveguide surface using a nanoimprinting technique. The transmission spectrum of the device was measured, and the results show that there is a very narrow transmission peak, with a 3 dB bandwidth of 0.011 nm in the 0.38 nm rejection band of the waveguide Bragg grating. A quality factor of Q ≈ 1.41 × 10 5 is achieved. The insertion loss and the extinction ratio of the Fabry–Perot filter are about −12.5 dB and 17 dB, respectively. In addition, the measured transmission spectrum is in excellent accordance with the numerical simulation. (paper)

Photoelectrochemical etching of gallium nitride surface by complexation dissolution mechanism

Energy Technology Data Exchange (ETDEWEB)

Zhang, Miao-Rong [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou (China); University of Chinese Academy of Sciences, 100049 Beijing (China); Hou, Fei; Wang, Zu-Gang; Zhang, Shao-Hui [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou (China); Changchun University of Science and Technology, 130022 Changchun (China); Pan, Ge-Bo, E-mail: gbpan2008@sinano.ac.cn [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 215123 Suzhou (China)

2017-07-15

Graphical abstract: GaN surface was etched by 0.3 M EDTA-2Na. The proposed complexation dissolution mechanism can be applicable to almost all neutral etchants under the prerequisite of strong light and electric field. - Highlights: • GaN surface was etched by EDTA-2Na. • GaN may be dissolved into EDTA-2Na by forming Ga–EDTA complex. • We propose the complexation dissolution mechanism for the first time. - Abstract: Gallium nitride (GaN) surface was etched by 0.3 M ethylenediamine tetraacetic acid disodium (EDTA-2Na) via photoelectrochemical etching technique. SEM images reveal the etched GaN surface becomes rough and irregular. The pore density is up to 1.9 × 10{sup 9} per square centimeter after simple acid post-treatment. The difference of XPS spectra of Ga 3d, N 1s and O 1s between the non-etched and freshly etched GaN surfaces can be attributed to the formation of Ga–EDTA complex at the etching interface between GaN and EDTA-2Na. The proposed complexation dissolution mechanism can be broadly applicable to almost all neutral etchants under the prerequisite of strong light and electric field. From the point of view of environment, safety and energy, EDTA-2Na has obvious advantages over conventionally corrosive etchants. Moreover, as the further and deeper study of such nearly neutral etchants, GaN etching technology has better application prospect in photoelectric micro-device fabrication.

Single Mode Optical Fiber based Refractive Index Sensor using Etched Cladding

OpenAIRE

Kumar, Ajay; Gupta, Geeta; Mallik, Arun; Bhatnagar, Anuj

2011-01-01

The use of optical fiber for sensor applications is a topic of current interest. We report the fabrication of etched single mode optical fiber based refractive index sensor. Experiments are performed to determine the etch rate of fiber in buffered hydrofluoric acid, which can be high or low depending upon the temperature at which etching is carried out. Controlled wet etching of fiber cladding is performed using these measurements and etched fiber region is tested for refractive index sensing...

Plasma atomic layer etching using conventional plasma equipment

International Nuclear Information System (INIS)

Agarwal, Ankur; Kushner, Mark J.

2009-01-01

The decrease in feature sizes in microelectronics fabrication will soon require plasma etching processes having atomic layer resolution. The basis of plasma atomic layer etching (PALE) is forming a layer of passivation that allows the underlying substrate material to be etched with lower activation energy than in the absence of the passivation. The subsequent removal of the passivation with carefully tailored activation energy then removes a single layer of the underlying material. If these goals are met, the process is self-limiting. A challenge of PALE is the high cost of specialized equipment and slow processing speed. In this work, results from a computational investigation of PALE will be discussed with the goal of demonstrating the potential of using conventional plasma etching equipment having acceptable processing speeds. Results will be discussed using inductively coupled and magnetically enhanced capacitively coupled plasmas in which nonsinusoidal waveforms are used to regulate ion energies to optimize the passivation and etch steps. This strategy may also enable the use of a single gas mixture, as opposed to changing gas mixtures between steps

High-speed two-dimensional laser scanner based on Bragg gratings stored in photothermorefractive glass.

Science.gov (United States)

Yaqoob, Zahid; Arain, Muzammil A; Riza, Nabeel A

2003-09-10

A high-speed free-space wavelength-multiplexed optical scanner with high-speed wavelength selection coupled with narrowband volume Bragg gratings stored in photothermorefractive (PTR) glass is reported. The proposed scanner with no moving parts has a modular design with a wide angular scan range, accurate beam pointing, low scanner insertion loss, and two-dimensional beam scan capabilities. We present a complete analysis and design procedure for storing multiple tilted Bragg-grating structures in a single PTR glass volume (for normal incidence) in an optimal fashion. Because the scanner design is modular, many PTR glass volumes (each having multiple tilted Bragg-grating structures) can be stacked together, providing an efficient throughput with operations in both the visible and the infrared (IR) regions. A proof-of-concept experimental study is conducted with four Bragg gratings in independent PTR glass plates, and both visible and IR region scanner operations are demonstrated.

Degradation of the Bragg peak due to inhomogeneities.

Science.gov (United States)

Urie, M; Goitein, M; Holley, W R; Chen, G T

1986-01-01

The rapid fall-off of dose at the end of range of heavy charged particle beams has the potential in therapeutic applications of sparing critical structures just distal to the target volume. Here we explored the effects of highly inhomogeneous regions on this desirable depth-dose characteristic. The proton depth-dose distribution behind a lucite-air interface parallel to the beam was bimodal, indicating the presence of two groups of protons with different residual ranges, creating a step-like depth-dose distribution at the end of range. The residual ranges became more spread out as the interface was angled at 3 degrees, and still more at 6 degrees, to the direction of the beam. A second experiment showed little significant effect on the distal depth-dose of protons having passed through a mosaic of teflon and lucite. Anatomic studies demonstrated significant effects of complex fine inhomogeneities on the end of range characteristics. Monoenergetic protons passing through the petrous ridges and mastoid air cells in the base of skull showed a dramatic degradation of the distal Bragg peak. In beams with spread out Bragg peaks passing through regions of the base of skull, the distal fall-off from 90 to 20% dose was increased from its nominal 6 to well over 32 mm. Heavy ions showed a corresponding degradation in their ends of range. In the worst case in the base of skull region, a monoenergetic neon beam showed a broadening of the full width at half maximum of the Bragg peak to over 15 mm (compared with 4 mm in a homogeneous unit density medium). A similar effect was found with carbon ions in the abdomen, where the full width at half maximum of the Bragg peak (nominally 5.5 mm) was found to be greater than 25 mm behind gas-soft-tissue interfaces. We address the implications of these data for dose computation with heavy charged particles.

Bragg reflection transmission filters for variable resolution monochromators

International Nuclear Information System (INIS)

Chapman, D.

1989-01-01

There are various methods for improving the angular and spectral resolution of monochromator and analyzer systems. The novel system described here, though limited to higher x-ray energies (>20keV), is based on a dynamical effect occurring on the transmitted beam with a thin perfect crystal plate set in the Bragg reflection case. In the case of Bragg reflection from a perfect crystal, the incident beam is rapidly attenuated as it penetrates the crystal in the range of reflection. This extinction length is of the order of microns. The attenuation length, which determines the amount of normal transmission through the plate is generally much longer. Thus, in the range of the Bragg reflection the attenuation of the transmitted beam can change by several orders of magnitude with a small change in energy or angle. This thin crystal plate cuts a notch in the transmitted beam with a width equal to its Darwin width, thus acting as a transmission filter. When used in a non-dispersive mode with other monochromator crystals, the filter when set at the Bragg angle will reflect the entire Darwin width of the incident beam and transmit the wings of the incident beam distribution. When the element is offset in angle by some fraction of the Darwin width, the filter becomes useful in adjusting the angular width of the transmitted beam and removing a wing. Used in pairs with a symmetric offset, the filters can be used to continuously adjust the intrinsic angular divergence of the beam with good wing reduction. Instances where such filters may be useful are in improving the angular resolution of a small angle scattering camera. These filters may be added to a Bonse-Hart camera with one pair on the incident beam to reduce the intrinsic beam divergence and a second pair on the analyzer arm to improve the analyzer resolution. 2 refs., 3 Figs

Chemical etching of fission tracks in ethylene-tetrafluoroethylene copolymer

International Nuclear Information System (INIS)

Komaki, Y.; Tsujimura, S.; Seguchi, T.

1979-01-01

The chemical etching of fission tracks in ethylene-tetrafluoroethylene copolymer was studied. Etched holes 3000 to 4000 A in diameter were recognized by electron microscopy for a film bombarded by fission fragments in oxygen and etched in a 12N sodium hydroxide solution at 125 0 C. The radial etching rate at 125 0 C was 6 to 8 A/hr, which is less than 17 A/hr for polyvinylidene fluoride in the same sodium hydroxide concentration at 85 0 C. The smaller rate is a reflection of the larger chemical resistivity of ethylene-tetrafluoroethylene copolymer than polyvinylidene fluoride. (author)

Preparation of Track Etch Membrane Filters Using Polystyrene Film

International Nuclear Information System (INIS)

Kaewsaenee, Jerawut; Ratanatongchai, Wichian; Supaphol, Pitt; Visal-athaphand, Pinpan

2007-08-01

Full text: Polystyrene nuclear track etch membrane filters was prepared by exposed 13 .m thin film polystyrene with fission fragment. Nuclear latent track was enlarged to through hole on the film by etching with 80 o C 40% H 2 SO 4 with K 2 Cr 2 O 7 solution for 6-10 hour. The hole size was depend on concentration of etching solution and etching time with 1.3-3.4 .m hole diameter. The flow rate test of water was 0.79-1.56 mm cm-2 min-1 at 109.8-113.7 kPa pressure

Thermal etching of silver: Influence of rolling defects

Energy Technology Data Exchange (ETDEWEB)

Ollivier, M., E-mail: o.maelig@imperial.ac.uk [Department of Materials, Imperial College London, SW7 2AZ (United Kingdom); Harker, R.M. [AWE Aldermaston, Aldermaston, Reading RG7 4PR (United Kingdom); Chater, R.J.; Gourlay, C.M. [Department of Materials, Imperial College London, SW7 2AZ (United Kingdom)

2016-08-15

Silver is well known to be thermally etched in an oxygen-rich atmosphere and has been extensively studied in the laboratory to understand thermal etching and to limit its effect when this material is used as a catalyst. Yet, in many industrial applications the surface of rolled silver sheets is used without particular surface preparation. Here, it is shown by combining FIB-tomography, FIB-SIMS and analytical SEM that the kinetics of thermal etch pitting are significantly faster on rolled Ag surfaces than on polished surfaces. This occurs due to range of interacting phenomena including (i) the reaction of subsurface carbon-contamination with dissolved oxygen to form pores that grow to intersect the surface, (ii) surface reconstruction around corrosion pits and surface scratches, and (iii) sublimation at low pressure and high temperature. A method to identify subsurface pores is developed to show that the pores have (111) and (100) internal facets and may be filled with a gas coming from the chemical reaction of oxygen and carbon contamination. - Highlights: Thermal etching of industrial silver sheets vs. polished silver sheets Effect of annealing atmosphere on the thermal etching of silver: surface and subsurface characterization Link between etch pitting and defects induced by rolling. FIB-tomography coupled with EBSD for determining crystal planes of the facets of subsurface pores. FIB-SIMS characterization to probe the gas confined inside subsurface pores.

Acid-catalyzed kinetics of indium tin oxide etching

Energy Technology Data Exchange (ETDEWEB)

Choi, Jae-Hyeok; Kim, Seong-Oh; Hilton, Diana L. [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, 637553 (Singapore); Cho, Nam-Joon, E-mail: njcho@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, 637553 (Singapore); School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459 (Singapore)

2014-08-28

We report the kinetic characterization of indium tin oxide (ITO) film etching by chemical treatment in acidic and basic electrolytes. It was observed that film etching increased under more acidic conditions, whereas basic conditions led to minimal etching on the time scale of the experiments. Quartz crystal microbalance was employed in order to track the reaction kinetics as a function of the concentration of hydrochloric acid and accordingly solution pH. Contact angle measurements and atomic force microscopy experiments determined that acid treatment increases surface hydrophilicity and porosity. X-ray photoelectron spectroscopy experiments identified that film etching is primarily caused by dissolution of indium species. A kinetic model was developed to explain the acid-catalyzed dissolution of ITO surfaces, and showed a logarithmic relationship between the rate of dissolution and the concentration of undisassociated hydrochloric acid molecules. Taken together, the findings presented in this work verify the acid-catalyzed kinetics of ITO film dissolution by chemical treatment, and support that the corresponding chemical reactions should be accounted for in ITO film processing applications. - Highlights: • Acidic conditions promoted indium tin oxide (ITO) film etching via dissolution. • Logarithm of the dissolution rate depended linearly on the solution pH. • Acid treatment increased ITO surface hydrophilicity and porosity. • ITO film etching led to preferential dissolution of indium species over tin species.

Etching of germanium-tin using ammonia peroxide mixture

Energy Technology Data Exchange (ETDEWEB)

Dong, Yuan; Ong, Bin Leong; Wang, Wei; Gong, Xiao; Liang, Gengchiau; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Zhang, Zheng; Pan, Jisheng [Institute of Material Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, #08-03, Innovis, Singapore 138634 (Singapore); Tok, Eng-Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

2015-12-28

The wet etching of germanium-tin (Ge{sub 1-x}Sn{sub x}) alloys (4.2% < x < 16.0%) in ammonia peroxide mixture (APM) is investigated. Empirical fitting of the data points indicates that the etch depth of Ge{sub 1-x}Sn{sub x} is proportional to the square root of the etch time t and decreases exponentially with increasing x for a given t. In addition, X-ray photoelectron spectroscopy results show that increasing t increases the intensity of the Sn oxide peak, whereas no obvious change is observed for the Ge oxide peak. This indicates that an accumulation of Sn oxide on the Ge{sub 1-x}Sn{sub x} surface decreases the amount of Ge atoms exposed to the etchant, which accounts for the decrease in etch rate with increasing etch time. Atomic force microscopy was used to examine the surface morphologies of the Ge{sub 0.918}Sn{sub 0.082} samples. Both root-mean-square roughness and undulation periods of the Ge{sub 1-x}Sn{sub x} surface were observed to increase with increasing t. This work provides further understanding of the wet etching of Ge{sub 1-x}Sn{sub x} using APM and may be used for the fabrication of Ge{sub 1-x}Sn{sub x}-based electronic and photonic devices.

Omnidirectional mirror based on Bragg stacks with a periodic gain-loss modulation

International Nuclear Information System (INIS)

Manzanares-Martinez, Jesus; Ham-Rodriguez, Carlos Ivan; Moctezuma-Enriquez, Damian; Manzanares-Martinez, Betsabe

2014-01-01

In this work we demonstrate that a Bragg Stack with a periodic gain-loss modulation can function as an Omnidirectional Mirror (OM) with complete reflection at any angle of incidence irrespective of the light polarization. The Bragg Stack is composed by the periodic variation of two layers with the same value of the real part of the refractive index (n r ) and a periodic modulation in the imaginary part (n i ). The origin of the band gaps is due to the interference of complex waves with propagating and evanescent fields in each layer. It is found that the band gaps are wider as the contrast n i /n r increases. We have found the ambient conditions to obtain an OM considering an auxiliary medium n ′ external to the Bragg Stack

Strain induced tunable wavelength filters based on flexible polymer waveguide Bragg reflector.

Science.gov (United States)

Kim, Kyung-Jo; Seo, Jun-Kyu; Oh, Min-Cheol

2008-02-04

A tunable wavelength filter is demonstrated by imposing a strain on a polymeric Bragg reflection waveguide fabricated on a flexible substrate. The highly elastic property of flexible polymer device enables much wider tuning than the silica fiber. To produce a uniform grating pattern on a flexible plastic substrate, a post lift-off process along with an absorbing layer is incorporated. The flexible Bragg reflector shows narrow bandwidth, which is convincing the uniformity of the grating structure fabricated on plastic film. By stretching the flexible polymer device, the Bragg reflection wavelength is tuned continuously up to 45 nm for the maximum strain of 31,690 muepsilon, which is determined by the elastic expansion limit of waveguide polymer. From the linear wavelength shift proportional to the strain, the photoelastic coefficient of the ZPU polymer is found.

Surfactant-enhanced control of track-etch pore morphology

International Nuclear Information System (INIS)

Apel', P.Yu.; Blonskaya, I.V.; Didyk, A.Yu.; Dmitriev, S.N.; Orelovich, O.L.; Samojlova, L.I.; Vutsadakis, V.A.; Root, D.

2000-01-01

The influence of surfactants on the process of chemical development of ion tracks in polymers is studied. Based on the experimental data, a mechanism of the surfactant effect on the track-etch pore morphology is proposed. In the beginning of etching the surfactant is adsorbed on the surface and creates a layer that is quasi-solid and partially protects the surface from the etching agent. However, some etchant molecules diffuse through the barrier and react with the polymer surface. This results in the formation of a small hole at the entrance to the ion track. After the hole has attained a few annometers in diameter, the surfactant molecules penetrate into the track and cover its walls. Further diffusion of the surfactant into the growing pore is hindered. The adsorbed surfactant layer is not permeable for large molecules. In contrast, small alkali molecules and water molecules diffuse into the track and provide the etching process enlarging the pore. At this stage the transport of the surfactant into the pore channel can proceed only due to the lateral diffusion in the adsorbed layer. The volume inside the pore is free of surfactant molecules and grows at a higher rate than pore entrance. After a more prolonged etching the bottle-like (or 'cigar-like') pore channels are formed. The bottle-like shape of the pore channels depends on the etching conditions such as alkali and surfactant concentration, temperature, and type of the surfactant. The use of surfactants enables one to produce track-etch membranes with improved flow rate characteristics compared with those having cylindrical pores with the same nominal pore diameters

Defect sensitive etching of hexagonal boron nitride single crystals

Science.gov (United States)

Edgar, J. H.; Liu, S.; Hoffman, T.; Zhang, Yichao; Twigg, M. E.; Bassim, Nabil D.; Liang, Shenglong; Khan, Neelam

2017-12-01

Defect sensitive etching (DSE) was developed to estimate the density of non-basal plane dislocations in hexagonal boron nitride (hBN) single crystals. The crystals employed in this study were precipitated by slowly cooling (2-4 °C/h) a nickel-chromium flux saturated with hBN from 1500 °C under 1 bar of flowing nitrogen. On the (0001) planes, hexagonal-shaped etch pits were formed by etching the crystals in a eutectic mixture of NaOH and KOH between 450 °C and 525 °C for 1-2 min. There were three types of pits: pointed bottom, flat bottom, and mixed shape pits. Cross-sectional transmission electron microscopy revealed that the pointed bottom etch pits examined were associated with threading dislocations. All of these dislocations had an a-type burgers vector (i.e., they were edge dislocations, since the line direction is perpendicular to the [ 2 11 ¯ 0 ]-type direction). The pit widths were much wider than the pit depths as measured by atomic force microscopy, indicating the lateral etch rate was much faster than the vertical etch rate. From an Arrhenius plot of the log of the etch rate versus the inverse temperature, the activation energy was approximately 60 kJ/mol. This work demonstrates that DSE is an effective method for locating threading dislocations in hBN and estimating their densities.

High force measurement sensitivity with fiber Bragg gratings fabricated in uniform-waist fiber tapers

International Nuclear Information System (INIS)

Wieduwilt, Torsten; Brückner, Sven; Bartelt, Hartmut

2011-01-01

Fiber Bragg gratings inscribed in the waist of tapered photosensitive fibers offer specific attractive properties for sensing applications. A small-diameter fiber reduces structural influences for imbedded fiber sensing elements. In the case of application as a force-sensing element for tensile forces, sensitivity scales inversely with the fiber cross-sectional area. It is therefore possible to increase force sensitivity by several orders of magnitude compared to Bragg grating sensors in conventionally sized fibers. Special requirements for such Bragg grating arrangements are discussed and experimental measurements for different fiber taper diameters down to 4 µm are presented

Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

Science.gov (United States)

Min, Rui; Marques, Carlos; Bang, Ole; Ortega, Beatriz

2018-03-01

We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different periods to create a Moiré grating with only two pulses (one pulse is 15 ns) of UV power. Experimental characterization of the filter is provided under different conditions where the strain and temperature sensitivities were measured.

Etching and oxidation of InAs in planar inductively coupled plasma

Energy Technology Data Exchange (ETDEWEB)

Dultsev, F.N., E-mail: fdultsev@thermo.isp.nsc.ru [Institute of Semiconductor Physics SB RAS, Lavrentiev av. 13, Novosibirsk 630090 (Russian Federation); Kesler, V.G. [Institute of Semiconductor Physics SB RAS, Lavrentiev av. 13, Novosibirsk 630090 (Russian Federation)

2009-10-15

The surface of InAs (1 1 1)A was investigated under plasmachemical etching in the gas mixture CH{sub 4}/H{sub 2}/Ar. Etching was performed using the RF (13.56 MHz) and ICP plasma with the power 30-150 and 50-300 W, respectively; gas pressure in the reactor was 3-10 mTorr. It was demonstrated that the composition of the subsurface layer less than 5 nm thick changes during plasmachemical etching. A method of deep etching of InAs involving ICP plasma and hydrocarbon based chemistry providing the conservation of the surface relief is proposed. Optimal conditions and the composition of the gas phase for plasmachemical etching ensuring acceptable etch rates were selected.

Etching and oxidation of InAs in planar inductively coupled plasma

Science.gov (United States)

Dultsev, F. N.; Kesler, V. G.

2009-10-01

The surface of InAs (1 1 1)A was investigated under plasmachemical etching in the gas mixture CH 4/H 2/Ar. Etching was performed using the RF (13.56 MHz) and ICP plasma with the power 30-150 and 50-300 W, respectively; gas pressure in the reactor was 3-10 mTorr. It was demonstrated that the composition of the subsurface layer less than 5 nm thick changes during plasmachemical etching. A method of deep etching of InAs involving ICP plasma and hydrocarbon based chemistry providing the conservation of the surface relief is proposed. Optimal conditions and the composition of the gas phase for plasmachemical etching ensuring acceptable etch rates were selected.

Etching and oxidation of InAs in planar inductively coupled plasma

International Nuclear Information System (INIS)

Dultsev, F.N.; Kesler, V.G.

2009-01-01

The surface of InAs (1 1 1)A was investigated under plasmachemical etching in the gas mixture CH 4 /H 2 /Ar. Etching was performed using the RF (13.56 MHz) and ICP plasma with the power 30-150 and 50-300 W, respectively; gas pressure in the reactor was 3-10 mTorr. It was demonstrated that the composition of the subsurface layer less than 5 nm thick changes during plasmachemical etching. A method of deep etching of InAs involving ICP plasma and hydrocarbon based chemistry providing the conservation of the surface relief is proposed. Optimal conditions and the composition of the gas phase for plasmachemical etching ensuring acceptable etch rates were selected.

Etching and anti-etching strategy for sensitive colorimetric sensing of H2O2 and biothiols based on silver/carbon nanomaterial.

Science.gov (United States)

Hou, Wenli; Liu, Xiaoying; Lu, Qiujun; Liu, Meiling; Zhang, Youyu; Yao, Shouzhuo

2018-02-01

In this paper, the colorimetric sensing of H 2 O 2 related molecules and biothiols based on etching and anti-etching strategy was firstly proposed. Ag/carbon nanocomposite (Ag/C NC) was served as the sensing nanoprobe, which was synthesized via carbon dots (C-dots) as the reductant and stabilizer. The characteristic surface plasmon resonance (SPR) absorbance of Ag nanoparticles (AgNPs) was sensitive to the amount of hydrogen peroxide (H 2 O 2 ). It exhibited strong optical responses to H 2 O 2 with the solution colour changing from yellow to nearly colourless, which is resulted from the etching of Ag by H 2 O 2 . The sensing platform was further extended to detect H 2 O 2 related molecules such as lactate in coupling with the specific catalysis oxidation of L-lactate by lactate oxidase (LOx) and formation of H 2 O 2 . It provides wide linear range for detecting H 2 O 2 in 0.1-80μM and 80-220μM with the detection limit as low as 0.03μM (S/N=3). In the presence of biothiols, the etching from the H 2 O 2 can be hampered. Other biothiols exhibit anti-etching effects well. The strategy works well in detecting of typical biothiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH). Thus, a simple colorimetric strategy for sensitive detection of H 2 O 2 and biothiols is proposed. It is believed that the colorimetric sensor based on etching and anti-etching strategy can be applied in other systems in chemical and biosensing areas. Copyright © 2017 Elsevier B.V. All rights reserved.

Temperature increase beneath etched dentin discs during composite polymerization.

Science.gov (United States)

Karaarslan, Emine Sirin; Secilmis, Asli; Bulbul, Mehmet; Yildirim, Cihan; Usumez, Aslihan

2011-01-01

The purpose of this in vitro study was to measure the temperature increase during the polymerization of a composite resin beneath acid-etched or laser-etched dentin discs. The irradiation of dentin with an Er:YAG laser may have a positive effect on the thermal conductivity of dentin. This technique has not been studied extensively. Forty dentin discs (5 mm in diameter and 0.5 or 1 mm in height) were prepared from extracted permanent third molars. These dentin discs were etched with 20% orthophosphoric acid or an Er:YAG laser, and were then placed on an apparatus developed to measure temperature increases. The composite resin was polymerized with a high-intensity quartz tungsten halogen (HQTH) or light-emitting diode unit (LED). The temperature increase was measured under the dentin disc with a J-type thermocouple wire that was connected to a data logger. Five measurements were made for each dentin disc, curing unit, and etching system combination. Differences between the initial and the highest temperature readings were taken, and the five calculated temperature changes were averaged to determine the value of the temperature increase. Statistical analysis was performed with a three-way ANOVA and Tukey HSD tests at a 0.05 level of significance. Further SEM examinations were performed. The temperature increase values varied significantly, depending on etching systems (p < 0.05), dentin thicknesses (p < 0.05), and curing units (p < 0.05). Temperature increases measured beneath laser-etched discs were significantly higher than those for acid-etched dentin discs (p < 0.05). The HQTH unit induced significantly higher temperature increases than the LED unit (p < 0.05). The LED unit induced the lowest temperature change (5.2°C) in the 1-mm, acid-etched dentin group. The HQTH unit induced the highest temperature change (10.4°C) for the 0.5-mm, laser-etched dentin group. The risk of heat-induced pulpal damage should be taken into consideration

Process margin enhancement for 0.25-μm metal etch process

Science.gov (United States)

Lee, Chung Y.; Ma, Wei Wen; Lim, Eng H.; Cheng, Alex T.; Joy, Raymond; Ross, Matthew F.; Wong, Selmer S.; Marlowe, Trey

2000-06-01

This study evaluates electron beam stabilization of UV6, a positive tone Deep-UV (DUV) resist from Shipley, for a 0.25 micrometer metal etch application. Results are compared between untreated resist and resist treated with different levels of electron beam stabilization. The electron beam processing was carried out in an ElectronCureTM flood electron beam exposure system from Honeywell International Inc., Electron Vision. The ElectronCureTM system utilizes a flood electron beam source which is larger in diameter than the substrate being processed, and is capable of variable energy so that the electron range is matched to the resist film thickness. Changes in the UV6 resist material as a result of the electron beam stabilization are monitored via spectroscopic ellipsometry for film thickness and index of refraction changes and FTIR for analysis of chemical changes. Thermal flow stability is evaluated by applying hot plate bakes of 150 degrees Celsius and 200 degrees Celsius, to patterned resist wafers with no treatment and with an electron beam dose level of 2000 (mu) C/cm2. A significant improvement in the thermal flow stability of the patterned UV6 resist features is achieved with the electron beam stabilization process. Etch process performance of the UV6 resist was evaluated by performing a metal pattern transfer process on wafers with untreated resist and comparing these with etch results on wafers with different levels of electron beam stabilization. The etch processing was carried out in an Applied Materials reactor with an etch chemistry including BCl3 and Cl2. All wafers were etched under the same conditions and the resist was treated after etch to prevent further erosion after etch but before SEM analysis. Post metal etch SEM cross-sections show the enhancement in etch resistance provided by the electron beam stabilization process. Enhanced process margin is achieved as a result of the improved etch resistance, and is observed in reduced resist side

Level Set Approach to Anisotropic Wet Etching of Silicon

Directory of Open Access Journals (Sweden)

Branislav Radjenović

2010-05-01

Full Text Available In this paper a methodology for the three dimensional (3D modeling and simulation of the profile evolution during anisotropic wet etching of silicon based on the level set method is presented. Etching rate anisotropy in silicon is modeled taking into account full silicon symmetry properties, by means of the interpolation technique using experimentally obtained values for the etching rates along thirteen principal and high index directions in KOH solutions. The resulting level set equations are solved using an open source implementation of the sparse field method (ITK library, developed in medical image processing community, extended for the case of non-convex Hamiltonians. Simulation results for some interesting initial 3D shapes, as well as some more practical examples illustrating anisotropic etching simulation in the presence of masks (simple square aperture mask, convex corner undercutting and convex corner compensation, formation of suspended structures are shown also. The obtained results show that level set method can be used as an effective tool for wet etching process modeling, and that is a viable alternative to the Cellular Automata method which now prevails in the simulations of the wet etching process.

Etched ion track polymer membranes for sustained drug delivery

International Nuclear Information System (INIS)

Rao, Vijayalakshmi; Amar, J.V.; Avasthi, D.K.; Narayana Charyulu, R.

2003-01-01

The method of track etching has been successfully used for the production of polymer membranes with capillary pores. In the present paper, micropore membranes have been prepared by swift heavy ion irradiation of polycarbonate (PC). PC films were irradiated with ions of gold, silicon and oxygen of varying energies and fluence. The ion tracks thus obtained were etched chemically for various time intervals to get pores and these etched films were used as membranes for the drug release. Ciprofloxacine hydrochloride was used as model drug for the release studies. The drug content was estimated spectrophotometrically. Pore size and thus the drug release is dependent on the etching conditions, ions used, their energy and fluence. Sustained drug release has been observed in these membranes. The films can be selected for practical utilization by optimizing the irradiation and etching conditions. These films can be used as transdermal patches after medical treatment

Mode Dynamics in the Bragg FEL Based on Coupling of Propagating and Trapped Waves

CERN Document Server

Ginzburg, N S; Peskov, N Yu; Rozental, R M; Sergeev, A; Zaslavsky, V Yu

2005-01-01

A novel Bragg FEL scheme is discussed in which an electron beam synchronously interacts with a propagating wave, and the latter is coupled to a quasi cut-off mode. This coupling is realized by either helical or asimuthally symmetric corrugation of the waveguide walls. The quasi cut-off mode provides feedback in the system leading to self-excitation of the whole system while the efficiency in steady-state regime of generation is almost completely determined by the propagating mode, synchronous to the beam. Analysis based on averaged time domain approach as well as on direct PIC code simulation shows that the efficiency of such a device in the single mode single frequency regime can be rather high. The main advantage of the novel Bragg resonator is provision of higher selectivity over transverse index than traditional scheme of Bragg FEL. The cold microwave testing of the Bragg structure based on coupling of propagating and trapped waves in the Ka band demonstrated a good agreement with theoretical consideratio...

Simulation of convection-driven wet-chemical etching

NARCIS (Netherlands)

Driesen, C.H.

1999-01-01

a wet-chemical etching process, the resulting etched shape is smaller than the originally designed shape at the mask. This is caused by the fact that, as soon as material next to the mask is dissolved, material under the mask will be dissolved too. This is the so-called undercut effect. During an

Optimization of some electrochemical etching parameters for cellulose derivatives

International Nuclear Information System (INIS)

Chowdhury, Annis; Gammage, R.B.

1978-01-01

Electrochemical etching of fast neutron induced recoil particle tracks in cellulose derivatives and other polymers provides an inexpensive and sensitive means of fast neutron personnel dosimetry. A study of the shape, clarity, and size of the tracks in Transilwrap polycarbonate indicated that the optimum normality of the potassium hydroxide etching solution is 9 N. Optimizations have also been attempted for cellulose nitrate, triacetate, and acetobutyrate with respect to such electrochemical etching parameters as frequency, voltage gradient, and concentration of the etching solution. The measurement of differential leakage currents between the undamaged and the neutron damaged foils aided in the selection of optimum frequencies. (author)

Photonic bandgap narrowing in conical hollow core Bragg fibers

Energy Technology Data Exchange (ETDEWEB)

Ozturk, Fahri Emre; Yildirim, Adem; Kanik, Mehmet [UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Bayindir, Mehmet, E-mail: bayindir@nano.org.tr [UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Department of Physics, Bilkent University, 06800 Ankara (Turkey)

2014-08-18

We report the photonic bandgap engineering of Bragg fibers by controlling the thickness profile of the fiber during the thermal drawing. Conical hollow core Bragg fibers were produced by thermal drawing under a rapidly alternating load, which was applied by introducing steep changes to the fiber drawing speed. In conventional cylindrical Bragg fibers, light is guided by omnidirectional reflections from interior dielectric mirrors with a single quarter wave stack period. In conical fibers, the diameter reduction introduced a gradient of the quarter wave stack period along the length of the fiber. Therefore, the light guided within the fiber encountered slightly smaller dielectric layer thicknesses at each reflection, resulting in a progressive blueshift of the reflectance spectrum. As the reflectance spectrum shifts, longer wavelengths of the initial bandgap cease to be omnidirectionally reflected and exit through the cladding, which narrows the photonic bandgap. A narrow transmission bandwidth is particularly desirable in hollow waveguide mid-infrared sensing schemes, where broadband light is coupled to the fiber and the analyte vapor is introduced into the hollow core to measure infrared absorption. We carried out sensing simulations using the absorption spectrum of isopropyl alcohol vapor to demonstrate the importance of narrow bandgap fibers in chemical sensing applications.

Simulation of convection-driven wet-chemical etching

NARCIS (Netherlands)

Driesen, C.H.

1999-01-01

In a wet-chemical etching process, the resulting etched shape is smaller than the originally designed shape at the mask. This is caused by the fact that, as soon as material next to the mask is dissolved, material under the mask will be dissolved too. This is the so-called undercut effect. During an

Etch induction time in cellulose nitrate: a new particle identification parameter

International Nuclear Information System (INIS)

Ruddy, F.H.; Knowles, H.B.; Luckstead, S.C.; Tripard, G.E.

1977-01-01

By the use of a 'continuous etch' method, it has been ascertained that particle tracks do not appear in cellulose nitrate track detectors until a certain finite time after etch has been started: this etch induction time may provide a unique signal for distinguishing ions of different atomic number, Z, and possibly also resolving the mass, M, of such ions. Empirical relations between etch induction time and various experimental quantities are described, as is a simple theory of the cause of etch induction time, which can be related to experimental evidence on hand. There is reason to believe that etch induction time appears in other types of plastic track detectors and may indeed be a general phenomenon in all track detectors. (Auth.)

Feedback control of chlorine inductively coupled plasma etch processing

International Nuclear Information System (INIS)

Lin Chaung; Leou, K.-C.; Shiao, K.-M.

2005-01-01

Feedback control has been applied to poly-Si etch processing using a chlorine inductively coupled plasma. Since the positive ion flux and ion energy incident upon the wafer surface are the key factors that influence the etch rate, the ion current and the root mean square (rms) rf voltage on the wafer stage, which are measured using an impedance meter connected to the wafer stage, are adopted as the controlled variables to enhance etch rate. The actuators are two 13.56 MHz rf power generators, which adjust ion density and ion energy, respectively. The results of closed-loop control show that the advantages of feedback control can be achieved. For example, with feedback control, etch rate variation under the transient chamber wall condition is reduced roughly by a factor of 2 as compared to the open-loop case. In addition, the capability of the disturbance rejection was also investigated. For a gas pressure variation of 20%, the largest etch rate variation is about 2.4% with closed-loop control as compared with as large as about 6% variation using open-loop control. Also the effect of ion current and rms rf voltage on etch rate was studied using 2 2 factorial design whose results were used to derive a model equation. The obtained formula was used to adjust the set point of ion current and rf voltage so that the desired etch rate was obtained

Unveiling the wet chemical etching characteristics of polydimethylsiloxane film for soft micromachining applications

International Nuclear Information System (INIS)

Kakati, A; Maji, D; Das, S

2017-01-01

Micromachining of a polydimethylsiloxane (PDMS) microstructure by wet chemical etching is explored for microelectromechanical systems (MEMS) and microfluidic applications. A 100 µ m thick PDMS film was patterned with different microstructure designs by wet chemical etching using a N-methyl-2-pyrrolidone (C 16 H 36 FN) and tetra-n-butylammonium fluoride (C 5 H 9 NO) mixture solution with 3:1 volume ratio after lithography for studying etching characteristics. The patterning parameters, such as etch rate, surface roughness, pH of etchant solution with time, were thoroughly investigated. A detailed study of surface morphology with etching time revealed nonlinear behaviour of the PDMS surface roughness and etch rate. A maximum rate of 1.45 µ m min −1 for 10 min etching with surface roughness of 360 nm was achieved. A new approach of wet chemical etching with pH controlled doped etchant was introduced for lower surface roughness of etched microstructures, and a constant etch rate during etching. Variation of the etching rate and surface roughness by pH controlled etching was performed by doping 5–15 gm l −1 of silicic acid (SiO 2xH2 O) into the traditional etchant solution. PDMS etching by silicic acid doped etchant solution showed a reduction in surface roughness from 400 nm to 220 nm for the same 15 µ m etching. This study is beneficial for micromachining of various MEMS and microfluidic structures such as micropillars, microchannels, and other PDMS microstructures. (paper)

Precision Recess of AlGaN/GaN with Controllable Etching Rate Using ICP-RIE Oxidation and Wet Etching

NARCIS (Netherlands)

Sokolovskij, R.; Sun, J.; Santagata, F.; Iervolino, E.; Li, S.; Zhang, G.Y.; Sarro, P.M.; Zhang, G.Q.

2016-01-01

A method for highly controllable etching of AlGaN/GaN for the fabrication of high sensitivity HEMT based sensors is developed. The process consists of cyclic oxidation of nitride with O₂ plasma using ICP-RIE etcher followed by wet etching of the oxidized layer. Previously reported

Omnidirectional mirror based on Bragg stacks with a periodic gain-loss modulation

Energy Technology Data Exchange (ETDEWEB)

Manzanares-Martinez, Jesus; Ham-Rodriguez, Carlos Ivan [Departamento de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088, Hermosillo, Sonora 83000 (Mexico); Moctezuma-Enriquez, Damian, E-mail: foxonicos@gmail.com [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua 31109 (Mexico); Manzanares-Martinez, Betsabe [Departamento de Fisica, Universidad de Sonora, Blvd. Luis Encinas y Rosales, Hermosillo, Sonora 83000 (Mexico)

2014-01-15

In this work we demonstrate that a Bragg Stack with a periodic gain-loss modulation can function as an Omnidirectional Mirror (OM) with complete reflection at any angle of incidence irrespective of the light polarization. The Bragg Stack is composed by the periodic variation of two layers with the same value of the real part of the refractive index (n{sub r}) and a periodic modulation in the imaginary part (n{sub i}). The origin of the band gaps is due to the interference of complex waves with propagating and evanescent fields in each layer. It is found that the band gaps are wider as the contrast n{sub i}/n{sub r} increases. We have found the ambient conditions to obtain an OM considering an auxiliary medium n{sup ′} external to the Bragg Stack.

Future developments in etched track detectors for neutron dosimetry

International Nuclear Information System (INIS)

Tommasino, L.

1987-01-01

Many laboratories engaged in the field of personal neutron dosimetry are interested in developing better etching processes and improving the CR-39 detecting materials. To know how much effort must still be devoted to the development of etch track dosimetry, it is necessary to understand the advantages. limitations and degree of exploitation of the currently available techniques. So much has been learned about the chemical and electrochemical etching processes that an optimised combination of etching processes could make possible the elimination of many of the existing shortcomings. Limitations of etched track detectors for neutron dosimetry arise mainly because the registration occurs only on the detector surface. These damage type detectors are based on radiation induced chain scission processes in polymers, which result in hole-type tracks in solids. The converse approach, yet to be discovered, would be the development of cure-track detectors, where radiation induced cross linking between organic polymer chains could result in solid tracks in liquids. (author)

Ion track etching revisited: II. Electronic properties of aged tracks in polymers

Science.gov (United States)

Fink, D.; Muñoz Hernández, G.; Cruz, S. A.; Garcia-Arellano, H.; Vacik, J.; Hnatowicz, V.; Kiv, A.; Alfonta, L.

2018-02-01

We compile here electronic ion track etching effects, such as capacitive-type currents, current spike emission, phase shift, rectification and background currents that eventually emerge upon application of sinusoidal alternating voltages across thin, aged swift heavy ion-irradiated polymer foils during etching. Both capacitive-type currents and current spike emission occur as long as obstacles still prevent a smooth continuous charge carrier passage across the foils. In the case of sufficiently high applied electric fields, these obstacles are overcome by spike emission. These effects vanish upon etchant breakthrough. Subsequent transmitted currents are usually of Ohmic type, but shortly after breakthrough (during the track' core etching) often still exhibit deviations such as strong positive phase shifts. They stem from very slow charge carrier mobility across the etched ion tracks due to retarding trapping/detrapping processes. Upon etching the track's penumbra, one occasionally observes a split-up into two transmitted current components, one with positive and another one with negative phase shifts. Usually, these phase shifts vanish when bulk etching starts. Current rectification upon track etching is a very frequent phenomenon. Rectification uses to inverse when core etching ends and penumbra etching begins. When the latter ends, rectification largely vanishes. Occasionally, some residual rectification remains which we attribute to the aged polymeric bulk itself. Last not least, we still consider background currents which often emerge transiently during track etching. We could assign them clearly to differences in the electrochemical potential of the liquids on both sides of the etched polymer foils. Transient relaxation effects during the track etching cause their eventually chaotic behaviour.

Metallographic examination of TD-nickel base alloys. [thermal and chemical etching technique evaluation

Science.gov (United States)

Kane, R. D.; Petrovic, J. J.; Ebert, L. J.

1975-01-01

Techniques are evaluated for chemical, electrochemical, and thermal etching of thoria dispersed (TD) nickel alloys. An electrochemical etch is described which yielded good results only for large grain sizes of TD-nickel. Two types of thermal etches are assessed for TD-nickel: an oxidation etch and vacuum annealing of a polished specimen to produce an etch. It is shown that the first etch was somewhat dependent on sample orientation with respect to the processing direction, the second technique was not sensitive to specimen orientation or grain size, and neither method appear to alter the innate grain structure when the materials were fully annealed prior to etching. An electrochemical etch is described which was used to observe the microstructures in TD-NiCr, and a thermal-oxidation etch is shown to produce better detail of grain boundaries and to have excellent etching behavior over the entire range of grain sizes of the sample.

Cyclic etching of tin-doped indium oxide using hydrogen-induced modified layer

Science.gov (United States)

Hirata, Akiko; Fukasawa, Masanaga; Nagahata, Kazunori; Li, Hu; Karahashi, Kazuhiro; Hamaguchi, Satoshi; Tatsumi, Tetsuya

2018-06-01

The rate of etching of tin-doped indium oxide (ITO) and the effects of a hydrogen-induced modified layer on cyclic, multistep thin-layer etching were investigated. It was found that ITO cyclic etching is possible by precisely controlling the hydrogen-induced modified layer. Highly selective etching of ITO/SiO2 was also investigated, and it was suggested that cyclic etching by selective surface adsorption of Si can precisely control the etch rates of ITO and SiO2, resulting in an almost infinite selectivity for ITO over SiO2 and in improved profile controllability.

Shear bond strength of self-etch and total-etch bonding systems at different dentin depths

Directory of Open Access Journals (Sweden)

Ana Carolina Maito Villela-Rosa

2011-04-01

Full Text Available The purpose of this study was to evaluate the dentin shear bond strength of four adhesive systems (Adper Single Bond 2, Adper Prompt L-Pop, Magic Bond DE and Self Etch Bond in regards to buccal and lingual surfaces and dentin depth. Forty extracted third molars had roots removed and crowns bisected in the mesiodistal direction. The buccal and lingual surfaces were fixed in a PVC/acrylic resin ring and were divided into buccal and lingual groups assigned to each selected adhesive. The same specimens prepared for the evaluation of superficial dentin shear resistance were used to evaluate the different depths of dentin. The specimens were identified and abraded at depths of 0.5, 1.0, 1.5 and 2.0 mm. Each depth was evaluated by ISO TR 11405 using an EMIC-2000 machine regulated at 0.5 mm/min with a 200 Kgf load cell. We performed statistical analyses on the results (ANOVA, Tukey and Scheffé tests. Data revealed statistical differences (p < 0.01 in the adhesive and depth variation as well as adhesive/depth interactions. The Adper Single Bond 2 demonstrated the highest mean values of shear bond strength. The Prompt L-Pop product, a self-etching adhesive, revealed higher mean values compared with Magic Bond DE and Self Etch Bond adhesives, a total and self-etching adhesive respectively. It may be concluded that the shear bond strength of dentin is dependent on material (adhesive system, substrate depth and adhesive/depth interaction.

Wavelength interrogation of fiber Bragg grating sensors using tapered hollow Bragg waveguides.

Science.gov (United States)

Potts, C; Allen, T W; Azar, A; Melnyk, A; Dennison, C R; DeCorby, R G

2014-10-15

We describe an integrated system for wavelength interrogation, which uses tapered hollow Bragg waveguides coupled to an image sensor. Spectral shifts are extracted from the wavelength dependence of the light radiated at mode cutoff. Wavelength shifts as small as ~10  pm were resolved by employing a simple peak detection algorithm. Si/SiO₂-based cladding mirrors enable a potential operational range of several hundred nanometers in the 1550 nm wavelength region for a taper length of ~1  mm. Interrogation of a strain-tuned grating was accomplished using a broadband amplified spontaneous emission (ASE) source, and potential for single-chip interrogation of multiplexed sensor arrays is demonstrated.

Bond efficacy and interface morphology of self-etching adhesives to ground enamel

NARCIS (Netherlands)

Abdalla, A.I.; El Zohairy, A.A.; Mohsen, M.M.A.; Feilzer, A.J.

2010-01-01

Purpose: This study compared the microshear bond strengths to ground enamel of three one-step self-etching adhesive systems, a self-etching primer system and an etch-and-rinse adhesive system. Materials and Methods: Three self-etching adhesives, Futurabond DC (Voco), Clearfil S Tri Bond (Kuraray)

High-efficiency FEL with Bragg resonator driven by linear induction accelerator

Energy Technology Data Exchange (ETDEWEB)

Ginzburg, N S; Kaminskij, A A; Kaminskij, A K; Peskov, N Yu; Sedykh, S N; Sergeev, A P; Sergeev, A S [Russian Academy of Sciences, Nizhny Novgorod (Russian Federation). Inst. of Applied Physics

1997-12-31

A narrow-band high-efficiency FEL-oscillator with a Bragg resonator was constructed based on a linear induction accelerator which formed a 1 MeV, 200 A, 200 ns electron beam. At the frequency of 31 GHz, radiation with a power of 31 MW and efficiency of 25% was measured. A high efficiency and a narrow width of the spectrum were achieved owing to the selective properties of the Bragg resonator in combination with the high quality of the helical electron beam formed in the reversed guide field regime. (author). 3 figs., 3 refs.

Fiber Bragg Grating vibration sensor with DFB laser diode

Science.gov (United States)

Siska, Petr; Brozovic, Martin; Cubik, Jakub; Kepak, Stanislav; Vitasek, Jan; Koudelka, Petr; Latal, Jan; Vasinek, Vladimir

2012-01-01

The Fiber Bragg Grating (FBG) sensors are nowadays used in many applications. Thanks to its quite big sensitivity to a surrounding environment, they can be used for sensing of temperature, strain, vibration or pressure. A fiber Bragg grating vibration sensor, which is interrogated by a distributed feedback laser diode (DFB) is demonstrated in this article. The system is based on the intensity modulation of the narrow spectral bandwidth of the DFB laser, when the reflection spectrum of the FBG sensor is shifted due to the strain that is applied on it in form of vibrations caused by acoustic wave pressure from loud speaker. The sensor's response in frequency domain and strain is measured; also the factor of sensor pre-strain impact on its sensitivity is discussed.

Capacity of Wavelength and Time Division Multiplexing for Quasi-Distributed Measurement Using Fiber Bragg Gratings

Directory of Open Access Journals (Sweden)

Marcel Fajkus

2015-01-01

Full Text Available In this paper, an analysis of the use of wavelength and time division multiplexing techniques for quasi-distributed measurement in uniform fiber Bragg gratings is presented. To date, publications have concentrated on the determination of the maximum number of fiber Bragg gratings on one optical fiber using wavelength and time division multiplexing. In this paper, these techniques will be extended to determine the spectral width of wavelength division multiplexing in terms of the spectral width of the light emitting diode, the spectral width of the Bragg gratings, the measurement ranges of the individual sensors, and the guard band between two adjacent Bragg gratings. For time division multiplexing, a description of the time and power conditions are given. In particular the reflected power, first order crosstalk and chromatic dispersion have been considered. Finally, these relationships were applied to verify a design in a simulation using OptiSystem software.

Optimize Etching Based Single Mode Fiber Optic Temperature Sensor

OpenAIRE

Ajay Kumar; Dr. Pramod Kumar

2014-01-01

This paper presents a description of etching process for fabrication single mode optical fiber sensors. The process of fabrication demonstrates an optimized etching based method to fabricate single mode fiber (SMF) optic sensors in specified constant time and temperature. We propose a single mode optical fiber based temperature sensor, where the temperature sensing region is obtained by etching its cladding diameter over small length to a critical value. It is observed that th...

Study on the etched carnelian beads unearthed in China

Institute of Scientific and Technical Information of China (English)

Deyun Zhao

2014-01-01

Etched carnelian beads originated in the Indus Civilization;this kind of ornaments and its manufacturing techniques were spread to the whole Eurasia Continent.The etched carnelian beads unearthed in China can be classified into four types,the comparisons of which to their foreign counterparts may reveal their different sources and diffusion routes.The etched carnelian beads and their glass imitations unearthed in China had influences to the making of the glass "eye beads" in

Catalytically-etched hexagonal boron nitride flakes and their surface activity

International Nuclear Information System (INIS)

Kim, Do-Hyun; Lee, Minwoo; Ye, Bora; Jang, Ho-Kyun; Kim, Gyu Tae; Lee, Dong-Jin; Kim, Eok-Soo; Kim, Hong Dae

2017-01-01

Highlights: • Hexagonal boron nitride flakes are etched at low temperature in air by catalysts. • The presence of transition metal oxides produces an etched structure in the flakes. • Etched surfaces become highly active due to vacancy defects formed in the flakes. - Abstract: Hexagonal boron nitride (h-BN) is a ceramic compound which is thermally stable up to 1000 °C in air. Due to this, it is a very challenging task to etch h-BN under air atmosphere at low temperature. In this study, we report that h-BN flakes can be easily etched by oxidation at 350 °C under air atmosphere in the presence of transition metal (TM) oxide. After selecting Co, Cu, and Zn elements as TM precursors, we simply oxidized h-BN sheets impregnated with the TM precursors at 350 °C in air. As a result, microscopic analysis revealed that an etched structure was created on the surface of h-BN flakes regardless of catalyst type. And, X-ray diffraction patterns indicated that the air oxidation led to the formation of Co_3O_4, CuO, and ZnO from each precursor. Thermogravimetric analysis showed a gradual weight loss in the temperature range where the weight of h-BN flakes increased by air oxidation. As a result of etching, pore volume and pore area of h-BN flakes were increased after catalytic oxidation in all cases. In addition, the surface of h-BN flakes became highly active when the h-BN samples were etched by Co_3O_4 and CuO catalysts. Based on these results, we report that h-BN flakes can be easily oxidized in the presence of a catalyst, resulting in an etched structure in the layered structure.

Catalytically-etched hexagonal boron nitride flakes and their surface activity

Energy Technology Data Exchange (ETDEWEB)

Kim, Do-Hyun, E-mail: nanotube@korea.ac.kr [School of Electrical Engineering, Korea University, 5-ga, Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of); Lee, Minwoo; Ye, Bora [Green Manufacturing 3Rs R& D Group, Korea Institute of Industrial Technology, Ulsan 681-310 (Korea, Republic of); Jang, Ho-Kyun; Kim, Gyu Tae [School of Electrical Engineering, Korea University, 5-ga, Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of); Lee, Dong-Jin [New Functional Components Research Team, Korea Institute of Footware & Leather Technology, 152 Danggamseo-ro, Busanjin-gu, Busan 614-100 (Korea, Republic of); Kim, Eok-Soo [Green Manufacturing 3Rs R& D Group, Korea Institute of Industrial Technology, Ulsan 681-310 (Korea, Republic of); Kim, Hong Dae, E-mail: hdkim@kitech.re.kr [Green Manufacturing 3Rs R& D Group, Korea Institute of Industrial Technology, Ulsan 681-310 (Korea, Republic of)

2017-04-30

Highlights: • Hexagonal boron nitride flakes are etched at low temperature in air by catalysts. • The presence of transition metal oxides produces an etched structure in the flakes. • Etched surfaces become highly active due to vacancy defects formed in the flakes. - Abstract: Hexagonal boron nitride (h-BN) is a ceramic compound which is thermally stable up to 1000 °C in air. Due to this, it is a very challenging task to etch h-BN under air atmosphere at low temperature. In this study, we report that h-BN flakes can be easily etched by oxidation at 350 °C under air atmosphere in the presence of transition metal (TM) oxide. After selecting Co, Cu, and Zn elements as TM precursors, we simply oxidized h-BN sheets impregnated with the TM precursors at 350 °C in air. As a result, microscopic analysis revealed that an etched structure was created on the surface of h-BN flakes regardless of catalyst type. And, X-ray diffraction patterns indicated that the air oxidation led to the formation of Co{sub 3}O{sub 4}, CuO, and ZnO from each precursor. Thermogravimetric analysis showed a gradual weight loss in the temperature range where the weight of h-BN flakes increased by air oxidation. As a result of etching, pore volume and pore area of h-BN flakes were increased after catalytic oxidation in all cases. In addition, the surface of h-BN flakes became highly active when the h-BN samples were etched by Co{sub 3}O{sub 4} and CuO catalysts. Based on these results, we report that h-BN flakes can be easily oxidized in the presence of a catalyst, resulting in an etched structure in the layered structure.

Characterization of silicon isotropic etch by inductively coupled plasma etcher for microneedle array fabrication

International Nuclear Information System (INIS)

Ji, J; Tay, F E H; Miao Jianmin; Sun Jianbo

2006-01-01

This work investigates the isotropic etching properties in inductively coupled plasma (ICP) etcher for microneedle arrays fabrication. The effects of process variables including powers, gas and pressure on needle structure generation are characterized by factorial design of experiment (DOE). The experimental responses of vertical etching depth, lateral etching length, ratio of vertical etching depth to lateral etching length and photoresist etching rate are reported. The relevance of the etching variables is also presented. The obtained etching behaviours for microneedle structure generation will be applied to develop recipes to fabricate microneedles in designed dimensions

Characterization of silicon isotropic etch by inductively coupled plasma etcher for microneedle array fabrication

Energy Technology Data Exchange (ETDEWEB)

Ji, J [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Tay, F E H [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Miao Jianmin [MicroMachines Center, School of Mechanical and Aerospace Engineering, Nanyang Technologica l University, 50 Nanyang Avenue, 639798 (Singapore); Sun Jianbo [MicroMachines Center, School of Mechanical and Aerospace Engineering, Nanyang Technologica l University, 50 Nanyang Avenue, 639798 (Singapore)

2006-04-01

This work investigates the isotropic etching properties in inductively coupled plasma (ICP) etcher for microneedle arrays fabrication. The effects of process variables including powers, gas and pressure on needle structure generation are characterized by factorial design of experiment (DOE). The experimental responses of vertical etching depth, lateral etching length, ratio of vertical etching depth to lateral etching length and photoresist etching rate are reported. The relevance of the etching variables is also presented. The obtained etching behaviours for microneedle structure generation will be applied to develop recipes to fabricate microneedles in designed dimensions.

Magnetic Nanoparticle-Assisted Tunable Optical Patterns from Spherical Cholesteric Liquid Crystal Bragg Reflectors

OpenAIRE

Lin, Yali; Yang, Yujie; Shan, Yuwei; Gong, Lingli; Chen, Jingzhi; Li, Sensen; Chen, Lujian

2017-01-01

Cholesteric liquid crystals (CLCs) exhibit selective Bragg reflections of circularly polarized (CP) light owing to their spontaneous self-assembly abilities into periodic helical structures. Photonic cross-communication patterns could be generated toward potential security applications by spherical cholesteric liquid crystal (CLC) structures. To endow these optical patterns with tunability, we fabricated spherical CLC Bragg reflectors in the shape of microshells by glass-capillary microfluidi...

Bragg transmission phase plates for the production of circularly polarized x-rays

International Nuclear Information System (INIS)

Lang, J.C.; Srajer, G.

1994-01-01

A thin-crystal Si (400) Bragg transmission x-ray phase plate has been constructed for the production of 5 to 12 keV circularly polarized x-rays. Using multiple beam diffraction from a GaAs crystal, a direct measurement of the degree of circular polarization as a function of off-Bragg position was made. These measurements indicated nearly complete circular polarization (|P c | ≥ 0.95) and full helicity reversal on opposite sides of the rocking curve

Optical fiber laser sensor with a cavity of 8.6 Km formed by two fiber Bragg gratings used as mirrors

Energy Technology Data Exchange (ETDEWEB)

May A, M.; Kuzin, E.A.; Vazquez S, R.A. [Instituto Nacional de Astrofisica, Optica y Electronica, A. P. 51 y 216, C.P. 72000 Puebla (Mexico); Basurto P, M.A. [Universidad Autonoma del Estado de Morelos, Av. Universidad No. 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Shlyagin, M.G.; Marquez B, I. [Centro de Investigacion Cientifica y de Ensenanza Superior de Ensenada, C.P. 22860 Ensenada, Baja California (Mexico)

2002-07-01

We report the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980 nm, an 8.67 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength is strained which can be used as a sensor element. The laser generation thus shows that the Bragg grating is under strain. Furthermore, our configuration give us the possibility for knowing the distance between two Bragg gratings when the laser beating frequency is measured. A measurement precision better than 25 m in 8.67 Km is shown to be feasible. (Author)

Optical fiber laser sensor with a cavity of 8.6 Km formed by two fiber Bragg gratings used as mirrors

CERN Document Server

May, M; Vázquez, R A; Basurto, M A; Shlyagin, M G; Márquez, I

2002-01-01

We report the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980 nm, an 8.67 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength is strained which can be used as a sensor element. The laser generation thus shows that the Bragg grating is under strain. Furthermore, our configuration give us the possibility for knowing the distance between two Bragg gratings when the laser beating frequency is measured. A measurement precision better than 25 m in 8.67 Km is shown to be feasible. (Author)

Pattern transfer with stabilized nanoparticle etch masks

International Nuclear Information System (INIS)

Hogg, Charles R; Majetich, Sara A; Picard, Yoosuf N; Narasimhan, Amrit; Bain, James A

2013-01-01

Self-assembled nanoparticle monolayer arrays are used as an etch mask for pattern transfer into Si and SiO x substrates. Crack formation within the array is prevented by electron beam curing to fix the nanoparticles to the substrate, followed by a brief oxygen plasma to remove excess carbon. This leaves a dot array of nanoparticle cores with a minimum gap of 2 nm. Deposition and liftoff can transform the dot array mask into an antidot mask, where the gap is determined by the nanoparticle core diameter. Reactive ion etching is used to transfer the dot and antidot patterns into the substrate. The effect of the gap size on the etching rate is modeled and compared with the experimental results. (paper)

Anisotropic etching of tungsten-nitride with ICP system

CERN Document Server

Lee, H G; Moon, H S; Kim, S H; Ahn, J; Sohn, S

1998-01-01

Inductively Coupled Plasma ion streaming etching of WN sub x film is investigated for preparing x-ray mask absorber patterns. SF sub 6 gas plasma provides for effective etching of WN sub x , and the addition of Ar and N sub 2 results in higher dissociation of SF sub 6 and sidewall passivation effect, respectively. Microloading effect observed for high aspect ratio patterns is minimized by multi-step etching and O sub 2 plasma treatment process. As a result, 0.18 mu m WN sub x line and space patterns with vertical sidewall profile are successfully fabricated.