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Sample records for 50-100 nm thick

  1. 41 CFR 128-50.100 - Storage and care.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Storage and care. 128-50.100 Section 128-50.100 Public Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF JUSTICE 50-SEIZED PERSONAL PROPERTY 50.1-Storage and Care of Seized Personal Property § 128-50.100 Storage...

  2. 41 CFR 128-50.100 - Storage and care.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Storage and care. 128-50.100 Section 128-50.100 Public Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF JUSTICE 50-SEIZED PERSONAL PROPERTY 50.1-Storage and Care of Seized Personal Property § 128-50.100 Storage...

  3. Magnetic hard disk overcoats in the 3-5 nm thickness range

    NASA Astrophysics Data System (ADS)

    Anoikin, E. V.; Yang, M. M.; Chao, J. L.; Russak, M. A.

    1999-04-01

    Protective properties of 3-5 nm thick carbon overcoat layers deposited on magnetic hard disks by ion beam deposition (IBD) and plasma-enhanced chemical vapor deposition (PECVD) were investigated. It is found that these overcoats are superior to the sputtered carbon films at thicknesses below 5 nm. Low-stiction performance of 3-nm-thick IBD films without any detectable wear was observed during 50 000 contact start-stop cycles at 55 °C and 10% relative humidity. Surface concentration of cobalt ions is reduced by as much as an order of magnitude as compared to the media with sputtered overcoats. Polarization resistivity values for IBD and PECVD overcoats are by an order of magnitude higher. The results show that thickness of protective carbon overcoats on magnetic hard disks can be reduced to 3-5 nm without compromising media reliability requirements. This reduction is critical for the continuing growth of storage density.

  4. Fabrication of sub-12 nm thick silicon nanowires by processing scanning probe lithography masks

    SciTech Connect

    Kyoung Ryu, Yu; Garcia, Ricardo; Aitor Postigo, Pablo; Garcia, Fernando

    2014-06-02

    Silicon nanowires are key elements to fabricate very sensitive mechanical and electronic devices. We provide a method to fabricate sub-12 nm silicon nanowires in thickness by combining oxidation scanning probe lithography and anisotropic dry etching. Extremely thin oxide masks (0.3–1.1 nm) are transferred into nanowires of 2–12 nm in thickness. The width ratio between the mask and the silicon nanowire is close to one which implies that the nanowire width is controlled by the feature size of the nanolithography. This method enables the fabrication of very small single silicon nanowires with cross-sections below 100 nm{sup 2}. Those values are the smallest obtained with a top-down lithography method.

  5. Atomic-resolution scanning transmission electron microscopy through 50-nm-thick silicon nitride membranes

    SciTech Connect

    Ramachandra, Ranjan; Jonge, Niels de; Demers, Hendrix

    2011-02-28

    Silicon nitride membranes can be used for windows of environmental chambers for in situ electron microscopy. We report that aberration corrected scanning transmission electron microscopy (STEM) achieved atomic resolution on gold nanoparticles placed on both sides of a 50-nm-thick silicon nitride membrane at 200 keV electron beam energy. Spatial frequencies of 1/1.2 A were visible for a beam semi-angle of 26.5 mrad. Imaging though a 100-nm-thick membrane was also tested. The achieved imaging contrast was evaluated using Monte Carlo simulations of the STEM imaging of a sample of with a representative geometry and composition.

  6. Sub-30 nm thick plasmonic films and structures with ultralow loss.

    PubMed

    Teo, Ee Jin; Toyoda, Noriaki; Yang, Chengyuan; Wang, Bing; Zhang, Nan; Bettiol, Andrew A; Teng, Jing Hua

    2014-03-21

    We report an alternative method of producing sub-30 nm thick silver films and structures with ultralow loss using gas cluster ion beam irradiation (GCIB). We have direct evidence showing that scattering from grain boundaries and voids rather than surface roughness are the main mechanisms for the increase in loss with reducing thickness. Using GCIB irradiation, we demonstrate the ability to reduce these scattering effects simultaneously through nanoscale surface smoothing, increase in grain width and lower percolation threshold. Significant improvement in electrical and optical properties by up to 4 times is obtained, before deviation from bulk silver properties starts to occur at 12 nm. We show that this is an enabling technology that can be applied post fabrication to metallic films or lithographically patterned nanostructures for enhanced plasmonic performance, especially in the ultrathin regime. PMID:24504045

  7. Fabrication of 5-20 nm thick β-W films

    SciTech Connect

    Narasimham, Avyaya J.; Medikonda, Manasa; Matsubayashi, Akitomo; Khare, Prasanna; Chong, Hyuncher; Matyi, Richard J.; Diebold, Alain; LaBella, Vincent P.

    2014-11-15

    A technique to fabricate 5 to 20 nm thick sputter deposited β W films on SiO{sub 2} and Si substrates is presented. This is achieved by growing tungsten on a 5 nm SiO{sub 2} layer or in an oxygen controlled environment by flowing 2 sccm of O{sub 2} during deposition. Resistivity, X-ray photoelectron spectroscopy, X-ray diffraction and reflectivity studies were performed to determine the phase and thickness of tungsten films. These results demonstrate a technique to grow this film on bare Si or a SiO{sub 2} substrate, which can enable growth on the bottom of a write unit in a non-volatile spin logic device.

  8. Three-dimensional sub-100 nm resolution fluorescence microscopy of thick samples.

    PubMed

    Juette, Manuel F; Gould, Travis J; Lessard, Mark D; Mlodzianoski, Michael J; Nagpure, Bhupendra S; Bennett, Brian T; Hess, Samuel T; Bewersdorf, Joerg

    2008-06-01

    Imaging volumes as thick as whole cells at three-dimensional (3D) super-resolution is required to reveal unknown features of cellular organization. We report a light microscope that generates images with translationally invariant 30 x 30 x 75 nm resolution over a depth of several micrometers. This method, named biplane (BP) FPALM, combines a double-plane detection scheme with fluorescence photoactivation localization microscopy (FPALM) enabling 3D sub-diffraction resolution without compromising speed or sensitivity. PMID:18469823

  9. Metallic Nanoshells with Sub-10 nm Thickness and Their Performance as Surface-Enhanced Spectroscopy Substrate.

    PubMed

    Zhang, Xuemin; Guo, Lei; Luo, Jinmin; Zhao, Xueqi; Wang, Tieqiang; Li, Yunong; Fu, Yu

    2016-04-20

    As a crucial structural parameter, shell thickness greatly influences the optical properties of metallic nanoshells. However, there still lacks a reliable approach to prepare ultrathin core-shell nanoparticles. To solve this problem, a two-step gold seeding process was pointed out to increase the packing density of gold seeds on the silica core. With use of this method, the packing density of gold seeds reaches ∼60%, enabling us to successfully reduce the shell thickness to the sub-10 nm range. Afterward, we investigated optical properties of the as-prepared ultrathin nanoshells. It is found that thinner nanoshells exhibit a wider optical tunability and a greater electromagnetic field enhancement than their thicker counterparts, which makes ultrathin nanoshells an ideal substrate for surface-enhanced spectroscopes. PMID:27019405

  10. Threshold and efficiency for perforation of 1 nm thick carbon nanomembranes with slow highly charged ions

    NASA Astrophysics Data System (ADS)

    Wilhelm, Richard A.; Gruber, Elisabeth; Ritter, Robert; Heller, René; Beyer, André; Turchanin, Andrey; Klingner, Nico; Hübner, René; Stöger-Pollach, Michael; Vieker, Henning; Hlawacek, Gregor; Gölzhäuser, Armin; Facsko, Stefan; Aumayr, Friedrich

    2015-09-01

    Cross-linking of a self-assembled monolayer of 1,1‧-biphenyl-4-thiol by low energy electron irradiation leads to the formation of a carbon nanomembrane, that is only 1 nm thick. Here we study the perforation of these freestanding membranes by slow highly charged ion irradiation with respect to the pore formation yield. It is found that a threshold in potential energy of the highly charged ions of about 10 keV must be exceeded in order to form round pores with tunable diameters in the range of 5-15 nm. Above this energy threshold, the efficiency for a single ion to form a pore increases from 70% to nearly 100% with increasing charge. These findings are verified by two independent methods, namely the analysis of individual membranes stacked together during irradiation and the detailed analysis of exit charge state spectra utilizing an electrostatic analyzer.

  11. Label-free imaging of thick tissue at 1550 nm using a femtosecond optical parametric generator.

    PubMed

    Trägårdh, Johanna; Robb, Gillian; Gadalla, Kamal K E; Cobb, Stuart; Travis, Christopher; Oppo, Gian-Luca; McConnell, Gail

    2015-08-01

    We have developed a simple wavelength-tunable optical parametric generator (OPG), emitting broadband ultrashort pulses with peak wavelengths at 1530-1790 nm, for nonlinear label-free microscopy. The OPG consists of a periodically poled lithium niobate crystal, pumped at 1064 nm by a ultrafast Yb:fiber laser with high pulse energy. We demonstrate that this OPG can be used for label-free imaging, by third-harmonic generation, of nuclei of brain cells and blood vessels in a >150 μm thick brain tissue section, with very little decay of intensity with imaging depth and no visible damage to the tissue at an incident average power of 15 mW. PMID:26258338

  12. Choroidal Haller's and Sattler's Layer Thickness Measurement Using 3-Dimensional 1060-nm Optical Coherence Tomography

    PubMed Central

    Esmaeelpour, Marieh; Kajic, Vedran; Zabihian, Behrooz; Othara, Richu; Ansari-Shahrezaei, Siamak; Kellner, Lukas; Krebs, Ilse; Nemetz, Susanne; Kraus, Martin F.; Hornegger, Joachim; Fujimoto, James G.; Drexler, Wolfgang; Binder, Susanne

    2014-01-01

    Objectives To examine the feasibility of automatically segmented choroidal vessels in three-dimensional (3D) 1060-nmOCT by testing repeatability in healthy and AMD eyes and by mapping Haller's and Sattler's layer thickness in healthy eyes Methods Fifty-five eyes (from 45 healthy subjects and 10 with non-neovascular age-related macular degeneration (AMD) subjects) were imaged by 3D-1060-nmOCT over a 36°x36° field of view. Haller's and Sattler's layer were automatically segmented, mapped and averaged across the Early Treatment Diabetic Retinopathy Study grid. For ten AMD eyes and ten healthy eyes, imaging was repeated within the same session and on another day. Outcomes were the repeatability agreement of Haller's and Sattler's layer thicknesses in healthy and AMD eyes, the validation with ICGA and the statistical analysis of the effect of age and axial eye length (AL) on both healthy choroidalsublayers. Results The coefficients of repeatability for Sattler's and Haller's layers were 35% and 21% in healthy eyes and 44% and 31% in AMD eyes, respectively. The mean±SD healthy central submacular field thickness for Sattler's and Haller's was 87±56 µm and 141±50 µm, respectively, with a significant relationship for AL (P<.001). Conclusions Automated Sattler's and Haller's thickness segmentation generates rapid 3D measurements with a repeatability correspondingto reported manual segmentation. Sublayers in healthy eyes thinnedsignificantly with increasing AL. In the presence of the thinned Sattler's layer in AMD, careful measurement interpretation is needed. Automatic choroidal vascular layer mapping may help to explain if pathological choroidal thinning affects medium and large choroidal vasculature in addition to choriocapillaris loss. PMID:24911446

  13. 120nm resolution in thick samples with structured illumination and adaptive optics

    NASA Astrophysics Data System (ADS)

    Thomas, Benjamin; Sloan, Megan; Wolstenholme, Adrian J.; Kner, Peter

    2014-03-01

    μLinear Structured Illumination Microscopy (SIM) provides a two-fold increase over the diffraction limited resolution. SIM produces excellent images with 120nm resolution in tissue culture cells in two and three dimensions. For SIM to work correctly, the point spread function (PSF) and optical transfer function (OTF) must be known, and, ideally, should be unaberrated. When imaging through thick samples, aberrations will be introduced into the optical system which will reduce the peak intensity and increase the width of the PSF. This will lead to reduced resolution and artifacts in SIM images. Adaptive optics can be used to correct the optical wavefront restoring the PSF to its unaberrated state, and AO has been used in several types of fluorescence microscopy. We demonstrate that AO can be used with SIM to achieve 120nm resolution through 25m of tissue by imaging through the full thickness of an adult C. elegans roundworm. The aberrations can be corrected over a 25μm × 45μm field of view with one wavefront correction setting, demonstrating that AO can be used effectively with widefield superresolution techniques.

  14. Ultra-soft 100 nm thick zero Poisson's ratio film with 60% reversible compressibility

    NASA Astrophysics Data System (ADS)

    Nguyen, Chieu; Szalewski, Steve; Saraf, Ravi

    2013-03-01

    Squeezing films of most solids, liquids and granular materials causes dilation in the lateral dimension which is characterized by a positive Poisson's ratio. Auxetic materials, such as, special foams, crumpled graphite, zeolites, spectrin/actin membrane, and carbon nanotube laminates shrink, i.e., their Poisson's ratio is negative. As a result of Poisson's effect, the force to squeeze an amorphous material, such as a viscous thin film coating adhered to rigid surface increases by over million fold as the thickness decreases from 10 μm to 100 nm due to constrain on lateral deformations and off-plane relaxation. We demonstrate, ultra-soft, 100 nm films of polymer/nanoparticle composite adhered to 1.25 cm diameter glass that can be reversibly squeezed over 60% strain between rigid plates requiring (very) low stresses below 100 KPa. Unlike non-zero Poisson's ratio materials, stiffness decreases with thickness, and the stress distribution is uniform over the film as mapped electro-optically. The high deformability at very low stresses is explained by considering reentrant cellular structure found in cork and the wings of beetles that have Poisson's ratio near zero.

  15. Effect of titanium oxide nanoparticle incorporation into nm thick coatings deposited using an atmospheric pressure plasma.

    PubMed

    Denis, Dowling P; Barry, Twomey; Gerry, Byrne

    2010-04-01

    This study reports on the use of an atmospheric plasma technique to incorporate metal oxide nanoparticles into nm thick siloxane coatings. Titanium dioxide (TiO2) particles with diameters of 30-80 nm, were mixed with a number of different siloxanes-polydimethylsiloxane, hexamethyldisiloxane and tetraethylorthosilicate (TEOS). The TiO2/TEOS mixture was found to give the most stable suspension, possibly due to the higher surface tension of TEOS compared with the other siloxanes. TiO2/TEOS mixtures with 2 to 10% by weight of the metal oxide were prepared and were then nebulised into a helium/oxygen atmospheric plasma. Polyethylene terepthalate (PET) and silicon wafer substrates were passed through this plasma using a reel-to-reel substrate manipulation system. SEM combined with EDX was used to examine the distribution of the metal oxide particles in the resultant coatings. The TEOS coating thickness without TiO2 addition was 9 nm. The composite coating consisted of a relatively homogeneous distribution of small agglomerates of the TiO2 nanoparticles in TEOS. A linear increase in the titanium surface concentration was observed with increase in the quantity of TiO2 added into the siloxane precursor. The chemical functionality of the siloxane coating was examined using FTIR spectroscopy and no significant spectrum differences was observed with the incorporation of the different concentrations of TiO2 into the polymer. There were also no changes observed in coating surface energy with TiO2 incorporation. Coating morphology was examined using optical profilometry and surface roughness (Ra) values increased from typical values of 0.8 nm for the TEOS coating to 4.1 nm for the TiO2/TEOS coating. The adhesion of the deposited coatings was compared using fragmentation tests. These were carried out through uniaxial tensile loading. The coating cracking pattern after applied strain of 20% was not observed to change significantly with the addition of TiO2 into the siloxane. PMID

  16. 1-nm-thick graphene tri-layer as the ultimate copper diffusion barrier

    SciTech Connect

    Nguyen, Ba-Son; Lin, Jen-Fin

    2014-02-24

    We demonstrate the thinnest ever reported Cu diffusion barrier, a 1-nm-thick graphene tri-layer. X-ray diffraction patterns and Raman spectra show that the graphene is thermally stable at up to 750 °C against Cu diffusion. Transmission electron microscopy images show that there was no inter-diffusion in the Cu/graphene/Si structure. Raman analyses indicate that the graphene may have degraded into a nanocrystalline structure at 750 °C. At 800 °C, the perfect carbon structure was damaged, and thus the barrier failed. The results of this study suggest that graphene could be the ultimate Cu interconnect diffusion barrier.

  17. Tunneling characteristics for nm-thick mesas consisting of a few intrinsic Josephson junctions

    NASA Astrophysics Data System (ADS)

    Suzuki, Minoru; Ohmaki, Masayuki; Takemura, Ryota; Hamada, Kenji; Watanabe, Takao; Ota, Kensuke; Kitano, Haruhisa; Maeda, Atsutaka

    2008-10-01

    Very thin mesa structures consisting of a few intrinsic Josephson junctions have been fabricated on single crystal surfaces of Bi2Sr2CaCu2O8+δ. In the fabrication procedure, annealing is conducted after the mesa structure is formed by Ar ion milling. Or, the annealing is skipped and, instead, the electrodes to the mesas have been deposited in vacuum immediately after crystals are cleaved. We have attained both uniform current-voltage (I-V) characteristics and small contact resistances, which are usually difficult to obtain at the same time in the case of nm-thick mesa structures. For the mesas thus fabricated, it is found that the Josephson critical current Jc of the top IJJ (the surface junction) is reduced significantly. The reduction of Jc is more significant when the doping level of the crystal used is lower. We argue that this is due to the proximity efiect of the surface junction, in which the top electrode is in close proximity with the Ag or Au film of a thickness of the order of 300 nm. For mesas obtained by this method, the switching probability distribution has been measured. It is found that when the mesa lateral size is larger than 2 μm the switching is unreproducible and lacking systematic temperature dependence. It is also found that escape temperature Tesc and the standard deviation σ for the switching probability distribution exhibits a large deviation from the Kramers' thermal activation theory. When the lateral size is no larger than 2 μm, the switching probability distribution results show coincidence with the theory in the temperature range from 1.3 K to 5 K. Below 0.5 K, the escape temperature tends to saturate and indicates a crossover near 0.5 K from the thermal activation to the macroscopic quantum tunneling.

  18. Leaping shampoo glides on a 500-nm-thick lubricating air layer

    NASA Astrophysics Data System (ADS)

    Li, Erqiang; Lee, Sanghyun; Marston, Jeremy; Bonito, Andrea; Thoroddsen, Sigurdur

    2013-11-01

    When a stream of shampoo is fed onto a pool in one's hand, a jet can leap sideways or rebound from the liquid surface in an intriguing phenomenon known as the Kaye effect. Earlier studies have debated whether non-Newtonian effects are the underlying cause of this phenomenon, making the jet glide on top of a shear-thinning liquid layer, or whether an entrained air layer is responsible. Herein we show unambiguously that the jet slides on a lubricating air layer [Lee et al., Phys. Rev. E 87, 061001 (2013)]. We identify this layer by looking through the pool liquid and observing its rupture into fine micro-bubbles. The resulting micro-bubble sizes suggest that the thickness of this air layer is around 500 nm. This thickness estimate is also supported by the tangential deceleration of the jet during the rebounding, with the shear stress within the thin air layer sufficient for the observed deceleration. Particle tracking within the jet shows uniform velocity, with no pronounced shear, which would be required for shear-thinning effects. The role of the surfactant may primarily be to stabilize the air film.

  19. Tunable spiral Bragg gratings in 60-nm-thick silicon-on-insulator strip waveguides.

    PubMed

    Zou, Zhi; Zhou, Linjie; Wang, Minjuan; Wu, Kan; Chen, Jianping

    2016-06-13

    We demonstrate spiral integrated Bragg gratings (IBGs) in 60-nm-thick strip waveguides on the silicon-on-insulator (SOI) platform. The length of the spiral IBG is 2 mm, occupying an area of 147 × 141 μm2 with a minimum bending radius of 20 μm. Experiments show that the spiral IBGs exhibit a single narrow transparent peak with a Q-factor of 1 × 105 in a broad stopband, induced by the phase shift of the S-junction at the spiral center. This phenomenon is analogous to the electromagnetically induced transparency (EIT) effect. The transparent peak can periodically shift in the stopband upon heating of the S-junction using a TiN-based heater on top. The peak transmittance and Q-factor are dependent on the reflectivity of the spiral IBG. The transparent peak can be completely eliminated under a certain tuning power, and the spiral IBG hence behaves as a bandstop optical filter. The bandwidth is 0.94 nm and the extinction ratio is as high as 43 dB. The stopband can also be shifted by heating the Bragg gratings using a separate TiN heater. The experimental results agree well with the modeling results based on the transfer matrix method. PMID:27410302

  20. Large-scale freestanding nanometer-thick graphite pellicles for mass production of nanodevices beyond 10 nm.

    PubMed

    Kim, Seul-Gi; Shin, Dong-Wook; Kim, Taesung; Kim, Sooyoung; Lee, Jung Hun; Lee, Chang Gu; Yang, Cheol-Woong; Lee, Sungjoo; Cho, Sang Jin; Jeon, Hwan Chul; Kim, Mun Ja; Kim, Byung-Gook; Yoo, Ji-Beom

    2015-09-21

    Extreme ultraviolet lithography (EUVL) has received much attention in the semiconductor industry as a promising candidate to extend dimensional scaling beyond 10 nm. We present a new pellicle material, nanometer-thick graphite film (NGF), which shows an extreme ultraviolet (EUV) transmission of 92% at a thickness of 18 nm. The maximum temperature induced by laser irradiation (λ = 800 nm) of 9.9 W cm(-2) was 267 °C, due to the high thermal conductivity of the NGF. The freestanding NGF was found to be chemically stable during annealing at 500 °C in a hydrogen environment. A 50 × 50 mm large area freestanding NGF was fabricated using the wet and dry transfer (WaDT) method. The NGF can be used as an EUVL pellicle for the mass production of nanodevices beyond 10 nm. PMID:26159369

  1. Pulsed-N{sub 2} assisted growth of 5-20 nm thick β-W films

    SciTech Connect

    Narasimham, Avyaya J.; Green, Avery; Matyi, Richard J.; Khare, Prasanna; Vo, Tuan; Diebold, Alain; LaBella, Vincent P.

    2015-11-15

    A technique to deposit 5-20 nm thick β-phase W using a 2-second periodic pulse of 1 sccm-N{sub 2} gas on Si(001) and SiN(5 nm)/Si(001) substrates is reported. Resistivity, X-ray photoelectron spectroscopy and X-ray reflectivity were utilized to determine phase, bonding and thickness, respectively. X-ray diffraction patterns were utilized to determine the crystal structure, lattice constant and crystal size using the LeBail method. The flow rate of Nitrogen gas (continuous vs. pulsing) had significant impact upon the crystallinity and formation of β-phase W.

  2. Dental caries in Rome, 50-100 AD.

    PubMed

    Fejerskov, O; Guldager Bilde, P; Bizzarro, M; Connelly, J N; Skovhus Thomsen, J; Nyvad, B

    2012-01-01

    Scarce information exists on the clinical features of dental caries in the Imperial Roman population and no structural data on caries lesions from this period have so far been published. We report on the findings of 86 teeth (50-100 AD) found during archaeological excavations of the temple of Castor and Pollux in the Forum Romanum. We found that nearly all teeth had large carious cavities extending into the pulp. The distribution and size of the caries lesions were similar to those found in contemporary adult populations in Africa and China living without access to dental care. Most lesions had a hypermineralized zone in the dentin at the advancing front of the carious cavities as revealed by micro-computed tomography. This biological dentin reaction combined with the morphology of the cavities might indicate that some temporary topical pain relief and intervention treatment slowed down the rate of lesion progression. This is indirectly supported by examination of cavities of similar size and depth from a contemporary population without access to dental health care. In contrast to the lesions in the Roman teeth, these lesions did not exhibit a hypermineralized dentin reaction. We investigated whether the Pb isotopic composition of enamel and/or dentin of a single tooth matched that of a sample of an ancient Forum water lead pipe. The Pb isotopic composition of the tooth did not match that of the tube, suggesting that the subjects were exposed to different Pb sources during their lifetime other than the lead tubes. PMID:22796661

  3. 2D Zeolite Coatings: Langmuir-Schaefer Deposition of 3 nm Thick MFI Zeolite Nanosheets.

    PubMed

    Rangnekar, Neel; Shete, Meera; Agrawal, Kumar Varoon; Topuz, Berna; Kumar, Prashant; Guo, Qiang; Ismail, Issam; Alyoubi, Abdulrahman; Basahel, Sulaiman; Narasimharao, Katabathini; Macosko, Christopher W; Mkhoyan, K Andre; Al-Thabaiti, Shaeel; Stottrup, Benjamin; Tsapatsis, Michael

    2015-05-26

    Stable suspensions of zeolite nanosheets (3 nm thick MFI layers) were prepared in ethanol following acid treatment, which partially removed the associated organic structure-directing agent. Nanosheets from these suspensions could then be dispersed at the air-water interface and transferred to silicon wafers using Langmuir-Schaefer deposition. Using layer-by-layer deposition, control on coating thickness was demonstrated. In-plane X-ray diffraction (XRD) revealed that the deposited nanosheets contract upon calcination similar to bulk MFI crystals. Different methods for secondary growth resulted in preferentially oriented thin films of MFI, which had sub-12-nm thickness in certain cases. Upon calcination, there was no contraction detectable by in-plane XRD, indicating well-intergrown MFI films that are strongly attached to the substrate. PMID:25864539

  4. Strain relaxation in nm-thick Cu and Cu-alloy films bonded to a rigid substrate

    NASA Astrophysics Data System (ADS)

    Herrmann, Ashley Ann Elizabeth

    In the wide scope of modern technology, nm-thick metallic films are increasingly used as lubrication layers, optical coatings, plating seeds, diffusion barriers, adhesion layers, metal contacts, reaction catalyzers, etc. A prominent example is the use of nm-thick Cu films as electroplating seed layers in the manufacturing of integrated circuits (ICs). These high density circuits are linked by on-chip copper interconnects, which are manufactured by filling Cu into narrow trenches by electroplating. The Cu fill by electroplating requires a thin Cu seed deposited onto high-aspect-ratio trenches. In modern ICs, these trenches are approaching 10 nm or less in width, and the seed layers less than 1 nm in thickness. Since nm-thick Cu seed layers are prone to agglomeration or delamination, achieving uniform, stable and highly-conductive ultra-thin seeds has become a major manufacturing challenge. A fundamental understanding of the strain behavior and thermal stability of nm-thick metal films adhered to a rigid substrate is thus critically needed. In this study, we focus on understanding the deformation modes of nm-thick Cu and Cu-alloy films bonded to a rigid Si substrate and under compressive stress. The strengthening of Cu films through alloying is also studied. In-situ transport measurements are used to monitor the deformation of such films as they are heated from room temperature to 400 °C. Ex-situ AFM is then used to help characterize the mode of strain relaxation. The relaxation modes are known to be sensitive to the wetting and adhesive properties of the film-substrate interface. We use four different liners (Ta, Ru, Mo and Co), interposed between the film and substrate to provide a wide range of interfacial properties to study their effect on the film's thermal stability. Our measurements indicate that when the film/liner interfacial energy is low, grain growth is the dominant relaxation mechanism. As the interface energy increases, grain growth is suppressed, and

  5. Thickness effect on laser-induced-damage threshold of indium-tin oxide films at 1064 nm

    SciTech Connect

    Wang Haifeng; Huang Zhimeng; Zhang Dayong; Luo Fei; Huang Lixian; Li Yanglong; Luo Yongquan; Wang Weiping; Zhao Xiangjie

    2011-12-01

    Laser-induced-damage characteristics of commercial indium-tin oxide (ITO) films deposited by DC magnetron sputtering deposition on K9 glass substrates as a function of the film thickness have been studied at 1064 nm with a 10 ns laser pulse in the 1-on-1 mode, and the various mechanisms for thickness effect on laser-induced-damage threshold (LIDT) of the film have been discussed in detail. It is observed that laser-damage-resistance of ITO film shows dramatic thickness effect with the LIDT of the 50-nm ITO film 7.6 times as large as the value of 300 nm film, and the effect of depressed carrier density by decreasing the film thickness is demonstrated to be the primary reason. Our experiment findings indicate that searching transparent conductive oxide (TCO) film with low carrier density and high carrier mobility is an efficient technique to improve the laser-damage-resistance of TCO films based on maintaining their well electric conductivity.

  6. Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

    NASA Astrophysics Data System (ADS)

    Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

    2015-11-01

    Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5-2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0-2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed.

  7. Thickness effect of ultra-thin Ta2O5 resistance switching layer in 28 nm-diameter memory cell

    PubMed Central

    Park, Tae Hyung; Song, Seul Ji; Kim, Hae Jin; Kim, Soo Gil; Chung, Suock; Kim, Beom Yong; Lee, Kee Jeung; Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

    2015-01-01

    Resistance switching (RS) devices with ultra-thin Ta2O5 switching layer (0.5–2.0 nm) with a cell diameter of 28 nm were fabricated. The performance of the devices was tested by voltage-driven current—voltage (I-V) sweep and closed-loop pulse switching (CLPS) tests. A Ta layer was placed beneath the Ta2O5 switching layer to act as an oxygen vacancy reservoir. The device with the smallest Ta2O5 thickness (0.5 nm) showed normal switching properties with gradual change in resistance in I-V sweep or CLPS and high reliability. By contrast, other devices with higher Ta2O5 thickness (1.0–2.0 nm) showed abrupt switching with several abnormal behaviours, degraded resistance distribution, especially in high resistance state, and much lower reliability performance. A single conical or hour-glass shaped double conical conducting filament shape was conceived to explain these behavioural differences that depended on the Ta2O5 switching layer thickness. Loss of oxygen via lateral diffusion to the encapsulating Si3N4/SiO2 layer was suggested as the main degradation mechanism for reliability, and a method to improve reliability was also proposed. PMID:26527044

  8. Measuring sub-nm adsorbed water layer thickness and desorption rate using a fused-silica whispering-gallery microresonator

    NASA Astrophysics Data System (ADS)

    Ganta, D.; Dale, E. B.; Rosenberger, A. T.

    2014-05-01

    We report an optical method for measuring the thickness of the water layer adsorbed onto the surface of a high-Q fused-silica microresonator. Light from a tunable diode laser operating near 1550 nm is coupled into the microresonator to excite whispering-gallery modes (WGMs). By observing thermal distortion or even bistability of the WGM resonances caused by absorption in the water layer, the contribution of that absorption to the total loss is determined. Thereby, the thickness of the water layer is found to be ˜0.1 nm (approximately one monolayer). This method is further extended to measure the desorption rate of the adsorbed water, which is roughly exponential with a decay time of ˜40 h when the fused-silica microresonator is held in a vacuum chamber at low pressure.

  9. Surface-dominated conduction in a 6 nm thick Bi2Se3 thin film.

    PubMed

    He, Liang; Xiu, Faxian; Yu, Xinxin; Teague, Marcus; Jiang, Wanjun; Fan, Yabin; Kou, Xufeng; Lang, Murong; Wang, Yong; Huang, Guan; Yeh, Nai-Chang; Wang, Kang L

    2012-03-14

    We report a direct observation of surface dominated conduction in an intrinsic Bi(2)Se(3) thin film with a thickness of six quintuple layers grown on lattice-matched CdS (0001) substrates by molecular beam epitaxy. Shubnikov-de Haas oscillations from the topological surface states suggest that the Fermi level falls inside the bulk band gap and is 53 ± 5 meV above the Dirac point, which is in agreement with 70 ± 20 meV obtained from scanning tunneling spectroscopies. Our results demonstrate a great potential of producing genuine topological insulator devices using Dirac Fermions of the surface states, when the film thickness is pushed to nanometer range. PMID:22316380

  10. The cutting of ultrathin sections with the thickness less than 20 nm from biological specimens embedded in resin blocks.

    PubMed

    Nebesářová, Jana; Hozák, Pavel; Frank, Luděk; Štěpan, Petr; Vancová, Marie

    2016-06-01

    Low voltage electron microscopes working in transmission mode, like LVEM5 (Delong Instruments, Czech Republic) working at accelerating voltage 5 kV or scanning electron microscope working in transmission mode with accelerating voltage below 1 kV, require ultrathin sections with the thickness below 20 nm. Decreasing of the primary electron energy leads to enhancement of image contrast, which is especially useful in the case of biological samples composed of elements with low atomic numbers. As a result treatments with heavy metals, like post-fixation with osmium tetroxide or ultrathin section staining, can by omitted. The disadvantage is reduced penetration ability of incident electrons influencing the usable thickness of the specimen resulting in the need of ultrathin sections of under 20 nm thickness. In this study we want to answer basic questions concerning the cutting of extremely ultrathin sections: Is it possible routinely and reproducibly to cut extremely thin sections of biological specimens embedded in commonly used resins with contemporary ultramicrotome techniques and under what conditions? Microsc. Res. Tech. 79:512-517, 2016. © 2016 Wiley Periodicals, Inc. PMID:27030160

  11. Crystalline ternary rare earth oxide with capacitance equivalent thickness below 1 nm for high-K application

    SciTech Connect

    Laha, Apurba; Bugiel, E.; Osten, H.J.; Fissel, A.

    2006-04-24

    Ternary neodymium-gadolinium oxide (NGO) thin films were grown epitaxially on Si(001) substrates using modified molecular beam epitaxy. The electrical properties of NGO thin films demonstrate that this ternary oxide could be one of the most promising candidates to replace the conventionally used SiO{sub 2} or SiO{sub x}N{sub y} in complementary metal oxide semiconductor devices. The films were characterized with various methods. The capacitance equivalent oxide thickness of 4.5 nm thin films extracted from capacitance-voltage (C-V) characteristics was 0.9 nm. For such films, leakage current density and the density of interface traps were 2.6x10{sup -4} A/cm{sup 2} at vertical bar V{sub g}-V{sub FBV} vertical bar=1 V and 1.4x10{sup 12}/cm{sup 2} eV{sup -1}, respectively.

  12. 60-nm-thick basic photonic components and Bragg gratings on the silicon-on-insulator platform.

    PubMed

    Zou, Zhi; Zhou, Linjie; Li, Xinwan; Chen, Jianping

    2015-08-10

    We demonstrate integrated basic photonic components and Bragg gratings using 60-nm-thick silicon-on-insulator strip waveguides. The ultra-thin waveguides exhibit a propagation loss of 0.61 dB/cm and a bending loss of approximately 0.015 dB/180° with a 30 μm bending radius (including two straight-bend waveguide junctions). Basic structures based on the ultra-thin waveguides, including micro-ring resonators, 1 × 2 MMI couplers, and Mach-Zehnder interferometers are realized. Upon thinning-down, the waveguide effective refractive index is reduced, making the fabrication of Bragg gratings possible using the standard 248-nm deep ultra-violet (DUV) photolithography process. The Bragg grating exhibits a stopband width of 1 nm and an extinction ratio of 35 dB, which is practically applicable as an optical filter or a delay line. The transmission spectrum can be thermally tuned via an integrated resistive micro-heater formed by a heavily doped silicon slab beside the waveguide. PMID:26367931

  13. nm- thick conformal pore-sealing of self-assembled mesoporous silica by plasma-assisted atomic layer deposition

    PubMed Central

    Jiang, Ying-Bing; Liu, Nanguo; Gerung, Henry; Cecchi, Joseph L.; Brinker, C. Jeffrey

    2009-01-01

    On a porous substrate, regular atomic layer deposition (ALD) not only takes place on top of the substrate but also penetrates into the internal porosity. Here we report a plasma-assisted process in which the ALD precursors are chosen to be non-reactive unless triggered by plasma, so that ALD can be spatially defined by the supply of plasma irradiation. Since plasma cannot penetrate within the internal porosity, ALD has been successfully confined to the immediate surface. This not only gives a possible solution for sealing of porous low dielectric constant films with a conformal layer of nm-scale thickness, but also enables us to progressively reduce the pore size of mesoporous materials in a sub-Å/cycle fashion for membrane formation. PMID:16925407

  14. Mechanical characterization of sub-100-nm-thick Au thin films by electrostatically actuated tensile testing with several strain rates

    NASA Astrophysics Data System (ADS)

    Oh, Hyun-Jin; Kawase, Shinya; Hanasaki, Itsuo; Isono, Yoshitada

    2014-02-01

    We have developed the tensile testing device based on MEMS technology and applied it to the Au thin films with thickness in the sub-100-nm regime. The specimen was fabricated by thermal deposition and sputtering processes in the course of device fabrication. This technique of device fabrication in combination with the specimen realizes the precise loading direction without preloading before tensile tests. The loads were applied electrostatically by the comb-drive actuator. The obtained Young’s modulus was 28 ± 3 GPa and was insensitive to the strain rate. The 0.2% yield strength was in the range from 192 to 519 MPa with a trend of decrease with decreasing strain rate in the range from 5 × 10-5 to 5 × 10-2 s-1.

  15. Dependence of Sheet Resistance of CoSi2 with Gate Length of 30 nm on Thickness of Titanium Nitride Capping Layer in Co-Salicide Process

    NASA Astrophysics Data System (ADS)

    Kawamura, Kazuo; Inagaki, Satoshi; Saiki, Takashi; Nakamura, Ryo; Kataoka, Yuji; Kase, Masataka

    2007-11-01

    Since the distribution of gate resistance using cobalt silicide (CoSi2) increases markedly for gate lengths of 30 nm or less, CoSi2 is now being replaced by NiSi. However, CoSi2 still has the advantages of a high thermal stability and a low degree of roughness at the interface between the silicide and silicon layers owing to the low degree of mismatch (1.2%) of between their lattice constants. We have achieved excellent sheet resistance (Rs) with a gate length Lg=30 nm by optimizing the thickness of a cobalt capping layer of titanium nitride. The results shows an abnormal Rs behavior, in which one σ of Rs increases with capping layer thickness in the range of 10-50 nm, while it decreases with increasing capping layer thickness in the range of 0-10 nm. Unlike the results of a previous report [K. Goto et al.: IEDM Tech. Dig., 1995, p. 449], the variation in the Rs with a gate length Lg=30 nm is small, even without a TiN capping layer thickness down to 5-10 nm. We suggest that the uniformity of Rs is determined by the thickness of the CoSi layer after selective etching and the titanium concentration in the CoSi layer for capping TiN thicknesses of 10-50 nm, while the uniformity is determined by the titanium concentration and the damage sustained during selective etching for TiN thickness of 0-10 nm. For this optimization, CoSi2 is applicable to the 65 nm node technology node or beyond.

  16. Characterization of 7-nm-thick strained Ge-on-insulator layer fabricated by Ge-condensation technique

    NASA Astrophysics Data System (ADS)

    Nakaharai, Shu; Tezuka, Tsutomu; Sugiyama, Naoharu; Moriyama, Yoshihiko; Takagi, Shin-ichi

    2003-10-01

    A strained Ge-on-insulator (GOI) structure with a 7-nm-thick Ge layer was fabricated for applications to high-speed transistors. The GOI layer was formed by thermal oxidation of a strained SiGe layer grown epitaxially on a silicon-on-insulator (SOI) wafer. In transmission electron microscopy measurements, the obtained GOI layer exhibited a single-crystal structure with the identical orientation to an original SOI substrate and a smooth Ge/SiO2 interface. The rms of the surface roughness of the GOI layer was evaluated to be 0.4 nm by atomic force microscopy. The residual Si fraction in the GOI layer was estimated to be lower than the detection limit of Raman spectroscopy of 0.5% and also than the electron energy loss spectroscope measurements of 3%. It was found that the obtained GOI layer was compressively strained with a strain of 1.1%, which was estimated by the Raman spectroscopy. Judging from the observed crystal quality and the strain value, this technique is promising for fabrication of high-mobility strained Ge channel of high-performance GOI metal-insulator-semiconductor (MIS) transistors.

  17. A Sub-ppm Acetone Gas Sensor for Diabetes Detection Using 10 nm Thick Ultrathin InN FETs

    PubMed Central

    Kao, Kun-Wei; Hsu, Ming-Che; Chang, Yuh-Hwa; Gwo, Shangjr; Yeh, J. Andrew

    2012-01-01

    An indium nitride (InN) gas sensor of 10 nm in thickness has achieved detection limit of 0.4 ppm acetone. The sensor has a size of 1 mm by 2.5 mm, while its sensing area is 0.25 mm by 2 mm. Detection of such a low acetone concentration in exhaled breath could enable early diagnosis of diabetes for portable physiological applications. The ultrathin InN epilayer extensively enhances sensing sensitivity due to its strong electron accumulation on roughly 5–10 nm deep layers from the surface. Platinum as catalyst can increase output current signals by 2.5-fold (94 vs. 37.5 μA) as well as reduce response time by 8.4-fold (150 vs. 1,260 s) in comparison with bare InN. More, the effect of 3% oxygen consumption due to breath inhalation and exhalation on 2.4 ppm acetone gas detection was investigated, indicating that such an acetone concentration can be analyzed in air. PMID:22969342

  18. A study of improved MHR 50/100 toward a higher level of inherent safety

    SciTech Connect

    Minatsuki, I.; Otani, T.; Shimizu, K.; Oyama, S.; Tsukamoto, H.; Kunitomi, K.

    2012-07-01

    A new concept of the Mitsubishi small-sized High temperature gas-cooled modular Reactors (MHR-50/100) had been developed and published in papers. The study results of the first design concept show that the MHR-50/100 can achieve the inherent safety level set as a design target in case of water ingress during steam generator tube rupture accident. And more specifically, the reactor was shown to remain stable during long-term station black out (SBO) with protection of only passive devices during a depressurization accident and with additional motion of steam dump system during a water ingress accident. Recently greater requirements for safety of future nuclear plants including the MHR-50/100 have been expected. This study has thus made a key design improvement for the MHR-50/100 in order to secure the inherent safety aspect without reliance on active steam dump system in case of a water ingress accident. The innovative technologies listed below have been created and investigated to achieve the improved MHR-50/100 design; (1) Design improvement of steam generator, (2) Heat balance optimization of steam cycle, (3) Control system design of differential pressure between primary helium gas and water/steam, (4) Study on operation procedure during a water ingress accident. (authors)

  19. Fabrication of 3-nm-thick Si3N4 membranes for solid-state nanopores using the poly-Si sacrificial layer process

    PubMed Central

    Yanagi, Itaru; Ishida, Takeshi; Fujisaki, Koji; Takeda, Ken-ichi

    2015-01-01

    To improve the spatial resolution of solid-state nanopores, thinning the membrane is a very important issue. The most commonly used membrane material for solid-state nanopores is silicon nitride (Si3N4). However, until now, stable wafer-scale fabrication of Si3N4 membranes with a thickness of less than 5 nm has not been reported, although a further reduction in thickness is desired to improve spatial resolution. In the present study, to fabricate thinner Si3N4 membranes with a thickness of less than 5 nm in a wafer, a new fabrication process that employs a polycrystalline-Si (poly-Si) sacrificial layer was developed. This process enables the stable fabrication of Si3N4 membranes with thicknesses of 3 nm. Nanopores were fabricated in the membrane using a transmission electron microscope (TEM) beam. Based on the relationship between the ionic current through the nanopores and their diameter, the effective thickness of the nanopores was estimated to range from 0.6 to 2.2 nm. Moreover, DNA translocation through the nanopores was observed. PMID:26424588

  20. Synthesis and characterization of 10 nm thick piezoelectric AlN films with high c-axis orientation for miniaturized nanoelectromechanical devices

    SciTech Connect

    Zaghloul, Usama; Piazza, Gianluca

    2014-06-23

    The scaling of piezoelectric nanoelectromechanical systems (NEMS) is challenged by the synthesis of ultrathin and high quality piezoelectric films on very thin electrodes. We report the synthesis and characterization of the thinnest piezoelectric aluminum nitride (AlN) films (10 nm) ever deposited on ultrathin platinum layers (2–5 nm) using reactive sputtering. X-ray diffraction, high-resolution transmission electron microscopy, and fast Fourier transform analyses confirmed the proper crystal orientation, fine columnar texture, and the continuous lattice structure within individual grains in the deposited AlN nanometer thick films. The average extracted d{sub 31} piezoelectric coefficient for the synthesized films is −1.73 pC/N, which is comparable to the reported values for micron thick and highly c-axis oriented AlN films. The 10 nm AlN films were employed to demonstrate two different types of optimized piezoelectric nanoactuators. The unimorph actuators exhibit vertical displacements as large as 1.1 μm at 0.7 V for 25 μm long and 30 nm thick beams. These results have a great potential to realize miniaturized NEMS relays with extremely low voltage, high frequency resonators, and ultrasensitive sensors.

  1. Photorefractive acousto-optic imaging in thick scattering media at 790 nm with a Sn(2)P(2)S(6):Te crystal.

    PubMed

    Farahi, Salma; Montemezzani, Germano; Grabar, Alexander A; Huignard, Jean-Pierre; Ramaz, François

    2010-06-01

    Acousto-optic imaging is based on ultrasound modulation of multiply scattered light in thick media. We experimentally demonstrate the possibility to perform a self-adaptive wavefront holographic detection at 790nm, within the optical therapeutic window where absorption of biological tissues is minimized. A high-gain Te-doped Sn(2)P(2)S(6) crystal is used for this purpose. Optical absorbing objects embedded within a thick scattering phantom are imaged by use of pulsed ultrasound to get a dynamic millimetric axial resolution. Our technique represents an interesting approach for breast cancer detection. PMID:20517420

  2. Thickness-dependent crystallization on thermal anneal for titania/silica nm-layer composites deposited by ion beam sputter method.

    PubMed

    Pan, Huang-Wei; Wang, Shun-Jin; Kuo, Ling-Chi; Chao, Shiuh; Principe, Maria; Pinto, Innocenzo M; DeSalvo, Riccardo

    2014-12-01

    Crystallization following thermal annealing of thin film stacks consisting of alternating nm-thick titania/silica layers was investigated. Several prototypes were designed, featuring a different number of titania/silica layer pairs, and different thicknesses (in the range from 4 to 40 nm, for the titania layers), but the same nominal refractive index (2.09) and optical thickness (a quarter of wavelength at 1064 nm). The prototypes were deposited by ion beam sputtering on silicon substrates. All prototypes were found to be amorphous as-deposited. Thermal annealing in air at progressive temperatures was subsequently performed. It was found that the titania layers eventually crystallized forming the anatase phase, while the silica layers remained always amorphous. However, progressively thinner layers exhibited progressively higher threshold temperatures for crystallization onset. Accordingly it can be expected that composites with thinner layers will be able to sustain higher annealing temperatures without crystallizing, and likely yielding better optical and mechanical properties for advanced coatings application. These results open the way to the use of materials like titania and hafnia, that crystallize easily under thermal anneal, but ARE otherwise promising candidate materials for HR coatings necessary for cryogenic 3rd generation laser interferometric gravitational wave detectors. PMID:25606914

  3. Conceptual definition of a 50-100 kWe NEP system for planetary science missions

    NASA Technical Reports Server (NTRS)

    Friedlander, Alan

    1993-01-01

    The Phase 1 objective of this project is to assess the applicability of a common Nuclear Electric Propulsion (NEP) flight system of the 50-100 kWe power class to meet the advanced transportation requirements of a suite of planetary science (robotic) missions, accounting for differences in mission-specific payloads and delivery requirements. The candidate missions are as follows: (1) Comet Nucleus Sample Return; (2) Multiple Mainbelt Asteroid Rendezvous; (3) Jupiter Grand Tour (Galilean satellites and magnetosphere); (4) Uranus Orbiter/Probe (atmospheric entry and landers); (5) Neptune Orbiter/Probe (atmospheric entry and landers); and (6) Pluto-Charon Orbiter/Lander. The discussion is presented in vugraph form.

  4. Conceptual definition of a 50-100 kWe NEP system for planetary science missions

    NASA Astrophysics Data System (ADS)

    Friedlander, Alan

    The Phase 1 objective of this project is to assess the applicability of a common Nuclear Electric Propulsion (NEP) flight system of the 50-100 kWe power class to meet the advanced transportation requirements of a suite of planetary science (robotic) missions, accounting for differences in mission-specific payloads and delivery requirements. The candidate missions are as follows: (1) Comet Nucleus Sample Return; (2) Multiple Mainbelt Asteroid Rendezvous; (3) Jupiter Grand Tour (Galilean satellites and magnetosphere); (4) Uranus Orbiter/Probe (atmospheric entry and landers); (5) Neptune Orbiter/Probe (atmospheric entry and landers); and (6) Pluto-Charon Orbiter/Lander. The discussion is presented in vugraph form.

  5. Estimation of anisotropy coefficient and total attenuation of swine liver at 850 nm based on a goniometric technique: influence of sample thickness.

    PubMed

    Saccomandi, P; Vogel, V; Bazrafshan, B; Schena, E; Vogl, T J; Silvestri, S; Mäntele, W

    2014-01-01

    Estimation of optical properties of biologic tissue is crucial for theoretical modeling of laser treatments in medicine. Tissue highly absorbs and scatters the light between 650 nm and 1300 nm, where the laser provides therapeutic effects. Among other properties, the characteristic of biological tissues to scatter the light traveling trough, is described by the anisotropy coefficient (g). The relationship between g and the distribution of the scattered light at different angles is described by Henyey-Greenstein phase function. The measurement of angular distribution of scattered light is performed by the goniometric technique. This paper describes the estimation of g and attenuation coefficient, μt, of swine liver at 850 nm, performed by an ad hoc designed goniometric-based system, where a spectrometer measures intensities of scattered light at fixed angles (0°, 30°, 45°, 60, 120°, 135° and 150°). Both one-term and two-term Henyey-Greenstein phase function have been employed to estimate anisotropy coefficient for forward (gfs) and backward scattering (gbs). Measurements are performed on samples of two thicknesses (60 um and 30 urn) to investigate the influence of this factor on g, and repeated 6 times for each thickness. The estimated values of gfs were 0.947 and 0.951 for thickness of 60 μm and 30 μm, respectively; the estimations of gfs were -0.498 and -0.270 for thickness of 60 μm and 30 μm, respectively. Moreover, μt of liver has been estimated (i.e., 90±20 cm(1)), through Lambert-Beer equation. The comparison of our results with data reported in literature encourages the use of the ad hoc designed tool for performing experiments on other tissue, and at other wavelengths. PMID:25571198

  6. Liquid crystal films as on-demand, variable thickness (50–5000 nm) targets for intense lasers

    SciTech Connect

    Poole, P. L. Andereck, C. D.; Schumacher, D. W.; Daskalova, R. L.; Feister, S.; George, K. M.; Willis, C.; Akli, K. U.; Chowdhury, E. A.

    2014-06-15

    We have developed a new type of target for intense laser-matter experiments that offers significant advantages over those currently in use. The targets consist of a liquid crystal film freely suspended within a metal frame. They can be formed rapidly on-demand with thicknesses ranging from nanometers to micrometers, where the particular value is determined by the liquid crystal temperature and initial volume as well as by the frame geometry. The liquid crystal used for this work, 8CB (4′-octyl-4-cyanobiphenyl), has a vapor pressure below 10{sup −6} Torr, so films made at atmospheric pressure maintain their initial thickness after pumping to high vacuum. Additionally, the volume per film is such that each target costs significantly less than one cent to produce. The mechanism of film formation and relevant physics of liquid crystals are described, as well as ion acceleration data from the first shots on liquid crystal film targets at the Ohio State University Scarlet laser facility.

  7. Liquid crystal films as on-demand, variable thickness (50-5000 nm) targets for intense lasers

    NASA Astrophysics Data System (ADS)

    Poole, P. L.; Andereck, C. D.; Schumacher, D. W.; Daskalova, R. L.; Feister, S.; George, K. M.; Willis, C.; Akli, K. U.; Chowdhury, E. A.

    2014-06-01

    We have developed a new type of target for intense laser-matter experiments that offers significant advantages over those currently in use. The targets consist of a liquid crystal film freely suspended within a metal frame. They can be formed rapidly on-demand with thicknesses ranging from nanometers to micrometers, where the particular value is determined by the liquid crystal temperature and initial volume as well as by the frame geometry. The liquid crystal used for this work, 8CB (4'-octyl-4-cyanobiphenyl), has a vapor pressure below 10-6 Torr, so films made at atmospheric pressure maintain their initial thickness after pumping to high vacuum. Additionally, the volume per film is such that each target costs significantly less than one cent to produce. The mechanism of film formation and relevant physics of liquid crystals are described, as well as ion acceleration data from the first shots on liquid crystal film targets at the Ohio State University Scarlet laser facility.

  8. A 50-100 kWe gas-cooled reactor for use on Mars.

    SciTech Connect

    Peters, Curtis D.

    2006-04-01

    In the space exploration field there is a general consensus that nuclear reactor powered systems will be extremely desirable for future missions to the outer solar system. Solar systems suffer from the decreasing intensity of solar radiation and relatively low power density. Radioisotope Thermoelectric Generators are limited to generating a few kilowatts electric (kWe). Chemical systems are short-lived due to prodigious fuel use. A well designed 50-100 kWe nuclear reactor power system would provide sufficient power for a variety of long term missions. This thesis will present basic work done on a 50-100 kWe reactor power system that has a reasonable lifespan and would function in an extraterrestrial environment. The system will use a Gas-Cooled Reactor that is directly coupled to a Closed Brayton Cycle (GCR-CBC) power system. Also included will be some variations on the primary design and their effects on the characteristics of the primary design. This thesis also presents a variety of neutronics related calculations, an examination of the reactor's thermal characteristics, feasibility for use in an extraterrestrial environment, and the reactor's safety characteristics in several accident scenarios. While there has been past work for space reactors, the challenges introduced by thin atmospheres like those on Mars have rarely been considered.

  9. Absorption enhancement through Fabry-Pérot resonant modes in a 430 nm thick InGaAs/GaAsP multiple quantum wells solar cell

    SciTech Connect

    Behaghel, B.; Tamaki, R.; Watanabe, K.; Sodabanlu, H.; Vandamme, N.; Dupuis, C.; Bardou, N.; Cattoni, A.; Okada, Y.; Sugiyama, M.; Collin, S.; Guillemoles, J.-F.

    2015-02-23

    We study light management in a 430 nm-thick GaAs p-i-n single junction solar cell with 10 pairs of InGaAs/GaAsP multiple quantum wells (MQWs). The epitaxial layer transfer on a gold mirror improves light absorption and increases the external quantum efficiency below GaAs bandgap by a factor of four through the excitation of Fabry-Perot resonances. We show a good agreement with optical simulation and achieve around 10% conversion efficiency. We demonstrate numerically that this promising result can be further improved by anti-reflection layers. This study paves the way to very thin MQWs solar cells.

  10. Randomised clinical trial evaluating best-corrected visual acuity and central macular thickness after 532-nm subthreshold laser grid photocoagulation treatment in diabetic macular oedema

    PubMed Central

    Pei-pei, W; Shi-zhou, H; Zhen, T; Lin, L; Ying, L; Jiexiong, O; Wen-bo, Z; Chen-jin, J

    2015-01-01

    Purpose To compare best-corrected visual acuity (BCVA) and central macular thickness (CMT) after 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation for the treatment of diabetic macular oedema (DME). Patients and methods Twenty-three patients (46 eyes) with binocular DME were enroled in this study. The two eyes of each patient were divided into a subthreshold photocoagulation group and a threshold photocoagulation group. The eyes of the subthreshold group underwent 532-nm patter scan laser system (PASCAL) 50% end point subthreshold laser grid photocoagulation therapy, whereas the threshold photocoagulation group underwent short-pulse grid photocoagulation with a 532-nm PASCAL system. BCVA and CMT were assessed in all patients before treatment, 7 days after treatment, and 1, 3, and 6 months after treatment. Results After grid photocoagulation, the mean BCVA improved in both the subthreshold group, and the threshold group, and the two groups did not differ statistically significantly from each other. Similarly, the macular oedema diminished in both groups after treatment, and the two groups did not differ statistically significantly from each other with regard to CMT. Conclusion Both 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation can improve the visual acuity and reduce CMT in DME patients. PMID:25697457

  11. Combined 60° Wide-Field Choroidal Thickness Maps and High-Definition En Face Vasculature Visualization Using Swept-Source Megahertz OCT at 1050 nm

    PubMed Central

    Mohler, Kathrin J.; Draxinger, Wolfgang; Klein, Thomas; Kolb, Jan Philip; Wieser, Wolfgang; Haritoglou, Christos; Kampik, Anselm; Fujimoto, James G.; Neubauer, Aljoscha S.; Huber, Robert; Wolf, Armin

    2015-01-01

    Purpose To demonstrate ultrahigh-speed swept-source optical coherence tomography (SS-OCT) at 1.68 million A-scans/s for choroidal imaging in normal and diseased eyes over a ∼60° field of view. To investigate and correlate wide-field three-dimensional (3D) choroidal thickness (ChT) and vascular patterns using ChT maps and coregistered high-definition en face images extracted from a single densely sampled Megahertz-OCT (MHz-OCT) dataset. Methods High-definition, ∼60° wide-field 3D datasets consisting of 2088 × 1024 A-scans were acquired using a 1.68 MHz prototype SS-OCT system at 1050 nm based on a Fourier-domain mode-locked laser. Nine subjects (nine eyes) with various chorioretinal diseases or without ocular pathology are presented. Coregistered ChT maps, choroidal summation maps, and depth-resolved en face images referenced to either the retinal pigment epithelium or the choroidal–scleral interface were generated using manual segmentation. Results Wide-field ChT maps showed a large inter- and intraindividual variance in peripheral and central ChT. In only four of the nine eyes, the location with the largest ChT was coincident with the fovea. The anatomy of the large lumen vessels of the outer choroid seems to play a major role in determining the global ChT pattern. Focal ChT changes with large thickness gradients were observed in some eyes. Conclusions Different ChT and vascular patterns could be visualized over ∼60° in patients for the first time using OCT. Due to focal ChT changes, a high density of thickness measurements may be favorable. High-definition depth-resolved en face images are complementary to cross sections and thickness maps and enhance the interpretation of different ChT patterns. PMID:26431482

  12. Demonstrating 1 nm-oxide-equivalent-thickness HfO{sub 2}/InSb structure with unpinning Fermi level and low gate leakage current density

    SciTech Connect

    Trinh, Hai-Dang; Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi ; Lin, Yueh-Chin; Nguyen, Hong-Quan; Luc, Quang-Ho; Nguyen, Minh-Thuy; Duong, Quoc-Van; Nguyen, Manh-Nghia; Wang, Shin-Yuan; Yi Chang, Edward; Department of Electronic Engineering, National Chiao Tung University 1001, University Rd., Hsinchu 300, Taiwan

    2013-09-30

    In this work, the band alignment, interface, and electrical characteristics of HfO{sub 2}/InSb metal-oxide-semiconductor structure have been investigated. By using x-ray photoelectron spectroscopy analysis, the conduction band offset of 1.78 ± 0.1 eV and valence band offset of 3.35 ± 0.1 eV have been extracted. The transmission electron microscopy analysis has shown that HfO{sub 2} layer would be a good diffusion barrier for InSb. As a result, 1 nm equivalent-oxide-thickness in the 4 nm HfO{sub 2}/InSb structure has been demonstrated with unpinning Fermi level and low leakage current of 10{sup −4} A/cm{sup −2}. The D{sub it} value of smaller than 10{sup 12} eV{sup −1}cm{sup −2} has been obtained using conduction method.

  13. Commissioning a 50-100 kV X-ray unit for skin cancer treatment.

    PubMed

    Sheu, Ren-Dih; Powers, Allison; Lo, Yeh-Chi

    2015-01-01

    This study provides the authors' experience along with dosimetric data from the commissioning of two Sensus SRT-100 50-100 kV X-ray units. Data collected during the commissioning process included: a) HVL, b) output (dose rate), c) applicator cone factors, and d) percentage depth dose. A Farmer-type chamber (PTW-N23333), and a thin-window parallel plate ion chamber (PTW-N23342) were used for dose rate measurements and dose profiles were measured with EBT3 GafChromic film. The average HVL values for 50, 70, and 100 kV of the two treatment units were found to be 0.52, 1.15, and 2.20 mm Al, respectively. The HVL's were 5%-9% lower when measured with the Farmer chamber, as compared to measurements with the parallel plate chamber, for energies of 70 and 100 kV. Dose rates were also measured to be 3%-4% lower with the Farmer chamber. The dose rate variation between the two units was found to be 2%-9% for 50, 70, and 100 kV. The dose uniformity over a circle of 2 cm diameter was within 4% in four cardinal directions; however, the dose profiles for the 5 cm applicator were nonuniform, especially in the cathode-anode direction. Measurements indicated as much as 15% lower dose for the 50 kV beam at field edge on the anode side, when normalized to the center. The crossline profile was relatively more symmetric, with a maximum deviation of 10% at the field edge. All ion chamber readings agreed with film measurements within 3%. The nonuniform profile produced by these units may introduce uncertainty in dose rate measurements, especially for larger applicators. Since there is no intrinsic tool (crosshair or field light) for alignment with the beam axis, the user should take care when positioning the chamber for output measurements. The data obtained with a Farmer-type chamber should be used cautiously and as a reference only for the SRT-100 X-ray treatment unit. PMID:26103186

  14. Conceptual Design of a 50--100 MW Electron Beam Accelerator System for the National Hypersonic Wind Tunnel Program

    SciTech Connect

    SCHNEIDER,LARRY X.

    2000-06-01

    The National Hypersonic Wind Tunnel program requires an unprecedented electron beam source capable of 1--2 MeV at a beam power level of 50--100 MW. Direct-current electron accelerator technology can readily generate high average power beams to approximately 5 MeV at output efficiencies greater than 90%. However, due to the nature of research and industrial applications, there has never been a requirement for a single module with an output power exceeding approximately 500 kW. Although a 50--100 MW module is a two-order extrapolation from demonstrated power levels, the scaling of accelerator components appears reasonable. This paper presents an evaluation of component and system issues involved in the design of a 50--100 MW electron beam accelerator system with precision beam transport into a high pressure flowing air environment.

  15. Hybrid Laser-Arc Welding of 10-mm-Thick Cast Martensitic Stainless Steel CA6NM: As-Welded Microstructure and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Mirakhorli, Fatemeh; Cao, Xinjin; Pham, Xuan-Tan; Wanjara, Priti; Fihey, Jean-Luc

    2016-07-01

    Cast CA6NM martensitic stainless steel plates, 10 mm in thickness, were welded using hybrid laser-arc welding. The effect of different welding speeds on the as-welded joint integrity was characterized in terms of the weld bead geometry, defects, microstructure, hardness, ultimate tensile strength, and impact energy. Significant defects such as porosity, root humping, underfill, and excessive penetration were observed at a low welding speed (0.5 m/min). However, the underfill depth and excessive penetration in the joints manufactured at welding speeds above 0.75 m/min met the specifications of ISO 12932. Characterization of the as-welded microstructure revealed untempered martensite and residual delta ferrite dispersed at prior-austenite grain boundaries in the fusion zone. In addition, four different heat-affected zones in the weldments were differentiated through hardness mapping and inference from the Fe-Cr-Ni ternary phase diagram. The tensile fracture occurred in the base metal for all the samples and fractographic analysis showed that the crack path is within the martensite matrix, along primary delta ferrite-martensite interfaces and within the primary delta ferrite. Additionally, Charpy impact testing demonstrated slightly higher fracture energy values and deeper dimples on the fracture surface of the welds manufactured at higher welding speeds due to grain refinement and/or lower porosity.

  16. Hybrid Laser-Arc Welding of 10-mm-Thick Cast Martensitic Stainless Steel CA6NM: As-Welded Microstructure and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Mirakhorli, Fatemeh; Cao, Xinjin; Pham, Xuan-Tan; Wanjara, Priti; Fihey, Jean-Luc

    2016-04-01

    Cast CA6NM martensitic stainless steel plates, 10 mm in thickness, were welded using hybrid laser-arc welding. The effect of different welding speeds on the as-welded joint integrity was characterized in terms of the weld bead geometry, defects, microstructure, hardness, ultimate tensile strength, and impact energy. Significant defects such as porosity, root humping, underfill, and excessive penetration were observed at a low welding speed (0.5 m/min). However, the underfill depth and excessive penetration in the joints manufactured at welding speeds above 0.75 m/min met the specifications of ISO 12932. Characterization of the as-welded microstructure revealed untempered martensite and residual delta ferrite dispersed at prior-austenite grain boundaries in the fusion zone. In addition, four different heat-affected zones in the weldments were differentiated through hardness mapping and inference from the Fe-Cr-Ni ternary phase diagram. The tensile fracture occurred in the base metal for all the samples and fractographic analysis showed that the crack path is within the martensite matrix, along primary delta ferrite-martensite interfaces and within the primary delta ferrite. Additionally, Charpy impact testing demonstrated slightly higher fracture energy values and deeper dimples on the fracture surface of the welds manufactured at higher welding speeds due to grain refinement and/or lower porosity.

  17. Accelerated aging of 28 Gb s-1 850 nm vertical-cavity surface-emitting laser with multiple thick oxide apertures

    NASA Astrophysics Data System (ADS)

    Kropp, J. R.; Steinle, G.; Schäfer, G.; Shchukin, V. A.; Ledentsov, N. N.; Turkiewicz, J. P.; Zoldak, M.

    2015-04-01

    850 nm vertical-cavity surface-emitting lasers with multiple thick oxide apertures suitable for temperature-insensitive error free transmission at 28 Gb s-1 are subjected to accelerated aging at high current densities and chip temperatures. The devices withstand a 20% power change test at a high current density (18 kA c{{m}-2}) at an ambient temperature of 120 {}^\\circ C for 2500 h. At 90-95 {}^\\circ C at this current density no degradation was observed up to 5000 h. We performed the studies at further elevated current densities and temperatures and define the acceleration factor as AF={{({{J}stress}/{{J}use})}8}exp [(1.3 eV/{{k}B})(1/{{T}use}-1/{{T}stress})]. The extrapolated lifetime for 20% power drop is estimated as 20 thousand years at 300 K at current density of 18 kA c{{m}-2} which is sufficient for 28 Gb s-1 error-free temperature-insensitive data transmission.

  18. Sub-0.5 nm equivalent oxide thickness scaling for Si-doped Zr1-xHfxO2 thin film without using noble metal electrode.

    PubMed

    Ahn, Ji-Hoon; Kwon, Se-Hun

    2015-07-22

    The dielectric properties of the Si-doped Zr1-xHfxO2 thin films were investigated over a broad compositional range with the goal of improving their properties for use as DRAM capacitor materials. The Si-doped Zr1-xHfxO2 thin films were deposited on TiN bottom electrodes by atomic layer deposition using a TEMA-Zr/TEMA-Hf mixture precursor for deposition of Zr1-xHfxO2 film and Tris-EMASiH as a Si precursor. The Si stabilizer increased the tetragonality and the dielectric constant; however, at high fractions of Si, the crystal structure degraded to amorphous and the dielectric constant decreased. Doping with Si exhibited a larger influence on the dielectric constant at higher Hf content. A Si-doped Hf-rich Zr1-xHfxO2 thin film, with tetragonal structure, exhibited a dielectric constant of about 50. This is the highest value among all reported results for Zr and Hf oxide systems, and equivalent oxide thickness (EOT) value of under 0.5 nm could be obtained with a leakage current of under 10(-7) A·cm(-2), which is the lowest EOT value ever reported for a DRAM storage capacitor system without using a noble-metal-based electrode. PMID:26125098

  19. Snow accumulation rate on Qomolangma (Mount Everest), Himalaya: synchroneity with sites across the Tibetan Plateau on 50-100 year timescales

    NASA Astrophysics Data System (ADS)

    Kaspari, Susan; Hooke, Roger Leb.; Mayewski, Paul Andrew; Kang, Shichang; Hou, Shugui; Qin, Dahe

    Annual-layer thickness data, spanning AD 1534-2001, from an ice core from East Rongbuk Col on Qomolangma (Mount Everest, Himalaya) yield an age-depth profile that deviates systematically from a constant accumulation-rate analytical model. The profile clearly shows that the mean accumulation rate has changed every 50-100 years. A numerical model was developed to determine the magnitude of these multi-decadal-scale rates. The model was used to obtain a time series of annual accumulation. The mean annual accumulation rate decreased from ˜0.8 m ice equivalent in the 1500s to ˜0.3 m in the mid-1800s. From ˜1880 to ˜1970 the rate increased. However, it has decreased since ˜1970. Comparison with six other records from the Himalaya and the Tibetan Plateau shows that the changes in accumulation in East Rongbuk Col are broadly consistent with a regional pattern over much of the Plateau. This suggests that there may be an overarching mechanism controlling precipitation and mass balance over this area. However, a record from Dasuopu, only 125 km northwest of Qomolangma and 700 m higher than East Rongbuk Col, shows a maximum in accumulation during the 1800s, a time during which the East Rongbuk Col and Tibetan Plateau ice-core and tree-ring records show a minimum. This asynchroneity may be due to altitudinal or seasonal differences in monsoon versus westerly moisture sources or complex mountain meteorology.

  20. Improvement design study on steam generator of MHR-50/100 aiming higher safety level after water ingress accident

    SciTech Connect

    Oyama, S.; Minatsuki, I.; Shimizu, K.

    2012-07-01

    Mitsubishi Heavy Industries, Ltd. (MHI) has been studying on MHI original High Temperature Gas cooled Reactor (HTGR), namely MHR-50/100, for commercialization with supported by JAEA. In the heat transfer system, steam generator (SG) is one of the most important components because it should be imposed a function of heat transfer from reactor power to steam turbine system and maintaining a nuclear grade boundary. Then we especially focused an effort of a design study on the SG having robustness against water ingress accident based on our design experience of PWR, FBR and HTGR. In this study, we carried out a sensitivity analysis from the view point of economic and plant efficiency. As a result, the SG design parameter of helium inlet/outlet temperature of 750 deg. C/300 deg. C, a side-by-side layout and one unit of SG attached to a reactor were selected. In the next, a design improvement of SG was carried out from the view point of securing the level of inherent safety without reliance on active steam dump system during water ingress accident considering the situation of the Fukushima nuclear power plant disaster on March 11, 2011. Finally, according to above basic design requirement to SG, we performed a conceptual design on adapting themes of SG structure improvement. (authors)

  1. REE Sorption Study of Seived -50 +100 Mesh Fraction of Media #1 in Brine #1 at Different Concentrations of REE at 70C

    SciTech Connect

    Gary Garland

    2015-06-29

    This dataset shows the sorption capacities of smaller grain size (-50 +100 mesh) of media #1 in brine #1 at different starting concentrations of REE's at elevated temperature of 70C. The experimental conditions are 2g of -50 +100 mesh media #1 to 150mL of REE solution at concentartions of .2ppm each, 2ppm each, and 20ppm each. The pH of the solution is 5.5, and the temperature was at 70C.

  2. Giant moving vortex mass in thick magnetic nanodots

    NASA Astrophysics Data System (ADS)

    Guslienko, K. Y.; Kakazei, G. N.; Ding, J.; Liu, X. M.; Adeyeye, A. O.

    2015-09-01

    Magnetic vortex is one of the simplest topologically non-trivial textures in condensed matter physics. It is the ground state of submicron magnetic elements (dots) of different shapes: cylindrical, square etc. So far, the vast majority of the vortex dynamics studies were focused on thin dots with thickness 5-50 nm and only uniform across the thickness vortex excitation modes were observed. Here we explore the fundamental vortex mode in relatively thick (50-100nm) dots using broadband ferromagnetic resonance and show that dimensionality increase leads to qualitatively new excitation spectra. We demonstrate that the fundamental mode frequency cannot be explained without introducing a giant vortex mass, which is a result of the vortex distortion due to interaction with spin waves. The vortex mass depends on the system geometry and is non-local because of important role of the dipolar interaction. The mass is rather small for thin dots. However, its importance increases drastically with the dot thickness increasing.

  3. REE Sorption Study of Sieved -50 +100 mesh Media #1 in Brine #1 with Different Starting pH's at 70C

    SciTech Connect

    Gary Garland

    2015-07-21

    This dataset described shaker table experiments ran with sieved -50 +100 mesh media #1 in brine #1 that have 2ppm each of the 7 REE metals at different starting pH's of 3.5, 4.5, and 5.5. The experimental conditions are 2g media to 150mL of REE solution, at 70C.

  4. Epitaxial GeSn film formed by solid phase epitaxy and its application to Yb{sub 2}O{sub 3}-gated GeSn metal-oxide-semiconductor capacitors with sub-nm equivalent oxide thickness

    SciTech Connect

    Lee, Ching-Wei; Wu, Yung-Hsien; Hsieh, Ching-Heng; Lin, Chia-Chun

    2014-11-17

    Through the technique of solid phase epitaxy (SPE), an epitaxial Ge{sub 0.955}Sn{sub 0.045} film was formed on a Ge substrate by depositing an amorphous GeSn film followed by a rapid thermal annealing at 550 °C. A process that uses a SiO{sub 2} capping layer on the amorphous GeSn film during SPE was proposed and it prevents Sn precipitation from occurring while maintaining a smooth surface due to the reduced surface mobility of Sn atoms. The high-quality epitaxial GeSn film was observed to have single crystal structure, uniform thickness and composition, and tiny surface roughness with root mean square of 0.56 nm. With a SnO{sub x}-free surface, Yb{sub 2}O{sub 3}-gated GeSn metal-oxide-semiconductor (MOS) capacitors with equivalent oxide thickness (EOT) of 0.55 nm were developed. A small amount of traps inside the Yb{sub 2}O{sub 3} was verified by negligible hysteresis in capacitance measurement. Low leakage current of 0.4 A/cm{sup 2} at gate bias of flatband voltage (V{sub FB})-1 V suggests the high quality of the gate dielectric. In addition, the feasibility of using Yb{sub 2}O{sub 3} to well passivate GeSn surface was also evidenced by the small interface trap density (D{sub it}) of 4.02 × 10{sup 11} eV{sup −1} cm{sup −2}, which can be attributed to smooth GeSn surface and Yb{sub 2}O{sub 3} valency passivation. Both leakage current and D{sub it} performance outperform other passivation techniques at sub-nm EOT regime. The proposed epitaxial GeSn film along with Yb{sub 2}O{sub 3} dielectric paves an alternative way to enable high-performance GeSn MOS devices.

  5. Hour-long continuous operation of a tabletop soft x-ray laser at 50-100 Hz repetition rate.

    PubMed

    Reagan, Brendan A; Li, Wei; Urbanski, Lukasz; Wernsing, Keith A; Salsbury, Chase; Baumgarten, Cory; Marconi, Mario C; Menoni, Carmen S; Rocca, Jorge J

    2013-11-18

    We report the uninterrupted operation of an 18.9 nm wavelength tabletop soft x-ray laser at 100 Hz repetition rate for extended periods of time. An average power of about 0.1 mW was obtained by irradiating a Mo target with pulses from a compact diode-pumped chirped pulse amplification Yb:YAG laser. Series of up to 1.8 x 10(5) consecutive laser pulses of ~1 µJ energy were generated by displacing the surface of a high shot-capacity rotating molybdenum target by ~2 µm between laser shots. As a proof-of-principle demonstration of the use of this compact ultrashort wavelength laser in applications requiring a high average power coherent beam, we lithographically printed an array of nanometer-scale features using coherent Talbot self-imaging. PMID:24514347

  6. Thermal and plasma treatments for improved (sub-)1 nm equivalent oxide thickness planar and FinFET-based replacement metal gate high-k last devices and enabling a simplified scalable CMOS integration scheme

    NASA Astrophysics Data System (ADS)

    Veloso, Anabela; Boccardi, Guillaume; Ragnarsson, Lars-Åke; Higuchi, Yuichi; Arimura, Hiroaki; Lee, Jae Woo; Simoen, Eddy; Cho, Moon Ju; Roussel, Philippe J.; Paraschiv, Vasile; Shi, Xiaoping; Schram, Tom; Aik Chew, Soon; Brus, Stephan; Dangol, Anish; Vecchio, Emma; Sebaai, Farid; Kellens, Kristof; Heylen, Nancy; Devriendt, Katia; Dekkers, Harold; Van Ammel, Annemie; Witters, Thomas; Conard, Thierry; Vaesen, Inge; Richard, Olivier; Bender, Hugo; Athimulam, Raja; Chiarella, Thomas; Thean, Aaron; Horiguchi, Naoto

    2014-01-01

    We report on aggressively scaled replacement metal gate, high-k last (RMG-HKL) planar and multi-gate fin field-effect transistor (FinFET) devices, systematically investigating the impact of post high-k deposition thermal (PDA) and plasma (SF6) treatments on device characteristics, and providing a deeper insight into underlying degradation mechanisms. We demonstrate that: 1) substantially reduced gate leakage (JG) and noise can be obtained for both type of devices with PDA and F incorporation in the gate stack by SF6, without equivalent oxide thickness (EOT) penalty; 2) SF6 enables improved mobility and reduced interface trapped charge density (Nit) down to narrower fin devices [fin width (WFin) ≥ 5 nm], mitigating the impact of fin patterning and fin sidewall crystal orientations, while allowing a simplified dual-effective work function (EWF) CMOS scheme suitable for both device architectures; 3) PDA yields smaller, in absolute values, PMOS threshold voltage |VT|, and substantially improved reliability behavior due to reduction of bulk defects.

  7. Crystalline ZrTiO{sub 4} gated p-metal–oxide–semiconductor field effect transistors with sub-nm equivalent oxide thickness featuring good electrical characteristics and reliability

    SciTech Connect

    Wu, Chao-Yi; Hsieh, Ching-Heng; Lee, Ching-Wei; Wu, Yung-Hsien

    2015-02-02

    ZrTiO{sub 4} crystallized in orthorhombic (o-) phase was stacked with an amorphous Yb{sub 2}O{sub 3} interfacial layer as the gate dielectric for Si-based p-MOSFETs. With thermal annealing after gate electrode, the gate stack with equivalent oxide thickness (EOT) of 0.82 nm achieves high dielectric quality by showing a low interface trap density (D{sub it}) of 2.75 × 10{sup 11 }cm{sup −2}eV{sup −1} near the midgap and low oxide traps. Crystallization of ZrTiO{sub 4} and post metal annealing are also proven to introduce very limited amount of metal induced gap states or interfacial dipole. The p-MOSFETs exhibit good sub-threshold swing of 75 mV/dec which is ascribed to the low D{sub it} value and small EOT. Owing to the Y{sub 2}O{sub 3} interfacial layer and smooth interface with Si substrate that, respectively, suppress phonon and surface roughness scattering, the p-MOSFETs also display high hole mobility of 49 cm{sup 2}/V-s at 1 MV/cm. In addition, I{sub on}/I{sub off} ratio larger than 10{sup 6} is also observed. From the reliability evaluation by negative bias temperature instability test, after stressing with an electric field of −10 MV/cm at 85 °C for 1000 s, satisfactory threshold voltage shift of 12 mV and sub-threshold swing degradation of 3% were obtained. With these promising characteristics, the Yb{sub 2}O{sub 3}/o-ZrTiO{sub 4} gate stack holds the great potential for next-generation electronics.

  8. Effect of thickness variation in high-efficiency InGaN/GaN light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Narayan, J.; Wang, H.; Ye, Jinlin; Hon, Schang-Jing; Fox, Kenneth; Chen, Jyh Chia; Choi, H. K.; Fan, John C. C.

    2002-07-01

    InxGa(1-x)N/GaN multiquantum-well light-emitting diodes (LEDs) having periodic thickness variations (TVs) in InxGa(1-x)N active layers exhibit substantially higher optical efficiency than LEDs with uniform InxGa(1-x)N layers. In these nanostructured LEDs, the thickness variation of the active layers is found to be more important than the In composition fluctuation in quantum confinement of excitons (carriers). Detailed scanning transmission electron microscopy-atomic number Z contrast analysis, where image contrast is proportional to Z2 (Z being the atomic number), was carried out to investigate the variation in thickness as well as the spatial distribution of In. In the nanostructured LEDs, there are short-range thickness variations (SR-TVs) (3-4 nm) and long-range thickness variations (LR-TVs) (50-100 nm) in InxGa(1-x)N layers. It is envisaged that LR-TV is key to quantum confinement of the carriers and enhancement of the optical efficiency. We propose that the LR-TV is caused by two-dimensional strain in the InxGa(1-x)N layer below its critical thickness. The SR-TV may be caused by In composition fluctuation.

  9. Resistive switching and magnetic behavior of Bi0.8Ba0.2FeO3 / SrRuO3 / SrTiO3 films: role of thickness-dependent strain

    NASA Astrophysics Data System (ADS)

    Vagadia, Megha; Ravalia, Ashish; Trivedi, Priyanka; Jethva, Sadaf; Katba, Savan; Kuberkar, D. G.

    2016-05-01

    The thickness-dependent resistive switching and magnetic behavior of Bi0.8Ba0.2FeO3/SRO/STO (1 0 0) films have been studied in the context of strain modifications introduced by varying the film thickness. Generation of misfit dislocation results in strain relaxation with an increase in film thickness. All films (50, 100 and 200 nm) show hysteresis in I–V behavior at room temperature with applied voltage V max  =  ±5 V. Fitting of I–V data suggests that trap-controlled SCLC governs the conduction in HRS in the 50 nm film while in the 100 nm and 200 nm films, the charge transport mechanism is ohmic-type throughout the applied field. The ON/OFF switching ratio and current retention performance decrease with an increase in film thickness, suggesting that substrate-induced strain and interface modifications play an important role in governing the resistive switching mechanism in Bi0.8Ba0.2FeO3 films. A film with lower thickness ~50 nm is found to exhibit the highest magnetization which may be attributed to the increase in oxygen vacancies and compressive strain.

  10. Effect of film thickness and texture morphology on the physical properties of lead sulfide thin films

    NASA Astrophysics Data System (ADS)

    Azadi Motlagh, Z.; Azim Araghi, M. E.

    2016-02-01

    Lead sulfide (PbS) thin films were prepared onto ultra-clean quartz substrate by the electron beam gun (EBG) evaporation method. The thicknesses of the thin films were 50, 100, 150 and 200 nm. They were annealed at 423 K for 2 h. Field emission scanning electron microscopy (FESEM) images of the thin films showed their texture morphology at the surface of the quartz substrate. X-ray diffraction (XRD) patterns of the thin films showed that they have a cubic phase and rock-salt structure after annealing. The average crystallite size for the thin films was in the range of 32-100 nm. Optical measurements confirmed that crystalline thin films have a direct band gap that increases by decreasing the film thickness. This blue shift of the band gap of thin films compared to the bulk structure can be attributed to the quantum confinement effects in the nanoparticles. A decrease in conductivity by increasing the temperature confirmed the positive temperature coefficient of resistance in the thin films that showed the dominant conduction mechanism is via a band-like transition. The density of localized states at the Fermi level increases by increasing the film thickness. Current-voltage behavior of the thin films showed an increase in both dark current and photocurrent by increasing the crystallite size which is discussed, based on the presence of trap states and barriers in nanostructures.

  11. Low interfacial trap density and sub-nm equivalent oxide thickness in In0.53Ga0.47As (001) metal-oxide-semiconductor devices using molecular beam deposited HfO2/Al2O3 as gate dielectrics

    NASA Astrophysics Data System (ADS)

    Chu, L. K.; Merckling, C.; Alian, A.; Dekoster, J.; Kwo, J.; Hong, M.; Caymax, M.; Heyns, M.

    2011-07-01

    We investigated the passivation of In0.53Ga0.47As (001) surface by molecular beam epitaxy techniques. After growth of strained In0.53Ga0.47As on InP (001) substrate, HfO2/Al2O3 high-κ oxide stacks have been deposited in-situ after surface reconstruction engineering. Excellent capacitance-voltage characteristics have been demonstrated along with low gate leakage currents. The interfacial density of states (Dit) of the Al2O3/In0.53Ga0.47As interface have been revealed by conductance measurement, indicating a downward Dit profile from the energy close to the valence band (medium 1012 cm-2eV-1) towards that close to the conduction band (1011 cm-2eV-1). The low Dit's are in good agreement with the high Fermi-level movement efficiency of greater than 80%. Moreover, excellent scalability of the HfO2 has been demonstrated as evidenced by the good dependence of capacitance oxide thickness on the HfO2 thickness (dielectric constant of HfO2 ˜20) and the remained low Dit's due to the thin Al2O3 passivation layer. The sample with HfO2 (3.4 nm)/Al2O3 (1.2 nm) as the gate dielectrics has exhibited an equivalent oxide thickness of ˜0.93 nm.

  12. Charge transport-accumulation in multilayer structures with Si{sub 3}N{sub 4} and thick(5.5 nm) SiO{sub 2}

    SciTech Connect

    Novikov, Yu. N.

    2015-04-21

    Double-injection, transport, and accumulation of charge in metal-thick oxide-nitride-silicon and silicon-tunnel oxide-nitride-thick oxide-silicon structures have been theoretically studied. Calculation results were compared to experimental results. The charge transport in Si{sub 3}N{sub 4} is quantitatively described assuming the multiphonon ionization theory of neutral traps with a capture cross-section less than 10{sup −14} cm{sup 2}. With traps amphoterism taken into account, the calculation predicts the existence of a layer with their excessive concentration near the SiO{sub 2}/Si{sub 3}N{sub 4} interface. The model satisfactorily describes the write/erase characteristics in silicon-oxide-nitride-oxide-silicon-structures from Bu and White (Solid-State Electron. 45, 113 (2001))

  13. Low interfacial trap density and sub-nm equivalent oxide thickness in In{sub 0.53}Ga{sub 0.47}As (001) metal-oxide-semiconductor devices using molecular beam deposited HfO{sub 2}/Al{sub 2}O{sub 3} as gate dielectrics

    SciTech Connect

    Chu, L. K.; Merckling, C.; Dekoster, J.; Caymax, M.; Alian, A.; Heyns, M.; Kwo, J.; Hong, M.

    2011-07-25

    We investigated the passivation of In{sub 0.53}Ga{sub 0.47}As (001) surface by molecular beam epitaxy techniques. After growth of strained In{sub 0.53}Ga{sub 0.47}As on InP (001) substrate, HfO{sub 2}/Al{sub 2}O{sub 3} high-{kappa} oxide stacks have been deposited in-situ after surface reconstruction engineering. Excellent capacitance-voltage characteristics have been demonstrated along with low gate leakage currents. The interfacial density of states (D{sub it}) of the Al{sub 2}O{sub 3}/In{sub 0.53}Ga{sub 0.47}As interface have been revealed by conductance measurement, indicating a downward D{sub it} profile from the energy close to the valence band (medium 10{sup 12} cm{sup -2}eV{sup -1}) towards that close to the conduction band (10{sup 11} cm{sup -2}eV{sup -1}). The low D{sub it}'s are in good agreement with the high Fermi-level movement efficiency of greater than 80%. Moreover, excellent scalability of the HfO{sub 2} has been demonstrated as evidenced by the good dependence of capacitance oxide thickness on the HfO{sub 2} thickness (dielectric constant of HfO{sub 2}{approx}20) and the remained low D{sub it}'s due to the thin Al{sub 2}O{sub 3} passivation layer. The sample with HfO{sub 2} (3.4 nm)/Al{sub 2}O{sub 3} (1.2 nm) as the gate dielectrics has exhibited an equivalent oxide thickness of {approx}0.93 nm.

  14. Thick Toenails

    MedlinePlus

    ... be seen in individuals with nail fungus (onychomycosis), psoriasis, and hypothyroidism. Those who have problems with the thickness of their toenails should consult a foot and ankle surgeon for proper diagnosis and treatment. and or or and or or, browse by ...

  15. A 60-nm-thick enhancement mode In0.65Ga0.35As/InAs/In0.65Ga0.35As high-electron-mobility transistor fabricated using Au/Pt/Ti non-annealed ohmic technology for low-power logic applications

    NASA Astrophysics Data System (ADS)

    Aizad Fatah, Faiz; Lin, Yueh-Chin; Liu, Ren-Xuan; Yang, Kai-Chun; Lin, Tai-We; Hsu, Heng-Tung; Yang, Jung-Hsiang; Miyamoto, Yasuyuki; Iwai, Hiroshi; Calvin Hu, Chenming; Salahuddin, Sayeef; Chang, Edward Yi

    2016-02-01

    A 60-nm-thick E-mode In0.65Ga0.35As/InAs/In0.65Ga0.35As high-electron-mobility transistor (HEMT) was successfully fabricated and evaluated by using Au/Pt/Ti-based non-annealed ohmic technology for high-speed and low-power logic applications. The device exhibited a minimal SS of 69 mV/decade, a lower DIBL of 30 mV/V, an ION/IOFF ratio above 1.2 × 104 at VDS = 0.5 V and a high fT of 378 GHz and fmax of 214 GHz at VDS = 1.0 V. These results demonstrate that non-annealed ohmic contacts can be used for fabricating E-mode In0.65Ga0.35As/InAs/In0.65Ga0.35As HEMTs with excellent electrical characteristics. The fabricated HEMTs are likely to find use in future high-speed and low-power logic applications.

  16. Improvement in thickness uniformity of thick SOI by numerically controlled local wet etching.

    PubMed

    Yamamura, Kazuya; Ueda, Kazuaki; Hosoda, Mao; Zettsu, Nobuyuki

    2011-04-01

    Silicon-on-insulator (SOI) wafers are promising semiconductor materials for high-speed LSIs, low-power-consumption electric devices and micro electro mechanical systems (MEMS). The thickness distribution of an SOI causes the variation of threshold voltage in electronic devices manufactured on the SOI wafer. The thickness distribution of a thin SOI, which is manufactured by applying a smart cut technique, is comparatively uniform. On the other hand, a thick SOI has a large thickness distribution because a bonded wafer is thinned by conventional grinding and polishing. For a thick SOI wafer with a thickness of 1 microm, it is required that the tolerance of thickness variation is less than 50 nm. However, improving the thickness uniformity of a thick SOI layer to a tolerance of +/- 5% is difficult by conventional machining because of the fundamental limitations of these techniques. We have developed numerically controlled local wet etching (NC-LWE) technique as a novel deterministic subaperture figuring and finishing technique, which utilizes a localized chemical reaction between the etchant and the surface of the workpiece. We demonstrated an improvement in the thickness distribution of a thick SOI by NC-LWE using an HF/HNO3 mixture, and thickness variation improved from 480 nm to 200 nm within a diameter of 170 mm. PMID:21776652

  17. UV - ALBUQUERQUE NM

    EPA Science Inventory

    Brewer 109 is located in Albuquerque NM, measuring ultraviolet solar radiation. Irradiance and column ozone are derived from this data. Ultraviolet solar radiation is measured with a Brewer Mark IV, single-monochrometer, spectrophotometer manufactured by SCI-TEC Instruments, Inc....

  18. A unique approach to accurately measure thickness in thick multilayers.

    PubMed

    Shi, Bing; Hiller, Jon M; Liu, Yuzi; Liu, Chian; Qian, Jun; Gades, Lisa; Wieczorek, Michael J; Marander, Albert T; Maser, Jorg; Assoufid, Lahsen

    2012-05-01

    X-ray optics called multilayer Laue lenses (MLLs) provide a promising path to focusing hard X-rays with high focusing efficiency at a resolution between 5 nm and 20 nm. MLLs consist of thousands of depth-graded thin layers. The thickness of each layer obeys the linear zone plate law. X-ray beamline tests have been performed on magnetron sputter-deposited WSi(2)/Si MLLs at the Advanced Photon Source/Center for Nanoscale Materials 26-ID nanoprobe beamline. However, it is still very challenging to accurately grow each layer at the designed thickness during deposition; errors introduced during thickness measurements of thousands of layers lead to inaccurate MLL structures. Here, a new metrology approach that can accurately measure thickness by introducing regular marks on the cross section of thousands of layers using a focused ion beam is reported. This new measurement method is compared with a previous method. More accurate results are obtained using the new measurement approach. PMID:22514179

  19. Albuquerque, NM, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Albuquerque, NM (35.0N, 106.5W) is situated on the edge of the Rio Grande River and flood plain which cuts across the image. The reddish brown surface of the Albuquerque Basin is a fault depression filled with ancient alluvial fan and lake bed sediments. On the slopes of the Manzano Mountains to the east of Albuquerque, juniper and other timber of the Cibola National Forest can be seen as contrasting dark tones of vegetation.

  20. Accurate thickness measurement of graphene

    NASA Astrophysics Data System (ADS)

    Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.

    2016-03-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  1. Holographic recording in acrylamide photopolymers: thickness limitations.

    PubMed

    Mahmud, Mohammad Sultan; Naydenova, Izabela; Pandey, Nitesh; Babeva, Tzwetanka; Jallapuram, Raghavendra; Martin, Suzanne; Toal, Vincent

    2009-05-10

    Holographic recording in thick photopolymer layers is important for application in holographic data storage, volume holographic filters, and correlators. Here, we studied the characteristics of acrylamide-based photopolymer layers ranging in thickness from 250 microm to 1 mm. For each thickness, samples with three different values of absorbance were studied. By measuring the diffraction efficiency growth of holographically recorded gratings and studying the diffraction patterns obtained, the influence of scattering on the diffraction efficiency of thick volume holographic gratings was analyzed. It was found that, above a particular thickness and absorbance, the diffraction efficiency significantly decreased because of increased holographic scattering. From the diffraction efficiency dependence on absorbance and thickness it is possible to choose photopolymer layer properties that are suitable for a particular holographic application. This study was carried out to determine the highest layer thickness that could be used for phase code multiplexed holographic data storage utilizing thick photopolymer layers as a recording medium. Based on our studies to date we believe that the layer to be used for phase coded reference beam recording with 0.1 absorbance at 532 nm can have a thickness up to 450 microm. The potential use of thicker layers characterized by low scattering losses is part of our continuing research. PMID:19424384

  2. Electron Beam Lithography of 15×15 nm2 Pitched Nanodot Arrays with a Size of Less than 10 nm Using High Development Contrast Salty Developer

    NASA Astrophysics Data System (ADS)

    Komori, Takuya; Zhang, Hui; Akahane, Takashi; Mohamad, Zulfakri; Yin, You; Hosaka, Sumio

    2012-06-01

    We investigated the effects of developer and hydrogen silsesquioxane (HSQ) resist thickness in the formation of dot arrays with a pitch of <18×18 nm2 by using 30-keV electron beam (EB) lithography for bit patterned media (BPM). Optimum resist thickness and developer were investigated for the formation of fine dot arrays. We found that a 12-nm-thick HSQ resist was suitable to form fine dot patterns and the addition of NaCl into tetramethylammonium hydroxide (TMAH) could improve the development contrast (γ-value) of HSQ (the highest is 9.7). By using the 12-nm-thick HSQ resist film and 2.3 wt % TMAH/4 wt % NaCl developer, we successfully fabricated very fine resist dot arrays with a dot size of <10 nm and a pitch of 15×15 nm2, which corresponds to a storage density of about 3 Tbit/in.2 in BPM.

  3. Corneal thickness in glaucoma.

    PubMed

    De Cevallos, E; Dohlman, C H; Reinhart, W J

    1976-02-01

    The central corneal stromal thickness of patients with open angle glaucoma, secondary glaucoma (the majority aphakic), or a history of unilateral acute angle closure glaucoma were measured and compared with the stromal thickness of a group of normal patients. In open angle glaucoma, there was a small but significant increase in the average stromal thickness. This thickness increase was, in all likelihood, due to an abnormal function of the endothelium in this disease since the level of the intraocular pressure did not seem to be a factor. There was no correlation between stromal thickness and duration of the glaucoma or type of anti-glaucomatous medication. Most cases of secondary glaucome, controlled medically or not, had markedly increased corneal thickness, again, most likely, due to endothelial damage rather than to level of intraocular pressure. After an angle closure attack, permanent damage to the cornea was found to be rare. PMID:1247273

  4. Lead Thickness Measurements

    SciTech Connect

    Rucinski, R.; /Fermilab

    1998-02-16

    The preshower lead thickness applied to the outside of D-Zero's superconducting solenoid vacuum shell was measured at the time of application. This engineering documents those thickness measurements. The lead was ordered in sheets 0.09375-inch and 0.0625-inch thick. The tolerance on thickness was specified to be +/- 0.003-inch. The sheets all were within that thickness tolerance. The nomenclature for each sheet was designated 1T, 1B, 2T, 2B where the numeral designates it's location in the wrap and 'T' or 'B' is short for 'top' or 'bottom' half of the solenoid. Micrometer measurements were taken at six locations around the perimeter of each sheet. The width,length, and weight of each piece was then measured. Using an assumed pure lead density of 0.40974 lb/in{sup 3}, an average sheet thickness was calculated and compared to the perimeter thickness measurements. In every case, the calculated average thickness was a few mils thinner than the perimeter measurements. The ratio was constant, 0.98. This discrepancy is likely due to the assumed pure lead density. It is not felt that the perimeter is thicker than the center regions. The data suggests that the physical thickness of the sheets is uniform to +/- 0.0015-inch.

  5. Thick film hydrogen sensor

    DOEpatents

    Hoffheins, Barbara S.; Lauf, Robert J.

    1995-01-01

    A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.

  6. Thick film hydrogen sensor

    DOEpatents

    Hoffheins, B.S.; Lauf, R.J.

    1995-09-19

    A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors. 8 figs.

  7. Education and "Thick" Epistemology

    ERIC Educational Resources Information Center

    Kotzee, Ben

    2011-01-01

    In this essay Ben Kotzee addresses the implications of Bernard Williams's distinction between "thick" and "thin" concepts in ethics for epistemology and for education. Kotzee holds that, as in the case of ethics, one may distinguish between "thick" and "thin" concepts of epistemology and, further, that this distinction points to the importance of…

  8. 469nm Fiber Laser Source

    SciTech Connect

    Drobshoff, A; Dawson, J W; Pennington, D M; Payne, S A; Beach, R

    2005-01-20

    We have demonstrated 466mW of 469nm light from a frequency doubled continuous wave fiber laser. The system consisted of a 938nm single frequency laser diode master oscillator, which was amplified in two stages to 5 Watts using cladding pumped Nd{sup 3+} fiber amplifiers and then frequency doubled in a single pass through periodically poled KTP. The 3cm long PPKTP crystal was made by Raicol Crystals Ltd. with a period of 5.9 {micro}m and had a phase match temperature of 47 degrees Centigrade. The beam was focused to a 1/e{sup 2} diameter in the crystal of 29 {micro}m. Overall conversion efficiency was 11% and the results agreed well with standard models. Our 938nm fiber amplifier design minimizes amplified spontaneous emission at 1088nm by employing an optimized core to cladding size ratio. This design allows the 3-level transition to operate at high inversion, thus making it competitive with the 1088nm 4-level transition. We have also carefully chosen the fiber coil diameter to help suppress propagation of wavelengths longer than 938 nm. At 2 Watts, the 938nm laser had an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >10:1).

  9. Origami of thick panels

    NASA Astrophysics Data System (ADS)

    Chen, Yan; Peng, Rui; You, Zhong

    2015-07-01

    Origami patterns, including the rigid origami patterns in which flat inflexible sheets are joined by creases, are primarily created for zero-thickness sheets. In order to apply them to fold structures such as roofs, solar panels, and space mirrors, for which thickness cannot be disregarded, various methods have been suggested. However, they generally involve adding materials to or offsetting panels away from the idealized sheet without altering the kinematic model used to simulate folding. We develop a comprehensive kinematic synthesis for rigid origami of thick panels that differs from the existing kinematic model but is capable of reproducing motions identical to that of zero-thickness origami. The approach, proven to be effective for typical origami, can be readily applied to fold real engineering structures.

  10. Measuring coal thickness

    NASA Technical Reports Server (NTRS)

    Barker, C.; Blaine, J.; Geller, G.; Robinson, R.; Summers, D.; Tyler, J.

    1980-01-01

    Laboratory tested concept, for measuring thickness of overhead coal using noncontacting sensor system coupled to controller and high pressure water jet, allows mining machines to remove virtually all coal from mine roofs without danger of cutting into overlying rock.

  11. Importance of Corneal Thickness

    MedlinePlus

    ... News About Us Donate In This Section The Importance of Corneal Thickness email Send this article to ... is important because it can mask an accurate reading of eye pressure, causing doctors to treat you ...

  12. United States crustal thickness

    NASA Technical Reports Server (NTRS)

    Allenby, R. J.; Schnetzler, C. C.

    1983-01-01

    The thickness of the crust, the thickness of the basal (intermediate or lower) crustal layer, and the average velocity at the top of the mantle have been mapped using all available deep-penetrating seismic-refraction profiles in the conterminous United States and surrounding border areas. These profiles are indexed to their literature data sources. The more significant long wavelength anomalies on the three maps are briefly discussed and analyzed. An attempt to use Bouguer gravity to validate mantle structure was inconclusive.

  13. Detection limits of 405 nm and 633 nm excited PpIX fluorescence for brain tumor detection during stereotactic biopsy

    NASA Astrophysics Data System (ADS)

    Markwardt, Niklas; Götz, Marcus; Haj-Hosseini, Neda; Hollnburger, Bastian; Sroka, Ronald; Stepp, Herbert; Zelenkov, Petr; Rühm, Adrian

    2016-04-01

    5-aminolevulinic-acid-(5-ALA)-induced protoporphyrin IX (PpIX) fluorescence may be used to improve stereotactic brain tumor biopsies. In this study, the sensitivity of PpIX-based tumor detection has been investigated for two potential excitation wavelengths (405 nm, 633 nm). Using a 200 μm fiber in contact with semi-infinite optical phantoms containing ink and Lipovenös, PpIX detection limits of 4.0 nM and 200 nM (relating to 1 mW excitation power) were determined for 405 nm and 633 nm excitation, respectively. Hence, typical PpIX concentrations in glioblastomas of a few μM should be well detectable with both wavelengths. Additionally, blood layers of selected thicknesses were placed between fiber and phantom. Red excitation was shown to be considerably less affected by blood interference: A 50 μm blood layer, for instance, blocked the 405- nm-excited fluorescence completely, but reduced the 633-nm-excited signal by less than 50%. Ray tracing simulations demonstrated that - without blood layer - the sensitivity advantage of 405 nm rises for decreasing fluorescent volume from 50-fold to a maximum of 100-fold. However, at a tumor volume of 1 mm3, which is a typical biopsy sample size, the 633-nm-excited fluorescence signal is only reduced by about 10%. Further simulations revealed that with increasing fiber-tumor distance, the signal drops faster for 405 nm. This reduces the risk of detecting tumor tissue outside the needle's coverage, but diminishes the overlap between optically and mechanically sampled volumes. While 405 nm generally offers a higher sensitivity, 633 nm is more sensitive to distant tumors and considerably superior in case of blood-covered tumor tissue.

  14. Synchronized ps fiber lasers with pulse durations (25, 50, 100-2000ps) and repetition rates (100kHz-150Mhz) continuously tunable over three orders of magnitude

    NASA Astrophysics Data System (ADS)

    Dupuis, Alexandre; Burgoyne, Bryan; Pena, Guido; Archambault, André; Lemieux, Dominic; Solomonean, Vasile; Duong, Maxime; Villeneuve, Alain

    2013-03-01

    Ultrafast lasers are enabling precision machining of a wide variety of materials. However, the optimal laser parameters for proper material processing can differ greatly from one material to another. In order to cut high aspect-ratio features at high processing speeds the laser parameters such as pulse energy, repetition rate, and cutting speed need to be optimized. In particular, a shorter pulse duration plays an important role in reducing the thermal damage in the Heat-Affected Zones. In this paper we present a novel ps fiber laser whose electronically tunable parameters aim to facilitate the search for optimal processing parameters. The 20W 1064nm Yb fiber laser is based on a Master Oscillator Power Amplifier (MOPA) architecture with a repetition rate that can be tuned continuously from 120kHz to 120MHz. More importantly, the integration of three different pulse generators enables the pulse duration to be switched from 25ps to 50ps, or to any value within the 55ps to 2000ps range. By reducing the pulse duration from the ns-regime down to 25ps, the laser approaches the transition from the thermal processing regime to the ablation regime of most materials. Moreover, in this paper we demonstrate the synchronization of the pulses from two such MOPA lasers. This enables more elaborate multipulse processing schemes where the pulses of each laser can be set to different parameter values, such as an initial etching pulse followed by a thermal annealing pulse. It should be noted that all the laser parameters are controlled electronically with no moving parts, including the synchronization.

  15. Evaluation of dental pulp repair using low level laser therapy (688 nm and 785 nm) morphologic study in capuchin monkeys

    NASA Astrophysics Data System (ADS)

    Pretel, H.; Oliveira, J. A.; Lizarelli, R. F. Z.; Ramalho, L. T. O.

    2009-02-01

    The aim of this study was to evaluate the hypothesis that low-level laser therapy (LLLT) 688 nm and 785 nm accelerate dentin barrier formation and repair process after traumatic pulp exposure. The sample consisted of 45 premolars of capuchin monkeys (Cebus apella) with pulp exposure Class V cavities. All premolars were treated with calcium hydroxide (Ca(OH)2), divided in groups of 15 teeth each, and analyzed on 7th, 25th, and 60th day. Group GI - only Ca(OH)2, GII - laser 688 nm, and GIII - laser 785 nm. Laser beam was used in single and punctual dose with the parameters: continuous, 688 nm and 785 nm wavelength, tip's area of 0.00785 cm2, power 50 mW, application time 20 s, dose 255 J/cm2, energy 2 J. Teeth were capped with Ca(OH)2, Ca(OH)2 cement and restored with amalgam. All groups presented pulp repair. On 25th day the thickness of the formed dentin barrier was different between the groups GI and GII (p < 0.05) and between groups GI and GIII (p < 0.01). On 60th day there was difference between GI and GIII (p < 0.01). It may be concluded that, LLLT 688 nm and 785 nm accelerated dentin barrier formation and consequently pulp repair process, with best results using infrared laser 785 nm.

  16. Effect of Magnetic Film Thickness on the Spatial Resolution of Magnetic Force Microscope Tips

    NASA Astrophysics Data System (ADS)

    Nagano, Katsumasa; Tobari, Kousuke; Ohtake, Mitsuru; Futamoto, Masaaki

    2011-07-01

    Magnetic force microscope (MFM) tips were prepared by coating commercial atomic force microscope (AFM) tips of 5 nm radius with Co and CoCrPt magnetic thin films varying the thickness in a range of 10-80 nm. The structural and the magnetic properties of coated magnetic thin films were investigated by scanning electron microscopy, AFM, X-ray diffraction, and vibrating sample magnetometry. The tip radius and the film surface roughness increase with increasing the film thickness. With increasing the film thickness, the MFM signal sensitivity increases, whereas the resolution decreases due to increase of tip radius. The MFM observation resolutions of 10 nm and 23 nm are obtained with the tips coated with 20-nm-thick Co and 40-nm-thick CoCrPt films, respectively. The MFM resolution is influenced by both the tip radius and the magnetic moment of coated material.

  17. Critical thickness for the agglomeration of thin metal films

    SciTech Connect

    Boragno, C.; Buatier de Mongeot, F.; Felici, R.; Robinson, I.K.

    2009-09-15

    A thin metal film can exist in a metastable state with respect to breaking into small clusters. In this paper we report on grazing incidence small-angle x-ray scattering studies carried out in situ during the annealing of thin Ni films, between 2 and 10 nm thick, deposited on an amorphous SiO{sub 2} substrate. Our results show the presence of two different regimes which depend on the initial film thickness. For thicknesses less than 5 nm the annealing results in the formation of small, compact clusters on top of a residual Ni wetting layer. For thicknesses greater than 5 nm the film breaks into large, well-separated clusters and the substrate shows an uncovered clean surface.

  18. Fabricating nanopores with diameters of sub-1 nm to 3 nm using multilevel pulse-voltage injection

    PubMed Central

    Yanagi, Itaru; Akahori, Rena; Hatano, Toshiyuki; Takeda, Ken-ichi

    2014-01-01

    To date, solid-state nanopores have been fabricated primarily through a focused-electronic beam via TEM. For mass production, however, a TEM beam is not suitable and an alternative fabrication method is required. Recently, a simple method for fabricating solid-state nanopores was reported by Kwok, H. et al. and used to fabricate a nanopore (down to 2 nm in size) in a membrane via dielectric breakdown. In the present study, to fabricate smaller nanopores stably—specifically with a diameter of 1 to 2 nm (which is an essential size for identifying each nucleotide)—via dielectric breakdown, a technique called “multilevel pulse-voltage injection” (MPVI) is proposed and evaluated. MPVI can generate nanopores with diameters of sub-1 nm in a 10-nm-thick Si3N4 membrane with a probability of 90%. The generated nanopores can be widened to the desired size (as high as 3 nm in diameter) with sub-nanometre precision, and the mean effective thickness of the fabricated nanopores was 3.7 nm. PMID:24847795

  19. Optimization of EUVL reticle thickness for image placement accuracy

    NASA Astrophysics Data System (ADS)

    Zheng, Liang; Mikkelson, Andrew R.; Abdo, Amr Y.; Engelstad, Roxann L.; Lovell, Edward G.; White, Thomas J.

    2003-12-01

    Extreme ultraviolet lithography (EUVL) is one of the leading candidates for next-generation lithography in the sub-65 nm regime. The International Technology Roadmap for Semiconductors proposes overlay error budgets of 18 nm and 13 nm for the 45 nm and 32 nm nodes, respectively. Full three-dimensional finite element (FE) models were developed to identify the optimal mask thickness to minimize image placement (IP) errors. Five thicknesses of the EUVL reticle have been investigated ranging from 2.3 mm to 9.0 mm. The mask fabrication process was simulated, as well as the e-beam mounting, pattern transfer, and exposure mounting, utilizing FE structural models. Out-of-plane distortions and in-plane distortions were tracked for each process step. Both electrostatic and 3-point mounts were considered for the e-beam tool and exposure tool. In this case, increasing the thickness of the reticle will reduce the magnitude of the distortions. The effect of varying the reticle thickness on chucking was also studied. FE models were utilized to predict how changing the reticle thickness would affect the overall clamping response. By decreasing the reticle thickness (and therefore the effective bending stiffness), the deformed reticle is easier to flatten during chucking. In addition, the thermomechanical response of the reticle during exposure was investigated for different reticle thicknesses. Since conduction to the chuck is the main heat dissipation mechanism, decreasing the reticle thickness results in more energy being conducted away from the reticle, which reduces the maximum temperature rise and the corresponding thermal distortion. The FE simulations illustrate the optimal thickness to keep IP errors within the allotted error budget as well as provide the necessary flatness during typical chucking procedures.

  20. Liquid thickness gauge

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M. (Inventor)

    1988-01-01

    A method and apparatus are developed to measure the thickness of a liquid on a surface independent of liquid conductivity. Two pairs of round, corrosion resistant wires are mounted in an insulating material such that the cross-sectional area of each wire is flush with and normal to the surface. The resistance between each pair of wires is measured using two ac resistance measuring circuits, in which the ratio of the outputs of the two resistance measuring circuits is indicative of the thickness of the liquid on the surface.

  1. Deep ultraviolet (254 nm) focal plane array

    NASA Astrophysics Data System (ADS)

    Cicek, Erdem; Vashaei, Zahra; McClintock, Ryan; Razeghi, Manijeh

    2011-10-01

    We report the synthesis, fabrication and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, AlxGa1-xN-based detectors, fully realized within our research laboratory. We implemented a novel pulsed atomic layer deposition technique for the metalorganic chemical vapor deposition (MOCVD) growth of crackfree, thick, and high Al composition AlxGa1-xN layers. Following the growth, the wafer was processed into a 320 × 256 array of 25 μm × 25 μm pixels on a 30 μm pixel-pitch and surrounding mini-arrays. A diagnostic mini-array was hybridized to a silicon fan-out chip to allow the study of electrical and optical characteristics of discrete pixels of the FPA. At a reverse bias of 1 V, an average photodetector exhibited a low dark current density of 1.12×10-8 A/cm2. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower and falling off three orders of magnitude by 285 nm. After indium bump deposition and dicing, the FPA is hybridized to a matching ISC 9809 readout integrated circuit (ROIC). By developing a novel masking technology, we significantly reduced the visible response of the ROIC and thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allowed the FPA to achieve high external quantum efficiency (EQE): at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated.

  2. Dependence of magnetization process on thickness of Permalloy antidot arrays

    SciTech Connect

    Merazzo, K. J.; Real, R. P. del; Asenjo, A.; Vazquez, M.

    2011-04-01

    Nanohole films or antidot arrays of Permalloy have been prepared by the sputtering of Ni{sub 80}Fe{sub 20} onto anodic alumina membrane templates. The film thickness varies from 5 to 47 nm and the antidot diameters go from 42 to 61 nm, for a hexagonal lattice parameter of 105 nm. For the thinner antidot films (5 and 10 nm thick), magnetic moments locally distribute in a complex manner to reduce the magnetostatic energy, and their mostly reversible magnetization process is ascribed to spin rotations. In the case of the thicker (20 and 47 nm) antidot films, pseudodomain walls appear and the magnetization process is mostly irreversible where hysteresis denotes the effect of nanoholes pinning to wall motion.

  3. Thick Film Interference.

    ERIC Educational Resources Information Center

    Trefil, James

    1983-01-01

    Discusses why interference effects cannot be seen with a thick film, starting with a review of the origin of interference patterns in thin films. Considers properties of materials in films, properties of the light source, and the nature of light. (JN)

  4. Photoionization of Nitromethane at 355nm and 266nm

    NASA Astrophysics Data System (ADS)

    Martínez, Denhi; Betancourt, Francisco; Poveda, Juan Carlos; Guerrero, Alfonso; Cisneros, Carmen; Álvarez, Ignacio

    2014-05-01

    Nitromethane is one of the high-yield clean liquid fuels, i.e., thanks to the oxygen contained in nitromethane, much less atmospheric oxygen is burned compared to hydrocarbons such as gasoline, making the nitromethane an important prototypical energetic material, the understanding of its chemistry is relevant in other fields such as atmospheric chemistry or biochemistry. In this work we present the study of photoionization dynamics by multiphoton absorption with 355 nm and 266 nm wavelength photons, using time of flight spectrometry in reflectron mode (R-TOF). Some of the observed ion products appear for both wavelength and other only in one of them; both results were compared with preview observations and new ions were detected. This work is supported by CONACYT grant 165410 and DGAPA-UNAM grants IN-107-912 and IN-102-613.

  5. OISL transmitter at 985 nm

    NASA Astrophysics Data System (ADS)

    Larose, Robert; Lauzon, Jocelyn; Mohrdiek, Stefan; Harder, Christoph S.; Changkakoti, Rupak; Park, Peter

    1999-04-01

    For high data rate (greater than 1 Gbps) Optical Inter- Satellite Link (OISL), a compact laser transmitter with high power and good efficiency is required. A trade-off analysis between the technologies such as the mature 840 nm laser diodes, 1064 nm diode-pumped solid state laser and the more recent 1550 nm Erbium Doped Fiber Amplifier (EDFA) is used to find the optical solution. The Si-APDs are preferred for their large detector areas and good noise figures which reduce the tracking requirements and simplify optical design of the receiver. Because of significant amount of power needed to close the link distance up to 7000 km (LEO-LEO), use of 840 nm diodes is limited. In this paper, we present an alternative system based on a system concept denoted as the SLYB (Semiconductor Laser Ytterbium Booster). The SLYB uses a polarization maintaining double-clad ytterbium fiber as a power amplifier. The device houses two semiconductor diodes that are designed to meet telecom reliability: a broad-area 917 nm pump diode and a directly modulated FP laser for signal generation. The output signal is in a linearly polarized state with an extinction ratio of 20 dB. The complete module (15 X 12 X 4.3 cm3) weighs less than 0.9 kg and delivers up to 27 dBm average output power at 985 nm. Designed primarily for direct detection using Si APDs, the transmitter offers a modulation data rate of at least 1.5 Gb/s with a modulation extinction ratio better than 13 dB. Total power consumption is expected to be lower than 8 W by using an uncooled pump laser. Preliminary radiation testing of the fiber indicates output power penalty of 1.5 dB at the end of 10 years in operation. We are presently investigating the fabrication of an improved radiation-hardened Yb-fiber for the final prototype to reduce this penalty. For higher data rate the design can be extended to a Wavelength Division Multiplexing (WDM) scheme adding multiple channels.

  6. Precise Fabrication of Nanopores with Diameters of Sub-1 nm to 3 nm Using Multilevel Pulse-voltage Injection

    NASA Astrophysics Data System (ADS)

    Yanagi, Itaru; Akahori, Rena; Yokoi, Takahide; Takeda, Ken-Ichi

    2015-03-01

    To date, solid-state nanopores have been fabricated primarily through a focused-electronic beam via TEM. For mass production, however, a TEM beam is not suitable and an alternative fabrication method is required. Recently, a simple nanopore-fabrication method has been reported that is based on a dielectric breakdown phenomenon of a thin membrane. In this study, to stably fabricate nanopores with diameters of 1 to 2 nm (which is an essential size for distinguishing each nucleotide) via dielectric breakdown, a technique called multilevel pulse-voltage injection (MPVI) is proposed and demonstrated. MPVI uses pulse voltages for generating the nanopores, and the generation of the nanopores is verified by measuring the current through a membrane at low voltage. This method can generate nanopores with diameters of less than 1 nm in a 10-nm-thick Si3N4 membrane with a probability of 90%. The diameter of the generated nanopores can be widened to the desired diameters (up to 3 nm) with sub-nanometre precision. The mean effective thickness of the fabricated nanopores was 3.7 nm. These findings are derived from TEM images of the fabricated nanopores and analyses of ionic-current blockades during single-stranded DNA translocation.

  7. Characteristics of blue organic light emitting diodes with different thick emitting layers

    NASA Astrophysics Data System (ADS)

    Li, Chong; Tsuboi, Taiju; Huang, Wei

    2014-08-01

    We fabricated blue organic light emitting diodes (called blue OLEDs) with emitting layer (EML) of diphenylanthracene derivative 9,10-di(2-naphthyl)anthracene (ADN) doped with blue-emitting DSA-ph (1-4-di-[4-(N,N-di-phenyl)amino]styryl-benzene) to investigate how the thickness of EML and hole injection layer (HIL) influences the electroluminescence characteristics. The driving voltage was observed to increase with increasing EML thickness from 15 nm to 70 nm. The maximum external quantum efficiency of 6.2% and the maximum current efficiency of 14 cd/A were obtained from the OLED with 35 nm thick EML and 75 nm thick HIL. High luminance of 120,000 cd/m2 was obtained at 7.5 V from OLED with 15 nm thick EML.

  8. Thick film ink chemistry

    NASA Astrophysics Data System (ADS)

    Gehman, R. W.

    1982-03-01

    Twenty-six thick film inks from two vendors were proved for hybrid microcircuit production use. A data base of chemical information was established for all the inks to aid in future diagnostic and failure analysis activities. Efforts included both organic chemical analysis of printing vehicles and binders and inorganic chemical analysis of glass frits and electrically active phases. Analytical methods included infrared spectroscopy, mass spectroscopy, gas chromatography, X-ray fluorescence, emission spectroscopy, atomic absorption spectroscopy, and wet chemical techniques.

  9. Absolute Measurements of Radiation Damage in Nanometer Thick Films

    PubMed Central

    Alizadeh, Elahe; Sanche, Léon

    2013-01-01

    We address the problem of absolute measurements of radiation damage in films of nanometer thicknesses. Thin films of DNA (~ 2–160nm) are deposited onto glass substrates and irradiated with varying doses of 1.5 keV X-rays under dry N2 at atmospheric pressure and room temperature. For each different thickness, the damage is assessed by measuring the loss of the supercoiled configuration as a function of incident photon fluence. From the exposure curves, the G-values are deduced, assuming that X-ray photons interacting with DNA, deposit all of their energy in the film. The results show that the G-value (i.e., damage per unit of deposited energy) increases with film thickness and reaches a plateau at 30±5 nm. This thickness dependence provides a correction factor to estimate the actual G-value for films with thicknesses below 30nm thickness. Thus, the absolute values of damage can be compared with that of films of any thickness under different experimental conditions. PMID:22562941

  10. Fabrication of a thin silicon detector with excellent thickness uniformity

    NASA Astrophysics Data System (ADS)

    Valtonen, E.; Eronen, T.; Nenonen, S.; Andersson, H.; Miikkulainen, K.; Eränen, S.; Ronkainen, H.; Mäkinen, J.; Husu, H.; Lassila, A.; Punkkinen, R.; Hirvonen, M.

    2016-02-01

    We have fabricated and tested a thin silicon detector with the specific goal of having a very good thickness uniformity. SOI technology was used in the detector fabrication. The detector was designed to be used as a ΔE detector in a silicon telescope for measuring solar energetic particles in space. The detector thickness was specified to be 20 μm with an rms thickness uniformity of±0.5%. The active area consists of three separate elements, a round centre area and two surrounding annular segments. A new method was developed for measuring the thickness uniformity based on a modified Fizeau interferometer. The thickness uniformity specification was well met with the measured rms thickness variation of 43 nm. The detector was electrically characterized by measuring the I- V and C- V curves and the performance was verified using a 241Am alpha source.

  11. Thickness-dependent bending modulus of hexagonal boron nitride nanosheets

    NASA Astrophysics Data System (ADS)

    Li, Chun; Bando, Yoshio; Zhi, Chunyi; Huang, Yang; Golberg, Dmitri

    2009-09-01

    Bending modulus of exfoliation-made single-crystalline hexagonal boron nitride nanosheets (BNNSs) with thicknesses of 25-300 nm and sizes of 1.2-3.0 µm were measured using three-point bending tests in an atomic force microscope. BNNSs suspended on an SiO2 trench were clamped by a metal film via microfabrication based on electron beam lithography. Calculated by the plate theory of a doubly clamped plate under a concentrated load, the bending modulus of BNNSs was found to increase with the decrease of sheet thickness and approach the theoretical C33 value of a hexagonal BN single crystal in thinner sheets (thickness<50 nm). The thickness-dependent bending modulus was suggested to be due to the layer distribution of stacking faults which were also thought to be responsible for the layer-by-layer BNNS exfoliation.

  12. Comparison of 885 nm pumping and 808 nm pumping in Nd:CNGG laser operating at 1061 nm and 935 nm

    NASA Astrophysics Data System (ADS)

    Shi, Yuxian; Li, Qinan; Zhang, Dongxiang; Feng, Baohua; Zhang, Zhiguo; Zhang, Huaijin; Wang, Jiyang

    2010-07-01

    A Nd:CNGG laser operated at 935 nm and 1061 nm pumped at 885 nm and 808 nm, respectively, is demonstrated. The 885 nm direct pumping scheme shows some advantages over the 808 nm traditional pumping scheme. It includes higher slope efficiency, lower threshold, and better beam quality at high output power. With the direct pumping, the slope efficiency increases by 43% and the threshold decreases by 10% compared with traditional pumping in the Nd:CNGG laser operated at 935 nm. When the Nd:CNGG laser operates at 1061 nm, the direct pumping increases the slope efficiency by 14% with a 20% reduction in the oscillation threshold.

  13. Segmentation of the macular choroid in OCT images acquired at 830nm and 1060nm

    NASA Astrophysics Data System (ADS)

    Lee, Sieun; Beg, Mirza F.; Sarunic, Marinko V.

    2013-06-01

    Retinal imaging with optical coherence tomography (OCT) has rapidly advanced in ophthalmic applications with the broad availability of Fourier domain (FD) technology in commercial systems. The high sensitivity afforded by FD-OCT has enabled imaging of the choroid, a layer of blood vessels serving the outer retina. Improved visualization of the choroid and the choroid-sclera boundary has been investigated using techniques such as enhanced depth imaging (EDI), and also with OCT systems operating in the 1060-nm wavelength range. We report on a comparison of imaging the macular choroid with commercial and prototype OCT systems, and present automated 3D segmentation of the choroid-scleral layer using a graph cut algorithm. The thickness of the choroid is an important measurement to investigate for possible correlation with severity, or possibly early diagnosis, of diseases such as age-related macular degeneration.

  14. Fetal nuchal translucency thickness.

    PubMed

    Witters, I; Fryns, J R

    2007-01-01

    In the early 1990s Nicolaides introduced screening for trisomy 21 by fetal nuchal translucency thickness measurement with ultrasound between 11-13(+6) weeks. Already in 1866 L. Down noted that common features of patients with trisomy 21 are a skin being too large for the body and a flat face with a small nose. While detection rates for trisomy 21, given an invasive testing rate of 5%, were only 30% for screening by maternal age and 65% for screening by maternal serum triple test, the detection rate for screening by nuchal translucency combined with maternal age was 75% and this could be increased to 90% in combination with maternal serum screening (serum B-human chorionic gonadotropin and pregnancy-associated plasma protein-A) at 11-13(+6) weeks. The additional soft markers in the first trimester are the fetal nasal bone, the Doppler velocity waveform in the ductus venosus and tricuspid regurgitation and these markers can be used to further increase the detection rate of trisomy 21. In addition increased nuchal translucency thickness can also identify other chromosomal defects (mainly trisomy 13 and 18 and monosomy X) and major congenital malformations (mainly cardiac defects) and genetic syndromes. PMID:17515296

  15. Steady State Perched Groundwater Mounds on Thick Sublayers

    NASA Astrophysics Data System (ADS)

    Brock, Richard R.

    1982-04-01

    Perched mounds that develop beneath a strip recharge basin are considered using the potential theory for a saturated flow. The mounds are assumed to develop upon an aquitard or sublayer whose thickness is large enough so that the vertical velocity at the base of the mound does not vary with distance from the centerline of the basin. A finite difference technique was used to solve the potential theory, and 20 mound profiles were determined for K/KL = 10, 50, 100, 500 and R/K = 0.2, 0.35, 0.50, 0.65, 0.80. K/KL is the ratio of the permeabilities, and R is the recharge rate. These profiles are compared to those based on the approximate Dupuit-Forchheimer (DF) theory, and a criterion for the range of validity of the DF theory for predicting the maximum mount thickness H0 is derived. It is found that for a sufficiently large value of K/KL, which depends on R/K and the desired accuracy, the DF theory is adequate. For smaller values of K/KL the potential theory must be used. Equipotential lines and velocity distributions are presented for a typical case where the potential and DF mound profiles are quite different.

  16. Ultrasonic Inspection Of Thick Sections

    NASA Technical Reports Server (NTRS)

    Friant, C. L.; Djordjevic, B. B.; O'Keefe, C. V.; Ferrell, W.; Klutz, T.

    1993-01-01

    Ultrasonics used to inspect large, relatively thick vessels for hidden defects. Report based on experiments in through-the-thickness transmission of ultrasonic waves in both steel and filament-wound composite cases of solid-fuel rocket motors.

  17. Quasi-cw tissue transillumination at 1064 nm

    NASA Astrophysics Data System (ADS)

    Bernini, Umberto; Ramaglia, Antonio; Russo, Paolo

    1997-08-01

    An extended series of transillumination experiments has been performed in vitro on animal samples (bovine muscle, up to 30- mm-thick; chicken wing and quail femur, 12-mm-thick) and in vivo on the human hand (thickness, about 20 mm), using a pulsed light source (7 ns, about 10-4 J/pulse, 10 Hz rep rate) from a collimated (1.2 m) Nd:YAG laser beam (1064 nm). A PIN photodiode connected to a digital oscilloscope was used to measure the maximum intensity of the beam pulse transmitted through the sample (i.e., no temporal discrimination of the output signal was attempted) while it was scanned across the source/detector assembly. One dimensional scans were performed on bovine muscle samples in which thin metallic test objects were embedded, in order to study the spatial resolution of the technique (for bovine muscle at 1064 nm, absorption and reduced scattering coefficients are reported to be about 1 cm-1 and 3 cm-1, respectively). The measured spatial resolution was as good as 3.6 mm in 30 mm of tissue thickness. In the two-dimensional scans of the chicken and quail sample, fat and bone tissues can be easily seen with good resolution, whereas imaging of the middle finger of a human hand shows cartilaginoid and bone tissue with 1 - 2 mm resolution. Hence, this simple collimated quasi-cw technique gives significantly better results for tissue imaging than pure cw transillumination. Use of (pulsed) light above 1000 nm and a high energy content per pulse are supposed to explain the positive experimental findings.

  18. Simultaneous orientation and thickness mapping in transmission electron microscopy

    SciTech Connect

    Tyutyunnikov, Dmitry; Özdöl, V. Burak; Koch, Christoph T.

    2014-12-04

    In this paper we introduce an approach for simultaneous thickness and orientation mapping of crystalline samples by means of transmission electron microscopy. We show that local thickness and orientation values can be extracted from experimental dark-field (DF) image data acquired at different specimen tilts. The method has been implemented to automatically acquire the necessary data and then map thickness and crystal orientation for a given region of interest. We have applied this technique to a specimen prepared from a commercial semiconductor device, containing multiple 22 nm technology transistor structures. The performance and limitations of our method are discussed and compared to those of other techniques available.

  19. Thickness Dependence of Properties of ITO Films Deposited on PET Substrates.

    PubMed

    Kim, Seon Tae; Kim, Tae Gyu; Cho, Hyun; Yoon, Su Jong; Kim, Hye Sung; Kim, Jin Kon

    2016-02-01

    Indium tin oxide (ITO) films with various thicknesses from 104 nm to 513 nm were prepared onto polyethylene terephthalate (PET) substrates by using r.f. magnetron sputtering without intentionally heating the substrates. The structural, optical, and electrical properties of ITO films were investigated as a function of film thickness. It was found that the amorphous nature of the ITO film was dominant below the thickness of about 200 nm but the degree of the crystallinity increased with an increasing thickness above the thickness of about 250 nm, resulting in the increase of carrier concentration and therefore reducing the electrical resistivity from 5.1 x 10(-3) to 9.4 x 10(-4) omega x cm. The average transmittance (400-800 nm) of the ITO deposited PET substrates decreased as the film thickness was increasing and was above 80% for the thickness below 315 nm. The results show that the improvement of the film crystallinity with the film thickness contributes to the increase of the carrier concentration and the enhancement of the electrical conductivity. PMID:27433686

  20. Efficient 1061 and 1329 nm laser emission of Nd:CNGG lasers under 885 nm diode pumping into the emitting level

    NASA Astrophysics Data System (ADS)

    Li, Y. L.; Jiang, H. L.; Ni, T. Y.; Zhang, T. Y.; Tao, Z. H.; Zeng, Y. H.

    2011-03-01

    We report an efficiency Nd:CNGG laser operating at 1061 and 1329 nm, respectively, direct pumped by a diode laser at 885 nm for the first time to our knowledge. The maximum outputs of 4.5 and 2.9 W, at 1061 and 1329 nm, respectively, are obtained in a 6-mm-thick 0.5 at % Nd:CNGG crystal with 13.5 W of absorbed pump power at 885 nm, leading to a high slope efficiency with respect to the absorbed pump power of 32.2 and 22.1%. Under traditional pumping at 808 nm, the maximum outputs of 3.9 and 2.7 W, at 1061 and 1329 nm, respectively, are obtained with 15.4 W of absorbed pump power, corresponding to the slope efficiency with respect to the absorbed pump power of 25.2 and 17.9%.

  1. Structure and corrosion behavior of sputter deposited cerium oxide based coatings with various thickness on Al 2024-T3 alloy substrates

    NASA Astrophysics Data System (ADS)

    Liu, Yuanyuan; Huang, Jiamu; Claypool, James B.; Castano, Carlos E.; O'Keefe, Matthew J.

    2015-11-01

    Cerium oxide based coatings from ∼100 to ∼1400 nm in thickness were deposited onto Al 2024-T3 alloy substrates by magnetron sputtering of a 99.99% pure CeO2 target. The crystallite size of CeO2 coatings increased from 15 nm to 46 nm as the coating thickness increased from ∼100 nm to ∼1400 nm. The inhomogeneous lattice strain increased from 0.36% to 0.91% for the ∼100 nm to ∼900 nm thick coatings and slightly decreased to 0.89% for the ∼1400 nm thick coating. The highest adhesion strength to Al alloy substrates was for the ∼210 nm thick coating, due to a continuous film coverage and low internal stress. Electrochemical measurements indicated that sputter deposited crystalline CeO2 coatings acted as physical barriers that provide good cathodic inhibition for Al alloys in saline solution. The ∼900 nm thick CeO2 coated sample had the best corrosion performance that increased the corrosion resistance by two orders magnitude and lowered the cathodic current density 30 times compared to bare Al 2024-T3 substrates. The reduced defects and exposed surface, along with suppressed charge mobility, likely accounts for the improved corrosion performance as coating thickness increased from ∼100 nm to ∼900 nm. The corrosion performance decreased for ∼1400 nm thick coatings due in part to an increase in coating defects and porosity along with a decrease in adhesion strength.

  2. Effect of Ru thickness on spin pumping in Ru/Py bilayer

    SciTech Connect

    Behera, Nilamani; Singh, M. Sanjoy; Chaudhary, Sujeet; Pandya, Dinesh K. Muduli, P. K.

    2015-05-07

    We report the effect of Ru thickness (t{sub Ru}) on ferromagnetic resonance (FMR) line-width of Ru(t{sub Ru})/Py(23 nm) bilayer samples grown on Si(100)/SiO{sub 2} substrates at room temperature by magnetron sputtering. The FMR line-width is found to vary linearly with frequency for all thicknesses of Ru, indicating intrinsic origin of damping. For Ru thicknesses below 15 nm, Gilbert-damping parameter, α is almost constant. We ascribe this behavior to spin back flow that is operative for Ru thicknesses lower than the spin diffusion length in Ru, λ{sub sd}. For thicknesses >15 nm (>λ{sub sd}), the damping constant increases with Ru thickness, indicating spin pumping from Py into Ru.

  3. Waterway Ice Thickness Measurements

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The ship on the opposite page is a U. S. Steel Corporation tanker cruising through the ice-covered waters of the Great Lakes in the dead of winter. The ship's crew is able to navigate safely by plotting courses through open water or thin ice, a technique made possible by a multi-agency technology demonstration program in which NASA is a leading participant. Traditionally, the Great Lakes-St. Lawrence Seaway System is closed to shipping for more than three months of winter season because of ice blockage, particularly fluctuations in the thickness and location of ice cover due to storms, wind, currents and variable temperatures. Shippers have long sought a system of navigation that would allow year-round operation on the Lakes and produce enormous economic and fuel conservation benefits. Interrupted operations require that industrial firms stockpile materials to carry them through the impassable months, which is costly. Alternatively, they must haul cargos by more expensive overland transportation. Studies estimate the economic benefits of year-round Great Lakes shipping in the hundreds of millions of dollars annually and fuel consumption savings in the tens of millions of gallons. Under Project Icewarn, NASA, the U.S. Coast Guard and the National Oceanic Atmospheric Administration collaborated in development and demonstration of a system that permits safe year-round operations. It employs airborne radars, satellite communications relay and facsimile transmission to provide shippers and ships' masters up-to-date ice charts. Lewis Research Center contributed an accurate methods of measuring ice thickness by means of a special "short-pulse" type of radar. In a three-year demonstration program, Coast Guard aircraft equipped with Side-Looking Airborne Radar (SLAR) flew over the Great Lakes three or four times a week. The SLAR, which can penetrate clouds, provided large area readings of the type and distribution of ice cover. The information was supplemented by short

  4. Effects of p-type GaN thickness on optical properties of GaN-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Xu, Ming-sheng; Zhang, Heng; Zhou, Quan-bin; Wang, Hong

    2016-07-01

    The influence of p-type GaN (pGaN) thickness on the light output power ( LOP) and internal quantum efficiency ( IQE) of light emitting diode (LED) was studied by experiments and simulations. The LOP of GaN-based LED increases as the thickness of pGaN layer decreases from 300 nm to 100 nm, and then decreases as the thickness decreases to 50 nm. The LOP of LED with 100-nm-thick pGaN increases by 30.9% compared with that of the conventional LED with 300-nm-thick pGaN. The variation trend of IQE is similar to that of LOP as the decrease of GaN thickness. The simulation results demonstrate that the higher light efficiency of LED with 100-nm-thick pGaN is ascribed to the improvements of the carrier concentrations and recombination rates.

  5. Nanometer-thick flat lens with adjustable focus

    SciTech Connect

    Son, T. V.; Haché, A.; Ba, C. O. F.; Vallée, R.

    2014-12-08

    We report laser beam focusing by a flat, homogeneous film with a thickness of less than 100 nm. The effect relies on refractive index changes occurring in vanadium dioxide as it undergoes a phase transition from insulator to metal. Phase front curvature is achieved by means of temperature gradients, and adjustable focal lengths from infinity to 30 cm are attained.

  6. Sub-180 nm generation with borate crystal

    NASA Astrophysics Data System (ADS)

    Qu, Chen; Yoshimura, Masashi; Tsunoda, Jun; Kaneda, Yushi; Imade, Mamoru; Sasaki, Takatomo; Mori, Yusuke

    2014-10-01

    We demonstrated a new scheme for the generation of 179 nm vacuum-ultraviolet (VUV) light with an all-solid-state laser system. It was achieved by mixing the deep-ultraviolet (DUV) of 198.8 nm and the infrared (IR) of 1799.9 nm. While CsB3O5 (CBO) did not satisfy the phase-matching at around 180 nm, 179 nm output was generated with LiB3O5 (LBO) for the first time. The phase-matching property of LBO at around 180 nm was also investigated. There was small deviation from theoretical curve in the measurement, which is still considered reasonable.

  7. Efficient methylammonium lead iodide perovskite solar cells with active layers from 300 to 900 nm

    SciTech Connect

    Momblona, C.; Malinkiewicz, O.; Soriano, A.; Gil-Escrig, L.; Bandiello, E.; Scheepers, M.; Bolink, H. J.; Edri, E.

    2014-08-01

    Efficient methylammonium lead iodide perovskite-based solar cells have been prepared in which the perovskite layer is sandwiched in between two organic charge transporting layers that block holes and electrons, respectively. This configuration leads to stable and reproducible devices that do not suffer from strong hysteresis effects and when optimized lead to efficiencies close to 15%. The perovskite layer is formed by using a dual-source thermal evaporation method, whereas the organic layers are processed from solution. The dual-source thermal evaporation method leads to smooth films and allows for high precision thickness variations. Devices were prepared with perovskite layer thicknesses ranging from 160 to 900 nm. The short-circuit current observed for these devices increased with increasing perovskite layer thickness. The main parameter that decreases with increasing perovskite layer thickness is the fill factor and as a result optimum device performance is obtained for perovskite layer thickness around 300 nm. However, here we demonstrate that with a slightly oxidized electron blocking layer the fill factor for the solar cells with a perovskite layer thickness of 900 nm increases to the same values as for the devices with thin perovskite layers. As a result the power conversion efficiencies for the cells with 300 and 900 nm are very similar, 12.7% and 12%, respectively.

  8. 147-nm photolysis of disilane

    SciTech Connect

    Perkins, G.G.A.; Lampe, F.W.

    1980-05-21

    The photodecomposition of Si/sub 2/H/sub 6/ at 147 nm results in the formation of H/sub 2/, SiH/sub 4/, Si/sub 3/H/sub 8/, Si/sub 4/H/sub 10/, Si/sub 5/H/sub 12/, and a solid film of amorphous silicon hydride (a-Si:H). Three primary processes are proposed to account for the results, namely, (a) Si/sub 2/H/sub 6/ + h..nu.. ..-->.. SiH/sub 2/ + SiH/sub 3/ + H (phi/sub a/ = 0.61); (b) Si/sub 2/H/sub 6/ + h..nu.. ..-->.. SiH/sub 3/SiH + 2H (phi/sub b/ = 0.18); (c) Si/sub 2/H/sub 6/ + h..nu.. ..-->.. Si/sub 2/H/sub 5/ + H (phi/sub c/ = 0.21). The overall quantum yields depend on the pressure but at 1 Torr partial pressure of Si/sub 2/H/sub 6/ are PHI(-Si/sub 2/H/sub 6/) = 4.3 +- 0.2, PHI(SiH/sub 4/) = 1.2 +- 0.4, PHI(Si/sub 3/H/sub 8/) = 0.91 +- 0.08, PHI(Si/sub 4/H/sub 10/) = 0.62 +- 0.03, PHI(Si,wall) = 2.2. Quantum yields for H/sub 2/ formation were not measured. A mechanism is proposed which is shown to be in accord with the experimental facts.

  9. Thickness Dependence Magnetization in Laser Ablated Ni-Cu-Zn Ferrite Nanostructured Thin Films.

    PubMed

    Raghavender, A T; Hong, Nguyen Hoa; Lee, Kyu Joon; Jung, Myung-Hwa

    2016-01-01

    Ni₀.₅Cu₀.₃Zn₀.₂Fe₂O₄ thin films with thickness ranging from 25 nm to 500 nm were grown on Si substrate using pulsed laser deposition technique and their structural and magnetic properties were investigated. From the atomic force microscopy (AFM) analysis, it is observed that the film roughness (Ra) depends strongly on the thickness of the fabricated film. The magnetizations of the thin films were found to decrease when the film thickness increases. The thinner films showed a larger magnetization than the thick films. All the films showed a blocking temperature indicating their superparamagnetic behavior. PMID:27398528

  10. Development of the nitride film thickness standard (NFTS)

    NASA Astrophysics Data System (ADS)

    Durga Pal, Prabha

    1998-07-01

    The semiconductor industry has been demanding film thickness reference material for films other than thermally grown silicon dioxide for sometime. To meet this challenge, Nitride Film Thickness Standard (NFTS) has been developed in four nominal thickness values, 20.0 nm, 90.0 nm, 120.0 nm and 200.0 nm. These are silicon nitride (Si3N4) films on silicon crystal substrate. Work is underway to develop a 9.0 nm standard. Thin nitride films are particularly needed for calibration of the thickness of nitride layers in capacitors and isolation masks for LOCOS (local oxidation of silicon). The reference material is certified for derived film thickness. The study consists of measurements made on four different sets of wafers that included patterned and unpatterned wafers. The measurements made on these wafer sets were used for answering issues related to film stability and cleaning. The stability study includes the search for a cleaning process that will restore a prior surface condition. On two sets of wafers two different types of cleaning procedures were used. Results indicate that a sulfuric acidmegasonic clean will etch the nitride film while an isopropyl alcohol clean followed by a deionized water rinse can be used over and over again. The third set of wafers was never cleaned and measurements were made on these over a period of two years. The last set of wafers is patterned. These are cleaned prior to measurement. Results show that LPCVD silicon nitride films are stable and can be used with confidence over a long period of time for calibrating optical metrology instruments.

  11. Thickness dependent wetting properties and surface free energy of HfO2 thin films

    NASA Astrophysics Data System (ADS)

    Zenkin, Sergei; Belosludtsev, Alexandr; Kos, Šimon; Čerstvý, Radomír; Haviar, Stanislav; Netrvalová, Marie

    2016-06-01

    We show here that intrinsic hydrophobicity of HfO2 thin films can be easily tuned by the variation of film thickness. We used the reactive high-power impulse magnetron sputtering for preparation of high-quality HfO2 films with smooth topography and well-controlled thickness. Results show a strong dependence of wetting properties on the thickness of the film in the range of 50-250 nm due to the dominance of the electrostatic Lifshitz-van der Waals component of the surface free energy. We have found the water droplet contact angle ranging from ≈120° for the thickness of 50 nm to ≈100° for the thickness of 2300 nm. At the same time the surface free energy grows from ≈25 mJ/m2 for the thickness of 50 nm to ≈33 mJ/m2 for the thickness of 2300 nm. We propose two explanations for the observed thickness dependence of the wetting properties: influence of the non-dominant texture and/or non-monotonic size dependence of the particle surface energy.

  12. Optical spectroscopy of sputtered nanometer-thick yttrium iron garnet films

    SciTech Connect

    Jakubisova-Liskova, Eva Visnovsky, Stefan; Chang, Houchen; Wu, Mingzhong

    2015-05-07

    Nanometer (nm)-thick yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}, YIG) films present interest for spintronics. This work employs spectral ellipsometry and magneto-optic Kerr effect (MOKE) spectra to characterize nm-thick YIG films grown on single-crystal Gd{sub 3}Ga{sub 5}O{sub 12} substrates by magnetron sputtering. The thickness (t) of the films ranges between 10 nm and 40 nm. Independent on t, the polar MOKE hysteresis loops saturate in the field of about 1.8 kOe, consistent with the saturation magnetization in bulk YIG (4πM{sub s} ≈ 1.75 kG). The MOKE spectrum measured at photon energies between 1.3 eV and 4.5 eV on the 38-nm-thick film agrees with that measured on single-crystal YIG bulk materials. The MOKE spectrum of the 12-nm-thick film still preserves the structure of the bulk YIG but its amplitude at lower photon energies is modified due to the fact that the radiation penetration depth exceeds 20 nm. The t dependence of the MOKE amplitude is consistent with MOKE calculations. The results indicate that the films are stoichiometric, strain free, without Fe{sup 2+}, and preserve bulk YIG properties down to t ≈ 10 nm.

  13. Full-field imprinting of sub-40 nm patterns

    NASA Astrophysics Data System (ADS)

    Yeo, Jeongho; Kim, Hoyeon; Eynon, Ben

    2008-03-01

    Imprint lithography has been included on the ITRS Lithography Roadmap at the 32, 22 and 16 nm nodes. Step and Flash Imprint Lithography (S-FIL (R)) is a unique patterning method that has been designed from the beginning to enable precise overlay to enable multilevel device fabrication. A photocurable low viscosity resist is dispensed dropwise to match the pattern density requirements of the device, thus enabling patterning with a uniform residual layer thickness across a field and across multiple wafers. Further, S-FIL provides sub-50 nm feature resolution without the significant expense of multi-element projection optics or advanced illumination sources. However, since the technology is 1X, it is critical to address the infrastructure associated with the fabrication of imprint masks (templates). For sub-32 nm device manufacturing, one of the major technical challenges remains the fabrication of full-field 1x imprint masks with commercially viable write times. Recent progress in the writing of sub-40 nm patterns using commercial variable shape e-beam tools and non-chemically amplified resists has demonstrated a very promising route to realizing these objectives, and in doing so, has considerably strengthened imprint lithography as a competitive manufacturing technology for the sub-32nm node. Here we report the first imprinting results from sub-40 nm full-field patterns, using Samsung's current flash memory production device design. The fabrication of the imprint mask and the resulting critical dimension control and uniformity are discussed, along with image placement results. The imprinting results are described in terms of CD uniformity, etch results, and overlay.

  14. Scatterometry for EUV lithography at the 22-nm node

    NASA Astrophysics Data System (ADS)

    Bunday, Benjamin; Vartanian, Victor; Ren, Liping; Huang, George; Montgomery, Cecilia; Montgomery, Warren; Elia, Alex; Liu, Xiaoping

    2011-03-01

    Moore's Law continues to drive improvements to lithographic resolution to increase integrated circuit transistor density, improve performance, and reduce cost. For the 22 nm node and beyond, extreme ultraviolet lithography (EUVL) is a promising technology with λ=13.5 nm, a larger k1 value and lower cost of ownership than other available technologies. For small feature sizes, process control will be increasingly challenging, as small features will create measurement uncertainties, yet with tighter specifications. Optical scatterometry is a primary candidate metrology for EUV lithography process control. Using simulation and experimental data, this work will explore scatterometry's application to a typical lithography process being used for EUV development, which should be representative of lithography processes that will be utilized for EUV High Volume manufacturing (HVM). EUV lithography will be performed using much thinner photoresist thicknesses than were used at the 248nm or 193nm lithography generations, and will probably include underlayers for adhesion improvement; these new processes conditions were investigated in this metrological study.

  15. Encapsulated inorganic resist technology applied to 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Fedynyshyn, Theodore H.; Sinta, Roger F.; Sworin, Michael; Goodman, Russell B.; Doran, Scott P.; Sondi, I.; Matijevic, Egon

    2001-08-01

    In order to increase plasma etch selectivity in traditional single layer organic resists SiO2 nanoparticles have been added to typical 248nm resist formulations. Formulation modifications are necessary due to the dissolution acceleration effect of the particles. Surface functionalization of the nanoparticle surfaces with organic groups lessens this effect and allows the inclusion of acid labile groups. This allows for a wider formulation window and limits unexposed film thickness losses (UFTL). Both t- butyl ester groups and poly(t-butyl acrylate) have been used to achieve this effect. Encapsulated inorganic resist technology (EIRT) can be used as a single layer hard mask compatible with existing resist processing steps and replace complex and costly multilevel resist approaches. Lithogrpahic evaluations have been performed with electron beam, and with 248nm and 157nm projection systems. Greater transparency at 157nm is achieved by the addition of these materials, thus enabling the use of thicker films. High resolution imaging is demonstrated at these wavelengths.

  16. Step and flash imprint lithography for sub-100-nm patterning

    NASA Astrophysics Data System (ADS)

    Colburn, Matthew; Grot, Annette; Amistoso, Marie N.; Choi, Byung J.; Bailey, Todd C.; Ekerdt, John G.; Sreenivasan, S. V.; Hollenhorst, James; Willson, C. Grant

    2000-07-01

    Step and Flash Imprint Lithography (SFIL) is an alternative to photolithography that efficiently generates high aspect-ratio, sub-micron patterns in resist materials. Other imprint lithography techniques based on physical deformation of a polymer to generate surface relief structures have produced features in PMMA as small as 10 nm, but it is very difficult to imprint large depressed features or to imprint a thick films of resist with high aspect-ratio features by these techniques. SFIL overcomes these difficulties by exploiting the selectivity and anisotropy of reactive ion etch (RIE). First, a thick organic 'transfer' layer (0.3 micrometer to 1.1 micrometer) is spin coated to planarize the wafer surface. A low viscosity, liquid organosilicon photopolymer precursor is then applied to the substrate and a quartz template applied at 2 psi. Once the master is in contact with the organosilicon solution, a crosslinking photopolymerization is initiated via backside illumination with broadband UV light. When the layer is cured the template is removed. This process relies on being able to imprint the photopolymer while leaving the minimal residual material in the depressed areas. Any excess material is etched away using a CHF3/He/O2 RIE. The exposed transfer layer is then etched with O2 RIE. The silicon incorporated in the photopolymer allows amplification of the low aspect ratio relief structure in the silylated resist into a high aspect ratio feature in the transfer layer. The aspect ratio is limited only by the mechanical stability of the transfer layer material and the O2 RIE selectivity and anisotropy. This method has produced 60 nm features with 6:1 aspect ratios. This lithography process was also used to fabricate alternating arrays of 100 nm Ti lines on a 200 nm pitch that function as efficient micropolarizers. Several types of optical devices including gratings, polarizers, and sub-wavelength structures can be easily patterned by SFIL.

  17. Influence of magnetic electrodes thicknesses on the transport properties of magnetic tunnel junctions with perpendicular anisotropy

    SciTech Connect

    Cuchet, Léa; Rodmacq, Bernard; Auffret, Stéphane; Sousa, Ricardo C.; Dieny, Bernard

    2014-08-04

    The influence of the bottom and top magnetic electrodes thicknesses on both perpendicular anisotropy and transport properties is studied in (Co/Pt)/Ta/CoFeB/MgO/FeCoB/Ta magnetic tunnel junctions. By carefully investigating the relative magnetic moment of the two electrodes as a function of their thicknesses, we identify and quantify the presence of magnetically dead layers, likely localized at the interfaces with Ta, that is, 0.33 nm for the bottom electrode and 0.60 nm for the top one. Critical thicknesses (spin-reorientation transitions) are determined as 1.60 and 1.65 nm for bottom and top electrodes, respectively. The tunnel magnetoresistance ratio reaches its maximum value, as soon as both effective (corrected from dead layer) electrode thicknesses exceed 0.6 nm.

  18. Influence of magnetic electrodes thicknesses on the transport properties of magnetic tunnel junctions with perpendicular anisotropy

    NASA Astrophysics Data System (ADS)

    Cuchet, Léa; Rodmacq, Bernard; Auffret, Stéphane; Sousa, Ricardo C.; Dieny, Bernard

    2014-08-01

    The influence of the bottom and top magnetic electrodes thicknesses on both perpendicular anisotropy and transport properties is studied in (Co/Pt)/Ta/CoFeB/MgO/FeCoB/Ta magnetic tunnel junctions. By carefully investigating the relative magnetic moment of the two electrodes as a function of their thicknesses, we identify and quantify the presence of magnetically dead layers, likely localized at the interfaces with Ta, that is, 0.33 nm for the bottom electrode and 0.60 nm for the top one. Critical thicknesses (spin-reorientation transitions) are determined as 1.60 and 1.65 nm for bottom and top electrodes, respectively. The tunnel magnetoresistance ratio reaches its maximum value, as soon as both effective (corrected from dead layer) electrode thicknesses exceed 0.6 nm.

  19. Measuring Thicknesses of Wastewater Films

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Davenport, R. J.

    1987-01-01

    Sensor determines when thickness of film of electrically conductive wastewater on rotating evaporator drum exceeds preset value. Sensor simple electrical probe that makes contact with liquid surface. Made of materials resistant to chemicals in liquid. Mounted on shaft in rotating cylinder, liquid-thickness sensor extends toward cylinder wall so tip almost touches. Sensor body accommodates probe measuring temperature of evaporated water in cylinder.

  20. Simultaneous three-wavelength continuous wave laser at 946 nm, 1319 nm and 1064 nm in Nd:YAG

    NASA Astrophysics Data System (ADS)

    Lü, Yanfei; Zhao, Lianshui; Zhai, Pei; Xia, Jing; Fu, Xihong; Li, Shutao

    2013-01-01

    A continuous-wave (cw) diode-end-pumped Nd:YAG laser that generates simultaneous laser at the wavelengths 946 nm, 1319 nm and 1064 nm is demonstrated. The optimum oscillation condition for the simultaneous three-wavelength operation has been derived. Using the separation of the three output couplers, we obtained the maximum output powers of 0.24 W at 946 nm, 1.07 W at 1319 nm and 1.88 W at 1064 nm at the absorbed pump power of 11.2 W. A total output power of 3.19 W for the three-wavelength was achieved at the absorbed pump power of 11.2 W with optical conversion efficiency of 28.5%.

  1. Thermal thickness and evolution of Precambrian lithosphere: A global study

    USGS Publications Warehouse

    Artemieva, I.M.; Mooney, W.D.

    2001-01-01

    The thermal thickness of Precambrian lithosphere is modeled and compared with estimates from seismic tomography and xenolith data. We use the steady state thermal conductivity equation with the same geothermal constraints for all of the Precambrian cratons (except Antarctica) to calculate the temperature distribution in the stable continental lithosphere. The modeling is based on the global compilation of heat flow data by Pollack et al. [1993] and more recent data. The depth distribution of heat-producing elements is estimated using regional models for ???300 blocks with sizes varying from 1?? ?? 1?? to about 5?? ?? 5?? in latitude and longitude and is constrained by laboratory, seismic and petrologic data and, where applicable, empirical heat flow/heat production relationships. Maps of the lateral temperature distribution at depths 50, 100, and 150 km are presented for all continents except Antarctica. The thermal thickness of the lithosphere is calculated assuming a conductive layer overlying the mantle with an adiabat of 1300??C. The Archean and early Proterozoic lithosphere is found to have two typical thicknesses, 200-220 km and 300-350 km. In general, thin (???220 km) roots are found for Archean and early Proterozoic cratons in the Southern Hemisphere (South Africa, Western Australia, South America, and India) and thicker (>300 km) roots are found in the Northern Hemisphere (Baltic Shield, Siberian Platform, West Africa, and possibly the Canadian Shield). We find that the thickness of continental lithosphere generally decreases with age from >200 km beneath Archean cratons to intermediate values of 200 ?? 50 km in early Proterozoic lithosphere, to about 140 ?? 50 km in middle and late Proterozoic cratons. Using known crustal thickness, our calculated geotherms, and assuming that isostatic balance is achieved at the base of the lithosphere, we find that Archean and early Proterozoic mantle lithosphere is 1.5% less dense (chemically depleted) than the

  2. The dynamics of femtosecond pulsed laser removal of 20 nm Ni films from an interface

    NASA Astrophysics Data System (ADS)

    Schrider, Keegan J.; Torralva, Ben; Yalisove, Steven M.

    2015-09-01

    The dynamics of femtosecond laser removal of 20 nm Ni films on glass substrates was studied using time-resolved pump-probe microscopy. 20 nm thin films exhibit removal at two distinct threshold fluences, removal of the top 7 nm of Ni above 0.14 J/cm2, and removal of the entire 20 nm film above 0.36 J/cm2. Previous work shows the top 7 nm is removed through liquid spallation, after irradiation the Ni melts and rapidly expands leading to tensile stress and cavitation within the Ni film. This work shows that above 0.36 J/cm2 the 20 nm film is removed in two distinct layers, 7 nm and 13 nm thick. The top 7 nm layer reaches a speed 500% faster than the bottom 13 nm layer at the same absorbed fluence, 500-2000 m/s and 300-700 m/s in the fluence ranges studied. Significantly different velocities for the top 7 nm layer and bottom 13 nm layer indicate removal from an interface occurs by a different physical mechanism. The method of measuring film displacement from the development of Newton's rings was refined so it could be shown that the 13 nm layer separates from the substrate within 70 ps and accelerates to its final velocity within several hundred picoseconds. We propose that removal of the bottom 13 nm is consistent with heterogeneous nucleation and growth of vapor at the Ni-glass interface, but that the rapid separation and acceleration of the 13 nm layer from the Ni-glass interface requires consideration of exotic phases of Ni after excitation.

  3. influence of film thickness on optical constants of antimony-based bismuth-doped super-resolution mask layer

    NASA Astrophysics Data System (ADS)

    Lu, Xinmiao; Wu, Yiqun; Wang, Yang; Wei, Jinsong

    As the demand for ultrahigh density information storage continues to grow, recording mark size of several tens nanometer which is smaller than the optical diffraction limit is required in optical memory. Functional film super-resolution technique is one of practical approaches to overcome the optical diffraction limit. Optical constants are important parameters to optical films as super-resolution masks. In this paper, the influence of film thickness on optical constants of antimony-based bismuth-doped super-resolution mask layer is investigated. The structure of the samples with different thickness was studied by X-ray diffraction. The transmission spectrum was measured by spectrophotometry. The optical constants of the films in the range of 300-800 nm were measured by spectroscopic ellipsometry. The results show that the structure of the film transforms from amorphous state to crystal state when the thickness increases from 7 nm to 300 nm. In the range of 300-800 nm, the refractive index and extinction coefficient increase with increasing wavelength. The transmission decreases rapidly when the thickness increases from 7 nm to 30 nm. The influences of film thickness on optical constants are more significant in the thickness range of 7-50 nm than that in the thickness above 50 nm.

  4. Thick lanthanum zirconate buffer layers from water-based precursor solutions on Ni-5%W substrates

    SciTech Connect

    Narayanan, Vyshnavi; Lommens, Petra; De Buysser, Klaartje; Huehne, Ruben; Van Driessche, Isabel

    2011-11-15

    In this work, water-based precursor solutions suitable for dip-coating of thick La{sub 2}Zr{sub 2}O{sub 7} (LZO) buffer layers for coated conductors on Ni-5%W substrates were developed. The solutions were prepared based on chelate chemistry using water as the main solvent. The effect of polymer addition on the maximum crack-free thickness of the deposited films was investigated. This novel solution preparation method revealed the possibility to grow single, crack-free layers with thicknesses ranging 100-280 nm with good crystallinity and an in-plane grain misalignment with average FWHM of 6.55{sup o}. TEM studies illustrated the presence of nanovoids, typical for CSD-LZO films annealed under Ar-5%H{sub 2} gas flow. The appropriate buffer layer action of the film in preventing the Ni diffusion was studied using XPS. It was found that the Ni diffusion was restricted to the first 30 nm of a 140 nm thick film. The surface texture of the film was improved using a seed layer. - Graphical abstract: Thick LZO buffer layers from water-based precursor solutions were synthesized and their crystallinity, microstructure and buffer layer action were studied. The buffer layer action of the LZO layer was substantial to restrict the Ni penetration within 30 nm of a 140 nm thick film. Highlights: > LZO buffer layers with high thicknesses for use in coated conductors were prepared. > Prepared from water-based solutions. > Polymeric PVP increases the crack-free critical thickness of thick films. > Thick films showed good barrier action against Ni penetration. > Seed layers promote epitaxial growth of thick layers.

  5. Microstructure evolution with varied layer thickness in magnetron-sputtered Ni/C multilayer films

    PubMed Central

    Peng, Jichang; Li, Wenbin; Huang, Qiushi; Wang, Zhanshan

    2016-01-01

    The microstructure evolution of magnetron-sputtered Ni/C multilayers was investigated by varying the Ni and C layer thickness in the region of a few nanometers. For the samples having 2.6-nm-thick C layers, the interface width increases from 0.37 to 0.81 nm as the Ni layer thickness decreases from 4.3 to 1.3 nm. Especially for the samples with Ni layers less than 2.0 nm, the interface width changes significantly due to the discontinuously distributed Ni crystallites. For the samples having 2.8-nm-thick Ni layers, the interface width increases from 0.37 to 0.59 nm when the C layer thickness decreases from 4.3 to 0.7 nm. The evolution of interface microstructures with varied Ni and C layers is explained based on a proposed simple growth model of Ni and C layers. PMID:27515586

  6. Comparison of Failure Thickness and Critical Diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.; Higgins, Andrew J.

    2006-07-01

    The critical diameter and failure thickness of both neat liquid nitromethane and a 65% nitromethane/35% nitroethane blend confined by aluminum are determined experimentally. A comparison of these two parameters provides insight into the failure mechanism of detonation in these explosives. If the failure of detonation in a critical charge diameter (or thickness) experiment is due to reaction quenching resulting from expansion losses (wave curvature), then it is expected that the failure thickness should be half the value of the critical diameter. The critical diameter and failure thickness of neat nitromethane confined in aluminum are found to be 2.5 mm and 0.75 mm respectively for a temperature range of 26 ± 1°C. The critical diameter and failure thickness of the 65NM/35NE blend confined in aluminum are found to be 6.2 mm and 1.7 mm respectively for a temperature range of 28 ± 1°C. The ratio of critical diameter to failure thickness for these experiments is found to lie between 3:1 and 4:1 rather than 2:1 as expected from wave curvature theory. By comparing the experimentally determined values of critical diameter and thickness for the test explosives and examining the failure patterns recovered on witness plates, a mechanism of propagation in thin rectangular channels is proposed based on complex wave interactions.

  7. Evaluation of Retinal and Choroidal Thickness in Fuchs' Uveitis Syndrome

    PubMed Central

    Ozsutcu, Mustafa

    2016-01-01

    Purpose. We aimed to investigate retinal and choroidal thickness in the eyes of patients with Fuchs' uveitis syndrome (FUS). Methods. Fifteen patients with unilateral FUS and 20 healthy control subjects were enrolled. Spectral domain optical coherence tomography (Spectralis HRA+OCT, 870 nm; Heidelberg Engineering, Heidelberg, Germany) was used to obtain retinal and choroidal thickness measurements. The retinal nerve fiber layer (RNFL) thickness, macular thickness, and choroidal thickness of the eyes with FUS were compared with the unaffected eye and the eyes of healthy control subjects. Results. The mean choroidal thickness at fovea and at each point within the horizontal nasal and temporal quadrants at 500 μm intervals to a distance of 1500 µm from the foveal center was significantly thinner in the affected eye of FUS patients compared with the unaffected eye of FUS patients or the eyes of healthy control subjects. However, there were no significant differences in RNFL or macular thickness between groups. Conclusions. Affected eyes in patients with FUS tend to have thinner choroids as compared to eyes of unaffected fellow eyes and healthy individuals, which might be a result of the chronic inflammation associated with the disease. PMID:27579176

  8. Shape from equal thickness contours

    SciTech Connect

    Cong, G.; Parvin, B.

    1998-05-10

    A unique imaging modality based on Equal Thickness Contours (ETC) has introduced a new opportunity for 3D shape reconstruction from multiple views. We present a computational framework for representing each view of an object in terms of its object thickness, and then integrating these representations into a 3D surface by algebraic reconstruction. The object thickness is inferred by grouping curve segments that correspond to points of second derivative maxima. At each step of the process, we use some form of regularization to ensure closeness to the original features, as well as neighborhood continuity. We apply our approach to images of a sub-micron crystal structure obtained through a holographic process.

  9. Laser detection of material thickness

    DOEpatents

    Early, James W.

    2002-01-01

    There is provided a method for measuring material thickness comprising: (a) contacting a surface of a material to be measured with a high intensity short duration laser pulse at a light wavelength which heats the area of contact with the material, thereby creating an acoustical pulse within the material: (b) timing the intervals between deflections in the contacted surface caused by the reverberation of acoustical pulses between the contacted surface and the opposite surface of the material: and (c) determining the thickness of the material by calculating the proportion of the thickness of the material to the measured time intervals between deflections of the contacted surface.

  10. The SEMATECH Berkeley MET: extending EUV learning to 16-nm half pitch

    SciTech Connect

    Anderson, Christopher N.; Baclea-an, Lorie Mae; Denham, Paul E.; George, Simi; Goldberg, Kenneth A.; Jones, Michael; Smith, Nathan; Wallow, Thomas; Montgomery, Warren; Naulleau, Patrick P.

    2011-03-18

    Several high-performing resists identified in the past two years have been exposed at the 0.3-numerical-aperture (NA) SEMATECH Berkeley Microfield Exposure Tool (BMET) with an engineered dipole illumination optimized for 18-nm half pitch. Five chemically amplified platforms were found to support 20-nm dense patterning at a film thickness of approximately 45 nm. At 19-nm half pitch, however, scattered bridging kept all of these resists from cleanly resolving larger areas of dense features. At 18-nm half pitch, none of the resists were are able to cleanly resolve a single line within a bulk pattern. With this same illumination a directly imageable metal oxide hardmask showed excellent performance from 22-nm half pitch to 17-nm half pitch, and good performance at 16-nm half pitch, closely following the predicted aerial image contrast. This indicates that observed limitations of the chemically amplified resists are indeed coming from the resist and not from a shortcoming of the exposure tool. The imageable hardmask was also exposed using a Pseudo Phase-Shift-Mask technique and achieved clean printing of 15-nm half pitch lines and modulation all the way down to the theoretical 12.5-nm resolution limit of the 0.3-NA SEMATECH BMET.

  11. Improved Coal-Thickness Measurement

    NASA Technical Reports Server (NTRS)

    Barr, T. A.

    1984-01-01

    Summed signals and dielectric-filled antenna improve measurement. Improved FM radar for measuring thickness of coal seam eliminates spectrum splitting and reduces magnitude of echo from front coal surface.

  12. Metal thickness measurements using radiography

    NASA Astrophysics Data System (ADS)

    Achrekar, P. M.

    1986-04-01

    The present invention relates broadly to a radiographic inspection technique, and in particular to a metal thickness measurement method using radiography. The localized areas wherein the effective metal thickness is less than the minimum that is required for radiation shielding and which can render a shielding enclosure functionless, is readily determined. The invention comprises a process for assuring metal thickness in small regions. The actual metal thickness of small regions can be verified by comparing the optical densities of sections of the metal i.e., stepwedge. A comparator microphotometer, which compares optical densities of spectrum lines from spectrophotometers, compares the optical density of spectrum lines on an exposed spectrum plate (metal under test) with a standard plate (stepwedge).

  13. Edge-on thick discs

    NASA Astrophysics Data System (ADS)

    Kasparova, A.; Katkov, I.; Chilingarian, I.; Silchenko, O.; Moiseev, A.; Borisov, S.

    2016-06-01

    Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations. Using the Russian 6-m telescope BTA we collected deep spectra of thick discs in three edge-on early-type disc galaxies located in different environments: NGC4111 in a dense group, NGC4710 in the Virgo cluster, and NGC5422 in a sparse group. We see intermediate age (4 ‑ 5 Gyr) metal rich ([Fe/H] ~ ‑0.2 ‑ 0.0 dex) stellar populations in NGC4111 and NGC4710. On the other hand, NGC5422 does not harbour young stars, its only disc is thick and old (10 Gyr) and its α-element abundance suggests a long formation epoch implying its formation at high redshift. Our results prove the diversity of thick disc formation scenarios.

  14. Peripapillary choroidal thickness in childhood.

    PubMed

    Read, Scott A; Alonso-Caneiro, David; Vincent, Stephen J; Collins, Michael J

    2015-06-01

    Changes in the thickness of the invivo peripapillary choroid have been documented in a range of ocular conditions in adults; however, choroidal thickness in the peripapillary region of children has not been examined in detail. This study therefore aimed to investigate the thickness of the peripapillary choroid and the overlying retinal nerve fibre layer (RNFL) in a population of normal children with a range of refractive errors. Ninety-three children (37 myopes and 56 non-myopes) aged between 11 and 16 years, had measurements of peripapillary choroidal and RNFL thickness derived from enhanced depth imaging optical coherence tomography images (EDI-OCT, Heidelberg Spectralis). The average thickness was determined in a series of five 0.25 mm width concentric annuli (each divided into 8 equal sized 45° sectors) centred on the optic nerve head boundary, accounting for individual ocular magnification factors and the disc-fovea angle. Significant variations in peripapillary choroidal thickness were found to occur with both annulus location (p < 0.001) and sector position (p < 0.001) in this population of children. The innermost annulus (closest to the edge of the optic disc) exhibited the thinnest choroid (mean 77 ± 16 μm) and the outermost annulus, the thickest choroid (191 ± 52 μm). The choroid was thinnest inferior to the optic nerve head (139 ± 38 μm) and was thickest in the superior temporal sector (157 ± 40 μm). Significant differences in the distribution of choroidal thickness were also associated with myopia, with myopic children having significantly thinner choroids in the inner and outer annuli of the nasal and temporal sectors respectively (p < 0.001). RNFL thickness also varied significantly with annulus location and sector (p < 0.001), and showed differences in thickness distribution associated with refractive error. This study establishes the normal variations in the thickness of the peripapillary choroid with radial distance and azimuthal angle

  15. Thin film type 248-nm bottom antireflective coatings

    NASA Astrophysics Data System (ADS)

    Enomoto, Tomoyuki; Nakayama, Keisuke; Mizusawa, Kenichi; Nakajima, Yasuyuki; Yoon, Sangwoong; Kim, Yong-Hoon; Kim, Young-Ho; Chung, Hoesik; Chon, Sang Mun

    2003-06-01

    A frequent problem encountered by photoresists during the manufacturing of semiconductor device is that activating radiation is reflected back into the photoresist by the substrate. So, it is necessary that the light reflection is reduced from the substrate. One approach to reduce the light reflection is the use of bottom anti-reflective coating (BARC) applied to the substrate beneath the photoresist layer. The BARC technology has been utilized for a few years to minimize the reflectivity. As the chip size is reduced to sub 0.13-micron, the photoresist thickness has to decrease with the aspect ratio being less than 3.0. Therefore, new Organic BARC is strongly required which has the minimum reflectivity with thinner BARC thickness and higher etch selectivity towards resist. SAMSUNG Electronics has developed the advanced Organic BARC with Nissan Chemical Industries, Ltd. and Brewer Science, Inc. for achieving the above purpose. As a result, the suitable high performance SNAC2002 series KrF Organic BARCs were developed. Using CF4 gas as etchant, the plasma etch rate of SNAC2002 series is about 1.4 times higher than that of conventional KrF resists and 1.25 times higher than the existing product. The SNAC2002 series can minimize the substrate reflectivity at below 40nm BARC thickness, shows excellent litho performance and coating properties.

  16. Optical metrology solutions for 10nm films process control challenges

    NASA Astrophysics Data System (ADS)

    Mahendrakar, Sridhar; Vaid, Alok; Venkataraman, Kartik; Lenahan, Michael; Seipp, Steven; Fang, Fang; Saxena, Shweta; Hu, Dawei; Yoon, Nam Hee; Song, Da; Camp, Janay; Ren, Zhou

    2016-03-01

    Controlling thickness and composition of gate stack layers in logic and memory devices is critical to ensure transistor performance meets requirements, especially at 10nm node due to the 3-d geometry of devices and tight process budget. It has become necessary to measure and control each layer in the gate stack before and after dielectric and metal gate deposition sequences. A typical gate stack can have 5-7 layers including the interfacial layer, high-k dielectric, metal gate stack, work function layers, and cap layers. Similarly, PMOS channel strain is controlled using a graded SixGe1-x stack grown epitaxially over fins in the source/drain regions. This graded stack can have 2-4 layers of different thicknesses and Ge concentrations. This paper discusses the benefit of using spectroscopic ellipsometry with multiple angles of incidence to accurately and precisely determine the thickness of individual layers in critical gate layer stacks at various process steps on planar and grating surfaces. We will also show the benefit of using an advanced laser-based ellipsometer, for ultra-precise measurement of the gate interfacial layer oxides.

  17. High accuracy wall thickness loss monitoring

    NASA Astrophysics Data System (ADS)

    Gajdacsi, Attila; Cegla, Frederic

    2014-02-01

    Ultrasonic inspection of wall thickness in pipes is a standard technique applied widely in the petrochemical industry. The potential precision of repeat measurements with permanently installed ultrasonic sensors however significantly surpasses that of handheld sensors as uncertainties associated with coupling fluids and positional offsets are eliminated. With permanently installed sensors the precise evaluation of very small wall loss rates becomes feasible in a matter of hours. The improved accuracy and speed of wall loss rate measurements can be used to evaluate and develop more effective mitigation strategies. This paper presents an overview of factors causing variability in the ultrasonic measurements which are then systematically addressed and an experimental setup with the best achievable stability based on these considerations is presented. In the experimental setup galvanic corrosion is used to induce predictable and very small wall thickness loss. Furthermore, it is shown that the experimental measurements can be used to assess the effect of reduced wall loss that is produced by the injection of corrosion inhibitor. The measurements show an estimated standard deviation of about 20nm, which in turn allows us to evaluate the effect and behaviour of corrosion inhibitors within less than an hour.

  18. Complementary metal-oxide-semiconductor compatible 1060 nm photodetector with ultrahigh gain under low bias.

    PubMed

    Hall, David; Li, Baoxia; Liu, Yu-Hsin; Yan, Lujiang; Lo, Yu-Hwa

    2015-10-01

    Falling on the tail of the absorption spectrum of silicon, 1060 nm Si detectors often suffer from low responsivity unless an exceedingly thick absorption layer is used, a design that requires high operation voltage and high purity epitaxial or substrate material. We report an all-silicon 1060 nm detector with ultrahigh gain to allow for low operation voltage (<4  V) and thin (200 nm) effective absorption layer, using the recently discovered cycling excitation process. With 1% external quantum efficiency, a responsivity of 93 A/W was demonstrated in a p/n junction device compatible with the complementary metal-oxide-semiconductor process. PMID:26421551

  19. Ion transport in sub-5-nm graphene nanopores

    NASA Astrophysics Data System (ADS)

    Suk, Myung E.; Aluru, N. R.

    2014-02-01

    Graphene nanopore is a promising device for single molecule sensing, including DNA bases, as its single atom thickness provides high spatial resolution. To attain high sensitivity, the size of the molecule should be comparable to the pore diameter. However, when the pore diameter approaches the size of the molecule, ion properties and dynamics may deviate from the bulk values and continuum analysis may not be accurate. In this paper, we investigate the static and dynamic properties of ions with and without an external voltage drop in sub-5-nm graphene nanopores using molecular dynamics simulations. Ion concentration in graphene nanopores sharply drops from the bulk concentration when the pore radius is smaller than 0.9 nm. Ion mobility in the pore is also smaller than bulk ion mobility due to the layered liquid structure in the pore-axial direction. Our results show that a continuum analysis can be appropriate when the pore radius is larger than 0.9 nm if pore conductivity is properly defined. Since many applications of graphene nanopores, such as DNA and protein sensing, involve ion transport, the results presented here will be useful not only in understanding the behavior of ion transport but also in designing bio-molecular sensors.

  20. Ion transport in sub-5-nm graphene nanopores

    SciTech Connect

    Suk, Myung E.; Aluru, N. R.

    2014-02-28

    Graphene nanopore is a promising device for single molecule sensing, including DNA bases, as its single atom thickness provides high spatial resolution. To attain high sensitivity, the size of the molecule should be comparable to the pore diameter. However, when the pore diameter approaches the size of the molecule, ion properties and dynamics may deviate from the bulk values and continuum analysis may not be accurate. In this paper, we investigate the static and dynamic properties of ions with and without an external voltage drop in sub-5-nm graphene nanopores using molecular dynamics simulations. Ion concentration in graphene nanopores sharply drops from the bulk concentration when the pore radius is smaller than 0.9 nm. Ion mobility in the pore is also smaller than bulk ion mobility due to the layered liquid structure in the pore-axial direction. Our results show that a continuum analysis can be appropriate when the pore radius is larger than 0.9 nm if pore conductivity is properly defined. Since many applications of graphene nanopores, such as DNA and protein sensing, involve ion transport, the results presented here will be useful not only in understanding the behavior of ion transport but also in designing bio-molecular sensors.

  1. Tailoring of Luminous Transmittance upon Switching for Thermochromic VO2 Films by Thickness Control

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Jin, Ping; Tazawa, Masato; Yoshimura, Kazuki

    2004-01-01

    The difference in luminous transmittance (Δ Tlum) upon switching of VO2 films strongly affects its solar controllability when used as a thermochromic window. It was found that Δ Tlum is controllable by film thickness. Optical calculation for a VO2 film on quartz glass revealed that the low-temperature semiconductor phase exhibits lower Tlum than the high-temperature metallic phase for thickness below 50 nm, while the relationship is reversed above 50 nm. The calculation was confirmed by film deposition and measurement. Maximum Δ Tlum is located near 80 nm. An enhanced Δ Tlum contributes largely to solar efficiency.

  2. RF magnetron sputtering of thick platinum coatings on glass microspheres

    SciTech Connect

    Meyer, S.F.; Hsieh, E.J.; Burt, R.J.

    1980-05-28

    Thick platinum coatings on glass microspheres are needed for proposed Laser Fusion targets. The spherical nature of these substrates coupled with the small dimensions (approx. 100 ..mu..m OD) make it difficult to achieve a smooth and uniform coating. Coating problems encountered include a rough surface and porous microstructure from the oblique incidence and lack of temperature and bias control, clumping of the microspheres causing non-uniformities, and particle accumulation causing cone defects. Sputtering parameters significantly affecting the coatings include total pressure, DC substrate bias, and the addition of doping gases. Using an ultrasonic vibrating screened cage and RF magnetron Sputtergun, we have successfully batch coated microspheres with up to 6 ..mu..m of Pt, with a surface roughness of 200 nm, thickness non-concentricity of 300 nm, and density greater than 98% of bulk Pt.

  3. Low leakage ZrO2 based capacitors for sub 20 nm dynamic random access memory technology nodes

    NASA Astrophysics Data System (ADS)

    Pešić, Milan; Knebel, Steve; Geyer, Maximilian; Schmelzer, Sebastian; Böttger, Ulrich; Kolomiiets, Nadiia; Afanas'ev, Valeri V.; Cho, Kyuho; Jung, Changhwa; Chang, Jaewan; Lim, Hanjin; Mikolajick, Thomas; Schroeder, Uwe

    2016-02-01

    During dynamic random access memory (DRAM) capacitor scaling, a lot of effort was put searching for new material stacks to overcome the scaling limitations of the current material stack, such as leakage and sufficient capacitance. In this study, very promising results for a SrTiO3 based capacitor with a record low capacitance equivalent thickness value of 0.2 nm at target leakage current are presented. Due to the material properties of SrTiO3 films (high vacancy concentration and low band gap), which are leading to an increased leakage current, a physical thickness of at least 8 nm is required at target leakage specifications. However, this physical thickness would not fit into an 18 nm DRAM structure. Therefore, two different new approaches to develop a new ZrO2 based DRAM capacitor stack by changing the inter-layer material from Al2O3 to SrO and the exchange of the top electrode material from TiN to Pt are presented. A combination of these two approaches leads to a capacitance equivalent thickness value of 0.47 nm. Most importantly, the physical thickness of <5 nm for the dielectric stack is in accordance with the target specifications. Detailed evaluation of the leakage current characteristics leads to a capacitor model which allows the prediction of the electrical behavior with thickness scaling.

  4. Measurement of absolute optical thickness distribution of a mask-glass by wavelength tuning interferometry

    NASA Astrophysics Data System (ADS)

    Hibino, Kenichi; Yangjin, Kim; Bitou, Youichi; Ohsawa, Sonko; Sugita, Naohiko; Mitsuishi, Mamoru

    2008-08-01

    The surface flatness and the uniformity in thickness and refractive index of a mask-blank glass have been requested in semiconductor industry. The absolute optical thickness of a mask-blank glass of seven-inch square and 3mm thickness was measured by three-surface interferometry in a wavelength tuning Fizeau interferometer. Wavelength-tuning interferometry can separate in frequency space the three interference signals of the surface shape and the optical thickness. The wavelength of a tunable laser diode source was scanned linearly from 632 nm to 642 nm and a CCD detector recorded two thousand interference images. The number of phase variation of the interference fringes during the wavelength scanning was counted by a temporal discrete Fourier transform. The initial and final phases of the interferograms before and after the scanning were measured by a phase shifting technique with fine tunings of the wavelengths at 632 nm and 642 nm. The optical thickness defined by the group refractive index at the central wavelength of 337 nm can be measured by this technique. Experimental results show that the cross talk in multiple-surface interferometry caused a systematic error of 2.0 microns in the measured optical thickness.

  5. Change in Tear Film Lipid Layer Thickness, Corneal Thickness, Volume and Topography after Superficial Cauterization for Conjunctivochalasis

    PubMed Central

    Chan, Tommy C. Y.; Ye, Cong; Ng, Paul KF; Li, Emmy Y. M.; Yuen, Hunter K. L.; Jhanji, Vishal

    2015-01-01

    We evaluated the change in tear film lipid layer thickness, corneal thickness, volume and topography after superficial cauterization of symptomatic conjunctivochalasis. Bilateral superficial conjunctival cauterization was performed in 36 eyes of 18 patients with symptomatic conjunctivochalasis. The mean age of patients (12 males, 6 females) was 68.6 ± 10.9 years (range: 44–83 years). Preoperatively, 28 eyes (77.8%) had grade 1 conjunctivochalasis, and 8 eyes (22.2%) had grade 2 conjunctivochalasis. At 1 month postoperatively, the severity of conjunctivochalasis decreased significantly (p < 0.001) and 29 eyes (80.6%) had grade 0 conjunctivochalasis whereas 7 eyes (19.4%) had grade 1 conjunctivochalasis. The mean Ocular Surface Disease Index score decreased from 31.5 ± 15.2 preoperatively to 21.5 ± 14.2 at the end of 1 month postoperatively (p = 0.001). There was a statistically significant increase in mean tear film lipid layer thickness 1 month after the surgery (49.6 ± 16.1 nm vs 62.6 ± 21.6 nm; p < 0.001). The central corneal thickness, thinnest corneal thickness and corneal volume decreased significantly postoperatively (p < 0.001). Our study showed that superficial conjunctival cauterization is an effective technique for management of conjunctivochalasis in the short term. An increase in tear film lipid layer thickness along with a decrease in corneal thickness and volume were observed after surgical correction of conjunctivochalasis. PMID:26184418

  6. Simultaneous triple 914 nm, 1084 nm, and 1086 nm operation of a diode-pumped Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Lü, Yanfei; Xia, Jing; Liu, Huilong; Pu, Xiaoyun

    2014-10-01

    We report a diode-pumped continuous-wave (cw) triple-wavelength Nd:YVO4 laser operating at 914, 1084, and 1086 nm. A theoretical analysis has been introduced to determine the threshold conditions for simultaneous triple-wavelength laser. Using a T-shaped cavity, we realized an efficient triple-wavelength operation at 4F3/2→4I9/2 and 4F3/2→4I11/2 transitions for Nd:YVO4 crystal, simultaneously. At an absorbed pump power of 16 W (or 25 W of incident pump power), the maximum output power was 2.3 W, which included 914 nm, 1084 nm, and 1086 nm three wavelengths, and the optical conversion efficiency with respect to the absorbed pump power was 14.4%.

  7. Metrology Challenges for 45 nm Strained-Si Devices

    NASA Astrophysics Data System (ADS)

    Vartanian, V.; Sadaka, M.; Zollner, S.; Thean, A. V.-Y.; White, T.; Nguyen, B.-Y.; Zavala, M.; McCormick, L.; Prabhu, L.; Eades, D.; Parsons, S.; Collard, H.; Kim, K.; Jiang, J.; Dhandapani, V.; Hildreth, J.; Powers, R.; Spencer, G.; Ramani, N.; Mogab, J.; Kottke, M.; Canonico, M.; Xie, Q.; Wang, X.-D.; Vella, J.; Contreras, L.; Theodore, D.; Lu, B.; Kriske, T.; Gregory, R.; Liu, R.

    2005-09-01

    The semiconductor industry has sustained its historical exponential performance gains by aggressively scaling transistor dimensions. However, as devices approach sub-100 nm dimensions, scaling becomes more challenging and new materials are required to overcome the fundamental physical limits imposed by existing materials. For example, as power supply voltages continue to decrease with successive scaling, enhanced carrier mobility using biaxially tensile-strained-Si on SOI or on bulk substrates have become viable options to sustain continual drive current increases without traditional scaling. Although the addition of strained-Si to conventional MOSFET devices is compatible with existing mainstream CMOS process technology, there are new device and process integration challenges, wafer quality monitoring demands, and stringent requirements for film morphology and strain uniformity, imposing new demands on material characterization. Material requirements for strained-Si CMOS devices include homogeneous Si or SiGe film thickness, Ge composition, strain distribution to maintain uniform device performance. Also important are having good interface quality and low defect density (misfit and threading dislocation densities below 1e4/cm2) to ensure high minority carrier lifetimes and transconductance, and low surface roughness (<3Å RMS) to minimize the impact of interface scattering on carrier mobilities. Non-destructive, in-line metrology techniques include spectroscopic ellipsometry (SE) for film thickness and Ge composition, xray reflectivity (XRR) for thickness, density, and roughness measurements, xray fluorescence (XRF) for Ge composition, UV-Raman spectroscopy for channel strain characterization, IR photoluminescence (PL) for defect detection, and xray diffraction (XRD) for film thickness, Ge content, and strain measurement. While most of these techniques are well established in the semiconductor industry, some will require performance enhancements and development

  8. Portable x-ray fluorescence spectrometer for coating thickness measurement

    SciTech Connect

    Carapelle, Alain; Fleury-Frenette, Karl; Collette, Jean-Paul; Garnir, Henri-Pierre; Harlet, Philippe

    2007-12-15

    A handheld x-ray spectrometer has been realized and tested. The purpose of the device is to measure the thickness of coated samples in the range of 1-1500 nm in an industrial environment. Accuracy of {approx}3% has been achieved in this range with a measurement time of 1 min. Automated software has been implemented to allow utilization by a nonspecialist operator. An automated calibration procedure, based on measurements of reference samples, is used.

  9. Ultrathin GaN quantum disk nanowire LEDs with sub-250 nm electroluminescence

    NASA Astrophysics Data System (ADS)

    Sarwar, A. T. M. Golam; May, Brelon J.; Chisholm, Matthew F.; Duscher, Gerd J.; Myers, Roberto C.

    2016-04-01

    By quantum confining GaN at monolayer thickness with AlN barriers inside of a nanowire, deep ultraviolet LEDs are demonstrated. Full three-dimensional strain dependent energy band simulations are carried out within multiple quantum disk (MQD) GaN/AlN nanowire superlattice heterostructures. It is found that, even within the same nanowire MQD, the emission energy of the ultrathin GaN QDs varies from disk to disk due to the changing strain distribution and polarization charge induced energy band bending along the axial nanowire direction. MQD heterostructures are grown by plasma-assisted molecular beam epitaxy to form self-assembled catalyst-free nanowires with 1 to 2 monolayer thick GaN insertions within an AlN matrix. Photoluminescence peaks are observed at 295 nm and 283 nm from the 2 ML and 1 ML thick MQD samples, respectively. Polarization-doped nanowire LEDs are grown incorporating 1 ML thick GaN MQD active regions from which we observe deep ultraviolet electroluminescence. The shortest LED wavelength peak observed is 240 nm and attributed to electron hole recombination within 1 ML thick GaN QDs.

  10. Ultrathin GaN quantum disk nanowire LEDs with sub-250 nm electroluminescence

    DOE PAGESBeta

    Chisholm, Matthew F.; Golam Sarwar, A. T. M.; Myers, Roberto C.; Mays, Brelon J.; Duscher, Gerd J.

    2016-03-18

    By quantum confining GaN at monolayer thickness with AlN barriers inside of a nanowire, deep ultraviolet LEDs are demonstrated. Full three-dimensional strain dependent energy band simulations are carried out within multiple quantum disk (MQD) GaN/AlN nanowire superlattice heterostructures. It is found that, even within the same nanowire MQD, the emission energy of the ultrathin GaN QDs varies from disk to disk due to the changing strain distribution and polarization charge induced energy band bending along the axial nanowire direction. MQD heterostructures are grown by plasma-assisted molecular beam epitaxy to form self-assembled catalyst-free nanowires with 1 to 2 monolayer thick GaNmore » insertions within an AlN matrix. Photoluminescence peaks are observed at 295 nm and 283 nm from the 2 ML and 1 ML thick MQD samples, respectively. Polarization-doped nanowire LEDs are grown incorporating 1 ML thick GaN MQD active regions from which we observe deep ultraviolet electroluminescence. As a result, the shortest LED wavelength peak observed is 240 nm and attributed to electron hole recombination within 1 ML thick GaN QDs.« less

  11. Influence of film thickness on laser ablation threshold of transparent conducting oxide thin-films

    NASA Astrophysics Data System (ADS)

    Rung, S.; Christiansen, A.; Hellmann, R.

    2014-06-01

    We report on a comprehensive study of the laser ablation threshold of transparent conductive oxide thin films. The ablation threshold is determined for both indium tin oxide and gallium zinc oxide as a function of film thickness and for different laser wavelengths. By using a pulsed diode pumped solid state laser at 1064 nm, 532 nm, 355 nm and 266 nm, respectively, the relationship between optical absorption length and film thickness is studied. We find that the ablation threshold decreases with increasing film thickness in a regime where the absorption length is larger than the film thickness. In turn, the ablation threshold increases in case the absorption length is smaller than the film thickness. In particular, we observe a minimum of the ablation threshold in a region where the film thickness is comparable to the absorption length. To the best of our knowledge, this behaviour previously predicted for thin metal films, has been unreported for all three regimes in case of transparent conductive oxides, yet. For industrial laser scribing processes, these results imply that the efficiency can be optimized by using a laser where the optical absorption length is close to the film thickness.

  12. Tube wall thickness measurement apparatus

    DOEpatents

    Lagasse, Paul R.

    1987-01-01

    An apparatus for measuring the thickness of a tube's wall for the tube's entire length and circumference by determining the deviation of the tube wall thickness from the known thickness of a selected standard item. The apparatus comprises a base and a first support member having first and second ends. The first end is connected to the base and the second end is connected to a spherical element. A second support member is connected to the base and spaced apart from the first support member. A positioning element is connected to and movable relative to the second support member. An indicator is connected to the positioning element and is movable to a location proximate the spherical element. The indicator includes a contact ball for first contacting the selected standard item and holding it against the spherical element. The contact ball then contacts the tube when the tube is disposed about the spherical element. The indicator includes a dial having a rotatable needle for indicating the deviation of the tube wall thickness from the thickness of the selected standard item.

  13. Tube wall thickness measurement apparatus

    DOEpatents

    Lagasse, P.R.

    1985-06-21

    An apparatus for measuring the thickness of a tube's wall for the tube's entire length and radius by determining the deviation of the tube wall thickness from the known thickness of a selected standard item. The apparatus comprises a base and a first support member having first and second ends. The first end is connected to the base and the second end is connected to a spherical element. A second support member is connected to the base and spaced apart from the first support member. A positioning element is connected to and movable relative to the second support member. An indicator is connected to the positioning element and is movable to a location proximate the spherical element. The indicator includes a contact ball for first contacting the selected standard item and holding it against the spherical element. The contact ball then contacts the tube when the tube is disposed about the spherical element. The indicator includes a dial having a rotatable needle for indicating the deviation of the tube wall thickness from the thickness of the selected standard item.

  14. System for measuring film thickness

    DOEpatents

    Batishko, Charles R.; Kirihara, Leslie J.; Peters, Timothy J.; Rasmussen, Donald E.

    1990-01-01

    A system for determining the thicknesses of thin films of materials exhibiting fluorescence in response to exposure to excitation energy from a suitable source of such energy. A section of film is illuminated with a fixed level of excitation energy from a source such as an argon ion laser emitting blue-green light. The amount of fluorescent light produced by the film over a limited area within the section so illuminated is then measured using a detector such as a photomultiplier tube. Since the amount of fluorescent light produced is a function of the thicknesses of thin films, the thickness of a specific film can be determined by comparing the intensity of fluorescent light produced by this film with the intensity of light produced by similar films of known thicknesses in response to the same amount of excitation energy. The preferred embodiment of the invention uses fiber optic probes in measuring the thicknesses of oil films on the operational components of machinery which are ordinarily obscured from view.

  15. Sub-10 nm nanopantography

    SciTech Connect

    Tian, Siyuan Donnelly, Vincent M. E-mail: economou@uh.edu; Economou, Demetre J. E-mail: economou@uh.edu; Ruchhoeft, Paul

    2015-11-09

    Nanopantography, a massively parallel nanopatterning method over large areas, was previously shown to be capable of printing 10 nm features in silicon, using an array of 1000 nm-diameter electrostatic lenses, fabricated on the substrate, to focus beamlets of a broad area ion beam on selected regions of the substrate. In the present study, using lens dimensional scaling optimized by computer simulation, and reduction in the ion beam image size and energy dispersion, the resolution of nanopantography was dramatically improved, allowing features as small as 3 nm to be etched into Si.

  16. CMOS downsizing toward sub-10 nm

    NASA Astrophysics Data System (ADS)

    Iwai, Hiroshi

    2004-04-01

    Recently, CMOS downsizing has been accelerated very aggressively in both production and research level, and even transistor operation of a 6 nm gate length p-channel MOSFET was reported in a conference. However, many serious problems are expected for implementing such small-geometry MOSFETs into large scale integrated circuits, and it is still questionable whether we can successfully introduce sub-10 nm CMOS LSIs into the market or not. In this paper, limitation and its possible causes for the downscaling of CMOS towards sub-10 nm are discussed with consideration of past CMOS predictions for the limitation.

  17. Fabrication of 10nm diameter carbon nanopores

    SciTech Connect

    Radenovic, Aleksandra; Trepagnier, Eliane; Csencsits, Roseann; Downing, Kenneth H; Liphardt, Jan

    2008-09-25

    The addition of carbon to samples, during imaging, presents a barrier to accurate TEM analysis, the controlled deposition of hydrocarbons by a focused electron beam can be a useful technique for local nanometer-scale sculpting of material. Here we use hydrocarbon deposition to form nanopores from larger focused ion beam (FIB) holes in silicon nitride membranes. Using this method, we close 100-200nm diameter holes to diameters of 10nm and below, with deposition rates of 0.6nm per minute. I-V characteristics of electrolytic flow through these nanopores agree quantitatively with a one dimensional model at all examined salt concentrations.

  18. Laser Damage Growth in Fused Silica with Simultaneous 351 nm and 1053 nm irradiation

    SciTech Connect

    Norton, M A; Carr, A V; Carr, C W; Donohue, E E; Feit, M D; Hollingsworth, W G; Liao, Z; Negres, R A; Rubenchik, A M; Wegner, P J

    2008-10-24

    Laser-induced growth of optical damage often determines the useful lifetime of an optic in a high power laser system. We have extended our previous work on growth of laser damage in fused silica with simultaneous 351 nm and 1053 nm laser irradiation by measuring the threshold for growth with various ratios of 351 nm and 1053 nm fluence. Previously we reported that when growth occurs, the growth rate is determined by the total fluence. We now find that the threshold for growth is dependent on both the magnitude of the 351 nm fluence as well as the ratio of the 351 nm fluence to the 1053 nm fluence. Furthermore, the data suggests that under certain conditions the 1053 nm fluence does not contribute to the growth.

  19. Ionospheric slab thickness and its seasonal variations observed by GPS

    NASA Astrophysics Data System (ADS)

    Jin, Shuanggen; Cho, Jung-Ho; Park, Jung-Uk

    2007-11-01

    The ionospheric slab thickness, the ratio of the total electron content (TEC) to the F2-layer peak electron density (NmF2), is closely related to the shape of the ionospheric electron density profile Ne (h) and the TEC. Therefore, the ionospheric slab thickness is a significant parameter representative of the ionosphere. In this paper, the continuous GPS observations in South Korea are firstly used to study the equivalent slab thickness (EST) and its seasonal variability. The averaged diurnal medians of December January February (DJF), March April May (MAM), June July August (JJA) and September October November (SON) in 2003 have been considered to represent the winter, spring, summer and autumn seasons, respectively. The results show that the systematic diurnal changes of TEC, NmF2 and EST significantly appeared in each season and the higher values of TEC and NmF2 are observed during the equinoxes (semiannual anomaly) as well as in the mid-daytime of each season. The EST is significantly smaller in winter than in summer, but with a consistent variation pattern. During 14 16 LT in daytime, the larger EST values are observed in spring and autumn, while the smaller ones are in summer and winter. The peaks of EST diurnal variation are around 10 18 LT which are probably caused by the action of the thermospheric wind and the plasmapheric flow into the F2-region.

  20. Fermion localization on thick branes

    SciTech Connect

    Melfo, Alejandra; Pantoja, Nelson; Tempo, Jose David

    2006-02-15

    We consider chiral fermion confinement in scalar thick branes, which are known to localize gravity, coupled through a Yukawa term. The conditions for the confinement and their behavior in the thin-wall limit are found for various different BPS branes, including double walls and branes interpolating between different AdS{sub 5} spacetimes. We show that only one massless chiral mode is localized in all these walls, whenever the wall thickness is keep finite. We also show that, independently of wall's thickness, chiral fermionic modes cannot be localized in dS{sub 4} walls embedded in a M{sub 5} spacetime. Finally, massive fermions in double wall spacetimes are also investigated. We find that, besides the massless chiral mode localization, these double walls support quasilocalized massive modes of both chiralities.

  1. LTCC Thick Film Process Characterization

    DOE PAGESBeta

    Girardi, M. A.; Peterson, K. A.; Vianco, P. T.

    2016-05-01

    Low temperature cofired ceramic (LTCC) technology has proven itself in military/space electronics, wireless communication, microsystems, medical and automotive electronics, and sensors. The use of LTCC for high frequency applications is appealing due to its low losses, design flexibility and packaging and integration capability. Moreover, we summarize the LTCC thick film process including some unconventional process steps such as feature machining in the unfired state and thin film definition of outer layer conductors. The LTCC thick film process was characterized to optimize process yields by focusing on these factors: 1) Print location, 2) Print thickness, 3) Drying of tapes and panels,more » 4) Shrinkage upon firing, and 5) Via topography. Statistical methods were used to analyze critical process and product characteristics in the determination towards that optimization goal.« less

  2. Applications of film thickness equations

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1983-01-01

    A number of applications of elastohydrodynamic film thickness expressions were considered. The motion of a steel ball over steel surfaces presenting varying degrees of conformity was examined. The equation for minimum film thickness in elliptical conjunctions under elastohydrodynamic conditions was applied to roller and ball bearings. An involute gear was also introduced, it was again found that the elliptical conjunction expression yielded a conservative estimate of the minimum film thickness. Continuously variable-speed drives like the Perbury gear, which present truly elliptical elastohydrodynamic conjunctions, are favored increasingly in mobile and static machinery. A representative elastohydrodynamic condition for this class of machinery is considered for power transmission equipment. The possibility of elastohydrodynamic films of water or oil forming between locomotive wheels and rails is examined. The important subject of traction on the railways is attracting considerable attention in various countries at the present time. The final example of a synovial joint introduced the equation developed for isoviscous-elastic regimes of lubrication.

  3. Noninvasive thickness measurements of metal films through microwave dielectric resonators

    NASA Astrophysics Data System (ADS)

    Jung, Ho Sang; Lee, Jae Hun; Han, Hyun Kyung; Lee, Sang Young

    2016-05-01

    Thicknesses of Pt films ranging from 60 to 950 nm are measured noninvasively using a TE 011-mode dielectric resonator with the resonant frequency of 8.5 - 9.8 GHz at temperatures of 77 K and 293 K. A cylindrical rutile rod is used as the dielectric, with a high- T C superconductive YBa2Cu3O7- δ film used as the bottom endplate of the resonator for measurements at 77 K. This method is based on two facts: i) Due to the electromagnetic interferences of incoming and reflected waves at the surface of the metal film surface, the effective surface resistance varies with the film thickness, and ii) the intrinsic surface resistance of normal metals is equal to the intrinsic surface reactance in the local limit. The measured thicknesses using the rutile resonator appear to be comparable with those obtained using a profilometer. [Figure not available: see fulltext.

  4. Simultaneous orientation and thickness mapping in transmission electron microscopy

    DOE PAGESBeta

    Tyutyunnikov, Dmitry; Özdöl, V. Burak; Koch, Christoph T.

    2014-12-04

    In this paper we introduce an approach for simultaneous thickness and orientation mapping of crystalline samples by means of transmission electron microscopy. We show that local thickness and orientation values can be extracted from experimental dark-field (DF) image data acquired at different specimen tilts. The method has been implemented to automatically acquire the necessary data and then map thickness and crystal orientation for a given region of interest. We have applied this technique to a specimen prepared from a commercial semiconductor device, containing multiple 22 nm technology transistor structures. The performance and limitations of our method are discussed and comparedmore » to those of other techniques available.« less

  5. Giant moving vortex mass in thick magnetic nanodots

    PubMed Central

    Guslienko, K. Y.; Kakazei, G. N.; Ding, J.; Liu, X. M.; Adeyeye, A. O.

    2015-01-01

    Magnetic vortex is one of the simplest topologically non-trivial textures in condensed matter physics. It is the ground state of submicron magnetic elements (dots) of different shapes: cylindrical, square etc. So far, the vast majority of the vortex dynamics studies were focused on thin dots with thickness 5–50 nm and only uniform across the thickness vortex excitation modes were observed. Here we explore the fundamental vortex mode in relatively thick (50–100 nm) dots using broadband ferromagnetic resonance and show that dimensionality increase leads to qualitatively new excitation spectra. We demonstrate that the fundamental mode frequency cannot be explained without introducing a giant vortex mass, which is a result of the vortex distortion due to interaction with spin waves. The vortex mass depends on the system geometry and is non-local because of important role of the dipolar interaction. The mass is rather small for thin dots. However, its importance increases drastically with the dot thickness increasing. PMID:26355430

  6. 308nm excimer laser in dermatology.

    PubMed

    Mehraban, Shadi; Feily, Amir

    2014-01-01

    308nm xenon-chloride excimer laser, a novel mode of phototherapy, is an ultraviolet B radiation system consisting of a noble gas and halide. The aim of this systematic review was to investigate the literature and summarize all the experiments, clinical trials and case reports on 308-nm excimer laser in dermatological disorders. 308-nm excimer laser has currently a verified efficacy in treating skin conditions such as vitiligo, psoriasis, atopic dermatitis, alopecia areata, allergic rhinitis, folliculitis, granuloma annulare, lichen planus, mycosis fungoides, palmoplantar pustulosis, pityriasis alba, CD30+ lympho proliferative disorder, leukoderma, prurigo nodularis, localized scleroderma and genital lichen sclerosus. Although the 308-nm excimer laser appears to act as a promising treatment modality in dermatology, further large-scale studies should be undertaken in order to fully affirm its safety profile considering the potential risk, however minimal, of malignancy, it may impose. PMID:25606333

  7. Characterization and optimization of residual layer thickness during UV imprint process for singlemode waveguide fabrication

    NASA Astrophysics Data System (ADS)

    An, Shinmo; Lee, Hyun-Shik; Park, Se-Guen; O, Beom-Hoan; Lee, Seung-Gol; Lee, El-Hang

    2009-02-01

    We report on the fabrication and characterization of a residual layer resulting from UV imprinting of singlemode optical waveguide. We have measured the residual thickness formed from the imprinting process for several-um-size singlemode waveguide fabrication using the parameters of the imprinting pressure, dropped volume, and viscosity of the used polymer. We found that the residual layer thickness is dependent on both the initial polymer volume and process pressure and the initial polymer volume is more critical than process pressure. Viscosity of polymer also affects the residual layer thickness, the lowest residual layer thickness of 29nm is achieved with nano-imprinting resin, 0.3uL volume, and imprint pressure more than 20bar. Even with optical resin, the residual layer thickness of 60nm is achieved with 0.3uL volume and imprinting pressure of 30bar.

  8. Surface-initiated polymerizations on initiator anchored substrates: Synthesis and characterization of nanometer thick functional polymer films

    NASA Astrophysics Data System (ADS)

    Bao, Zhiyi

    We describe the surface-initiated ring-opening polymerization (ROP) of lactide from poly(2-hydroxyethyl methacrylate) (PHEMA) brushes anchored to Au substrates. The resulting comb polymers have a "bottle brush" architecture. During hydrolytic degradation of PLA in pH 7.4 buffer at 55°C, large, highly symmetric domains (˜50-100 mum) unexpectedly formed. The purpose of the research described in this chapter was to devise a model that describes their formation. Control experiments during degradation study link high lactide polymerization temperature to the formation of the defects. A likely mechanism is the scission of Au-S bonds at high temperatures, causing defects that swell when placed in the buffer solution. We demonstrated enhanced control over polymer brushes through variation of the areal density of the immobilized initiators used for their growth. Reaction of mercaptoundecanol monolayers on Au with both an acyl bromide initiator and a structurally similar acyl bromide diluent yields monolayers whose composition reflects the ratio of the acyl bromides in solution. Similarly, derivatization of SiO2 with an initiator and a diluent monochlorosilane also affords control over initiator density. The thickness of polymer films grown from these modified substrates drop dramatically when the fractional coverage of the surface by initiator decreases below 10% of a monolayer because the area per polymer chain increases. However, reduced termination at low initiator coverage results in substantial increases in initiator efficiency as measured by film growth rates normalized by the fractional coverage of the surface by initiator. Variation of chain density also affords control over film swelling. PHEMA films prepared with 0.1% initiator densities swell 20-fold more in water than films grown from monolayers containing only initiators. Such control should prove valuable in the use of brushes for immobilization of active, accessible biomacromolecules such as single

  9. Optical extension at the 193-nm wavelength

    NASA Astrophysics Data System (ADS)

    Zandbergen, Peter; McCallum, Martin; Amblard, Gilles R.; Domke, Wolf-Dieter; Smith, Bruce W.; Zavyalova, Lena; Petersen, John S.

    1999-07-01

    Lithography at 193nm is the first optical lithography technique that will be introduced for manufacturing of technology levels. where the required dimensions are smaller than the actual wavelength. This paper explores several techniques to extend 193nm to low k1 lithography. Most attention is given to binary mask solution in at 130nm dimensions, where k1 is 0.4. Various strong and Gaussian quadrupole illuminators were designed, manufactured and tested for this application. Strong quadrupoles show that largest DOF improvements. The drawback however, is that these strong quadrupoles are very duty cycle and dimensions specific, resulting in large proximity biases between different duty cycles. Due to their design, Gaussian quadrupoles sample much wider frequency ranges, resulting in less duty cycles specific DOF improvements and less proximity basis. At sub-130nm dimensions, strong phase shift masks provide significant latitude improvements, when compared to binary masks with quadrupole illumination. However, differences in dose to size for different duty cycles were up to 25 percent. For definition of contact holes, linewidth biasing through silylation, a key feature of the CARL bi-layer resist approach, demonstrated significant DOF latitude improvements compared to SLR at 140nm and 160nm contact holes.

  10. The Double-ended 750 nm and 532 nm Laser Output from PPLN-FWM

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Li, Yu-Xiang; Yao, Jian-Quan; Guo, Ling; Wang, Zhuo; Han, Sha-Sha; Zhang, Cui-Ying; Zhong, Kai

    2013-06-01

    We investigate 750 nm and 532 nm dual-wavelength laser for applications in the internet of things. A kind of optical maser is developed, in which the semiconductor module outputs the 808 nm pump light and then it goes into a double-clad Nd3+ :YAG monocrystal optical fiber through the intermediate coupler and forms a 1064 nm laser. The laser outputs come from both left and right terminals. In the right branch, the laser goes into the right cycle polarization LinNbO3 (PPLN) crystal through the right coupler, produces the optical parametric oscillation and forms the signal light λ1 (1500 nm), the idle frequency light λ2 (3660.55 nm), and the second-harmonic of the signal light λ3 (750 nm). These three kinds of light and the pump light λ4 together form the frequency matching and the quasi-phase matching, then the four-wave mixing occurs to create the high-gain light at wavelength 750 nm. Meanwhile, in the left branch, the laser goes into the left PPLN crystal through the left coupler, engenders frequency doubling and forms the light at wavelength 532 nm. That is to say, the optical maser provides 750 nm and 532 nm dual-wavelength laser outputting from two terminals, which is workable.

  11. Eddy current thickness measurement apparatus

    DOEpatents

    Rosen, Gary J.; Sinclair, Frank; Soskov, Alexander; Buff, James S.

    2015-06-16

    A sheet of a material is disposed in a melt of the material. The sheet is formed using a cooling plate in one instance. An exciting coil and sensing coil are positioned downstream of the cooling plate. The exciting coil and sensing coil use eddy currents to determine a thickness of the solid sheet on top of the melt.

  12. Absolute thickness metrology with submicrometer accuracy using a low-coherence distance measuring interferometer.

    PubMed

    Zhao, Yang; Schmidt, Greg; Moore, Duncan T; Ellis, Jonathan D

    2015-09-01

    Absolute physical thickness across the sample aperture is critical in determining the index of a refraction profile from the optical path length profile for gradient index (GRIN) materials, which have a designed inhomogeneous refractive index. Motivated by this application, instrumentation was established to measure the absolute thickness of samples with nominally plane-parallel surfaces up to 50 mm thick. The current system is capable of measuring absolute thickness with 120 nm (1σ) repeatability and submicrometer expanded measurement uncertainty. Beside GRIN materials, this method is also capable of measuring other inhomogeneous and opaque materials. PMID:26368894

  13. Thickness and temperature dependence of stress relaxation in nanoscale aluminum films

    NASA Astrophysics Data System (ADS)

    Hyun, S.; Brown, W. L.; Vinci, R. P.

    2003-11-01

    We have found that stress relaxation of nanoscale Al thin films is strongly dependent on both film thickness and temperature. Films 33, 107, and 205 nm thick prepared by evaporation onto a silicon nitride membrane substrate were studied using membrane resonance. A single thermal cycle to 300 °C was used to establish a stress, after which the time dependence of the stress was measured for the three film thicknesses at 50, 75, and 100 °C. The relaxation rate is highest for the highest temperature and the thinnest film. A dislocation locking mechanism is suggested as a possible explanation for the observed thickness dependence.

  14. Passivation of c-Si surfaces by sub-nm amorphous silicon capped with silicon nitride

    NASA Astrophysics Data System (ADS)

    Wan, Yimao; Yan, Di; Bullock, James; Zhang, Xinyu; Cuevas, Andres

    2015-12-01

    A sub-nm hydrogenated amorphous silicon (a-Si:H) film capped with silicon nitride (SiNx) is shown to provide a high level passivation to crystalline silicon (c-Si) surfaces. When passivated by a 0.8 nm a-Si:H/75 nm SiNx stack, recombination current density J0 values of 9, 11, 47, and 87 fA/cm2 are obtained on 10 Ω.cm n-type, 0.8 Ω.cm p-type, 160 Ω/sq phosphorus-diffused, and 120 Ω/sq boron-diffused silicon surfaces, respectively. The J0 on n-type 10 Ω.cm wafers is further reduced to 2.5 ± 0.5 fA/cm2 when the a-Si:H film thickness exceeds 2.5 nm. The passivation by the sub-nm a-Si:H/SiNx stack is thermally stable at 400 °C in N2 for 60 min on all four c-Si surfaces. Capacitance-voltage measurements reveal a reduction in interface defect density and film charge density with an increase in a-Si:H thickness. The nearly transparent sub-nm a-Si:H/SiNx stack is thus demonstrated to be a promising surface passivation and antireflection coating suitable for all types of surfaces encountered in high efficiency c-Si solar cells.

  15. Thick resist for MEMS processing

    NASA Astrophysics Data System (ADS)

    Brown, Joe; Hamel, Clifford

    2001-11-01

    The need for technical innovation is always present in today's economy. Microfabrication methods have evolved in support of the demand for smaller and faster integrated circuits with price performance improvements always in the scope of the manufacturing design engineer. The dispersion of processing technology spans well beyond IC fabrication today with batch fabrication and wafer scale processing lending advantages to MEMES applications from biotechnology to consumer electronics from oil exploration to aerospace. Today the demand for innovative processing techniques that enable technology is apparent where only a few years ago appeared too costly or not reliable. In high volume applications where yield and cost improvements are measured in fractions of a percent it is imperative to have process technologies that produce consistent results. Only a few years ago thick resist coatings were limited to thickness less than 20 microns. Factors such as uniformity, edge bead and multiple coatings made high volume production impossible. New developments in photoresist formulation combined with advanced coating equipment techniques that closely controls process parameters have enable thick photoresist coatings of 70 microns with acceptable uniformity and edge bead in one pass. Packaging of microelectronic and micromechanical devices is often a significant cost factor and a reliability issue for high volume low cost production. Technologies such as flip- chip assembly provide a solution for cost and reliability improvements over wire bond techniques. The processing for such technology demands dimensional control and presents a significant cost savings if it were compatible with mainstream technologies. Thick photoresist layers, with good sidewall control would allow wafer-bumping technologies to penetrate the barriers to yield and production where costs for technology are the overriding issue. Single pass processing is paramount to the manufacturability of packaging

  16. Effects of Sample Thickness on the Optical Properties of Surface Plasmon-Coupled Emission

    PubMed Central

    Gryczynski, Ignacy; Malicka, Joanna; Nowaczyk, Kazimierz; Gryczynski, Zygmunt; Lakowicz, Joseph R.

    2016-01-01

    In recent reports, we demonstrated coupling of excited fluorophores with thin silver or gold films resulting in directional surface plasmon-coupled emission (SPCE) through the silver film and into the glass substrate. In the present report, we describe the spectral and spatial properties of SPCE from sulforhomamine 101 in polyvinyl alcohol (PVA) films of various thicknesses on 50-nm silver films. The PVA thickness varied from about 30 to 750 nm. In thin PVA films with a thickness less than 160 nm, SPCE occurred at a single angle in the glass substrate and displayed only p polarization. As the PVA thickness increased to 300 nm, we observed SPCE at two angles, with different s or p polarization for each angle. For PVA films from 500 to 750 nm thick, we observed SPCE at three or four angles, with alternating s and p polarizations. The multiple rings of SPCE and the unusual s-polarized emission are consistent with the expected waveguide modes in the silver–PVA composite film. However, in contrast to our expectations, the average lifetimes of SPCE were not substantially changed from the PVA films. The observation of SPCE at multiple angles and with different polarization opens new opportunities for the use of SPCE to study anisotropic systems or to develop unique sensing devices. PMID:27340372

  17. Chromosomes without a 30-nm chromatin fiber

    PubMed Central

    Joti, Yasumasa; Hikima, Takaaki; Nishino, Yoshinori; Kamada, Fukumi; Hihara, Saera; Takata, Hideaki; Ishikawa, Tetsuya; Maeshima, Kazuhiro

    2012-01-01

    How is a long strand of genomic DNA packaged into a mitotic chromosome or nucleus? The nucleosome fiber (beads-on-a-string), in which DNA is wrapped around core histones, has long been assumed to be folded into a 30-nm chromatin fiber, and a further helically folded larger fiber. However, when frozen hydrated human mitotic cells were observed using cryoelectron microscopy, no higher-order structures that included 30-nm chromatin fibers were found. To investigate the bulk structure of mitotic chromosomes further, we performed small-angle X-ray scattering (SAXS), which can detect periodic structures in noncrystalline materials in solution. The results were striking: no structural feature larger than 11 nm was detected, even at a chromosome-diameter scale (~1 μm). We also found a similar scattering pattern in interphase nuclei of HeLa cells in the range up to ~275 nm. Our findings suggest a common structural feature in interphase and mitotic chromatins: compact and irregular folding of nucleosome fibers occurs without a 30-nm chromatin structure. PMID:22825571

  18. 810nm, 980nm, 1470nm and 1950nm diode laser comparison: a preliminary "ex vivo" study on oral soft tissues

    NASA Astrophysics Data System (ADS)

    Fornaini, Carlo; Merigo, Elisabetta; Sozzi, Michele; Selleri, Stefano; Vescovi, Paolo; Cucinotta, Annamaria

    2015-02-01

    The introduction of diode lasers in dentistry has several advantages, mainly consisting on the reduced size, reduced cost and possibility to beam delivering by optical fibers. At the moment the two diode wavelengths normally utilized in the dental field are 810 and 980 nm for soft tissues treatments. The aim of this study was to compare the efficacy of four different diode wavelengths: 810, 980, 1470 and 1950 nm diode laser for the ablation of soft tissues. Several samples of veal tongue were exposed to the four different wavelengths, at different fluences. The internal temperature of the soft tissues, in the area close to the beam, was monitored with thermocouple during the experiment. The excision quality of the exposed samples have been characterized by means of an optical microscope. Tissue damages and the cut regularity have been evaluated on the base of established criteria. The lowest thermal increase was recorded for 1950 nm laser. Best quality and speed of incision were obtained by the same wavelength. By evaluating epithelial, stromal and vascular damages for all the used wavelengths, the best result, in terms of "tissue respect", have been obtained for 1470 and 1950 nm exposures. From the obtained results 1470 and 1950 nm diode laser showed to be the best performer wavelengths among these used in this "ex vivo" study, probably due to their greatest affinity to water.

  19. Radiation Failures in Intel 14nm Microprocessors

    NASA Technical Reports Server (NTRS)

    Bossev, Dobrin P.; Duncan, Adam R.; Gadlage, Matthew J.; Roach, Austin H.; Kay, Matthew J.; Szabo, Carl; Berger, Tammy J.; York, Darin A.; Williams, Aaron; LaBel, K.; Ingalls, James D.

    2016-01-01

    In this study the 14 nm Intel Broadwell 5th generation core series 5005U-i3 and 5200U-i5 was mounted on Dell Inspiron laptops, MSI Cubi and Gigabyte Brix barebones and tested with Windows 8 and CentOS7 at idle. Heavy-ion-induced hard- and catastrophic failures do not appear to be related to the Intel 14nm Tri-Gate FinFET process. They originate from a small (9 m 140 m) area on the 32nm planar PCH die (not the CPU) as initially speculated. The hard failures seem to be due to a SEE but the exact physical mechanism has yet to be identified. Some possibilities include latch-ups, charge ion trapping or implantation, ion channels, or a combination of those (in biased conditions). The mechanism of the catastrophic failures seems related to the presence of electric power (1.05V core voltage). The 1064 nm laser mimics ionization radiation and induces soft- and hard failures as a direct result of electron-hole pair production, not heat. The 14nm FinFET processes continue to look promising for space radiation environments.

  20. Influence of electron transport layer thickness on optical properties of organic light-emitting diodes

    SciTech Connect

    Liu, Guohong; Liu, Yong; Li, Baojun; Zhou, Xiang

    2015-06-07

    We investigate experimentally and theoretically the influence of electron transport layer (ETL) thickness on properties of typical N,N′-diphenyl-N,N′-bis(1-naphthyl)-[1,1′-biphthyl]-4,4′-diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq{sub 3}) heterojunction based organic light-emitting diodes (OLEDs), where the thickness of ETL is varied to adjust the distance between the emitting zone and the metal electrode. The devices showed a maximum current efficiency of 3.8 cd/A when the ETL thickness is around 50 nm corresponding to an emitter-cathode distance of 80 nm, and a second maximum current efficiency of 2.6 cd/A when the ETL thickness is around 210 nm corresponding to an emitter-cathode distance of 240 nm. We adopt a rigorous electromagnetic approach that takes parameters, such as dipole orientation, polarization, light emitting angle, exciton recombination zone, and diffusion length into account to model the optical properties of devices as a function of varying ETL thickness. Our simulation results are accurately consistent with the experimental results with a widely varying thickness of ETL, indicating that the theoretical model may be helpful to design high efficiency OLEDs.

  1. Diode laser (980nm) cartilage reshaping

    NASA Astrophysics Data System (ADS)

    El Kharbotly, A.; El Tayeb, T.; Mostafa, Y.; Hesham, I.

    2011-03-01

    Loss of facial or ear cartilage due to trauma or surgery is a major challenge to the otolaryngologists and plastic surgeons as the complicated geometric contours are difficult to be animated. Diode laser (980 nm) has been proven effective in reshaping and maintaining the new geometric shape achieved by laser. This study focused on determining the optimum laser parameters needed for cartilage reshaping with a controlled water cooling system. Harvested animal cartilages were angulated with different degrees and irradiated with different diode laser powers (980nm, 4x8mm spot size). The cartilage specimens were maintained in a deformation angle for two hours after irradiation then released for another two hours. They were serially measured and photographed. High-power Diode laser irradiation with water cooling is a cheep and effective method for reshaping the cartilage needed for reconstruction of difficult situations in otorhinolaryngologic surgery. Key words: cartilage,diode laser (980nm), reshaping.

  2. Mask process monitoring with optical CD measurements for sub-50-nm

    NASA Astrophysics Data System (ADS)

    Bang, Kyung-Yoon; Park, Jin-Back; Roh, Jeong-Hun; Chung, Dong-Hoon; Cho, Sung-Yong; Kim, Yong-Hoon; Woo, Sang-Gyun; Cho, Han-Ku

    2008-10-01

    Process control of line width and etch depth on the photomask production is more important as the industry moves toward 50nm node and beyond. In this paper, we report the ellipsometer-based scatterometry based metrology system that provides line width and resist thickness measurements on sub 50 nm node test masks for a mask process monitoring. Measurements were made with spectroscopic rotating compensator ellipsometer system. For analysis we made up modeling libraries with a 200 nm half pitch and checked and applied them to ADI and ACI measurements of binary and phase shift mask (PSM). We characterized the CD uniformity, linearity, thickness uniformity. Results show that linearity measured from fixed-pitch, varying line/space ratio targets show good correlation to top-down CD-SEM with R2 of more than 0.99. Resist thickness results show that depth bias is about 2nm between AFM and OCD in ADI step. The data show that optical CD measurements provide a nondestructive way to monitor mask processes with relatively little time loss from measurement step.

  3. Stability of Polymer Ultrathin Films (<7 nm) Made by a Top-Down Approach.

    PubMed

    Bal, Jayanta Kumar; Beuvier, Thomas; Unni, Aparna Beena; Chavez Panduro, Elvia Anabela; Vignaud, Guillaume; Delorme, Nicolas; Chebil, Mohamed Souheib; Grohens, Yves; Gibaud, Alain

    2015-08-25

    In polymer physics, the dewetting of spin-coated polystyrene ultrathin films on silicon remains mysterious. By adopting a simple top-down method based on good solvent rinsing, we are able to prepare flat polystyrene films with a controlled thickness ranging from 1.3 to 7.0 nm. Their stability was scrutinized after a classical annealing procedure above the glass transition temperature. Films were found to be stable on oxide-free silicon irrespective of film thickness, while they were unstable (<2.9 nm) and metastable (>2.9 nm) on 2 nm oxide-covered silicon substrates. The Lifshitz-van der Waals intermolecular theory that predicts the domains of stability as a function of the film thickness and of the substrate nature is now fully reconciled with our experimental observations. We surmise that this reconciliation is due to the good solvent rinsing procedure that removes the residual stress and/or the density variation of the polystyrene films inhibiting thermodynamically the dewetting on oxide-free silicon. PMID:26149069

  4. 157 nm F2-laser writing of silica optical waveguides in silicone rubber

    NASA Astrophysics Data System (ADS)

    Okoshi, Masayuki; Li, Jianzhao; Herman, Peter R.

    2005-10-01

    Silica (SiO2) optical waveguides have been fabricated on the surface of silicone [(SiO(CH3)2)n] rubber by photochemical modification of silicone rubber into silica with 157 nmF2-laser radiation. The 2 mm thick silicone was exposed through a thin (˜0.2 mm) air layer to generate oxygen radicals that chemically assisted in the silica transformation. Silica waveguides were defined in 8-16 µm wide exposure strips by a proximity Cr-on-CaF2 photomask. Optimum laser processing conditions are presented for generating crack-free waveguides with good optical transparency at red (635 nm) and infrared (1550 nm) wavelengths. A propagation loss of ˜6 dB/cm is reported at the 1550 nm wavelength.

  5. 157 nm F2-laser writing of silica optical waveguides in silicone rubber.

    PubMed

    Okoshi, Masayuki; Li, Jianzhao; Herman, Peter R

    2005-10-15

    Silica (SiO2) optical waveguides have been fabricated on the surface of silicone [(SiO(CH3)2)n] rubber by photochemical modification of silicone rubber into silica with 157 nm F2-laser radiation. The 2 mm thick silicone was exposed through a thin (approximately 0.2 mm) air layer to generate oxygen radicals that chemically assisted in the silica transformation. Silica waveguides were defined in 8-16 microm wide exposure strips by a proximity Cr-on-CaF2 photomask. Optimum laser processing conditions are presented for generating crack-free waveguides with good optical transparency at red (635 nm) and infrared (1550 nm) wavelengths. A propagation loss of approximately 6 dB/cm is reported at the 1550 nm wavelength. PMID:16252756

  6. Super ACO FEL oscillation at 300 nm

    NASA Astrophysics Data System (ADS)

    Nutarelli, D.; Garzella, D.; Renault, E.; Nahon, L.; Couprie, M. E.

    2000-05-01

    Some recent improvements, involving both the optical cavity mirrors and the positron beam dynamics in the storage ring, have allowed us to achieve a laser oscillation at 300 nm on the Super ACO Storage Ring FEL. The Super ACO storage ring is operated at 800 MeV which is the nominal energy for the usual synchrotron radiation users, and the highest energy for a storage ring FEL. The lasing at 300 nm could be kept during 2 h per injection, with a stored current ranging between 30 and 60 mA. The FEL characteristics are presented here. The longitudinal stability and the FEL optics behaviour are also discussed.

  7. 1550-nm wavelength-tunable HCG VCSELs

    NASA Astrophysics Data System (ADS)

    Chase, Christopher; Rao, Yi; Huang, Michael; Chang-Hasnain, Connie

    2014-02-01

    We demonstrate wavelength-tunable VCSELs using high contrast gratings (HCGs) as the top output mirror on VCSELs, operating at 1550 nm. Tunable HCG VCSELs with a ~25 nm mechanical tuning range as well as VCSELs with 2 mW output power were realized. Error-free operation of an optical link using directly-modulated tunable HCG VCSELs transmitting at 1.25 Gbps over 18 channels spaced by 100 GHz and transmitted over 20 km of single mode fiber is demonstrated, showing the suitability of the HCG tunable VCSEL as a low cost source for WDM communications systems.

  8. Comparative study of Nd:KGW lasers pumped at 808 nm and 877 nm

    NASA Astrophysics Data System (ADS)

    Huang, Ke; Ge, Wen-Qi; Zhao, Tian-Zhuo; He, Jian-Guo; Feng, Chen-Yong; Fan, Zhong-Wei

    2015-10-01

    The laser performance and thermal analysis of Nd:KGW laser continuously pumped by 808 nm and 877 nm are comparatively investigated. Output power of 670 mW and 1587 mW, with nearly TEM00 mode, are achieved respectively at 808 nm pump and 877 nm pump. Meanwhile, a high-power passively Q-switched Nd:KGW/Cr4+:YAG laser pumped at 877 nm is demonstrated. An average output power of 1495 mW is obtained at pump power of 5.22 W while the laser is operating at repetition of 53.17 kHz. We demonstrate that 877 nm diode laser is a more potential pump source for Nd:KGW lasers.

  9. 635nm diode laser biostimulation on cutaneous wounds

    NASA Astrophysics Data System (ADS)

    Solmaz, Hakan; Gülsoy, Murat; Ülgen, Yekta

    2014-05-01

    Biostimulation is still a controversial subject in wound healing studies. The effect of laser depends of not only laser parameters applied but also the physiological state of the target tissue. The aim of this project is to investigate the biostimulation effects of 635nm laser irradiation on the healing processes of cutaneous wounds by means of morphological and histological examinations. 3-4 months old male Wistar Albino rats weighing 330 to 350 gr were used throughout this study. Low-level laser therapy was applied through local irradiation of red light on open skin excision wounds of 5mm in diameter prepared via punch biopsy. Each animal had three identical wounds on their right dorsal part, at which two of them were irradiated with continuous diode laser of 635nm in wavelength, 30mW of power output and two different energy densities of 1 J/cm2 and 3 J/cm2. The third wound was kept as control group and had no irradiation. In order to find out the biostimulation consequences during each step of wound healing, which are inflammation, proliferation and remodeling, wound tissues removed at days 3, 7, 10 and 14 following the laser irradiation are morphologically examined and than prepared for histological examination. Fragments of skin including the margin and neighboring healthy tissue were embedded in paraffin and 6 to 9 um thick sections cut are stained with hematoxylin and eosin. Histological examinations show that 635nm laser irradiation accelerated the healing process of cutaneous wounds while considering the changes of tissue morphology, inflammatory reaction, proliferation of newly formed fibroblasts and formation and deposition of collagen fibers. The data obtained gives rise to examine the effects of two distinct power densities of low-level laser irradiation and compare both with the non-treatment groups at different stages of healing process.

  10. Preparation of thick molybdenum targets

    NASA Technical Reports Server (NTRS)

    Singh, J. J.

    1974-01-01

    Thick natural molybdenum deposits on nickel plated copper substrates were prepared by thermal decomposition of molybdenum hexacarbonyl vapors on a heated surface in an inert gas atmosphere. The molybdenum metal atoms are firmly bonded to the substrate atoms, thus providing an excellent thermal contact across the junction. Molybdenum targets thus prepared should be useful for internal bombardment in a cyclotron where thermal energy inputs can exceed 10 kW.

  11. Soliton models for thick branes

    NASA Astrophysics Data System (ADS)

    Peyravi, Marzieh; Riazi, Nematollah; Lobo, Francisco S. N.

    2016-05-01

    In this work, we present new soliton solutions for thick branes in 4+1 dimensions. In particular, we consider brane models based on the sine-Gordon (SG), φ 4 and φ 6 scalar fields, which have broken Z2 symmetry in some cases and are responsible for supporting and stabilizing the thick branes. The origin of the symmetry breaking in these models resides in the fact that the modified scalar field potential may have non-degenerate vacua. These vacua determine the cosmological constant on both sides of the brane. We also study the geodesic equations along the fifth dimension, in order to explore the particle motion in the neighborhood of the brane. Furthermore, we examine the stability of the thick branes, by determining the sign of the w^2 term in the expansion of the potential for the resulting Schrödinger-like equation, where w is the five-dimensional coordinate. It turns out that the φ ^4 brane is stable, while there are unstable modes for certain ranges of the model parameters in the SG and φ ^6 branes.

  12. Central Corneal Thickness in Children

    PubMed Central

    2011-01-01

    Objective To report the central corneal thickness (CCT) in healthy white, African-American, and Hispanic children from birth to 17 years of age. Design Prospective observational multicenter study. Central corneal thickness was measured with a hand-held contact pachymeter. Results Two thousand seventy-nine children were included in the study, with ages ranging from day of birth to 17 years. Included were 807 white, 494 Hispanic, and 474 African-American individuals, in addition to Asian, unknown and mixed race individuals. African-American children had thinner corneas on average than that of both white (p< .001) and Hispanic children (p< .001) by approximately 20 micrometers. Thicker median CCT was observed with each successive year of age from age 1 to 11 years, with year-to-year differences steadily decreasing and reaching a plateau after age 11 at 573 micrometers in white and Hispanic children and 551 micrometers in African-American children. For every 100 micrometers of thicker CCT measured, the intraocular pressure was 1.5 mmHg higher on average (p< 0.001). For every diopter of increased myopic refractive error (p< 0.001) CCT was 1 micrometer thinner on average. Conclusions Median CCT increases with age from 1 to 11 years with the greatest increase present in the youngest age groups. African-American children on average have thinner central corneas than white and Hispanic children, while white and Hispanic children demonstrate similar central corneal thickness. PMID:21911662

  13. Thickness of western mare basalts

    NASA Technical Reports Server (NTRS)

    Dehon, R. A.

    1979-01-01

    An isopach map of the basalt thickness in the western mare basins is constructed from measurements of the exposed external rim height of partially buried craters. The data, although numerically sparse, is sufficiently distributed to yield gross thickness variations. The average basalt thickness in Oceanus Procellarum and adjacent regions is 400 m with local lenses in excess of 1500 m in the circular maria. The total volume of basalt in the western maria is estimated to be in the range of 1.5 x 10 to the 6th power cu km. The chief distinction between the eastern and western maria appears to be one of basalt volumes erupted to the surface. Maximum volumes of basalt are deposited west of the central highlands and flood subjacent terrain to a greater extent than on the east. The surface structures of the western maria reflect the probability of a greater degree of isostatic response to a larger surface loading by the greater accumulation of mare basalt.

  14. Critical thickness and strain relaxation in molecular beam epitaxy-grown SrTiO3 films

    NASA Astrophysics Data System (ADS)

    Wang, Tianqi; Ganguly, Koustav; Marshall, Patrick; Xu, Peng; Jalan, Bharat

    2013-11-01

    We report on the study of the critical thickness and the strain relaxation in epitaxial SrTiO3 film grown on (La0.3Sr0.7)(Al0.65Ta0.35)O3 (001) (LSAT) substrate using the hybrid molecular beam epitaxy approach. No change in the film's lattice parameter (both the in-plane and the out-of-plane) was observed up to a film thickness of 180 nm, which is in sharp contrast to the theoretical critical thickness of ˜12 nm calculated using the equilibrium theory of strain relaxation. For film thicknesses greater than 180 nm, the out-of-plane lattice parameter was found to decrease hyperbolically in an excellent agreement with the relaxation via forming misfit dislocations. Possible mechanisms are discussed by which the elastic strain energy can be accommodated prior to forming misfit dislocations leading to such anomalously large critical thickness.

  15. Measuring Metal Thickness With an Electric Probe

    NASA Technical Reports Server (NTRS)

    Shumka, A.

    1986-01-01

    Thickness of metal parts measured from one side with aid of Kelvin probe. Method developed for measuring thickness of end plate on sealed metal bellows from outside. Suitable for thicknesses of few thousandth's of inch (few hundred micrometers). Method also used to determine thickness of metal coatings applied by sputtering, electroplating, and flame spraying.

  16. Measuring Rind Thickness on Polyurethane Foam

    NASA Technical Reports Server (NTRS)

    Johnson, C.; Miller, J.; Brown, H.

    1985-01-01

    Nondestructive test determines rind thickness of polyurethane foam. Surface harness of foam measured by Shore durometer method: hardness on Shore D scale correlates well with rind thickness. Shore D hardness of 20, for example, indicates rind thickness of 0.04 inch (1 millimeter). New hardness test makes it easy to determine rind thickness of sample nondestructively and to adjust fabrication variables accordingly.

  17. Radiation Tolerance of 65nm CMOS Transistors

    DOE PAGESBeta

    Krohn, M.; Bentele, B.; Christian, D. C.; Cumalat, J. P.; Deptuch, G.; Fahim, F.; Hoff, J.; Shenai, A.; Wagner, S. R.

    2015-12-11

    We report on the effects of ionizing radiation on 65 nm CMOS transistors held at approximately -20°C during irradiation. The pattern of damage observed after a total dose of 1 Grad is similar to damage reported in room temperature exposures, but we observe less damage than was observed at room temperature.

  18. Negative-tone 193-nm resists

    NASA Astrophysics Data System (ADS)

    Cho, Sungseo; Vander Heyden, Anthony; Byers, Jeff D.; Willson, C. Grant

    2000-06-01

    A great deal of progress has been made in the design of single layer positive tone resists for 193 nm lithography. Commercial samples of such materials are now available from many vendors. The patterning of certain levels of devices profits from the use of negative tone resists. There have been several reports of work directed toward the design of negative tones resists for 193 nm exposure but, none have performed as well as the positive tone systems. Polymers with alicyclic structures in the backbone have emerged as excellent platforms from which to design positive tone resists for 193 nm exposure. We now report the adaptation of this class of polymers to the design of high performance negative tone 193 nm resists. New systems have been prepared that are based on a polarity switch mechanism for modulation of the dissolution rate. The systems are based on a polar, alicyclic polymer backbone that includes a monomer bearing a glycol pendant group that undergoes the acid catalyzed pinacol rearrangement upon exposure and bake to produce the corresponding less polar ketone. This monomer was copolymerized with maleic anhydride and a norbornene bearing a bis-trifluoromethylcarbinol. The rearrangement of the copolymer was monitored by FT-IR as a function of temperature. The synthesis of the norbornene monomers will be presented together with characterization of copolymers of these monomers with maleic anhydride. The lithographic performance of the new resist system will also be presented.

  19. White Sands, Carrizozo Lava Beds, NM

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A truly remarkable view of White Sands and the nearby Carrizozo Lava Beds in southeast NM (33.5N, 106.5W). White Sands, site of the WW II atomic bomb development and testing facility and later post war nuclear weapons testing that can still be seen in the cleared circular patterns on the ground.

  20. Tuning the thickness of electrochemically grafted layers in large area molecular junctions

    SciTech Connect

    Fluteau, T.; Bessis, C.; Barraud, C. Della Rocca, M. L.; Lafarge, P.; Martin, P.; Lacroix, J.-C.

    2014-09-21

    We have investigated the thickness, the surface roughness, and the transport properties of oligo(1-(2-bisthienyl)benzene) (BTB) thin films grafted on evaporated Au electrodes, thanks to a diazonium-based electro-reduction process. The thickness of the organic film is tuned by varying the number of electrochemical cycles during the growth process. Atomic force microscopy measurements reveal the evolution of the thickness in the range of 2–27 nm. Its variation displays a linear dependence with the number of cycles followed by a saturation attributed to the insulating behavior of the organic films. Both ultrathin (2 nm) and thin (12 and 27 nm) large area BTB-based junctions have then been fabricated using standard CMOS processes and finally electrically characterized. The electronic responses are fully consistent with a tunneling barrier in case of ultrathin BTB film whereas a pronounced rectifying behavior is reported for thicker molecular films.

  1. Thickness dependent optical and electrical properties of CdSe thin films

    NASA Astrophysics Data System (ADS)

    Purohit, A.; Chander, S.; Nehra, S. P.; Lal, C.; Dhaka, M. S.

    2016-05-01

    The effect of thickness on the optical and electrical properties of CdSe thin films is investigated in this paper. The films of thickness 445 nm, 631 nm and 810 nm were deposited on glass and ITO coated glass substrates using thermal evaporation technique. The deposited thin films were thermally annealed in air atmosphere at temperature 100°C and were subjected to UV-Vis spectrophotometer and source meter for optical and electrical analysis respectively. The absorption coefficient is observed to increase with photon energy and found maximum in higher photon energy region. The extinction coefficient and refractive index are also calculated. The electrical analysis shows that the electrical resistivity is observed to be decreased with thickness.

  2. Unconventional spin distributions in thick Ni80Fe20 nanodisks

    NASA Astrophysics Data System (ADS)

    Kumar, D.; Lupo, P.; Haldar, A.; Adeyeye, A. O.

    2016-05-01

    We study the spin distributions in permalloy (Py: Ni80Fe20) nanodisks as a function of diameter D (300 nm ≤ D ≤ 1 μm) and thickness L (30 nm ≤ L ≤ 100 nm). We observed that beyond a certain thickness, for a fixed disk diameter, an unconventional spin topology precipitates which is marked by the presence of a divergence field within the magnetic vortex curl. The strength of this divergence changes anti-symmetrically from negative to positive—depending on the core polarity—along the axis of the cylindrical nanodisk. This is also accompanied by a skyrmion-like out-of-plane bending of the spin vectors farther away from the disk center. Additionally, the vortex core dilates significantly when compared to its typical size. This has been directly observed using magnetic force microscopy. We determined from the ferromagnetic resonance spectroscopy measurements that the unconventional topology in the thicker nanodisks gyrated at a frequency, which is significantly lower than what is predicted by a magnetic vortex based analytical model. Micromagnetic simulations involving dipolar and exchange interactions appear to satisfactorily reproduce the experimentally observed static and dynamic behaviors. Besides providing a physical example of an unconventional topology, these results can also aid the design of topologically protected memory elements.

  3. Effect of flake thickness on coercivity of nanocrystalline SmCo5 bulk prepared from anisotropic nanoflake powder

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Leontsev, S.; Sheets, A. O.; Horwath, J. C.; Turgut, Z.

    2016-05-01

    In this study, nanocrystalline SmCo5 bulk magnets were prepared by hot-pressing of nanoflake powders fabricated via surfactant-assisted high energy ball milling. Effect of the flake thickness on magnetic coercivity of the SmCo5 bulk was investigated. Anisotropic SmCo5 nanoflakes with thickness between 100 and 1000 nm were prepared by varying the milling parameter of ball-to-powder weight ratio. XRD analysis revealed that as-milled flake powders possessed nanocrystalline grains with no observable oxide peaks. The coercivity of the flake powders varied between 19.9 and 21.3 kOe for 1000 nm to 100 nm thick flakes, which indicated that the flake thickness in this range had no obvious effect on the coercivity of the powders. However, the coercivity of the bulks showed a strong dependence on the flake thickness. The bulk coercivity value of 10.97 kOe corresponding to the flake thickness of 100 nm, was 80% higher compared to the bulk prepared with the flakes of 1000 nm. XRD results on compacted samples did not show any grain growth, however, Sm2O3 and free Co were detected in SmCo5 bulks and their content increased with reduced flake thickness. Interestingly enough the bulk coercivity was not deteriorated with the presence of Sm oxide and Co.

  4. Activationless charge transport across 4.5 to 22 nm in molecular electronic junctions

    PubMed Central

    Yan, Haijun; Bergren, Adam Johan; McCreery, Richard; Della Rocca, Maria Luisa; Martin, Pascal; Lafarge, Philippe; Lacroix, Jean Christophe

    2013-01-01

    In this work, we bridge the gap between short-range tunneling in molecular junctions and activated hopping in bulk organic films, and greatly extend the distance range of charge transport in molecular electronic devices. Three distinct transport mechanisms were observed for 4.5–22-nm-thick oligo(thiophene) layers between carbon contacts, with tunneling operative when d < 8 nm, activated hopping when d > 16 nm for high temperatures and low bias, and a third mechanism consistent with field-induced ionization of highest occupied molecular orbitals or interface states to generate charge carriers when d = 8–22 nm. Transport in the 8–22-nm range is weakly temperature dependent, with a field-dependent activation barrier that becomes negligible at moderate bias. We thus report here a unique, activationless transport mechanism, operative over 8–22-nm distances without involving hopping, which severely limits carrier mobility and device lifetime in organic semiconductors. Charge transport in molecular electronic junctions can thus be effective for transport distances significantly greater than the 1–5 nm associated with quantum-mechanical tunneling. PMID:23509271

  5. Activationless charge transport across 4.5 to 22 nm in molecular electronic junctions.

    PubMed

    Yan, Haijun; Bergren, Adam Johan; McCreery, Richard; Della Rocca, Maria Luisa; Martin, Pascal; Lafarge, Philippe; Lacroix, Jean Christophe

    2013-04-01

    In this work, we bridge the gap between short-range tunneling in molecular junctions and activated hopping in bulk organic films, and greatly extend the distance range of charge transport in molecular electronic devices. Three distinct transport mechanisms were observed for 4.5-22-nm-thick oligo(thiophene) layers between carbon contacts, with tunneling operative when d < 8 nm, activated hopping when d > 16 nm for high temperatures and low bias, and a third mechanism consistent with field-induced ionization of highest occupied molecular orbitals or interface states to generate charge carriers when d = 8-22 nm. Transport in the 8-22-nm range is weakly temperature dependent, with a field-dependent activation barrier that becomes negligible at moderate bias. We thus report here a unique, activationless transport mechanism, operative over 8-22-nm distances without involving hopping, which severely limits carrier mobility and device lifetime in organic semiconductors. Charge transport in molecular electronic junctions can thus be effective for transport distances significantly greater than the 1-5 nm associated with quantum-mechanical tunneling. PMID:23509271

  6. New polymer for 157-nm single-layer resist based on fluorine-containing acryl copolymer

    NASA Astrophysics Data System (ADS)

    Ogata, Toshiyuki; Endo, Koutaro; Komano, Hiroshi; Nakayama, Toshimasa

    2001-08-01

    We are reporting on the development of acryl polymer based on novel methacrylate and acrylate monomers with various trifluoromethyl groups for the application to 157nm chemically amplified positive-tone resists. The (alpha) - trifluoromethylation of the alkyl ester in methacrylate or acrylate could employ the reduction of acrylpolymer absorbance at 157nm by spectra analysis with the VUV-200 spectrophotometer by JASCO. Although the trifluoromethyl groups could employ the reduction of base polymer absorbance at 157nm, the homopolymers have issued weak etch resistance as a photoresist base polymer. To take account of this issue, we have developed a novel monomer, trifluoromethyl- iso-adamantylmethacrylate (TFIAdMA) and a new co-polymer system with the combination of fluorinated methacrylate derivatives and substituted p-hydroxystyrene. The absorption coefficient of poly(p-tert-butoxystyren-co- hexafluoro-tert-butyl methacrylate-co-methacrylic acid) incicated to be less than 3 micrometers -1 at 157nm. Patterning results were obtained with a 157nm contact exposure system of VUVES-4500 by LTJ. One of the experimental resists, based on a particular polymer ratio and photo acid generator, has clearly achieved 180nm line and space pattern resolution. At 140nm resist film thickness, the sensitivity was 31 mJ/cm2 when using 0,26N tetrametylammonium hydroxide surfactant type developer.

  7. VizieR Online Data Catalog: Thorium spectrum from 250nm to 5500nm (Redman+, 2014)

    NASA Astrophysics Data System (ADS)

    Redman, S. L.; Nave, G.; Sansonetti, C. J.

    2014-04-01

    We observed the spectrum of a commercial sealed Th/Ar HCL running at 25mA for almost 15hr starting on 2011 November 2. The region of observation was limited to between 8500/cm and 28000/cm (360nm and 1200nm) by the sensitivity of the silicon photodiode detector. (5 data files).

  8. Influence of the interface on the magnetic properties of ferromagnetic ultrathin films with various adjacent copper thicknesses

    NASA Astrophysics Data System (ADS)

    Zhang, Dong; Jiang, Sheng; Luo, Chen; Wang, Yukun; Rui, Wenbin; Zhai, Ya; Du, Jun; Zhai, Hongru

    2014-05-01

    The interface and magnetic properties of two series of films with Ta(5 nm)/Fe20Ni80Nd0.017(3 nm)/Cu(t nm) and Ta(5 nm)/Cu(t nm)/Fe50Co50Gd0.07(3 nm)/Cu(2 nm) structures have been investigated by atomic force microscopy, vibrating sample magnetometer, and ferromagnetic resonance (FMR). The roughness of all films increases with increasing copper thickness, which causes the different grain sizes in the surface of films. The coercivity of FeCo-Gd films increases with increasing thickness of inserted Cu layer while decreases with increasing thickness of Cu capping layer for FeNi-Nd films. FMR linewidth exhibits huge dependence on the thickness of inserted Cu layer for FeCo-Gd films, increasing from 2270 to 3680 Oe, which comes from the additional contribution of effect of the two-magnon scattering. And the thickness of Cu capping layer shows also an influence on FMR linewidth of FeNi-Nd films, increasing from 190 to 320 Oe, which mainly comes from intrinsic FMR linewidth and plus minor inhomogeneous broadening. All of these extrinsic linewidth broadening are related to the interface roughness.

  9. Enhanced radiation tolerance in nitride multilayered nanofilms with small period-thicknesses

    SciTech Connect

    Hong Mengqing; Ren Feng; Zhang Hongxiu; Xiao Xiangheng; Tian Canxin; Fu Dejun; Jiang Changzhong; Yang Bing; Wang Yongqiang

    2012-10-08

    This paper demonstrates a substantial enhancement in radiation tolerance for small period-thickness of CrN/AlTiN multilayered nanofilms. CrN/AlTiN multilayered nanofilms with period-thicknesses of 3, 5, 7, and 9 nm were irradiated by 190 keV Ar{sup +} ions to fluences ranging from 1 to 5 Multiplication-Sign 10{sup 16} ions/cm{sup 2}. Nanofilm with 3 nm period-thickness begins to be amorphized under 5 Multiplication-Sign 10{sup 16} ions/cm{sup 2}, while those with larger period-thicknesses are amorphized under 3 Multiplication-Sign 10{sup 16} ions/cm{sup 2}. Our results show that multilayered ceramic nanofilms are potential radiation tolerant materials with good properties. The interfaces in the multilayered nanofilms act as good sinks to absorb the radiation-induced defects.

  10. Ultrathin to Nano Thickness TiN Coatings: Processing, Structural, Mechanical Behavior

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Kumar, Rakesh; Soni; Sreemany, M.; Pathak, L. C.

    2015-12-01

    The fabrication of titanium nitride (TiN) thin films with varying thicknesses by reactive magnetron sputtering at different substrate temperatures as well as deposition times has been investigated. With the increase of deposition times from 1 to 120 min, the TiN film thickness is increased from 15 nm to 2.1 µm. The effect of thickness and substrate temperature on the mechanical, microstructural, and structural behavior of these fabricated thin TiN films is investigated. The average hardness is found to vary between 22 and 42 GPa and modulus between 300 and 527 GPa. The grain sizes increase with the thickness of the deposited films and it is observed to vary between 20 and 65 nm.

  11. Thickness dependence on the optoelectronic properties of multilayered GaSe based photodetector

    NASA Astrophysics Data System (ADS)

    Ko, Pil Ju; Abderrahmane, Abdelkader; Takamura, Tsukasa; Kim, Nam-Hoon; Sandhu, Adarsh

    2016-08-01

    Two-dimensional (2D) layered materials exhibit unique optoelectronic properties at atomic thicknesses. In this paper, we fabricated metal–semiconductor–metal based photodetectors using layered gallium selenide (GaSe) with different thicknesses. The electrical and optoelectronic properties of the photodetectors were studied, and these devices showed good electrical characteristics down to GaSe flake thicknesses of 30 nm. A photograting effect was observed in the absence of a gate voltage, thereby implying a relatively high photoresponsivity. Higher values of the photoresponsivity occurred for thicker layers of GaSe with a maximum value 0.57 AW‑1 and external quantum efficiency of of 132.8%, and decreased with decreasing GaSe flake thickness. The detectivity was 4.05 × 1010 cm Hz1/2 W‑1 at 532 nm laser wavelength, underscoring that GaSe is a promising p-type 2D material for photodetection applications in the visible spectrum.

  12. Ordering of self-assembled 5-nm-diameter poly(dimethylsiloxane) nanodots with sub-10 nm pitch using ultra-narrow electron-beam-drawn guide lines and three-dimensional control

    SciTech Connect

    Zhang, Hui; Hosaka, Sumio; Yin, You

    2014-03-03

    We demonstrate the possibility of forming long-range ordered self-assembled arrays of 5-nm-diameter nanodots with pitch of 10 × 7.5 nm{sup 2} using guide line templates and low molecular weight (MW) (4700–1200 g/mol) poly(styrene)-poly(dimethylsiloxane) (PS-PDMS) for application in ultrahigh density patterned magnetic recording media. We propose a three-dimensional control which involves control of the height of the guide lines, the thickness of the PS-PDMS films, and the gap between the guide lines in order to produce 5-nm-diameter, sub-10 nm pitched nanodots with long-range order along the guide lines. Adopting a 13-nm-thick PS-PDMS film and 14-nm-high resist guide lines, the 5-nm-diameter and 10 × 7.5 nm{sup 2}-pitched self-assembled nanodots were ordered in 4–7 dot arrays with long-range order. The experimental results demonstrate that the method is suitable for the production of patterned media with magnetic recording densities of 8.6 Tbit/in.{sup 2} using low MW PS-PDMS and slim guide lines.

  13. Oxide thickness dependence of resistive switching characteristics for Ni/HfOx/Pt resistive random access memory device

    NASA Astrophysics Data System (ADS)

    Ito, Daisuke; Hamada, Yoshihumi; Otsuka, Shintaro; Shimizu, Tomohiro; Shingubara, Shoso

    2015-06-01

    The switching process of the conductive filament formed in Ni/HfOx/Pt resistive random access memory (ReRAM) devices were studied. We evaluated the oxide thickness dependence and temperature dependence of voltage for the Forming, Set and Reset operations for HfOx layers whose thickness are between 3.3 and 6.5 nm. The resistance of conductive filaments showed typical metallic behavior, which suggests Ni filament formation in the HfOx layer. There is a clear dependence of switching voltages for the Set and Reset processes on oxide thickness, which implies that the formation and rupture of conductive filaments occur in the entire thickness range of the HfOx layer. This finding differs from that of a previous study by Yang, which suggests the existence of a constant-thickness switching region. It is suggested that the thickness of the switching region in HfOx may be larger than 6.5 nm.

  14. Measurement of lateral charge diffusion in thick, fully depleted, back-illuminated CCDs

    SciTech Connect

    Karcher, Armin; Bebek, Christopher J.; Kolbe, William F.; Maurath, Dominic; Prasad, Valmiki; Uslenghi, Michela; Wagner, Martin

    2004-06-30

    Lateral charge diffusion in back-illuminated CCDs directly affects the point spread function (PSF) and spatial resolution of an imaging device. This can be of particular concern in thick, back-illuminated CCDs. We describe a technique of measuring this diffusion and present PSF measurements for an 800 x 1100, 15 mu m pixel, 280 mu m thick, back-illuminated, p-channel CCD that can be over-depleted. The PSF is measured over a wavelength range of 450 nm to 650 nm and at substrate bias voltages between 6 V and 80 V.

  15. Optimal thickness of silicon membranes to achieve maximum thermoelectric efficiency: A first principles study

    NASA Astrophysics Data System (ADS)

    Mangold, Claudia; Neogi, Sanghamitra; Donadio, Davide

    2016-08-01

    Silicon nanostructures with reduced dimensionality, such as nanowires, membranes, and thin films, are promising thermoelectric materials, as they exhibit considerably reduced thermal conductivity. Here, we utilize density functional theory and Boltzmann transport equation to compute the electronic properties of ultra-thin crystalline silicon membranes with thickness between 1 and 12 nm. We predict that an optimal thickness of ˜7 nm maximizes the thermoelectric figure of merit of membranes with native oxide surface layers. Further thinning of the membranes, although attainable in experiments, reduces the electrical conductivity and worsens the thermoelectric efficiency.

  16. Topography measurements of the critical thickness of ZnSe grown on GaAs

    NASA Astrophysics Data System (ADS)

    Horsburgh, G.; Prior, K. A.; Meredith, W.; Galbraith, I.; Cavenett, B. C.; Whitehouse, C. R.; Lacey, G.; Cullis, A. G.; Parbrook, P. J.; Möck, P.; Mizuno, K.

    1998-06-01

    Synchrotron-based x-ray topography (XRT) measurements have been used to study the initial stages of relaxation in ZnSe layers grown by molecular beam epitaxy on vertical gradient freeze Bridgman GaAs substrates. The formation of the very first strain-relieving misfit dislocations in the grown ZnSe layers has been detected in a layer of thickness 100 nm. No such dislocations have been observed in a corresponding layer of 95 nm thickness. The critical thickness for this material system is therefore estimated to be 97.5±2.5 nm, which is markedly lower than the widely accepted value of 150 nm. In contrast to the InGaAs/GaAs system, combined XRT and transmission electron microscopy studies indicate that the initial misfit dislocations observed for ZnSe/GaAs are not, in general, formed by the bending over of pre-existing threading dislocations into the interface, but by other mechanisms such as stacking fault decomposition. The critical thickness data obtained have been used to infer the maximum critical thickness of CdZnSe quantum wells possible in II-VI laser diodes.

  17. Thickness Considerations of Two-Dimensional Layered Semiconductors for Transistor Applications.

    PubMed

    Zhang, Youwei; Li, Hui; Wang, Haomin; Xie, Hong; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-01-01

    Layered two-dimensional semiconductors have attracted tremendous attention owing to their demonstrated excellent transistor switching characteristics with a large ratio of on-state to off-state current, Ion/Ioff. However, the depletion-mode nature of the transistors sets a limit on the thickness of the layered semiconductor films primarily determined by a given Ion/Ioff as an acceptable specification. Identifying the optimum thickness range is of significance for material synthesis and device fabrication. Here, we systematically investigate the thickness-dependent switching behavior of transistors with a wide thickness range of multilayer-MoS2 films. A difference in Ion/Ioff by several orders of magnitude is observed when the film thickness, t, approaches a critical depletion width. The decrease in Ion/Ioff is exponential for t between 20 nm and 100 nm, by a factor of 10 for each additional 10 nm. For t larger than 100 nm, Ion/Ioff approaches unity. Simulation using technical computer-aided tools established for silicon technology faithfully reproduces the experimentally determined scaling behavior of Ion/Ioff with t. This excellent agreement confirms that multilayer-MoS2 films can be approximated as a homogeneous semiconductor with high surface conductivity that tends to deteriorate Ion/Ioff. Our findings are helpful in guiding material synthesis and designing advanced field-effect transistors based on the layered semiconductors. PMID:27403803

  18. Thickness Considerations of Two-Dimensional Layered Semiconductors for Transistor Applications

    NASA Astrophysics Data System (ADS)

    Zhang, Youwei; Li, Hui; Wang, Haomin; Xie, Hong; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-07-01

    Layered two-dimensional semiconductors have attracted tremendous attention owing to their demonstrated excellent transistor switching characteristics with a large ratio of on-state to off-state current, Ion/Ioff. However, the depletion-mode nature of the transistors sets a limit on the thickness of the layered semiconductor films primarily determined by a given Ion/Ioff as an acceptable specification. Identifying the optimum thickness range is of significance for material synthesis and device fabrication. Here, we systematically investigate the thickness-dependent switching behavior of transistors with a wide thickness range of multilayer-MoS2 films. A difference in Ion/Ioff by several orders of magnitude is observed when the film thickness, t, approaches a critical depletion width. The decrease in Ion/Ioff is exponential for t between 20 nm and 100 nm, by a factor of 10 for each additional 10 nm. For t larger than 100 nm, Ion/Ioff approaches unity. Simulation using technical computer-aided tools established for silicon technology faithfully reproduces the experimentally determined scaling behavior of Ion/Ioff with t. This excellent agreement confirms that multilayer-MoS2 films can be approximated as a homogeneous semiconductor with high surface conductivity that tends to deteriorate Ion/Ioff. Our findings are helpful in guiding material synthesis and designing advanced field-effect transistors based on the layered semiconductors.

  19. Thickness Considerations of Two-Dimensional Layered Semiconductors for Transistor Applications

    PubMed Central

    Zhang, Youwei; Li, Hui; Wang, Haomin; Xie, Hong; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

    2016-01-01

    Layered two-dimensional semiconductors have attracted tremendous attention owing to their demonstrated excellent transistor switching characteristics with a large ratio of on-state to off-state current, Ion/Ioff. However, the depletion-mode nature of the transistors sets a limit on the thickness of the layered semiconductor films primarily determined by a given Ion/Ioff as an acceptable specification. Identifying the optimum thickness range is of significance for material synthesis and device fabrication. Here, we systematically investigate the thickness-dependent switching behavior of transistors with a wide thickness range of multilayer-MoS2 films. A difference in Ion/Ioff by several orders of magnitude is observed when the film thickness, t, approaches a critical depletion width. The decrease in Ion/Ioff is exponential for t between 20 nm and 100 nm, by a factor of 10 for each additional 10 nm. For t larger than 100 nm, Ion/Ioff approaches unity. Simulation using technical computer-aided tools established for silicon technology faithfully reproduces the experimentally determined scaling behavior of Ion/Ioff with t. This excellent agreement confirms that multilayer-MoS2 films can be approximated as a homogeneous semiconductor with high surface conductivity that tends to deteriorate Ion/Ioff. Our findings are helpful in guiding material synthesis and designing advanced field-effect transistors based on the layered semiconductors. PMID:27403803

  20. Structure and laser-fabrication mechanisms of microcones on silver films of variable thickness

    NASA Astrophysics Data System (ADS)

    Danilov, P. A.; Zayarny, D. A.; Ionin, A. A.; Kudryashov, S. I.; Nguyen, T. T. H.; Rudenko, A. A.; Saraeva, I. N.; Kuchmizhak, A. A.; Vitrik, O. B.; Kulchin, Yu. N.

    2016-04-01

    Submicron dimensions, nanoscale crystalline structure, and fabrication mechanisms of microcones on silver films of variable (50-380 nm) thickness deposited onto glass substrates by single strongly focused femtosecond laser pulses of different fluences are experimentally studied using scanning electron microscopy. Fabrication mechanisms for nanoholes and microcones are discussed for films of the different thickness, as well as the extraordinary shapes of their constituent nanocrystallites, strongly elongated along the melt flow direction in thin films.

  1. Laser damage database at 1064 nm

    SciTech Connect

    Rainer, F.; Gonzales, R.P.; Morgan, A.J.

    1990-03-01

    In conjunction with our diversification of laser damage testing capabilities, we have expanded upon a database of threshold measurements and parameter variations at 1064 nm. This includes all tests at low pulse-repetition frequencies (PRF) ranging from single shots to 120 Hz. These tests were conducted on the Reptile laser facility since 1987 and the Variable Pulse Laser (VPL) facility since 1988. Pulse durations ranged from 1 to 16 ns. 10 refs., 14 figs.

  2. Sunlight induced 685 nm fluorescence imagery

    NASA Technical Reports Server (NTRS)

    Kim, Hongsuk H.; Van Der Piepen, Heinz

    1986-01-01

    The capability of a new fluorescence method is evaluated using data from an aircraft fluorescence experiment conducted on the Elbe River on August 10-14, 1981. The technique measures chlorophyll concentrations by monitoring sunlight-induced fluorescence at 685 nm. Upwelling radiance spectra and vertical profiles of upwelling radiances are presented and analyzed. The image-processing algorithm used to retrieve fluorescence signals from raw data is described.

  3. Radiation Status of Sub-65 nm Electronics

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.

    2011-01-01

    Ultra-scaled complementary metal oxide semiconductor (CMOS) includes commercial foundry capabilities at and below the 65 nm technology node Radiation evaluations take place using standard products and test characterization vehicles (memories, logic/latch chains, etc.) NEPP focus is two-fold: (1) Conduct early radiation evaluations to ascertain viability for future NASA missions (i.e. leverage commercial technology development). (2) Uncover gaps in current testing methodologies and mechanism comprehension -- early risk mitigation.

  4. Binary 193nm photomasks aging phenomenon study

    NASA Astrophysics Data System (ADS)

    Dufaye, Félix; Sartelli, Luca; Pogliani, Carlo; Gough, Stuart; Sundermann, Frank; Miyashita, Hiroyuki; Hidenori, Yoshioka; Charras, Nathalie; Brochard, Christophe; Thivolle, Nicolas

    2011-05-01

    193nm binary photomasks are still used in the semiconductor industry for the lithography of some critical layers for the nodes 90nm and 65nm, with high volumes and over long period. These 193nm binary masks seem to be well-known but recent studies have shown surprising degrading effects, like Electric Field induced chromium Migration (EFM) [1] or chromium migration [2] [3] . Phase shift Masks (PSM) or Opaque MoSi On Glass (OMOG) might not be concerned by these effects [4] [6] under certain conditions. In this paper, we will focus our study on two layers gate and metal lines. We will detail the effects of mask aging, with SEM top view pictures revealing a degraded chromium edge profile and TEM chemical analyses demonstrating the growth of a chromium oxide on the sidewall. SEMCD measurements after volume production indicated a modified CD with respect to initial CD data after manufacture. A regression analysis of these CD measurements shows a radial effect, a die effect and an isolated-dense effect. Mask cleaning effectiveness has also been investigated, with sulphate or ozone cleans, to recover the mask quality in terms of CD. In complement, wafer intrafield CD measurements have been performed on the most sensitive structure to monitor the evolution of the aging effect on mask CD uniformity. Mask CD drift have been correlated with exposure dose drift and isolated-dense bias CD drift on wafers. In the end, we will try to propose a physical explanation of this aging phenomenon and a solution to prevent from it occurring.

  5. The dynamics of femtosecond pulsed laser removal of 20 nm Ni films from an interface

    SciTech Connect

    Schrider, Keegan J.; Yalisove, Steven M.; Torralva, Ben

    2015-09-21

    The dynamics of femtosecond laser removal of 20 nm Ni films on glass substrates was studied using time-resolved pump-probe microscopy. 20 nm thin films exhibit removal at two distinct threshold fluences, removal of the top 7 nm of Ni above 0.14 J/cm{sup 2}, and removal of the entire 20 nm film above 0.36 J/cm{sup 2}. Previous work shows the top 7 nm is removed through liquid spallation, after irradiation the Ni melts and rapidly expands leading to tensile stress and cavitation within the Ni film. This work shows that above 0.36 J/cm{sup 2} the 20 nm film is removed in two distinct layers, 7 nm and 13 nm thick. The top 7 nm layer reaches a speed 500% faster than the bottom 13 nm layer at the same absorbed fluence, 500–2000 m/s and 300–700 m/s in the fluence ranges studied. Significantly different velocities for the top 7 nm layer and bottom 13 nm layer indicate removal from an interface occurs by a different physical mechanism. The method of measuring film displacement from the development of Newton's rings was refined so it could be shown that the 13 nm layer separates from the substrate within 70 ps and accelerates to its final velocity within several hundred picoseconds. We propose that removal of the bottom 13 nm is consistent with heterogeneous nucleation and growth of vapor at the Ni-glass interface, but that the rapid separation and acceleration of the 13 nm layer from the Ni-glass interface requires consideration of exotic phases of Ni after excitation.

  6. High Density Crossbar Arrays with Sub- 15 nm Single Cells via Liftoff Process Only

    PubMed Central

    Khiat, Ali; Ayliffe, Peter; Prodromakis, Themistoklis

    2016-01-01

    Emerging nano-scale technologies are pushing the fabrication boundaries at their limits, for leveraging an even higher density of nano-devices towards reaching 4F2/cell footprint in 3D arrays. Here, we study the liftoff process limits to achieve extreme dense nanowires while ensuring preservation of thin film quality. The proposed method is optimized for attaining a multiple layer fabrication to reliably achieve 3D nano-device stacks of 32 × 32 nanowire arrays across 6-inch wafer, using electron beam lithography at 100 kV and polymethyl methacrylate (PMMA) resist at different thicknesses. The resist thickness and its geometric profile after development were identified to be the major limiting factors, and suggestions for addressing these issues are provided. Multiple layers were successfully achieved to fabricate arrays of 1 Ki cells that have sub- 15 nm nanowires distant by 28 nm across 6-inch wafer. PMID:27585643

  7. High Density Crossbar Arrays with Sub- 15 nm Single Cells via Liftoff Process Only.

    PubMed

    Khiat, Ali; Ayliffe, Peter; Prodromakis, Themistoklis

    2016-01-01

    Emerging nano-scale technologies are pushing the fabrication boundaries at their limits, for leveraging an even higher density of nano-devices towards reaching 4F(2)/cell footprint in 3D arrays. Here, we study the liftoff process limits to achieve extreme dense nanowires while ensuring preservation of thin film quality. The proposed method is optimized for attaining a multiple layer fabrication to reliably achieve 3D nano-device stacks of 32 × 32 nanowire arrays across 6-inch wafer, using electron beam lithography at 100 kV and polymethyl methacrylate (PMMA) resist at different thicknesses. The resist thickness and its geometric profile after development were identified to be the major limiting factors, and suggestions for addressing these issues are provided. Multiple layers were successfully achieved to fabricate arrays of 1 Ki cells that have sub- 15 nm nanowires distant by 28 nm across 6-inch wafer. PMID:27585643

  8. Micromagnetic simulations of 200-nm-diameter cobalt nanorings using a Reuleaux triangular geometry

    NASA Astrophysics Data System (ADS)

    Torres-Heredia, J. J.; López-Urías, F.; Muñoz-Sandoval, E.

    2006-10-01

    Using micromagnetic simulations, we investigated the magnetic states and switching processes of Co nanorings with lateral dimensions of 200 nm. We propose a special geometry of nanorings that adopts different Reuleaux triangular shapes. Reuleaux's triangles (RT) combine both the equilateral triangle and circular geometries. We studied the magnetic spin configurations of individual nanorings by varying the thickness and geometry of the nanomagnets. Our results demonstrated that in most nanomagnets exhibiting a thickness of less than 4 nm, there exists an onion-type state, which precedes either a twisted, double twisted, or cardioid state, when studying the magnetization reversal process. The hysteresis loops and magnetic states found in these RTs are compared with circular nanorings.

  9. AIMS mask qualification for 32nm node

    NASA Astrophysics Data System (ADS)

    Richter, Rigo; Thaler, Thomas; Seitz, Holger; Stroessner, Ulrich; Scheruebl, Thomas

    2009-10-01

    Moving forward to 32nm node and below optical lithography using 193nm is faced with complex requirements to be solved. Mask makers are forced to address both Double Patterning Techniques and Computational Lithography approaches such as Source Mask Optimizations and Inverse Lithography. Additionally, lithography at low k1 values increases the challenges for mask repair as well as for repair verification and review by AIMSTM. Higher CD repeatability, more flexibility in the illumination settings as well as significantly improved image performance must be added when developing the next generation mask qualification equipment. This paper reports latest measurement results verifying the appropriateness of the latest member of AIMSTM measurement tools - the AIMSTM 32-193i. We analyze CD repeatability measurements on lines and spaces pattern. The influence of the improved optical performance and newly introduced interferometer stage will be verified. This paper highlights both the new Double Patterning functionality emulating double patterning processes and the influence of its critical parameters such as overlay errors and resist impact. Beneficial advanced illumination schemes emulating scanner illumination document the AIMSTM 32-193i to meet mask maker community's requirements for the 32nm node.

  10. High-resolution projection image reconstruction of thick objects by hard x-ray diffraction microscopy

    SciTech Connect

    Takahashi, Yukio; Nishino, Yoshinori; Tsutsumi, Ryosuke; Zettsu, Nobuyuki; Matsubara, Eiichiro; Yamauchi, Kazuto; Ishikawa, Tetsuya

    2010-12-01

    Hard x-ray diffraction microscopy enables us to observe thick objects at high spatial resolution. The resolution of this method is limited, in principle, by only the x-ray wavelength and the largest scattering angle recorded. As the resolution approaches the wavelength, the thickness effect of objects plays a significant role in x-ray diffraction microscopy. In this paper, we report high-resolution hard x-ray diffraction microscopy for thick objects. We used highly focused coherent x rays with a wavelength of {approx}0.1 nm as an incident beam and measured the diffraction patterns of a {approx}150-nm-thick silver nanocube at the scattering angle of {approx}3 deg. We observed a characteristic contrast of the coherent diffraction pattern due to only the thickness effect and collected the diffraction patterns at nine incident angles so as to obtain information on a cross section of Fourier space. We reconstructed a pure projection image by the iterative phasing method from the patched diffraction pattern. The edge resolution of the reconstructed image was {approx}2 nm, which was the highest resolution so far achieved by x-ray microscopy. The present study provides us with a method for quantitatively observing thick samples at high resolution by hard x-ray diffraction microscopy.

  11. Orientations of Diblock Copolymer Microdomains at Different Film Thicknesses

    NASA Astrophysics Data System (ADS)

    Chaikin, Paul; Park, Miri; Harrison, Christopher; Register, Richard; Adamson, Doug

    1996-03-01

    We prepared films with a range of thicknesses (50-300 nm) of a styrene-butadiene diblock copolymer, synthesized to produce a cylindrical morphology. Solutions of different polymer concentrations in toluene were spun onto carbon-coated glass slides. The films were then placed onto a Transmission Electron Microscope (TEM) grid by water lift-off, annealed, stained with osmium tetraoxide, and examined with a TEM. Over a wide range of film thicknesses, the cylinders lie parallel to the substrate. We present preliminary results that show a cylinder orientation perpendicular to the substrate at a thickness of many microdomain spacings. We speculate that the alignment mechanism is different from that found in a previous study of Kraton D1102(M. A. van Dijk and R. van den Berg, Macromolecules 28), 6773 (1995) which shows a perpendicular orientation with spin-coated films, but for a film thickness between one and two microdomain spacings. This work was supported by the NSF under DMR 9400362.

  12. Characterization of a nanometer-thick sputtered polytetrafluoroethylene film

    NASA Astrophysics Data System (ADS)

    Li, Lei; Jones, Paul M.; Hsia, Yiao-Tee

    2011-02-01

    Fast growth of nanotechnology, e.g. hard disk drive (HDD) and microelectromechanical system/nanoelectromechanical system (MEMS/NEMS), requires nanometer-thick protection films with high thermal stability and low surface energy. In this paper, we report the characterization results of a nanometer-thick sputtered polytetrafluoroethylene (PTFE) film prepared by radio frequency (RF) sputtering. Atomic force microscopy (AFM) and X-ray reflectivity (XRR) results show that the nanometer-thick sputtered PTFE film has good uniformity. Thermally programmed desorption (TPD) results show that the film is thermally stable up to 430 °C. Surface energy measurement via contact angle method shows that the film has low surface energy with the thickness as low as 1.5 nm. X-ray photoelectron spectroscopy (XPS) data suggests that the film has crosslinked molecular structure, which results in amorphous morphology as shown by X-ray diffraction (XRD) data. Nano-indentation testing shows that the sputtered film has higher hardness and modulus than bulk PTFE. The structure-property relationship has been discussed.

  13. Sub-50nm extreme ultraviolet holographic imaging

    NASA Astrophysics Data System (ADS)

    Wachulak, P. W.; Marconi, M. C.; Bartels, R. A.; Menoni, C. S.; Rocca, J. J.

    2009-05-01

    Imaging tools for nanoscicence involving sub-100-nm scale objects have been dominated by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and electron microscopy (SEM, TEM). These imaging techniques have contributed substantially to the development of nanoscience, providing a very powerful diagnostic tool capable of obtaining images with atomic resolution or as a subsidiary mechanism to arrange or modify surfaces also at the atomic scale [1,2]. However, some important problems have persisted traditional nanoscale imaging techniques. For example when scanning a nanometer size object that is not attached rigidly to a surface the interaction with the tip significantly perturbs the specimen degrading or eventually precluding the image acquisition. Electron microscopy often requires surface preparation, consisting of metallization of the sample to avoid surface charging. Additionally the metallization of the sample may alter its characteristics and also limits the resolution. In both cases, if the sample is large (millimeters in size) due to the limited field of view, the image obtained with these conventional methods is only representative of a very small portion of the object. Wavelength-limited holographic imaging using carbon nanotubes as the test object with a table-top extreme ultraviolet (EUV) laser operating at 46.9 nm will be discussed. The resolution achieved in this imaging is evaluated with a rigorous correlation image analysis and confirmed with the conventional knife-edge test. The nano-holography presented requires no optics or critical beam alignment; thus the hologram recording scheme is very simple and does not need special sample preparation. In holography, image contrast requires absorption to provide scattering by the illuminating beam. The EUV laser wavelength employed in this experiment (46.9nm) is advantageous because carbon based materials typically exhibit very small attenuation lengths, around 25 nm. The high absorption of

  14. Compression behaviour of thick vertically aligned carbon nanotube blocks.

    PubMed

    Pavese, Matteo; Musso, Simone; Pugno, Nicola M

    2010-07-01

    Blocks of vertically aligned multiwall carbon nanotubes were prepared by thermal chemical vapor deposition starting from camphor and ferrocene precursors. The blocks, having a thickness of approximately 2 mm and composed of nanotubes with diameter ranging between 30 and 80 nm, were submitted to compression tests. The results were analyzed accordingly with a simple model consisting in a parallel array of nanotubes under compression and bending suffering microscopic instability and compaction. The model mostly fits the experimental stress-strain curves, with a small deviation attributed to dissipative phenomena, such as frictional forces and nanotube wall breakage. PMID:21128406

  15. Scaling of laser-induced contamination growth at 266nm and 355nm

    NASA Astrophysics Data System (ADS)

    Ließmann, M.; Jensen, L.; Balasa, I.; Hunnekuhl, M.; Büttner, A.; Weßels, P.; Neumann, J.; Ristau, D.

    2015-11-01

    The growth of laser-induced contamination (LIC) on optical components in extraterrestrial missions is a known issue especially for the UV spectral region. The Laser Zentrum Hannover e.V. is responsible for the development of a pulsed laser-system operating at a wavelength of 266 nm for the ExoMars mission and for the qualification of used optics and materials regarding LIC. In this context, toluene was utilized which is an often used model contaminant in LIC studies. Test cycles based on the application of the two UV wavelengths 355 nm and 266 nm on fused silica substrates and ARcoated optics are conducted and the observed contamination effects are compared. This scaling allows for a rough estimate of the destructive influence of LIC on space optics degradation at 266 nm. Further tests will be performed with materials integrated into the ExoMars-laser-head under near-operation environmental conditions.

  16. An 885-nm Direct Pumped Nd:CNGG 1061 nm Q-Switched Laser

    NASA Astrophysics Data System (ADS)

    Li, Qi-Nan; Zhang, Tao; Feng, Bao-Hua; Zhang, Zhi-Guo; Zhang, Huai-Jin; Wang, Ji-Yang

    2014-07-01

    The 885 nm direct pumping method, directly into the 4F3/2 emitting level of Nd3+ ion, is used to a Nd:CNGG crystal to product passive Q-switched 1061 nm laser pulses, for the first time to the best of our knowledge. A maximum average output power of 1.16 W for 1061 nm Q-switched pulses and a repetition rate of 12.54 kHz are obtained. The pulse width is measured to be 24 ns and the peak power is 3.843 kW. A high-quality fundamental transverse mode can be observed owing to the reduction of the thermal effect for Nd:CNGG crystal by 885 nm direct pumping.

  17. 1064 nm Nd:YAG laser intracavity pumped at 946 nm and sum-frequency mixing for an emission at 501 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Xia, J.; Jin, G. Y.; Wang, J. G.; Yin, X. D.; Zhang, A. F.

    2010-05-01

    We present for the first time a Nd:YAG laser emitting at 1064 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 809 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1064 nm intracavity pumped at 946 nm. Intracavity sum-frequency mixing at 946 and 1064 nm was then realized in a LBO crystal to reach the cyan range. We obtained a continuous-wave output power of 485 mW at 501 nm with a pump laser diode emitting 25.4 W at 809 nm.

  18. High Temperature Superconducting Thick Films

    DOEpatents

    Arendt, Paul N.; Foltyn, Stephen R.; Groves, James R.; Holesinger, Terry G.; Jia, Quanxi

    2005-08-23

    An article including a substrate, a layer of an inert oxide material upon the surface of the substrate, (generally the inert oxide material layer has a smooth surface, i.e., a RMS roughness of less than about 2 nm), a layer of an amorphous oxide or oxynitride material upon the inert oxide material layer, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the amorphous oxide material layer is provided together with additional layers such as at least one layer of a buffer material upon the oriented cubic oxide material layer or a HTS top-layer of YBCO directly upon the oriented cubic oxide material layer. With a HTS top-layer of YBCO upon at least one layer of a buffer material in such an article, Jc's of 1.4×106 A/cm2 have been demonstrated with projected Ic's of 210 Amperes across a sample 1 cm wide.

  19. Thickness dependence of dielectric loss in SrTiO3 thin films

    NASA Astrophysics Data System (ADS)

    Li, Hong-Cheng; Si, Weidong; West, Alexander D.; Xi, X. X.

    1998-07-01

    We have measured the dielectric loss in SrTiO3 thin films grown on SrRuO3 electrode layers with thickness ranging from 25 nm to 2.5 μm. The loss depends strongly on the thickness but differently above and below T≈80 K: as the thickness increases, the loss decreases at high temperatures but becomes higher at low temperatures. Our result suggests that, in the high temperature regime, the interfacial dead layer effect dominates while, in the low temperature regime, the losses related to the structural phase transition and quantum fluctuations are important.

  20. First-principles study of the critical thickness in asymmetric ferroelectric tunnel junctions

    NASA Astrophysics Data System (ADS)

    Cai, Meng-Qiu; Du, Yong; Huang, Bo-Yun

    2011-03-01

    The absent critical thickness of fully relaxed asymmetric ferroelectric tunnel junctions is investigated by first-principles calculations. The results show that PbTiO3 thin film between Pt and SrRuO3 electrodes can still retain a significant and stable polarization down to thicknesses as small as 0.8 nm, quite unlike the case of symmetric ferroelectric tunnel junctions. We trace this surprising result to the generation of a large electric field by the charge transfer between the electrodes caused by their different electronic environments, which acts against the depolarization field and enhances the ferroelectricity, leading to the reduction, or even complete elimination, for the critical thickness.

  1. Correlation of CsK{sub 2}Sb photocathode lifetime with antimony thickness

    SciTech Connect

    Mamun, M. A. Elmustafa, A. A.; Hernandez-Garcia, C.; Poelker, M.

    2015-06-01

    CsK{sub 2}Sb photocathodes with quantum efficiency on the order of 10% at 532 nm, and lifetime greater than 90 days at low voltage, were successfully manufactured via co-deposition of alkali species emanating from an effusion source. Photocathodes were characterized as a function of antimony layer thickness and alkali consumption, inside a vacuum chamber that was initially baked, but frequently vented without re-baking. Photocathode lifetime measured at low voltage is correlated with the antimony layer thickness. Photocathodes manufactured with comparatively thick antimony layers exhibited the best lifetime. We speculate that the antimony layer serves as a reservoir, or sponge, for the alkali.

  2. Correlation of CsK2Sb photocathode lifetime with antimony thickness

    SciTech Connect

    Mamun, M. A.; Hernandez-Garcia, C.; Poelker, M.; Elmustafa, A. A.

    2015-06-01

    CsK2Sb photocathodes with quantum efficiency on the order of 10% at 532 nm, and lifetime greater than 90 days at low voltage, were successfully manufactured via co-deposition of alkali species emanating from an effusion source. Photocathodes were characterized as a function of antimony layer thickness and alkali consumption, inside a vacuum chamber that was initially baked, but frequently vented without re-baking. Photocathode lifetime measured at low voltage is correlated with the antimony layer thickness. Photocathodes manufactured with comparatively thick antimony layers exhibited the best lifetime. We speculate that the antimony layer serves as a reservoir, or sponge, for the alkali.

  3. Effect of thickness on electrical properties of SILAR deposited SnS thin films

    NASA Astrophysics Data System (ADS)

    Akaltun, Yunus; Astam, Aykut; Cerhan, Asena; ćayir, Tuba

    2016-03-01

    Tin sulfide (SnS) thin films of different thickness were prepared on glass substrates by successive ionic layer adsorption and reaction (SILAR) method at room temperature using tin (II) chloride and sodium sulfide aqueous solutions. The thicknesses of the films were determined using spectroscopic ellipsometry measurements and found to be 47.2, 65.8, 111.0, and 128.7nm for 20, 25, 30 and 35 deposition cycles respectively. The electrical properties of the films were investigated using d.c. two-point probe method at room temperature and the results showed that the resistivity was found to decrease with increasing film thickness.

  4. Fluorinated dissolution inhibitors for 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Hamad, Alyssandrea H.; Bae, Young C.; Liu, Xiang-Qian; Ober, Christopher K.; Houlihan, Francis M.; Dabbagh, Gary; Novembre, Anthony E.

    2002-07-01

    Fluorinated dissolution inhibitors (DIs) for 157 nm lithography were designed and synthesized as part of an ongoing study on the structure/property relationships of photoresist additives. The problem of volatilization of small DI candidates was observed from matrices such as poly(methyl methacrylate) (PMMA) and poly(hexafluorohydroxy-isopropyl styrene) (PHFHIPS) during post-apply bake cycles using Fourier Transform Infrared Spectroscopy (FT-IR). To avoid this problem, low volatility fluorinated inhibitors were designed and synthesized. Three fluorinated DIs, perfluorosuberic acid bis-(2,2,2,-trifluoro-1-phenyl-1-trifluoromethyl-ethyl) ester (PFSE1), perfluorosuberic acid bis-[1-(4-trifluoromethyl-phenyl)-ethyl] ester (PFSE2) and a fluorinated phenylmethanediol diester (FPMD1), largely remained in a PHFHIPS film during the post-apply bake. The dissolution behavior of the two fluorinated diesters was studied and found to slow down the dissolution rate of PHFHIPS with inhibition factors of 1.9 and 1.6, respectively. The absorbance of PHFHIPS films containing 10 wt% of the diester inhibitors is 3.6 AU/micron compared with an absorbance of 3.3 AU/micron for the polymer itself. The absorbance of 10% FPMD1 in PHFHIPS was measured as 3.5 AU/micron compared with an absorbance of 3.4 AU/micron for the polymer itself. Thus, the non-volatility and transparency of the fluorinated inhibitors at 157 nm as well as their ability to reduce the development rate of fluorinated polymers make them suitable for use in a 157 nm resist system.

  5. Amputee Socks: Thickness of Multiple Socks

    PubMed Central

    Cagle, John C; Yu, Alan J; Ciol, Marcia A; Sanders, JE

    2015-01-01

    Background and Aim It is unclear how total sock ply and thickness are related when more than one sock is worn. The objectives were to determine if the thickness of one multi-ply amputee sock of ply P was the same as the thickness of a stack of reduced-ply socks of total ply P; and if the thickness of N single socks stacked one on top of the other was equal to the sum (1 to N) of the single sock thicknesses. Technique Using a custom instrument, compressive stresses were applied while sock thickness was measured. Discussion The thickness of one multi-ply sock of ply P was typically less than the thickness of a stack of reduced-ply socks of total ply P. The thickness of N single socks stacked one on top of the other was approximately equal to the sum (1 to N) of the single sock thicknesses. Clinical Relevance Our findings suggest three 1-ply socks to be 20% greater in thickness than one 3-ply sock, and one 3-ply + two 1-ply socks to be 30% greater in thickness than one 5-ply sock. PMID:24240023

  6. Quantitative comparison of the OCT imaging depth at 1300 nm and 1600 nm

    PubMed Central

    Kodach, V. M.; Kalkman, J.; Faber, D. J.; van Leeuwen, T. G.

    2010-01-01

    One of the present challenges in optical coherence tomography (OCT) is the visualization of deeper structural morphology in biological tissues. Owing to a reduced scattering, a larger imaging depth can be achieved by using longer wavelengths. In this work, we analyze the OCT imaging depth at wavelengths around 1300 nm and 1600 nm by comparing the scattering coefficient and OCT imaging depth for a range of Intralipid concentrations at constant water content. We observe an enhanced OCT imaging depth for 1600 nm compared to 1300 nm for Intralipid concentrations larger than 4 vol.%. For higher Intralipid concentrations, the imaging depth enhancement reaches 30%. The ratio of scattering coefficients at the two wavelengths is constant over a large range of scattering coefficients and corresponds to a scattering power of 2.8 ± 0.1. Based on our results we expect for biological tissues an increase of the OCT imaging depth at 1600 nm compared to 1300 nm for samples with high scattering power and low water content. PMID:21258456

  7. Near infrared imaging of teeth at wavelengths between 1200 and 1600 nm

    NASA Astrophysics Data System (ADS)

    Chung, Soojeong; Fried, Daniel; Staninec, Michal; Darling, Cynthia L.

    2011-03-01

    Near-IR (NIR) imaging is a new technology that is currently being investigated for the detection and assessment of dental caries without the use of ionizing radiation. Several papers have been published on the use of transillumination and reflectance NIR imaging to detect early caries in enamel. The purpose of this study was to investigate alternative near infrared wavelengths besides 1300-nm in the range from 1200- 1600-nm to determine the wavelengths that yield the highest contrast in both transmission and reflectance imaging modes. Artificial lesions were created on thirty tooth sections of varying thickness for transillumination imaging. NIR images at wavelengths from the visible to 1600-nm were also acquired for fifty-four whole teeth with occlusal lesions using a tungsten halogen lamp with several spectral filters and a Ge-enhanced CMOS image sensor. Cavity preparations were also cut into whole teeth and Z250 composite was used as a restorative material to determine the contrast between composite and enamel at NIR wavelengths. Slightly longer NIR wavelengths are likely to have better performance for the transillumination of occlusal caries lesions while 1300-nm appears best for the transillumination of proximal surfaces. Significantly higher performance was attained at wavelengths that have higher water absorption, namely 1460-nm and wavelengths greater than 1500-nm and these wavelength regions are likely to be more effective for reflectance imaging. Wavelengths with higher water absorption also provided higher contrast of composite restorations.

  8. Mechanisms involved in HBr and Ar cure plasma treatments applied to 193 nm photoresists

    NASA Astrophysics Data System (ADS)

    Pargon, E.; Menguelti, K.; Martin, M.; Bazin, A.; Chaix-Pluchery, O.; Sourd, C.; Derrough, S.; Lill, T.; Joubert, O.

    2009-05-01

    In this article, we have performed detailed investigations of the 193 nm photoresist transformations after exposure to the so-called HBr and Ar plasma cure treatments using various characterization techniques (x-ray photoelectron spectroscopy, Fourier transformed infrared, Raman analyses, and ellipsometry). By using windows with different cutoff wavelengths patched on the photoresist film, the role of the plasma vacuum ultraviolet (VUV) light on the resist modifications is clearly outlined and distinguished from the role of radicals and ions from the plasma. The analyses reveal that both plasma cure treatments induce severe surface and bulk chemical modifications of the resist films. The synergistic effects of low energetic ion bombardment and VUV plasma light lead to surface graphitization or cross-linking (on the order of 10 nm), while the plasma VUV light (110-210 nm) is clearly identified as being responsible for ester and lactone group removal from the resist bulk. As the resist modification depth depends strongly on the wavelength penetration into the material, it is found that HBr plasma cure that emits near 160-170 nm can chemically modify the photoresist through its entire thickness (240 nm), while the impact of Ar plasmas emitting near 100 nm is more limited. In the case of HBr cure treatment, Raman and ellipsometry analyses reveal the formation of sp2 carbon atoms in the resist bulk, certainly thanks to hydrogen diffusion through the resist film assisted by the VUV plasma light.

  9. Mechanisms involved in HBr and Ar cure plasma treatments applied to 193 nm photoresists

    SciTech Connect

    Pargon, E.; Menguelti, K.; Martin, M.; Bazin, A.; Joubert, O.; Lill, T.

    2009-05-01

    In this article, we have performed detailed investigations of the 193 nm photoresist transformations after exposure to the so-called HBr and Ar plasma cure treatments using various characterization techniques (x-ray photoelectron spectroscopy, Fourier transformed infrared, Raman analyses, and ellipsometry). By using windows with different cutoff wavelengths patched on the photoresist film, the role of the plasma vacuum ultraviolet (VUV) light on the resist modifications is clearly outlined and distinguished from the role of radicals and ions from the plasma. The analyses reveal that both plasma cure treatments induce severe surface and bulk chemical modifications of the resist films. The synergistic effects of low energetic ion bombardment and VUV plasma light lead to surface graphitization or cross-linking (on the order of 10 nm), while the plasma VUV light (110-210 nm) is clearly identified as being responsible for ester and lactone group removal from the resist bulk. As the resist modification depth depends strongly on the wavelength penetration into the material, it is found that HBr plasma cure that emits near 160-170 nm can chemically modify the photoresist through its entire thickness (240 nm), while the impact of Ar plasmas emitting near 100 nm is more limited. In the case of HBr cure treatment, Raman and ellipsometry analyses reveal the formation of sp{sup 2} carbon atoms in the resist bulk, certainly thanks to hydrogen diffusion through the resist film assisted by the VUV plasma light.

  10. Thickness-Dependent Structural and Optoelectronic Properties of In2O3 Films Prepared by Spray Pyrolysis Technique

    NASA Astrophysics Data System (ADS)

    Khan, M. A. Majeed; Khan, Wasi

    2016-08-01

    In this work, nanostructured In2O3 thin films with thickness in the range of 40-160 nm were deposited on glass substrates by the chemical spray pyrolysis technique. The microstructural, surface morphology and optical properties were investigated as a function of film thickness through x-ray diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy, atomic force microscopy, Raman spectroscopy, UV-visible spectroscopy and photoluminescence measurements. The x-ray diffraction analysis showed that the deposited films were polycrystalline in nature with a cubic structure having (222) as preferred orientation. The morphological analyses of the samples exhibited uniform and smooth surface of the films with systematical increments in the surface roughness with increasing film thickness. The grain size increased from 9 nm to 13 nm with increasing film thickness. Raman spectroscopy has been employed to study the crystalline quality and the structural disorder of the films. A blue-shift in the energy band gap ( E g) from 3.74 eV to 3.98 eV was observed with the increase of film thickness. Moreover, photoluminescence peaks of the In2O3 films appeared at 443 nm and 527 nm for all films. The thickness had a substantial influence on the microstructural and optical properties as well as on the luminescence intensity of the films. The strategy presented here indicates that the prepared films could be suitable candidates for optoelectronic device applications.

  11. Co thickness dependence of structural and magnetic properties in spin quantum cross devices utilizing stray magnetic fields

    SciTech Connect

    Kaiju, H. Kasa, H.; Mori, S.; Misawa, T.; Abe, T.; Nishii, J.; Komine, T.

    2015-05-07

    We investigate the Co thickness dependence of the structural and magnetic properties of Co thin-film electrodes sandwiched between borate glasses in spin quantum cross (SQC) devices that utilize stray magnetic fields. We also calculate the Co thickness dependence of the stray field between the two edges of Co thin-film electrodes in SQC devices using micromagnetic simulation. The surface roughness of Co thin films with a thickness of less than 20 nm on borate glasses is shown to be as small as 0.18 nm, at the same scanning scale as the Co film thickness, and the squareness of the hysteresis loop is shown to be as large as 0.96–1.0. As a result of the establishment of polishing techniques for Co thin-film electrodes sandwiched between borate glasses, we successfully demonstrate the formation of smooth Co edges and the generation of stray magnetic fields from Co edges. Theoretical calculation reveals that a strong stray field beyond 6 kOe is generated when the Co thickness is greater than 10 nm at a junction gap distance of 5 nm. From these experimental and calculation results, it can be concluded that SQC devices with a Co thickness of 10–20 nm can be expected to function as spin-filter devices.

  12. Thickness-Dependent Structural and Optoelectronic Properties of In2O3 Films Prepared by Spray Pyrolysis Technique

    NASA Astrophysics Data System (ADS)

    Khan, M. A. Majeed; Khan, Wasi

    2016-05-01

    In this work, nanostructured In2O3 thin films with thickness in the range of 40-160 nm were deposited on glass substrates by the chemical spray pyrolysis technique. The microstructural, surface morphology and optical properties were investigated as a function of film thickness through x-ray diffraction, scanning electron microscopy equipped with energy dispersive spectroscopy, atomic force microscopy, Raman spectroscopy, UV-visible spectroscopy and photoluminescence measurements. The x-ray diffraction analysis showed that the deposited films were polycrystalline in nature with a cubic structure having (222) as preferred orientation. The morphological analyses of the samples exhibited uniform and smooth surface of the films with systematical increments in the surface roughness with increasing film thickness. The grain size increased from 9 nm to 13 nm with increasing film thickness. Raman spectroscopy has been employed to study the crystalline quality and the structural disorder of the films. A blue-shift in the energy band gap (E g) from 3.74 eV to 3.98 eV was observed with the increase of film thickness. Moreover, photoluminescence peaks of the In2O3 films appeared at 443 nm and 527 nm for all films. The thickness had a substantial influence on the microstructural and optical properties as well as on the luminescence intensity of the films. The strategy presented here indicates that the prepared films could be suitable candidates for optoelectronic device applications.

  13. Photolysis of formic acid at 355 nm

    NASA Astrophysics Data System (ADS)

    Martinez, Denhi; Bautista, Teonanacatl; Guerrero, Alfonso; Alvarez, Ignacio; Cisneros, Carmen

    2015-05-01

    Formic acid is well known as a food additive and recently an application on fuel cell technology has emerged. In this work we have studied the dissociative ionization process by multiphoton absorption of formic acid molecules at 355nm wavelength photons, using TOF spectrometry in reflectron mode (R-TOF). Some of the most abundant ionic fragments produced are studied at different settings of the laser harmonic generator. The dependence of the products on these conditions is reported. This work was supported by CONACYT Project 165410 and PAPIIT IN102613 and IN101215.

  14. 248nm silicon photoablation: Microstructuring basics

    NASA Astrophysics Data System (ADS)

    Poopalan, P.; Najamudin, S. H.; Wahab, Y.; Mazalan, M.

    2015-05-01

    248nm pulses from a KrF excimer laser was used to ablate a Si wafer in order to ascertain the laser pulse and energy effects for use as a microstructuring tool for MEMS fabrication. The laser pulses were varied between two different energy levels of 8mJ and 4mJ while the number of pulses for ablation was varied. The corresponding ablated depths were found to range between 11 µm and 49 µm, depending on the demagnified beam fluence.

  15. 248nm silicon photoablation: Microstructuring basics

    SciTech Connect

    Poopalan, P.; Najamudin, S. H.; Wahab, Y.; Mazalan, M.

    2015-05-15

    248nm pulses from a KrF excimer laser was used to ablate a Si wafer in order to ascertain the laser pulse and energy effects for use as a microstructuring tool for MEMS fabrication. The laser pulses were varied between two different energy levels of 8mJ and 4mJ while the number of pulses for ablation was varied. The corresponding ablated depths were found to range between 11 µm and 49 µm, depending on the demagnified beam fluence.

  16. Demonstration of pattern transfer into sub-100 nm polysilicon line/space features patterned with extreme ultraviolet lithography

    SciTech Connect

    Cardinale, G. F.; Henderson, C. C.; Goldsmith, J. E. M.; Mangat, P. J. S.; Cobb, J.; Hector, S. D.

    1999-11-01

    In two separate experiments, we have successfully demonstrated the transfer of dense- and loose-pitch line/space (L/S) photoresist features, patterned with extreme ultraviolet (EUV) lithography, into an underlying hard mask material. In both experiments, a deep-UV photoresist ({approx}90 nm thick) was spin cast in bilayer format onto a hard mask (50-90 nm thick) and was subsequently exposed to EUV radiation using a 10x reduction EUV exposure system. The EUV reticle was fabricated at Motorola (Tempe, AZ) using a subtractive process with Ta-based absorbers on Mo/Si multilayer mask blanks. In the first set of experiments, following the EUV exposures, the L/S patterns were transferred first into a SiO{sub 2} hard mask (60 nm thick) using a reactive ion etch (RIE), and then into polysilicon (350 nm thick) using a triode-coupled plasma RIE etcher at the University of California, Berkeley, microfabrication facilities. The latter etch process, which produced steep (>85 degree sign ) sidewalls, employed a HBr/Cl chemistry with a large (>10:1) etch selectivity of polysilicon to silicon dioxide. In the second set of experiments, hard mask films of SiON (50 nm thick) and SiO{sub 2} (87 nm thick) were used. A RIE was performed at Motorola using a halogen gas chemistry that resulted in a hard mask-to-photoresist etch selectivity >3:1 and sidewall profile angles {>=}85 degree sign . Line edge roughness (LER) and linewidth critical dimension (CD) measurements were performed using Sandia's GORA(c) CD digital image analysis software. Low LER values (6-9 nm, 3{sigma}, one side) and good CD linearity (better than 10%) were demonstrated for the final pattern-transferred dense polysilicon L/S features from 80 to 175 nm. In addition, pattern transfer (into polysilicon) of loose-pitch (1:2) L/S features with CDs{>=}60 nm was demonstrated. (c) 1999 American Vacuum Society.

  17. High thickness acrylamide photopolymer for peristrophic multiplexing

    NASA Astrophysics Data System (ADS)

    Ortuño, M.; Fernández, E.; Márquez, A.; Gallego, S.; Neipp, C.; Pascual, I.

    2006-05-01

    The acrylamide photolymers are considered interesting materials for holographic media. They have high diffraction efficiency (ratio of the intensities of the diffracted and the incident beams), an intermediate energetic sensitivity among other materials and post-processing steps are not necessary, therefore the media is not altered. The layers of these materials, about 1 mm thick, are a suitable media for recording many diffraction gratings in the same volume of photopolymer using peristrophic multiplexing technique, with great practical importance in the field of holographic memories type WORM (write once read many). In this work we study the recording of diffraction gratings by peristrophic multiplexing with axis of rotation perpendicular to the recording media. The photopolymer is composed of acrylamide as the polymerizable monomer, triethanolamine as radical generator, yellowish eosin as sensitizer and a binder of polyvinyl alcohol. We analyze the holographic behaviour of the material during recording and reconstruction of diffraction gratings using a continuous Nd:YAG laser (532 nm) at an intensity of 5 mW/cm2 as recording laser. The response of the material is monitored after recording with an He-Ne laser. We study the recording process of unslanted diffraction gratings of 1125 lines/mm. The diffraction efficiency of each hologram is seen to decrease as the number of holograms recorded increases, due to consumption of the available dynamic range, in a constant exposure scheduling. It can be seen that the photopolymer works well with high energy levels, without excessive dispersion of light by noise gratings. In order to homogenize the diffraction efficiency of each hologram we use the method proposed by Pu. This method is designed to share all or part of the avaliable dynamic range of the recording material among the holograms to be multiplexed. Using exposure schedules derived from this method we have used 3 scheduling recordings from the algorithm used

  18. 240 kW peak power at 266 nm in nonlinear YAl3(BO3)4 single crystal.

    PubMed

    Ilas, Simon; Loiseau, Pascal; Aka, Gérard; Taira, Takunori

    2014-12-01

    We report the fourth harmonic generation at 266 nm using a type I YAl3(BO3)4 (YAB) single crystal from a Q-switch microchip laser Nd:YAG/Cr⁴⁺:YAG frequency doubled with a LiB3O5 (LBO) crystal. 240 kW peak power at 266 nm corresponding to a mean conversion efficiency of 12.2% from 532 to 266 nm has been obtained with a 2.94 mm thick YAB crystal. The influences of optical homogeneity and absorption on the conversion efficiency are discussed. PMID:25606961

  19. 1085 nm Nd:YVO4 laser intracavity pumped at 914 nm and sum-frequency mixing to reach cyan laser at 496 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Xia, J.; Yin, X. D.; Wang, D.; Zhang, X. H.

    2010-01-01

    We present for the first time a Nd:YVO4 laser at 1085 nm intracavity pumped at 914 nm by a Nd:YVO4 laser. We obtained intracavity powers of 57 W at 914 nm and 62 W at 1085 nm. Using type-I critical phase-matching LiB3O5 (LBO) crystal, a cyan laser at 496 nm is obtained by 914 and 1085 nm intracavity sum-frequency mixing. The maximum laser output power of 142 mW is obtained when an incident pump laser of 19.6 W is used.

  20. The art of photomask materials for low-k1-193nm lithography

    NASA Astrophysics Data System (ADS)

    Hashimoto, Masahiro; Iwashita, Hiroyuki; Mitsui, Hideaki

    2009-04-01

    The resolution of photomask patterns were improved with a hardmask (HM) system. The system which is thin Sicompounds layer is easily etched by the hyper-thin resist (below 100nm thickness). The HM material has sufficient etching selectivity against the chrome-compounds which is the second layer chrome absorber for the phase-shifter. This hardmask layer has been completely removed during the phase-shifter etching. It means that the conventional phase-shit mask (PSM) has been made with the ultimately high-resolution without configuration changes. Below 50nm resolution of PSM was made with 90nm thickness resist on HM layer in this paper. The CD bias between a resist feature CD and a chrome feature CD was almost zero (below 1nm) in the optimized etching condition. We confirmed that the mask performances were the equal to COMS (Cr-HM on MoSi binary mask) in resolution and CD linearity. The performances of hardmask blanks will be defined by resist performance because of almost zero bias.

  1. Synthesis of WS2 Nanowires as Efficient 808 nm-Laser-Driven Photothermal Nanoagents.

    PubMed

    Macharia, Daniel K; Yu, Nuo; Zhong, Runzhi; Xiao, Zhiyin; Yang, Jianmao; Chen, Zhigang

    2016-06-01

    A prerequisite for the development of photothermal ablation therapy for cancer is to obtain efficient photothermal nanoagents that can be irradiated by near-infrared (NIR) laser. Herein, we have reported the synthesis of WS2 nanowires as photothermal nanoagents by the reaction of WCl6 with CS2 in oleylamine at 280 degrees C. WS2 nanowires have the thickness of -2 nm and length of -100 nm. Importantly, the chloroform dispersion of WS2 nanowires exhibits strong photoabsorption in NIR region. The temperature of the dispersion (0.10-0.50 mg/mL) can increase by 12.8-23.9 degrees C in 5 min under the irradiation of 808 nm laser with a power density of 0.80 W/cm2. Therefore, WS2 nanowires have a great superiority as a new nanoagent for NIR-induced photothermal ablation of cancer, due to their small size and excellent photothermal performance. PMID:27427645

  2. The Fabrication of Sub-5-nm Nanochannels in Insulating Substrates using Focused Ion Beam Milling

    PubMed Central

    Menard, Laurent D.; Ramsey, J. Michael

    2011-01-01

    The use of focused ion beam (FIB) milling to fabricate nanochannels with critical dimensions extending below 5 nm is described. FIB milled lines have narrowing widths as they are milled deeper into a substrate. This focusing characteristic is coupled with a two-layered architecture consisting of a relatively thick (>100 nm) metal film deposited onto a substrate. A channel is milled through the metal layer until it penetrates a prescribed depth into the substrate material. The metal is then removed, leaving a nanochannel with smooth surfaces and lateral dimensions as small as sub-5 nm. These open nanochannels can be sealed with a cover plate and the resulting devices are well-suited for single-molecule DNA transport studies. This methodology is used with quartz, single-crystal silicon, and polydimethylsiloxane substrates to demonstrate its general utility. PMID:21171628

  3. Synthesis of boron nitride coatings on quartz fibers: Thickness control and mechanism research

    NASA Astrophysics Data System (ADS)

    Zheng, Yu; Wang, Shubin

    2011-10-01

    Boron nitride (BN) coatings were successfully synthesized on quartz fibers by dip-coating in boric acid and urea solutions at 700 °C. The SEM micrographs indicated that the quartz fibers were fully covered by coatings with smooth surface. The XRD, FT-IR, XPS spectra and HR-TEM results showed that the composition of the coatings which combined closely with the quartz fibers was polycrystalline h-BN. By changing the dip circles, the coating thickness was well controlled. The thicknesses of samples dipped less than six circles increased linearly with dipping-circles; and the increment of coating thickness would slow down when the fibers were dipped 10 circles. After being dipped for 10 circles, the thickness was about 300 nm. The coating thickness was also established by calculation and the calculated results were consistent with the results measured by micrograph.

  4. Effect of film thickness on the antifouling performance of poly(hydroxy-functional methacrylates) grafted surfaces.

    PubMed

    Zhao, Chao; Li, Lingyan; Wang, Qiuming; Yu, Qiuming; Zheng, Jie

    2011-04-19

    The development of nonfouling biomaterials to prevent nonspecific protein adsorption and cell/bacterial adhesion is critical for many biomedical applications, such as antithrombogenic implants and biosensors. In this work, we polymerize two types of hydroxy-functional methacrylates monomers of 2-hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA) into polymer brushes on the gold substrate via surface-initiated atom transfer radical polymerization (SI-ATRP). We systematically examine the effect of the film thickness of polyHEMA and polyHPMA brushes on their antifouling performance in a wide range of biological media including single-protein solution, both diluted and undiluted human blood serum and plasma, and bacteria culture. Surface plasmon resonance (SPR) results show a strong correlation between antifouling property and film thickness. Too thin or too thick polymer brushes lead to large protein adsorption. Surfaces with the appropriate film thickness of ∼25-45 nm for polyHPMA and ∼20-45 nm for polyHEMA can achieve almost zero protein adsorption (<0.3 ng/cm(2)) from single-protein solution and diluted human blood plasma and serum. For undiluted human blood serum and plasma, polyHEMA brushes at a film thickness of ∼20-30 nm adsorb only ∼3.0 and ∼3.5 ng/cm(2) proteins, respectively, while polyHPMA brushes at a film thickness of ∼30 nm adsorb more proteins of ∼13.5 and ∼50.0 ng/cm(2), respectively. Moreover, both polyHEMA and polyHPMA brushes with optimal film thickness exhibit very low bacteria adhesion. The excellent antifouling ability and long-term stability of polyHEMA and polyHPMA brushes make them, especially for polyHEMA, effective and stable antifouling materials for usage in blood-contacting devices. PMID:21405141

  5. Change of interface dipole energy with interfacial layer thickness and O2 plasma treatment in metal/organic interface

    NASA Astrophysics Data System (ADS)

    Kim, Soo Young; Hong, Kihyon; Lee, Jong-Lam

    2007-04-01

    The authors determined the interface dipole energies between interfacial layers with different thicknesses coated on indium tin oxides (ITOs) and 4,4'-bis[N-(1-naphtyl)-N-phenyl-amino]biphenyl using ultraviolet and synchrotron radiation photoemission spectroscopy. The interface dipole energy increased as a function of interfacial layer thickness up to 4nm. After O2 plasma treatment on thick-metal (>4nm) coated ITO, the work function and interface dipole energy increased. In thin-metal (<2nm) coated ITO, no change in the interface dipole energy was found though the work function increased. Thus, the O2 plasma treated thin (<2nm) interfacial layer reduced the hole injection barrier.

  6. Electrically-pumped 850-nm micromirror VECSELs.

    SciTech Connect

    Geib, Kent Martin; Peake, Gregory Merwin; Serkland, Darwin Keith; Keeler, Gordon Arthur; Mar, Alan

    2005-02-01

    Vertical-external-cavity surface-emitting lasers (VECSELs) combine high optical power and good beam quality in a device with surface-normal output. In this paper, we describe the design and operating characteristics of an electrically-pumped VECSEL that employs a wafer-scale fabrication process and operates at 850 nm. A curved micromirror output coupler is heterogeneously integrated with AlGaAs-based semiconductor material to form a compact and robust device. The structure relies on flip-chip bonding the processed epitaxial material to an aluminum nitride mount; this heatsink both dissipates thermal energy and permits high frequency modulation using coplanar traces that lead to the VECSEL mesa. Backside emission is employed, and laser operation at 850 nm is made possible by removing the entire GaAs substrate through selective wet etching. While substrate removal eliminates absorptive losses, it simultaneously compromises laser performance by increasing series resistance and degrading the spatial uniformity of current injection. Several aspects of the VECSEL design help to mitigate these issues, including the use of a novel current-spreading n type distributed Bragg reflector (DBR). Additionally, VECSEL performance is improved through the use of a p-type DBR that is modified for low thermal resistance.

  7. Microstrip dipole antennas on electrically thick substrates

    NASA Astrophysics Data System (ADS)

    Jackson, D. R.; Alexopoulos, N. G.

    1985-10-01

    Printed circuit antennas are attractive radiation sources both at microwave and millimeter wave frequencies. However, for millimeter wave applications where the substrate is likely to be electrically thick, it is important to understand the basic effects of a thick substrate on radiation characteristics. In particular, it is concluded here that dipole radiation properties become sensitive to loss as the substrate becomes thick. Furthermore, the efficiency of dipoles on thick substrates tends to be low, especially as the dielectric constant of the substrate increases. A method of improving both the efficiency and gain can be used for thick substrates, however, which uses a superstrate layer on top of the antenna.

  8. Intelligent processing for thick composites

    NASA Astrophysics Data System (ADS)

    Shin, Daniel Dong-Ok

    2000-10-01

    Manufacturing thick composite parts are associated with adverse curing conditions such as large in-plane temperature gradient and exotherms. The condition is further aggravated because the manufacturer's cycle and the existing cure control systems do not adequately counter such affects. In response, the forecast-based thermal control system is developed to have better cure control for thick composites. Accurate cure kinetic model is crucial for correctly identifying the amount of heat generated for composite process simulation. A new technique for identifying cure parameters for Hercules AS4/3502 prepreg is presented by normalizing the DSC data. The cure kinetics is based on an autocatalytic model for the proposed method, which uses dynamic and isothermal DSC data to determine its parameters. Existing models are also used to determine kinetic parameters but rendered inadequate because of the material's temperature dependent final degree of cure. The model predictions determined from the new technique showed good agreement to both isothermal and dynamic DSC data. The final degree of cure was also in good agreement with experimental data. A realistic cure simulation model including bleeder ply analysis and compaction is validated with Hercules AS4/3501-6 based laminates. The nonsymmetrical temperature distribution resulting from the presence of bleeder plies agreed well to the model prediction. Some of the discrepancies in the predicted compaction behavior were attributed to inaccurate viscosity and permeability models. The temperature prediction was quite good for the 3cm laminate. The validated process simulation model along with cure kinetics model for AS4/3502 prepreg were integrated into the thermal control system. The 3cm Hercules AS4/3501-6 and AS4/3502 laminate were fabricated. The resulting cure cycles satisfied all imposed requirements by minimizing exotherms and temperature gradient. Although the duration of the cure cycles increased, such phenomena was

  9. Passivation of c-Si surfaces by sub-nm amorphous silicon capped with silicon nitride

    SciTech Connect

    Wan, Yimao Yan, Di; Bullock, James; Zhang, Xinyu; Cuevas, Andres

    2015-12-07

    A sub-nm hydrogenated amorphous silicon (a-Si:H) film capped with silicon nitride (SiN{sub x}) is shown to provide a high level passivation to crystalline silicon (c-Si) surfaces. When passivated by a 0.8 nm a-Si:H/75 nm SiN{sub x} stack, recombination current density J{sub 0} values of 9, 11, 47, and 87 fA/cm{sup 2} are obtained on 10 Ω·cm n-type, 0.8 Ω·cm p-type, 160 Ω/sq phosphorus-diffused, and 120 Ω/sq boron-diffused silicon surfaces, respectively. The J{sub 0} on n-type 10 Ω·cm wafers is further reduced to 2.5 ± 0.5 fA/cm{sup 2} when the a-Si:H film thickness exceeds 2.5 nm. The passivation by the sub-nm a-Si:H/SiN{sub x} stack is thermally stable at 400 °C in N{sub 2} for 60 min on all four c-Si surfaces. Capacitance–voltage measurements reveal a reduction in interface defect density and film charge density with an increase in a-Si:H thickness. The nearly transparent sub-nm a-Si:H/SiN{sub x} stack is thus demonstrated to be a promising surface passivation and antireflection coating suitable for all types of surfaces encountered in high efficiency c-Si solar cells.

  10. Design and laser damage properties of a dichroic beam combiner coating for 22.5° incidence and S polarization with high-transmission at 527nm and high-reflection at 1054nm

    NASA Astrophysics Data System (ADS)

    Bellum, John C.; Field, Ella S.; Kletecka, Damon E.; Rambo, Patrick K.; Smith, Ian C.

    2015-11-01

    We have designed a dichroic beam combiner coating consisting of 11 HfO2/SiO2 layer pairs deposited on a large fused silica substrate. The coating provides high transmission (HT) at 527 nm and high reflection (HR) at 1054 nm for light at 22.5° angle of incidence (AOI) in air in S polarization (Spol). The coating's design is based on layers of near half-wave optical thickness in the design space for stable HT at 527 nm, with layer modifications that provide HR at 1054 nm while preserving HT at 527 nm. Its implementation in the 527 nm/1054 nm dual wavelength beam combiner arrangement has two options, with each option requiring one or the other of the high intensity beams to be incident on the dichroic coating from within the substrate (from glass). We show that there are differences between the two options with respect to the laser-induced damage threshold (LIDT) properties of the coating, and analyze the differences in terms of the 527 nm and 1054 nm E-field intensity behaviors for air --> coating and glass --> coating incidence. Our E-field analysis indicates that LIDTs for air --> coating incidence should be higher than for glass --> coating incidence. LIDT measurements for Spol at the use AOI with ns pulses at 532 nm and 1064 nm confirm this analysis with the LIDTs for glass --> coating incidence being about half those for air --> coating incidence at both wavelengths. These LIDT results and the E-field analysis clearly indicate that the best beam combiner option is the one for which the high intensity 527 nm beam is incident on the coating from air and the 1054 nm high intensity beam is incident on the coating from glass.

  11. Effect of coating thickness of iron oxide nanoparticles on their relaxivity in the MRI

    PubMed Central

    Hajesmaeelzadeh, Farzaneh; Shanehsazzadeh, Saeed; Grüttner, Cordula; Daha, Fariba Johari; Oghabian, Mohammad Ali

    2016-01-01

    Objective(s): Iron oxide nanoparticles have found prevalent applications in various fields including drug delivery, cell separation and as contrast agents. Super paramagnetic iron oxide (SPIO) nanoparticles allow researchers and clinicians to enhance the tissue contrast of an area of interest by increasing the relaxation rate of water. In this study, we evaluate the dependency of hydrodynamic size of iron oxide nanoparticles coated with Polyethylene glycol (PEG) on their relativities with 3 Tesla clinical MRI. Materials and Methods: We used three groups of nanoparticles with nominal sizes 20, 50 and 100 nm with a core size of 8.86 nm, 8.69 nm and 10.4 nm that they were covered with PEG 300 and 600 Da. A clinical magnetic resonance scanner determines the T1 and T2 relaxation times for various concentrations of PEG-coated nanoparticles. Results: The size measurement by photon correlation spectroscopy showed the hydrodynamic sizes of MNPs with nominal 20, 50 and 100 nm with 70, 82 and 116 nm for particles with PEG 600 coating and 74, 93 and 100 nm for particles with PEG 300 coating, respectively. We foud that the relaxivity decreased with increasing overall particle size (via coating thickness). Magnetic resonance imaging showed that by increasing the size of the nanoparticles, r2/r1 increases linearly. Conclusion: According to the data obtained from this study it can be concluded that increments in coating thickness have more influence on relaxivities compared to the changes in core size of magnetic nanoparticles. PMID:27081461

  12. Pavement thickness evaluation using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Harris, Dwayne Arthur

    Accurate knowledge of pavement thickness is important information to have both at a network and project level. This information aids in pavement management and design. Much of the time this information is missing, out of date, or unknown for highway sections. Current technologies for determining pavement thickness are core drilling, falling weight deflectometer (FWD), and ground penetrating radar (GPR). Core drilling provides very accurate pin point pavement thickness information; however, it is also time consuming, labor intensive, intrusive to traffic, destructive, and limited in coverage. FWD provides nondestructive estimates of both a surface thickness and total pavement structure thickness, including pavement, base and sub-base. On the other hand, FWD is intrusive to traffic and affected by the limitations and assumptions the method used to estimate thickness. GPR provides pavement surface course thickness estimates with excellent data coverage at highway speed. Yet, disadvantages include the pavement thickness estimation being affected by the electrical properties of the pavement, limitations of the system utilized, and heavy post processing of the data. Nevertheless, GPR has been successfully utilized by a number of departments of transportation (DOTs) for pavement thickness evaluation. This research presents the GPR thickness evaluation methods, develops GPRPAVZ the software used to implement the methodologies, and addresses the quality of GPR pavement thickness evaluation.

  13. Thickness effect on HVOF coatings

    SciTech Connect

    Thorpe, R.

    1994-12-31

    Hobart/Tafa`s JP-5000`s particle velocity has a unique effect on coatings. This paper discusses the effect of thickness on coating properties such as: integrity, bond strength, stresses and coating performance. Much has been said about the advantages of these coatings. The goal of this paper if to provide additional substantiation. Higher operating pressure gun with high particle velocity yields coating properties that allow them to be applied thicker than ever before. the properties of these thicker coatings are evaluated versus micro-integrity, porosity, bond strength, oxide content and performance. Other comparisons are considered. Stresses in those coatings are a key part of this evaluation. Due to the unique coating stresses, corrosion and stress-corrosion resistance properties are improved. Also, mechanical and thermal fatigue properties are enhanced. A few case histories will be examined as documentation of actual field history. The types of applications involved are high and low temperature particle erosion; impact and sliding wear; immersion and heat corrosion; dimensional restoration of superalloys.

  14. The effect of pulse duration on the growth rate of laser-induced damage sites at 351 nm on fused silica surfaces

    SciTech Connect

    Negres, R A; Norton, M A; Liao, Z M; Cross, D A; Bude, J D; Carr, C W

    2009-10-29

    Past work in the area of laser-induced damage growth has shown growth rates to be primarily dependent on the laser fluence and wavelength. More recent studies suggest that growth rate, similar to the damage initiation process, is affected by a number of additional parameters including pulse duration, pulse shape, site size, and internal structure. In this study, we focus on the effect of pulse duration on the growth rate of laser damage sites located on the exit surface of fused silica optics. Our results demonstrate, for the first time, a significant dependence of growth rate at 351 nm on pulse duration from 1 ns to 15 ns as {tau}{sup 0.3} for sites in the 50-100 {micro}m size range.

  15. Maskless pattern transfer using 355 nm laser

    NASA Astrophysics Data System (ADS)

    Gabran, S. R. I.; Mansour, R. R.; Salama, M. M. A.

    2012-05-01

    Low power near-ultraviolet laser can be employed in various pattern transfer techniques such as maskless lithography and organic film ablation. Laser maskless lithography allows rapid prototyping using thin as well as thick photoresist films. Non-photosensitive organic films can be patterned by laser ablation, and this technique is applied in creating micro-molds for metal deposition using electroplating and electroless deposition. This paper presents experimental results, a quantitative study and modeling of laser maskless processing using desktop Nd:YAG laser system using four different photoresists. Process variables were experimentally optimized to identify the appropriate laser parameters that would yield reliable and reproducible patterns. A finite element thermal model of the ablation process was created to investigate the effects of different substrate materials on the process quality.

  16. TCSPC FLIM in the wavelength range from 800 nm to 1700 nm (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Becker, Wolfgang; Shcheslavsky, Vladislav

    2016-03-01

    Excitation and detection in the wavelength range above 800nm is a convenient and relatively inexpensive way to increase the penetration depth in optical microscopy. Moreover, detection at long wavelength avoids the problem that tissue autofluorescence contaminates the signals from endogenous fluorescence probes. FLIM at NIR wavelength may therefore be complementary to multiphoton microscopy, especially if the lifetimes of NIR fluorophores report biological parameters of the tissue structures they are bound to. Unfortunately, neither the excitation sources nor the detectors of standard confocal and multiphoton laser scanning systems are directly suitable for excitation and detection of NIR fluorescence. Most of these problems can be solved, however, by using ps diode lasers or Ti:Sapphire lasers at their fundamental wavelength, and NIR-sensitive detectors. With NIR-sensitive PMTs the detection wavelength range can be extended up to 900 nm, with InGaAs SPAD detectors up to 1700 nm. Here, we demonstrate the use of a combination of laser scanning, multi-dimensional TCSPC, and advanced excitation sources and detectors for FLIM at up to 1700 nm. The performance was tested at tissue samples incubated with NIR dyes. The fluorescence lifetimes generally get shorter with increasing absorption and emission wavelengths of the dyes. For the cyanine dye IR1061, absorbing around 1060 nm, the lifetime was found to be as short as 70 ps. Nevertheless the fluorescence decay could still be clearly detected. Almost all dyes showed clear lifetime changes depending on the binding to different tissue constituents.

  17. Comparison of 980-nm and 1070-nm in endovenous laser treatment (EVLT)

    NASA Astrophysics Data System (ADS)

    Topaloglu, Nermin; Tabakoglu, Ozgur; Ergenoglu, Mehmet U.; Gülsoy, Murat

    2009-07-01

    The use of endovenous laser treatment for varicose veins has been increasing in recent years. It is a safer technique than surgical vein stripping. Its complications (e.g. bruising, pain) are less than the complications of surgical vein stripping. But best parameters such as optimum wavelength, power, and application duration are still under investigation to clarify uncertainties about this technique. To prevent its complications and improve its clinical outcomes, the exact mechanism of it has to be known. The aim of this study is to investigate the effect of different laser wavelengths on endovenous laser therapy. In this study 980-nm diode laser and 1070-nm fiber laser were used. Human veins were irradiated with 980-nm and 1070-nm lasers at 8 W and 10 W to find the optimal power and wavelength. After laser application, remarkable shrinkage was observed. Inner and outer diameters of the veins also narrowed for both of the laser types. 10 W of 980-nm laser application led to better shrinkage results.

  18. High power diode lasers emitting from 639 nm to 690 nm

    NASA Astrophysics Data System (ADS)

    Bao, L.; Grimshaw, M.; DeVito, M.; Kanskar, M.; Dong, W.; Guan, X.; Zhang, S.; Patterson, J.; Dickerson, P.; Kennedy, K.; Li, S.; Haden, J.; Martinsen, R.

    2014-03-01

    There is increasing market demand for high power reliable red lasers for display and cinema applications. Due to the fundamental material system limit at this wavelength range, red diode lasers have lower efficiency and are more temperature sensitive, compared to 790-980 nm diode lasers. In terms of reliability, red lasers are also more sensitive to catastrophic optical mirror damage (COMD) due to the higher photon energy. Thus developing higher power-reliable red lasers is very challenging. This paper will present nLIGHT's released red products from 639 nm to 690nm, with established high performance and long-term reliability. These single emitter diode lasers can work as stand-alone singleemitter units or efficiently integrate into our compact, passively-cooled Pearl™ fiber-coupled module architectures for higher output power and improved reliability. In order to further improve power and reliability, new chip optimizations have been focused on improving epitaxial design/growth, chip configuration/processing and optical facet passivation. Initial optimization has demonstrated promising results for 639 nm diode lasers to be reliably rated at 1.5 W and 690nm diode lasers to be reliably rated at 4.0 W. Accelerated life-test has started and further design optimization are underway.

  19. Dual illumination OCT at 1050nm and 840nm for whole eye segment imaging

    NASA Astrophysics Data System (ADS)

    Fan, Shanhui; Qin, Lin; Dai, Cuixia; Zhou, Chuanqing

    2014-11-01

    We presented an improved dual channel dual focus spectral domain optical coherence tomography (SD-OCT) with two illuminations at 840 nm and 1050 nm for whole eye segment imaging and biometry in vivo. The two light beams were coupled and optically optimized to scan the anterior and posterior segment of the eye simultaneously. This configuration with dichroic mirrors integrated in the sample arm enables us to acquire images from the anterior segment and retina effectively with minimum loss of sample signal. In addition, the full resolved complex (FRC) method was applied to double the imaging depth for the whole anterior segment imaging by eliminating the mirror image. The axial resolution for 1050 nm and 840 nm OCT was 14 μm and 8 μm in air, respectively. Finally, the system was successfully tested in imaging the unaccommodated and accommodated eyes. The preliminary results demonstrated the significant improvements comparing with our previous dual channel SD-OCT configuration in which the two probing beams had the same central wavelength of 840 nm.

  20. Dependence of light outcoupling in organic light-emitting devices on ITO thickness and roughness

    NASA Astrophysics Data System (ADS)

    Zhang, Yingjie; Aziz, Hany

    2015-09-01

    The efficiency of organic light-emitting devices (OLEDs) is shown to significantly depend on both the thickness and roughness of the indium tin oxide (ITO) anode. The effects of changing the ITO thickness from 45 nm to 130 nm are found to be able to vary the current efficiency by 40%. The underlying mechanism is studied and revealed to be related to microcavity effects. The transmittance of the ITO substrate changes significantly with the ITO thickness, resulting in variations in microcavity, and thus light outcoupling efficiency. On the other hand, the effects of increasing the ITO roughness (rms) from 3.3 nm to 8.5 nm are found to increase light scattering at the ITO/organic interface, thus improving extraction of light trapped in the organic/ITO wave-guided mode. In addition to the enhancement in current efficiency, the device fabricated on rough ITO shows similar driving voltage to that made on smooth ITO, indicating that charge balance is not altered by ITO roughness. Contrary to common belief in the community, the lifetime of the OLED is not affected when using rough ITO. The results demonstrate the significant efficiency benefits of using ITO with optimal thicknesses and higher roughness in OLEDs.

  1. Algorithms for muscle oxygenation monitoring corrected for adipose tissue thickness

    NASA Astrophysics Data System (ADS)

    Geraskin, Dmitri; Platen, Petra; Franke, Julia; Kohl-Bareis, Matthias

    2007-07-01

    The measurement of skeletal muscle oxygenation by NIRS methods is obstructed by the subcutaneous adipose tissue which might vary between < 1 mm to more than 12 mm in thickness. A new algorithm is developed to minimize the large scattering effect of this lipid layer on the calculation of muscle haemoglobin / myoglobin concentrations. First, we demonstrate by comparison with ultrasound imaging that the optical lipid signal peaking at 930 nm is a good predictor of the adipose tissue thickness (ATT). Second, the algorithm is based on measurements of the wavelength dependence of the slope ΔA/Δρ of attenuation A with respect to source detector distance ρ and Monte Carlo simulations which estimate the muscle absorption coefficient based on this slope and the additional information of the ATT. Third, we illustrate the influence of the wavelength dependent transport scattering coefficient of the new algorithm by using the solution of the diffusion equation for a two-layered turbid medium. This method is tested on experimental data measured on the vastus lateralis muscle of volunteers during an incremental cycling exercise under normal and hypoxic conditions (corresponding to 0, 2000 and 4000 m altitude). The experimental setup uses broad band detection between 700 and 1000 nm at six source-detector distances. We demonstrate that the description of the experimental data as judged by the residual spectrum is significantly improved and the calculated changes in oxygen saturation are markedly different when the ATT correction is included.

  2. 308-nm excimer laser in endodontics

    NASA Astrophysics Data System (ADS)

    Liesenhoff, Tim

    1992-06-01

    Root canal preparation was performed on 20 extracted human teeth. After opening the coronal pulp, the root canals were prepared by 308 nm excimer laser only. All root canals were investigated under SEM after separation in the axial direction. By sagittal separation of the mandibles of freshly slaughtered cows, it was possible to get access to the tissues and irradiate under optical control. Under irradiation of excimer laser light, tissue starts to fluoresce. It was possible to demonstrate that each tissue (dentin, enamel, bone, pulpal, and connective tissue) has a characteristic spectral pattern. The SEM analyses showed that it is well possible to prepare root canals safely. All organic soft tissue has been removed by excimer laser irradiation. There was no case of via falsa. The simultaneous spectroscopic identification of the irradiated tissue provides a safe protection from overinstrumentation. First clinical trials on 20 patients suffering of chronical apical parodontitis have been carried out successfully.

  3. 1064-nm Nd:YAG laser nucleotomy

    NASA Astrophysics Data System (ADS)

    Vari, Sandor G.; Pergadia, Vani R.; Shi, Wei-Qiang; Snyder, Wendy J.; Fishbein, Michael C.; Grundfest, Warren S.

    1993-07-01

    The high incidence of patients with clinical and neurological symptoms of lumbar disc herniation has spurred the development of less invasive and more cost efficient methods to treat patients. In this study we evaluated pulsed and continuous wave (cw) 1064 nm Nd:YAG laser ablation and induced thermal damage in sheep intervertebral disc. We used the Heraeus LaserSonics Hercules 5040 (Nd:YAG) laser system and 400 micrometers bare and 600 micrometers ball-tipped fibers in cw and pulsed mode. For the laser parameters and fibers used in this study, ablation of the intervertebral disc was successful and thermal damage did not exceed 0.5 mm. Varying beam diameters and focusing abilities (i.e., bare and ball) did not produce any difference in the coagulation thermal effect.

  4. Effects of Au source/drain thickness on electrical characteristics of pentacene thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kwon, Jin-Hyuk; Hahn, Joonku; Bae, Jin-Hyuk; Ham, Youngjin; Park, Jaehoon; Baang, Sungkeun

    2015-11-01

    We investigate the electrical characteristics of top-contact pentacene thin-film transistors (TFTs) fabricated with various thicknesses of the Au source and the drain (S/D) electrodes, i.e., 20, 30, 50, 70, and 105 nm. Pentacene TFTs exhibit enhancements in the drain current and the fieldeffect mobility with increasing thickness of Au S/D electrodes up to 50 nm, after which the TFT performance degrades with increasing Au thickness. A transmission line method is used to analyze the contact resistance between the Au electrode and the pentacene layer in the TFTs, and ultraviolet photoemission spectroscopy measurements are performed to determine the work function of the Au films. The lowest contact resistance, 73 kΩ·cm, is obtained for the 50-nm-thick Au case and is ascribed to the high work function (4.67 eV) of the film. Consequently, the effects of the Au S/D thickness on the performance of top-contact pentacene TFTs can be understood through the behavior of the charge injection at the Au electrode/pentacene interface.

  5. Magnetic relaxation due to spin pumping in thick ferromagnetic films in contact with normal metals

    NASA Astrophysics Data System (ADS)

    Rezende, S. M.; Rodríguez-Suárez, R. L.; Azevedo, A.

    2013-07-01

    Spin pumping is the most important magnetic relaxation channel in ultrathin ferromagnetic layers in contact with normal metals (NMs). Recent experiments indicate that in thick films of insulating yttrium iron garnet (YIG) there is a large broadening of the ferromagnetic resonance (FMR) lines with deposition of a thin Pt layer which cannot be explained by the known damping processes. Here we present a detailed study of the magnetic relaxation due to spin pumping in bilayers made of a ferromagnetic material (FM) and a NM. Two alternative approaches are used to calculate the transverse and longitudinal relaxation rates used in the Bloch-Bloembergen formulation of damping. In one we consider that the dynamic exchange coupling at the interface transfers magnetic relaxation from the heavily damped conduction electron spins in the NM layer to the magnetization of the FM layer while the other utilizes spin currents and the concept of the spin-mixing conductance at the interface. While in thin FM films, the relaxation rates vary with the inverse of the FM layer thickness; in thick films, they become independent of the thickness because in the FM/NM structure the FMR excitation has a surface mode character. Regardless of the thickness range the longitudinal relaxation rate is twice the transverse rate resulting in damping of the magnetization with constant amplitude characterizing a Gilbert process. The enhanced spin-pumping damping explains the experimental observations in YIG/Pt bilayers.

  6. Ligand-controlled polytypism of thick-shell CdSe/CdS nanocrystals.

    PubMed

    Mahler, Benoît; Lequeux, Nicolas; Dubertret, Benoît

    2010-01-27

    We report the synthesis of CdSe/CdS semiconductor core/shell nanocrystals with very thick (5 nm) CdS shells. As in the case of core CdSe nanocrystals, we show that a thick-shell CdSe/CdS core/shell structure can be synthesized in either a pure wurtzite (W) or a zinc-blende (ZB) crystal structure. While the growth of thick-shell wurtzite CdSe/CdS is quite straightforward, we observe that the growth of a CdS shell on zinc-blende CdSe cores is more difficult and leads to wurtzite/zinc-blende polytypism when primary amines are present during the shell formation. Using absorption spectra analysis to differentiate zinc blende from wurtzite CdSe, we show that primary amines can induce a nearly complete structural transformation of CdSe ZB cores into W cores. This better understanding of the CdSe ligand-dependent crystal structural evolution during shell growth is further used to grow large (10 nm)-diameter perfect zinc-blende CdSe core crystals emitting above 700 nm, and perfect ZB thick-shell CdSe/CdS nanocrystals. We observed that all thick-shell CdSe/CdS QDs have extremely reduced blinking events compared to thin-shell QDs, without any significant influence of crystalline structure and polytypism. PMID:20043669

  7. Surface micromachined MEMS tunable VCSEL at 1550 nm with > 70 nm single mode tuning

    NASA Astrophysics Data System (ADS)

    Gierl, Christian; Gründl, Tobias; Debernardi, Pierluigi; Zogal, Karolina; Davani, Hooman A.; Grasse, Christian; Böhm, Gerhard; Meissner, Peter; Küppers, Franko; Amann, Markus-Christian

    2012-03-01

    We present surface micro-machined tunable vertical-cavity surface-emitting lasers (VCSELs) operating around 1550nm with tuning ranges up to 100nm and side mode suppression ratios beyond 40 dB. The output power reaches 3.5mW at 1555 nm. The electro-thermal and the electro-statical actuation of a micro electro-mechanical system (MEMS) movable distributed Bragg reflector (DBR) membrane increases/decreases the cavity length which shifts the resonant wavelength of the cavity to higher/lower values. The wavelength is modulated with 200 Hz/120 kHz. Both tuning mechanisms can be used simultaneously within the same device. The newly developed surface micro-machining technology uses competitive dielectric materials for the MEMS, deposited with low temperature plasma enhanced chemical vapor deposition (PECVD), which is cost effective and capable for on wafer mass production.

  8. Time-resolved analysis of thickness-dependent dewetting and ablation of silver films upon nanosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Qi, Dongfeng; Paeng, Dongwoo; Yeo, Junyeob; Kim, Eunpa; Wang, Letian; Chen, Songyan; Grigoropoulos, Costas P.

    2016-05-01

    Nanosecond pulsed laser dewetting and ablation of thin silver films is investigated by time-resolved imaging. Laser pulses of 532 nm wavelength and 5 ns temporal width are irradiated on silver films of different thicknesses (50 nm, 80 nm, and 350 nm). Below the ablation threshold, it is observed that the dewetting process does not conclude until 630 ns after the laser irradiation for all samples, forming droplet-like particles in the spot central region. At higher laser intensities, ablative material removal occurs in the spot center. Cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter at about 700 ns following the laser pulse exposure. In addition to these features, droplet fingers are superposed upon irradiation of 350-nm thick silver films with higher intensity.

  9. Thickness dependence oscillations of transport properties in thin films of a topological insulator Bi91Sb9

    NASA Astrophysics Data System (ADS)

    Rogacheva, E. I.; Orlova, D. S.; Nashchekina, O. N.; Dresselhaus, M. S.; Tang, S.

    2012-07-01

    The dependences of the electrical conductivity, Hall coefficient, magnetoresistance, and Seebeck coefficient on the thickness d (d = 15-400 nm) of the topological insulator Bi91Sb9 thin films grown on mica substrates were obtained at room temperature. In addition to the oscillations with a period Δd = (105 ± 5) nm in the thickness range d = 100-400 nm which are attributed to the quantization of the semiconductor electron energy spectrum, oscillations with a period Δd = (8 ± 2) nm in the range d = 15-60 nm were also revealed. It is suggested that the existence of the high-frequency oscillations in the thin films may be connected with the quantization of the metallic surface states energy spectrum.

  10. Absorption Measurements of Periodically Poled Potassium Titanyl Phosphate (PPKTP) at 775 nm and 1550 nm

    PubMed Central

    Steinlechner, Jessica; Ast, Stefan; Krüger, Christoph; Singh, Amrit Pal; Eberle, Tobias; Händchen, Vitus; Schnabel, Roman

    2013-01-01

    The efficient generation of second-harmonic light and squeezed light requires non-linear crystals that have low absorption at the fundamental and harmonic wavelengths. In this work the photo-thermal self-phase modulation technique is exploited to measure the absorption coefficient of periodically poled potassium titanyl phosphate (PPKTP) at 1,550 nm and 775 nm. The measurement results are (84±40) ppm/cm and (127±24) ppm/cm, respectively. We conclude that the performance of state-of-the-art frequency doubling and squeezed light generation in PPKTP is not limited by absorption. PMID:23291574

  11. The Doubling of 846 nm Light to Produce 423 nm Light for use in Atom Interferometry

    NASA Astrophysics Data System (ADS)

    Archibald, James; Birrell, Jeremey; Tang, Rebecca; Erickson, Chris; Goggins, Landon; Durfee, Dallin

    2009-10-01

    We present progress on a 423 nm fluorescence probe/cooling laser for use in our neutral calcium atom interferometer. The finished system will include an 846 nm diode laser that is coupled to a tapered amplifier. This light will be sent to a buildup cavity where we will achieve second-harmonic generation (SHG) using either a BBO non-linear crystal or a periodically-poled KTP crystal. We will discuss the theoretical considerations relating to the doubling of light in a crystal and the construction of our buildup cavity. We will also discuss its proposed application for use in atom interferometry.

  12. Measurement of 100 nm and 60 nm Particle Standards by Differential Mobility Analysis

    PubMed Central

    Mulholland, George W.; Donnelly, Michelle K.; Hagwood, Charles R.; Kukuck, Scott R.; Hackley, Vincent A.; Pui, David Y. H.

    2006-01-01

    The peak particle size and expanded uncertainties (95 % confidence interval) for two new particle calibration standards are measured as 101.8 nm ± 1.1 nm and 60.39 nm ± 0.63 nm. The particle samples are polystyrene spheres suspended in filtered, deionized water at a mass fraction of about 0.5 %. The size distribution measurements of aerosolized particles are made using a differential mobility analyzer (DMA) system calibrated using SRM® 1963 (100.7 nm polystyrene spheres). An electrospray aerosol generator was used for generating the 60 nm aerosol to almost eliminate the generation of multiply charged dimers and trimers and to minimize the effect of non-volatile contaminants increasing the particle size. The testing for the homogeneity of the samples and for the presence of multimers using dynamic light scattering is described. The use of the transfer function integral in the calibration of the DMA is shown to reduce the uncertainty in the measurement of the peak particle size compared to the approach based on the peak in the concentration vs. voltage distribution. A modified aerosol/sheath inlet, recirculating sheath flow, a high ratio of sheath flow to the aerosol flow, and accurate pressure, temperature, and voltage measurements have increased the resolution and accuracy of the measurements. A significant consideration in the uncertainty analysis was the correlation between the slip correction of the calibration particle and the measured particle. Including the correlation reduced the expanded uncertainty from approximately 1.8 % of the particle size to about 1.0 %. The effect of non-volatile contaminants in the polystyrene suspensions on the peak particle size and the uncertainty in the size is determined. The full size distributions for both the 60 nm and 100 nm spheres are tabulated and selected mean sizes including the number mean diameter and the dynamic light scattering mean diameter are computed. The use of these particles for calibrating DMAs and for

  13. Thickness independent reduced forming voltage in oxygen engineered HfO{sub 2} based resistive switching memories

    SciTech Connect

    Sharath, S. U. Kurian, J.; Komissinskiy, P.; Hildebrandt, E.; Alff, L.; Bertaud, T.; Walczyk, C.; Calka, P.; Schroeder, T.

    2014-08-18

    The conducting filament forming voltage of stoichiometric hafnium oxide based resistive switching layers increases linearly with layer thickness. Using strongly reduced oxygen deficient hafnium oxide thin films grown on polycrystalline TiN/Si(001) substrates, the thickness dependence of the forming voltage is strongly suppressed. Instead, an almost constant forming voltage of about 3 V is observed up to 200 nm layer thickness. This effect suggests that filament formation and switching occurs for all samples in an oxidized HfO{sub 2} surface layer of a few nanometer thickness while the highly oxygen deficient thin film itself merely serves as a oxygen vacancy reservoir.

  14. IR spectroscopic study of the effect of polymer nanofilm thickness on its surface density

    NASA Astrophysics Data System (ADS)

    Tretinnikov, O. N.

    2008-01-01

    The effect of the thickness (in the range 50 10,000 nm) of free-standing (separated from substrate) polystyrene (PS) films on their surface density was investigated by FTIR spectroscopy. For this, an approach has been employed for the first time than consists of analyzing the distortions of the IR band shape caused by anomalous dispersion of the refractive index in the vicinities of these bands. It was found that the surface density of PS films is halved as the film thickness changes from 1500 to 150 nm. The fact that the density starts to decrease in the micron range of film thickness rather than in the submicron range may suggest that there are important factors not taken into account by existing theoretical models for thin and ultrathin polymer films.

  15. Thickness dependent fatigue life at microcrack nucleation for metal thin films on flexible substrates

    NASA Astrophysics Data System (ADS)

    Sun, X. J.; Wang, C. C.; Zhang, J.; Liu, G.; Zhang, G. J.; Ding, X. D.; Zhang, G. P.; Sun, J.

    2008-10-01

    For polymer-supported metal thin films used in flexible electronics, the definition of the fatigue lifetime at microcrack nucleation (FLMN) should be more physically meaningful than all the previous definitions at structural instability. In this paper, the FLMN of Cu films (with thickness from 100 nm to 3.75 µm) as well as Al thin films (from 80 to 800 nm) was experimentally characterized at different strain ranges and different thicknesses by using a simple electrical resistance measurement (ERM). A significant thickness dependence was revealed for the FLMN and a similar Coffin-Manson fatigue relationship observed commonly in bulk materials was found to be still operative in both the films. Microstructural analyses were carried out to verify the feasibility of ERM correspondingly.

  16. Plasmonic thickness variation study of gold nanostructures in ultraviolet-visible light regime

    NASA Astrophysics Data System (ADS)

    Ghosh, Pijush; Debu, Desalegn Tadesse; French, David; Bauman, Stephen; Herzog, Joseph B.

    Noble metal nanostructures exhibit strong surface plasmon resonances in the ultraviolet-visible light range that are not present in bulk metal. In this study, we have observed the plasmonic properties of different sized gold nanodisks and nanorods with varying thickness. The samples were fabricated by electron beam lithography on silicon dioxide substrates. Depending on the thickness of the nanostructures, strong and well-defined surface plasmon resonances were found (wavelength 400nm - 1000nm). For experimental and theoretical results, we have used Dark field spectroscopy and finite element method, respectively. We found that resonance peak was shifted with nanostructure thickness. By using Dark field spectroscopy, the scattered light from individual structures can be analyzed with less background noise and the incident light was at an angle to the substrate.

  17. Thin-thick coexistence behavior of 8CB liquid crystalline films on silicon.

    PubMed

    Garcia, R; Subashi, E; Fukuto, M

    2008-05-16

    The wetting behavior of thin films of 4-n-octyl-4'-cyanobiphenyl (8CB) on Si is investigated via optical and x-ray reflectivity measurement. An experimental phase diagram is obtained showing a broad thick-thin coexistence region spanning the bulk isotropic-to-nematic (T(IN)) and the nematic-to-smectic-A (T(NA)) temperatures. For Si surfaces with coverages between 47 and 72 +/- 3 nm, reentrant wetting behavior is observed twice as we increase the temperature, with separate coexistence behaviors near T(IN) and T(NA). For coverages less than 47 nm, however, the two coexistence behaviors merge into a single coexistence region. The observed thin-thick coexistence near the second-order NA transition is not anticipated by any previous theory or experiment. Nevertheless, the behavior of the thin and thick phases within the coexistence regions is consistent with this being an equilibrium phenomenon. PMID:18518487

  18. Atmospheric vapor phase deposition of nanometer-thick anti-stiction fluoropolymer coatings for silicon surfaces

    NASA Astrophysics Data System (ADS)

    Itoh, Shintaro; Takahashi, Kazuhiro; Morita, Hiroyuki; Fukuzawa, Kenji; Zhang, Hedong

    2016-06-01

    Anti-stiction coatings for silicon surfaces are a key technology to prevent the failure of nanoelectromechanical systems (NEMS) during operation and improve the forming accuracy in nanoimprint technology. In this study, we propose an atmospheric vapor phase deposition method to coat a silicon surface with fluoropolymers such as the perfluoropolyethers Fomblin Zdol 2000 and Zdol 4000. Thickness distributions, surface energies, coverages, and stiction forces for the deposited films were evaluated experimentally. The proposed method resulted in over 90% coverage with a film thickness of about 1 nm. The film thickness uniformity was around 0.1 nm over an area of 5 × 5 mm2. This coating effectively reduced the stiction forces by half compared with a bare silicon surface.

  19. Thickness dependence of the magnetic properties of ripple-patterned Fe/MgO(001) films

    NASA Astrophysics Data System (ADS)

    Büttner, Felix; Zhang, Kun; Seyffarth, Susanne; Liese, Tobias; Krebs, Hans-Ulrich; Vaz, C. A. F.; Hofsäss, Hans

    2011-08-01

    Grazing incidence Xe+ ion sputtering was used to create a nanoscale ripple pattern on a thin Fe film, epitaxially grown on MgO(001). The Fe film has a thickness gradient of 0-20 nm and a ripple height of about 3 nm, giving rise to a transition from a continuous film to separated nanorods with decreasing film thickness. This allowed the investigation of the competition between the uniaxial and biaxial anisotropy of the irradiated sample as a function of thickness. From magneto-optical Kerr effect measurements, we determine accurately the cubic magnetocrystalline anisotropy and the uniaxial anisotropy that originates from the ripple pattern using a coherent rotation model. Our results show that the uniaxial anisotropy strength increases, whereas the contribution of the biaxial crystal anisotropy decreases, when going from the continuous film to the nanorod structures.

  20. Interference method for monitoring the refractive index and the thickness of transparent films during deposition

    NASA Astrophysics Data System (ADS)

    Alius, H.; Schmidt, R.

    1990-04-01

    An interferometric method is described for simultaneous measurement of the refractive index and the thickness of transparent isotropic films during the deposition process. Two laser beams are focused impinging at two different angles onto the film. The intensity of the beams reflected from the growing film shows minima and maxima, which are counted and evaluated to determine the refractive index n and the thickness d of the film in the range of some 100 nm up to several micrometers using 633-nm laser light. n and d can be determined within an accuracy better than 1%, if the thickness is larger than three times the vacuum wavelength of the laser. The measurements are well in accordance with calculations of the intensity modulation. The method can easily be extended to multilayer systems.

  1. Cloud Thickness from Diffusion of Lidar Pulses in Clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Davis, A.; McGill, Matthew

    1999-01-01

    Measurements of the distribution of reflected light from a laser beam incident on an aqueous suspension of particles or "cloud" with known thickness and particle size distribution are reported. The distribution is referred to as the "cloud radiative Green's function", G. In the diffusion domain, G is sensitive to cloud thickness, allowing that important quantity to be retrieved. The goal of the laboratory simulation is to provide preliminary estimates of sensitivity of G to cloud thickness,for use in the optimal design of an offbeam Lidar instrument for remote sensing of cloud thickness (THOR, Thickness from Offbeam Returns). These clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The microsphere size distribution is roughly lognormal, from 0.5 microns to 25 microns, similar to real clouds. Density of suspended spheres is adjusted so mean-free-path of visible photons is about 10 cm, approximately 1000 times smaller than in real clouds. The light source is a ND:YAG laser at 530 nm. Detectors are flux and photon-counting Photomultiplier Tube (PMTS), with a glass probe for precise positioning. A Labview 5 VI controls positioning, and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider, and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns, and step size is selectable from the VI software. Far from the incident beam, the rate of exponential increase as the direction of the incident beam is approached scales as expected from diffusion theory, linearly with the cloud thickness, and inversely as the square root of the reduced optical thickness, and is independent of particle size. Near the beam the signal begins to increase faster than exponential, due to single and low-order scattering near the backward direction, and here the distribution depends on particle size. Results are being used to verify 3D Monte Carlo

  2. Variability of aerosol optical thickness and atmospheric turbidity in Tunisia

    NASA Astrophysics Data System (ADS)

    Masmoudi, M.; Chaabane, M.; Medhioub, K.; Elleuch, F.

    The aerosol optical thickness (AOT) τa computed from the spectral sun photometer in Thala (Tunisia) exhibited variability ranging from approximately 0.03 to greater than 2.0 at 870 nm for March-October 2001. These measurements are compared to the aerosol optical thickness computed in Ouagadougou (Burkina-Faso), Banizoumbou (Niger), IMC Oristano (Sardinia) and Rome Tor Vergata (Italy). Analysis of τa data from this observation network suggests that there is a high temporal and spatial variability of τa in the different sites. The Angström wavelength exponent α was found to vary with the magnitude of the aerosol optical thickness, with values as high as 1.5 for very low τa, and values of -0.1 for high τa situations. The relationship between the two parameters τa and α is investigated. Values of the turbidity coefficient β have been determined in Thala (Tunisia) for 8 months in 2001 based on a direct fitting method of the Angström power law expression using sun photometer data. The monthly averaged values of the turbidity coefficient β vary between 0.15 and 0.33. The months of July and October experienced the highest turbidity, while April experienced the lowest aerosol loading on average. The turbidity shows a maximum and minimum values for the Southwest and the Northwest wind directions, respectively. The single scattering albedo ωo for the 870 nm wavelength obtained from solar aureole data in Thala is analysed according to the particles' origin.

  3. Thickness dependence of superconducting properties in magnesium diboride thin films

    NASA Astrophysics Data System (ADS)

    Beringer, Douglas; Clavero, Cesar; Tan, Teng; Xi, Xiaoxing; Lukaszew, Rosa

    2013-03-01

    Thin film MgB2 is a promising material currently researched for improvements in superconducting radio frequency (SRF) technology and applications. At present, bulk niobium SRF accelerating cavities suffer from a fundamental upper limit in maximally sustained accelerating gradients; however, a scheme involving multi-layered superstructures consisting of superconducting-insulating-superconducting (SIS) layers has been proposed to overcome this fundamental material limit of 50 MV/m. The SIS multi-layer paradigm is reliant upon implementing a thin shielding material with a suitably high Hc1 which may prevent early field penetration in a bulk material layer and consequently delay the high field breakdown. It has been predicted that for thin superconducting films -- thickness less than the London penetration depth (~ 140 nm in the case of MgB2) -- the lower critical field Hc1 will be enhanced with decreasing thickness. Thus, MgB2, with a high bulk Hc1 value is a prime candidate for such SIS structures. Here we present our study on the structure, surface morphology and superconducting properties on a series of MgB2 thin films and correlate the effects of film thickness and surface morphology on Hc1. This work was supported in part by the U.S. Department of Energy (DE-SC0004410 and DE-AC05-06OR23177) and Defense Threat Reduction Agency (HDTRA1-10-1-0072).

  4. Ice thickness in the Northwest Passage

    NASA Astrophysics Data System (ADS)

    Haas, Christian; Howell, Stephen E. L.

    2015-09-01

    Recently, the feasibility of commercial shipping in the ice-prone Northwest Passage (NWP) has attracted a lot of attention. However, very little ice thickness information actually exists. We present results of the first ever airborne electromagnetic ice thickness surveys over the NWP carried out in April and May 2011 and 2015 over first-year and multiyear ice. These show modal thicknesses between 1.8 and 2.0 m in all regions. Mean thicknesses over 3 m and thick, deformed ice were observed over some multiyear ice regimes shown to originate from the Arctic Ocean. Thick ice features more than 100 m wide and thicker than 4 m occurred frequently. Results indicate that even in today's climate, ice conditions must still be considered severe. These results have important implications for the prediction of ice breakup and summer ice conditions, and the assessment of sea ice hazards during the summer shipping season.

  5. Sub-5 nm nanostructures fabricated by atomic layer deposition using a carbon nanotube template.

    PubMed

    Woo, Ju Yeon; Han, Hyo; Kim, Ji Weon; Lee, Seung-Mo; Ha, Jeong Sook; Shim, Joon Hyung; Han, Chang-Soo

    2016-07-01

    The fabrication of nanostructures having diameters of sub-5 nm is very a important issue for bottom-up nanofabrication of nanoscale devices. In this work, we report a highly controllable method to create sub-5 nm nano-trenches and nanowires by combining area-selective atomic layer deposition (ALD) with single-walled carbon nanotubes (SWNTs) as templates. Alumina nano-trenches having a depth of 2.6 ∼ 3.0 nm and SiO2 nano-trenches having a depth of 1.9 ∼ 2.2 nm fully guided by the SWNTs have been formed on SiO2/Si substrate. Through infilling ZnO material by ALD in alumina nano-trenches, well-defined ZnO nanowires having a thickness of 3.1 ∼ 3.3 nm have been fabricated. In order to improve the electrical properties of ZnO nanowires, as-fabricated ZnO nanowires by ALD were annealed at 350 °C in air for 60 min. As a result, we successfully demonstrated that as-synthesized ZnO nanowire using a specific template can be made for various high-density resistive components in the nanoelectronics industry. PMID:27188268

  6. Sub-5 nm nanostructures fabricated by atomic layer deposition using a carbon nanotube template

    NASA Astrophysics Data System (ADS)

    Woo, Ju Yeon; Han, Hyo; Kim, Ji Weon; Lee, Seung-Mo; Ha, Jeong Sook; Shim, Joon Hyung; Han, Chang-Soo

    2016-07-01

    The fabrication of nanostructures having diameters of sub-5 nm is very a important issue for bottom-up nanofabrication of nanoscale devices. In this work, we report a highly controllable method to create sub-5 nm nano-trenches and nanowires by combining area-selective atomic layer deposition (ALD) with single-walled carbon nanotubes (SWNTs) as templates. Alumina nano-trenches having a depth of 2.6 ∼ 3.0 nm and SiO2 nano-trenches having a depth of 1.9 ∼ 2.2 nm fully guided by the SWNTs have been formed on SiO2/Si substrate. Through infilling ZnO material by ALD in alumina nano-trenches, well-defined ZnO nanowires having a thickness of 3.1 ∼ 3.3 nm have been fabricated. In order to improve the electrical properties of ZnO nanowires, as-fabricated ZnO nanowires by ALD were annealed at 350 °C in air for 60 min. As a result, we successfully demonstrated that as-synthesized ZnO nanowire using a specific template can be made for various high-density resistive components in the nanoelectronics industry.

  7. Photodissociation of the Propargyl (C3D3) Radicals at 248 nm and 193 nm

    SciTech Connect

    Neumark., D.M.; Crider, P.E.; Castiglioni, L.; Kautzman, K.K.

    2009-01-21

    The photodissociation of perdeuterated propargyl (D{sub 2}CCCD) and propynyl (D{sub 3}CCC) radicals was investigated using fast beam photofragment translational spectroscopy. Radicals were produced from their respective anions by photodetachment at 540 nm and 450 nm (below and above the electron affinity of propynyl). The radicals were then photodissociated by 248 nm or 193 nm light. The recoiling photofragments were detected in coincidence with a time- and position-sensitive detector. Three channels were observed: D{sub 2} loss, CD + C{sub 2}D{sub 2}, and CD{sub 3} + C{sub 2}. Obervation of the D loss channel was incompatible with this experiment and was not attempted. Our translational energy distributions for D{sub 2} loss peaked at nonzero translational energy, consistent with ground state dissociation over small (< 1 eV) exit barriers with respect to separated products. Translational energy distributions for the two heavy channels peaked near zero kinetic energy, indicating dissociation on the ground state in the absence of exit barriers.

  8. Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

    PubMed Central

    Kiomarsi, Nazanin; Salim, Soheil; Sarraf, Pegah; Javad-Kharazifard, Mohammad

    2016-01-01

    Background The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching. Material and Methods The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05). Results A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching. Conclusions The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material. Key words:Laser, diode, dentin, tubule, diameter. PMID:27398172

  9. Characterization of LANDSAT Panels Using the NIST BRDF Scale from 1100 nm to 2500 nm

    NASA Technical Reports Server (NTRS)

    Markham, Brian; Tsai, Benjamin K.; Allen, David W.; Cooksey, Catherine; Yoon, Howard; Hanssen, Leonard; Zeng, Jinan; Fulton, Linda; Biggar, Stuart; Markham, Brian

    2010-01-01

    Many earth observing sensors depend on white diffuse reflectance standards to derive scales of radiance traceable to the St Despite the large number of Earth observing sensors that operate in the reflective solar region of the spectrum, there has been no direct method to provide NIST traceable BRDF measurements out to 2500 rim. Recent developments in detector technology have allowed the NIST reflectance measurement facility to expand the operating range to cover the 250 nm to 2500 nm range. The facility has been modified with and additional detector using a cooled extended range indium gallium arsenide (Extended InGaAs) detector. Measurements were made for two PTFE white diffuse reflectance standards over the 1100 nm to 2500 nm region at a 0' incident and 45' observation angle. These two panels will be used to support the OLI calibration activities. An independent means of verification was established using a NIST radiance transfer facility based on spectral irradiance, radiance standards and a diffuse reflectance plaque. An analysis on the results and associated uncertainties will be discussed.

  10. THE SPECTRUM OF THORIUM FROM 250 nm TO 5500 nm: RITZ WAVELENGTHS AND OPTIMIZED ENERGY LEVELS

    SciTech Connect

    Redman, Stephen L.; Nave, Gillian; Sansonetti, Craig J.

    2014-03-01

    We have made precise observations of a thorium-argon hollow cathode lamp emission spectrum in the region between 350 nm and 1175 nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists to re-optimize the energy levels of neutral, singly, and doubly ionized thorium (Th I, Th II, and Th III). Using the optimized level values, we calculate accurate Ritz wavelengths for 19, 874 thorium lines between 250 nm and 5500 nm (40, 000 cm{sup –1} to 1800 cm{sup –1}). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer and Engleman and typographical errors and incorrect classifications in Kerber et al. We also found a large scatter with respect to the thorium line list of Lovis and Pepe. We anticipate that our Ritz wavelengths will lead to improved measurement accuracy for current and future spectrographs that make use of thorium-argon or thorium-neon lamps as calibration standards.

  11. Inverse Design of a Thick Supercritical Airfoil

    NASA Astrophysics Data System (ADS)

    Pambagjo, Tjoetjoek Eko; Nakahashi, Kazuhiro; Obayashi, Shigeru

    In this paper, a study on designing a thick supercritical airfoil by utilizing Takanashi’s inverse design method is discussed. One of the problems to design a thick supercritical airfoil by Takanashi’s method is that an oscillation of the geometry may occur during the iteration process. To reduce the oscillation, an airfoil parameterization method is utilized as the smoothing procedure. A guideline to determine the target pressure distribution to realize the thick airfoil is also discussed.

  12. Do elliptical galaxies have thick disks?

    NASA Technical Reports Server (NTRS)

    Thomson, R. C.; Wright, A. E.

    1990-01-01

    The authors discuss new evidence which supports the existence of thick disks in elliptical/SO galaxies. Numerical simulations of weak interactions with thick disk systems produce shell structures very similar in appearance to those observed in many shell galaxies. The authors think this model presents a more plausible explanation for the formation of shell structures in elliptical/SO galaxies than does the merger model and, if correct, supports the existence of thick disks in elliptical/SO galaxies.

  13. Remote Measurement Of Thickness Of Ice

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.

    1994-01-01

    Technique for remote measurement of thickness of ice layer on surface proposed. Surfaces measured optoelectronically. Radiation in three near-infrared wavelength bands scattered from both test spot and nearby reference spot, and ratios of intensities compared to determine thickness of ice. Technique applicable to all surfaces appropriately lit with adequate radiation in three preselected bands. Useful in variety of applications, including aerospace applications, research, and measurement of ice thicknesses on aircraft surfaces.

  14. Localizing gravity on exotic thick 3-branes

    SciTech Connect

    Castillo-Felisola, Oscar; Melfo, Alejandra; Pantoja, Nelson; Ramirez, Alba

    2004-11-15

    We consider localization of gravity on thick branes with a nontrivial structure. Double walls that generalize the thick Randall-Sundrum solution, and asymmetric walls that arise from a Z{sub 2} symmetric scalar potential, are considered. We present a new asymmetric solution: a thick brane interpolating between two AdS{sub 5} spacetimes with different cosmological constants, which can be derived from a 'fake supergravity' superpotential, and show that it is possible to confine gravity on such branes.

  15. Analysis of cloud optical thickness retrieved from CIMEL measurements

    NASA Astrophysics Data System (ADS)

    Marshak, A.; Barker, H.; Evans, K.; Pavloski, C.; Knyazikhin, Y.; Holben, B.; Wiscombe, W.

    2002-05-01

    When conditions are inappropriate to make AERONET measurements that are suitable for aerosol studies, new measurements related to cloud physics can be made instead. As such, several AERONET CIMEL sunphotometers have been equipped with a new "cloud mode." This mode allows the CIMELs to make measurements of zenith radiance when the Sun in blocked by clouds. When in cloud mode, a CIMEL points straight up every 10-15 minutes and takes 10 measurements over a 9 second time interval at four wavelengths: 440, 670, 870, and 1020 nm. For cloudy conditions above green vegetation, the spectral contrast in surface albedo dominates over Rayleigh and aerosol effects; this makes normalized zenith radiances almost indistinguishable at 440 and 670 as well as at 870 and 1020 nm. We have developed a new method for retrieving cloud optical thickness, even for broken clouds, that uses data from the 670 and 870 nm channels to build a Normalized Difference Cloud Index (NDCI). The retrieval can be improved if, in addition to CIMEL zenith radiances, surface downward flux measurements at both wavelengths are also available. Based on theoretical calculations and preliminary analysis of CIMEL measurements at the ARM Central Facility in Oklahoma, there is good correlation between NDCI and cloud liquid water path retrieved from microwave radiometer for cloudy sky above green vegetation.

  16. Zebrafish Cardiac Muscle Thick Filaments: Isolation Technique and Three-Dimensional Structure

    PubMed Central

    González-Solá, Maryví; AL-Khayat, Hind A.; Behra, Martine; Kensler, Robert W.

    2014-01-01

    To understand how mutations in thick filament proteins such as cardiac myosin binding protein-C or titin, cause familial hypertrophic cardiomyopathies, it is important to determine the structure of the cardiac thick filament. Techniques for the genetic manipulation of the zebrafish are well established and it has become a major model for the study of the cardiovascular system. Our goal is to develop zebrafish as an alternative system to the mammalian heart model for the study of the structure of the cardiac thick filaments and the proteins that form it. We have successfully isolated thick filaments from zebrafish cardiac muscle, using a procedure similar to those for mammalian heart, and analyzed their structure by negative-staining and electron microscopy. The isolated filaments appear well ordered with the characteristic 42.9 nm quasi-helical repeat of the myosin heads expected from x-ray diffraction. We have performed single particle image analysis on the collected electron microscopy images for the C-zone region of these filaments and obtained a three-dimensional reconstruction at 3.5 nm resolution. This reconstruction reveals structure similar to the mammalian thick filament, and demonstrates that zebrafish may provide a useful model for the study of the changes in the cardiac thick filament associated with disease processes. PMID:24739166

  17. Theoretical Determination of The Optimum Thickness of Perylene Layer in Bilayer Phthalocyanine/Perylene Photovoltaic Device

    NASA Astrophysics Data System (ADS)

    Pratiwi, Herlina; Siahaan, Timothy; Satriawan, Mirza; Nurwantoro, Pekik; Triyana, Kuwat

    2009-09-01

    We do theoretical study on thickness of the active layers in a heterojunction bilayer thin film photovoltaic device based on copper phthalocyanine (CuPc)/perylene that gives the highest Incident Photon to Current Efficiency (IPCE). The device we study consists Glass (1 mm)/ITO (Indium Tin Oxide, 120 nm)/CuPc (50 nm)/PTCDA (3, 4, 9, 10-perylenetetracarboxylic dianhydride, x nm)/Ag (40 nm), where x is the thickness of the PTCDA layer that we calculate here. The calculation is based on assumption that the photocurrent generation process is the result of the creation of photogenerated excitons, which difuse before dissociated at the CuPc/PTCDA interface following the diffusion equation, by internal optical electric field that comes from light exposure. We also assume that almost all photocurrent is created in the CuPc/PTCDA interface. Because the order of the thickness of the active layers is the same or smaller than of the wavelength of visible light, we take into account the effect of reflection and interference in the calculation of internal optical electric field distribution inside the device by making use complex indices of refraction of the active materials in our calculation. The modulus of it is proportional with the number generated excitons. The general solution of the exciton diffusion equation was used for calculating the photocurrent and the IPCE. Here, we find the optimum thickness of PTCDA layer that gives greatest IPCE at the wavelength of 344 nm and 467 nm, which are the wavelengths at which the absorption coefficients of CuPc and PTCDA, respectively, reach the maximum values.

  18. Preparation and investigation of nano-thick FTO/Ag/FTO multilayer transparent electrodes with high figure of merit

    NASA Astrophysics Data System (ADS)

    Yu, Shihui; Li, Lingxia; Lyu, Xiaosong; Zhang, Weifeng

    2016-02-01

    In order to improve the conductivity of the single-layered nano-thick F doped SnO2 (FTO) thin films, an Ag mid-layer is embedded between the FTO layers. In our work, the effects of mid-layer Ag and top FTO layer on the structural, electrical and optical properties of FTO/Ag/FTO multilayered composite structures deposited on quartz glass substrates by magnetron sputtering at 100 °C have been investigated. As the thickness of Ag mid-layer increases, the resistivity decreases. As the top FTO layer thickness increases, the resistivity increases. The highest value of figure of merit φTC is 7.8 × 10-2 Ω-1 for the FTO (20 nm)/Ag (7 nm)/FTO (30 nm) multilayers, while the average optical transmittance is 95.5% in the visible range of wavelengths and the resistivity is 8.8 × 10-5 Ω·cm. In addition, we also describe the influence of Ag and top FTO layer thickness on structural, electrical and optical properties of the nano-thick FTO (20 nm)/Ag/FTO multilayers and the mechanism of the changes of electrical and optical properties at different Ag and top FTO layer thicknesses.

  19. Influence of thickness on physical properties of vacuum evaporated polycrystalline CdTe thin films for solar cell applications

    NASA Astrophysics Data System (ADS)

    Chander, Subhash; Dhaka, M. S.

    2016-02-01

    This paper presents the influence of thickness on physical properties of polycrystalline CdTe thin films. The thin films of thickness 450 nm, 650 nm and 850 nm were deposited employing thermal vacuum evaporation technique on glass and indium tin oxide (ITO) coated glass substrates. The physical properties of these as-grown thin films were investigated employing the X-ray diffraction (XRD), source meter, UV-Vis spectrophotometer, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The structural analysis reveals that the films have zinc-blende cubic structure and polycrystalline in nature with preferred orientation (111). The structural parameters like lattice constant, interplanar spacing, grain size, strain, dislocation density and number of crystallites per unit area are calculated. The average grain size and optical band gap are found in the range 15.16-21.22 nm and 1.44-1.63 eV respectively and observed to decrease with thickness. The current-voltage characteristics show that the electrical conductivity is observed to decrease with thickness. The surface morphology shows that films are free from crystal defects like pin holes and voids as well as homogeneous and uniform. The EDS patterns show the presence of cadmium and tellurium elements in the as grown films. The experimental results reveal that the film thickness plays significant role on the physical properties of as-grown CdTe thin films and higher thickness may be used as absorber layer to solar cells applications.

  20. Preparation and investigation of nano-thick FTO/Ag/FTO multilayer transparent electrodes with high figure of merit

    PubMed Central

    Yu, Shihui; Li, Lingxia; Lyu, Xiaosong; Zhang, Weifeng

    2016-01-01

    In order to improve the conductivity of the single–layered nano-thick F doped SnO2 (FTO) thin films, an Ag mid–layer is embedded between the FTO layers. In our work, the effects of mid–layer Ag and top FTO layer on the structural, electrical and optical properties of FTO/Ag/FTO multilayered composite structures deposited on quartz glass substrates by magnetron sputtering at 100 °C have been investigated. As the thickness of Ag mid–layer increases, the resistivity decreases. As the top FTO layer thickness increases, the resistivity increases. The highest value of figure of merit φTC is 7.8 × 10−2 Ω−1 for the FTO (20 nm)/Ag (7 nm)/FTO (30 nm) multilayers, while the average optical transmittance is 95.5% in the visible range of wavelengths and the resistivity is 8.8 × 10−5 Ω·cm. In addition, we also describe the influence of Ag and top FTO layer thickness on structural, electrical and optical properties of the nano-thick FTO (20 nm)/Ag/FTO multilayers and the mechanism of the changes of electrical and optical properties at different Ag and top FTO layer thicknesses. PMID:26833398

  1. Preparation and investigation of nano-thick FTO/Ag/FTO multilayer transparent electrodes with high figure of merit.

    PubMed

    Yu, Shihui; Li, Lingxia; Lyu, Xiaosong; Zhang, Weifeng

    2016-01-01

    In order to improve the conductivity of the single-layered nano-thick F doped SnO2 (FTO) thin films, an Ag mid-layer is embedded between the FTO layers. In our work, the effects of mid-layer Ag and top FTO layer on the structural, electrical and optical properties of FTO/Ag/FTO multilayered composite structures deposited on quartz glass substrates by magnetron sputtering at 100 °C have been investigated. As the thickness of Ag mid-layer increases, the resistivity decreases. As the top FTO layer thickness increases, the resistivity increases. The highest value of figure of merit φTC is 7.8 × 10(-2 ) Ω(-1) for the FTO (20 nm)/Ag (7 nm)/FTO (30 nm) multilayers, while the average optical transmittance is 95.5% in the visible range of wavelengths and the resistivity is 8.8 × 10(-5 ) Ω·cm. In addition, we also describe the influence of Ag and top FTO layer thickness on structural, electrical and optical properties of the nano-thick FTO (20 nm)/Ag/FTO multilayers and the mechanism of the changes of electrical and optical properties at different Ag and top FTO layer thicknesses. PMID:26833398

  2. Faster qualification of 193-nm resists for 100-nm development using photo cell monitoring

    NASA Astrophysics Data System (ADS)

    Jones, Chris M.; Kallingal, Chidam; Zawadzki, Mary T.; Jeewakhan, Nazneen N.; Kaviani, Nazila N.; Krishnan, Prakash; Klaum, Arthur D.; Van Ess, Joel

    2003-05-01

    The development of 100-nm design rule technologies is currently taking place in many R&D facilities across the world. For some critical alyers, the transition to 193-nm resist technology has been required to meet this leading edge design rule. As with previous technology node transitions, the materials and processes available are undergoing changes and improvements as vendors encounter and solve problems. The initial implementation of the 193-nm resits process did not meet the photolithography requirements of some IC manufacturers due to very high Post Exposure Bake temperature sensitivity and consequently high wafer to wafer CD variation. The photoresist vendors have been working to improve the performance of the 193-nm resists to meet their customer's requirements. Characterization of these new resists needs to be carried out prior to implementation in the R&D line. Initial results on the second-generation resists evaluated at Cypress Semicondcutor showed better CD control compared to the aelrier resist with comparable Depth of Focus (DOF), Exposure Latitute, Etch Resistance, etc. In addition to the standard lithography parameters, resist characterization needs to include defect density studies. It was found that the new resists process with the best CD control, resulted in the introduction of orders of magnitude higher yield limiting defects at Gate, Contact adn Local Interconnect. The defect data were shared with the resists vendor and within days of the discovery the resist vendor was able to pinpoint the source of the problem. The fix was confirmed and the new resists were successfully released to production. By including defect monitoring into the resist qualification process, Cypress Semiconductor was able to 1) drive correction actions earlier resulting in faster ramp and 2) eliminate potential yield loss. We will discuss in this paper how to apply the Micro Photo Cell Monitoring methodology for defect monitoring in the photolithogprhay module and the

  3. Thickness dependence of the dielectric properties of thermally evaporated Sb2Te3 thin films

    NASA Astrophysics Data System (ADS)

    Ulutas, K.; Deger, D.; Yakut, S.

    2013-03-01

    Sb2Te3 thin films of different thickness (23 - 350 nm) were prepared by thermal evaporation technique. The thickness dependence of the ac conductivity and dielectric properties of the Sb2Te3 films have been investigated in the frequency range 10 Hz- 100 kHz and within the temperature range 293-373K. Both the dielectric constant epsilon1 and dielectric loss factor epsilon2 were found to depend on frequency, temperature and film thickness. The frequency and temperature dependence of ac conductivity (σac(ω)) has also been determined. The ac conductivity of our samples satisfies the well known ac power law; i.e., σac(ω) propto ωs where s<1 and independent of the film thickness. The temperature dependence of ac conductivity and parameter s is reasonably well interpreted by the correlated barrier hopping (CBH) model. The activation energies were evaluated for various thicknesses. The temperature coefficient of the capacitance (TCC) and permitivity (TCP) were determined as a function of the film thickness. The microstructure of the samples were analyzed using X-ray diffraction (XRD). This results are discussed on the base of the differences in their morphologies and thicknesses. The tendency for amorphization of the crystalline phases becomes evident as the film thickness increases.

  4. CaTiO(3) coating on titanium for biomaterial application--optimum thickness and tissue response.

    PubMed

    Ohtsu, Naofumi; Sato, Kenji; Yanagawa, Aya; Saito, Kesami; Imai, Yoshio; Kohgo, Takao; Yokoyama, Atsuro; Asami, Katsuhiko; Hanawa, Takao

    2007-08-01

    The objectives of this study were to determine the optimum thickness of a CaTiO(3) film for biomaterial applications and to investigate the biocompatibility and bone formation of titanium with a CaTiO(3) film. First, CaTiO(3) films of 10, 20, 30, and 50 nm in thickness were deposited on titanium substrates using radiofrequency magnetron sputtering followed by annealing at 873 K in air for 7.2 ks. The optimum thickness of the CaTiO(3) film for bone formation was determined by comparison with its performance regarding calcium phosphate formation in Hanks' balanced saline solution (HBSS). Regarding calcium phosphate formation, the performance of the specimen with a 50-nm-thick CaTiO(3) film was superior to those of specimens with other thicknesses. A titanium prism with a CaTiO(3) film of 50-nm in thickness was surgically inserted in both soft and hard rat tissues. The biocompatibility of CaTiO(3)-deposited titanium and bone formation on it was investigated by histological observations. A slight inflammatory reaction was observed around the titanium with the 50-nm-thick CaTiO(3) film, while no severe response, such as degeneration and necrosis, was observed in either soft or hard rat tissue. New bone formation on the titanium plate with the CaTiO(3) film was more active than that without the film. The 50-nm-thick CaTiO(3) film has biocompatibility and can facilitate new bone formation in vivo, and, consequently, it is an excellent surface modification method for biomaterial applications. PMID:17279562

  5. Changes in the temperature-dependent specific volume of supported polystyrene films with film thickness.

    PubMed

    Huang, Xinru; Roth, Connie B

    2016-06-21

    Recent studies have measured or predicted thickness-dependent shifts in density or specific volume of polymer films as a possible means of understanding changes in the glass transition temperature Tg(h) with decreasing film thickness with some experimental works claiming unrealistically large (25%-30%) increases in film density with decreasing thickness. Here we use ellipsometry to measure the temperature-dependent index of refraction of polystyrene (PS) films supported on silicon and investigate the validity of the commonly used Lorentz-Lorenz equation for inferring changes in density or specific volume from very thin films. We find that the density (specific volume) of these supported PS films does not vary by more than ±0.4% of the bulk value for film thicknesses above 30 nm, and that the small variations we do observe are uncorrelated with any free volume explanation for the Tg(h) decrease exhibited by these films. We conclude that the derivation of the Lorentz-Lorenz equation becomes invalid for very thin films as the film thickness approaches ∼20 nm, and that reports of large density changes greater than ±1% of bulk for films thinner than this likely suffer from breakdown in the validity of this equation or in the difficulties associated with accurately measuring the index of refraction of such thin films. For larger film thicknesses, we do observed small variations in the effective specific volume of the films of 0.4 ± 0.2%, outside of our experimental error. These shifts occur simultaneously in both the liquid and glassy regimes uniformly together starting at film thicknesses less than ∼120 nm but appear to be uncorrelated with Tg(h) decreases; possible causes for these variations are discussed. PMID:27334190

  6. Changes in the temperature-dependent specific volume of supported polystyrene films with film thickness

    NASA Astrophysics Data System (ADS)

    Huang, Xinru; Roth, Connie B.

    2016-06-01

    Recent studies have measured or predicted thickness-dependent shifts in density or specific volume of polymer films as a possible means of understanding changes in the glass transition temperature Tg(h) with decreasing film thickness with some experimental works claiming unrealistically large (25%-30%) increases in film density with decreasing thickness. Here we use ellipsometry to measure the temperature-dependent index of refraction of polystyrene (PS) films supported on silicon and investigate the validity of the commonly used Lorentz-Lorenz equation for inferring changes in density or specific volume from very thin films. We find that the density (specific volume) of these supported PS films does not vary by more than ±0.4% of the bulk value for film thicknesses above 30 nm, and that the small variations we do observe are uncorrelated with any free volume explanation for the Tg(h) decrease exhibited by these films. We conclude that the derivation of the Lorentz-Lorenz equation becomes invalid for very thin films as the film thickness approaches ˜20 nm, and that reports of large density changes greater than ±1% of bulk for films thinner than this likely suffer from breakdown in the validity of this equation or in the difficulties associated with accurately measuring the index of refraction of such thin films. For larger film thicknesses, we do observed small variations in the effective specific volume of the films of 0.4 ± 0.2%, outside of our experimental error. These shifts occur simultaneously in both the liquid and glassy regimes uniformly together starting at film thicknesses less than ˜120 nm but appear to be uncorrelated with Tg(h) decreases; possible causes for these variations are discussed.

  7. Influence of the layer thickness in plasmonic gold nanoparticles produced by thermal evaporation

    PubMed Central

    Gaspar, D.; Pimentel, A. C.; Mateus, T.; Leitão, J. P.; Soares, J.; Falcão, B. P.; Araújo, A.; Vicente, A.; Filonovich, S. A.; Águas, H.; Martins, R.; Ferreira, I.

    2013-01-01

    Metallic nanoparticles (NPs) have received recently considerable interest of photonic and photovoltaic communities. In this work, we report the optoelectronic properties of gold NPs (Au-NPs) obtained by depositing very thin gold layers on glass substrates through thermal evaporation electron-beam assisted process. The effect of mass thickness of the layer was evaluated. The polycrystalline Au-NPs, with grain sizes of 14 and 19 nm tend to be elongated in one direction as the mass thickness increase. A 2 nm layer deposited at 250°C led to the formation of Au-NPs with 10-20 nm average size, obtained by SEM images, while for a 5 nm layer the wide size elongates from 25 to 150 nm with a mean at 75 nm. In the near infrared region was observed an absorption enhancement of amorphous silicon films deposited onto the Au-NPs layers with a corresponding increase in the PL peak for the same wavelength region. PMID:23552055

  8. 193 nm excimer laser sclerostomy in pseudophakic patients with advanced open angle glaucoma.

    PubMed Central

    Allan, B D; van Saarloos, P P; Cooper, R L; Constable, I J

    1994-01-01

    A modified open mask system incorporating an en face air jet to dry the target area during ablation and a conjunctival plication mechanism, which allows ab externo delivery of the 193 nm excimer laser without prior conjunctival dissection, has been developed to form small bore sclerostomies accurately and atraumatically. Full thickness sclerostomies, and sclerostomies guarded by a smaller internal ostium can be created. A pilot therapeutic trial was conducted in pseudophakic patients with advanced open angle glaucoma. Six full thickness sclerostomies (200 microns and 400 microns diameter) and three guarded sclerostomies were created in nine patients by 193 nm excimer laser ablation (fluence per pulse 400 mJ/cm2, pulse rate 16 Hz, air jet pressure intraocular pressure +25 mm Hg). After 6 months' follow up, intraocular pressure was controlled (< or = 16 mm Hg) in eight of the nine patients (6/9 without medication). Early postoperative complications included hyphaema (trace--2.5 mm) (6/9), temporary fibrinous sclerostomy occlusion (4/9), profound early hypotony (all patients without fibrinous occlusion), and suprachoroidal haemorrhage in one case. Conjunctival laser wounds were self sealing. Small bore laser sclerostomy procedures are functionally equivalent to conventional full thickness procedures, producing early postoperative hypotony, with an increased risk of suprachoroidal haemorrhage in association with this. Further research is required to improve control over internal guarding in excimer laser sclerostomy before clinical trials of this technique can safely proceed. Images PMID:8148335

  9. Lactones in 193 nm resists: What do they do?

    NASA Astrophysics Data System (ADS)

    Ito, Hiroshi; Truong, Hoa D.; Brock, Phil J.

    2008-03-01

    Lactones are almost ubiquitously employed in 193 nm resists to increase the polarity of hydrophobic alicyclic polymers. What else do lactones do in 193 nm resists? We studied the behavior of methacrylate (MA) resists consisting of different protecting groups, hexafluoroalcohols, and norbornane lactone methacrylate (NLM, 2-oxo-3-oxatricyclo[4.2.1.04,8]nonan-5-yl methacrylate). When the protecting group is large [ethylcyclooctyl (ECO) and methyladamantyl (MAd)], thinning of the resist film that occurs in highly exposed areas upon postexposure bake (PEB) is significantly smaller than what is expected from the polymer composition. When the concentration of isopropylhexafluoroalcohol methacrylate (iPrHFAMA) is increased in the ECOMA-NLM polymer, the thinning increases and reaches 100% of theory and the ECOMA-norbornenehexafluoroalcohol methacrylate (NBHFAMA) resist loses quantitative thickness in highly-exposed areas upon PEB at 90 °C. This indicates that small lactones which are more basic than esters can trap deprotection fragments especially when the protecting group is large. Such entrapment was detected by IR spectroscopy and also observed at temperatures as high as 200 °C in thermogravimetric analysis (TGA). Incorporation of lactone appears to decrease the bake temperature sensitivity and the sensitivity of the resist perhaps due to trapping of photochemically generated acids by basic lactone. The lactone ring can be hydrolyzed during aqueous base development but does not seem to affect the dissolution rate, indicating that hydrolysis occurs in aqueous base solution after dissolution. Poly(methacrylic acid-NLM) dissolves as fast as poly(methacrylic acid) in 0.26 N tetramethylammonium hydroxide (TMAH) aqueous solution. While exposed P(ECOMA 47-NLM 53) resist dissolves in 0.26 N developer at about the same rate as authentically prepared poly(methacrylic acid 47-NLM 53), the dissolution rate of highly-exposed P(MAdMA 44-NLM 56) resist is much slower, indicating

  10. Aperiodic normal-incidence antimony-based multilayer mirrors in the 8 - 13-nm spectral range

    SciTech Connect

    Vishnyakov, E A; Luginin, M S; Pirozhkov, A S; Ragozin, Evgenii N; Startsev, S A

    2011-01-31

    The optical properties of several materials were analysed from the standpoint of fabrication of broadband normal-incidence multilayer mirrors possessing maximal uniform reflectivity in the 8-13-nm range. By solving the inverse problem of multilayer optics we show that aperiodic Sb/(B{sub 4}C, Sc, Si) multilayer structures optimised for maximum uniform reflectivity in the 8-13-nm range are able to afford a normal-incidence reflectivity R{approx}10 % throughout this range. The best results are exhibited by the pair Sb/B{sub 4}C, for which the average reflection coefficient amounts to about 13%. The dependence of optimisation result on the programmable limitation on the minimal layer thickness in the multilayer structure was numerically investigated. An empirical rule was established whereby setting the lower bound for a layer thickness at a level {approx}{lambda}{sub min}/4 (in this case, {lambda}{sub min} = 8 nm) does not result in an appreciable lowering of attainable uniform reflectivity. (quantum electronic devices)

  11. AlGaAs heterojunction visible (700 nm) light-emitting diodes on Si substrates fabricated by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Hashimoto, A.; Kawarada, Y.; Kamijoh, T.; Akiyama, M.; Watanabe, N.

    1986-06-01

    The fabrication of AlGaAs LEDs emitting at 700 nm (half width 45 nm) by the metal-organic chemical-vapor deposition (MOCVD) method of Akiyama et al. (1985) is reported. Using trimethylgallium, trimethylaluminum, and arsine as the source reactants in a horizontal reactor at 100 torr and flow rate 4 l/min, a 200-300-nm-thick layer of n-GaAs is grown on a 3-micron-thick (100) n-Si substrate at 425 C prior to MOCVD of a 1-micron-thick layer of n-Al(0.4)Ga(0.6)As, a 3-micron-thick layer of p-Al(0.35)Ga(0.65)As, and a 50-nm-thick p-GaAs ohmic-contact cap layer at 750 C and AlGaAs growth rate 120 nm/min. The 350-micron-square LED chips exhibit forward voltages 1.38 V at 10 microA and 2.4 V at 100 mA, reverse voltage 11 V at 10 microA, and optical output power 600 microW at 100 mA and room temperature, corresponding to external efficiency 0.3 percent.

  12. Red fluorescent biofilm: the thick, the old, and the cariogenic

    PubMed Central

    Volgenant, Catherine M.C.; Hoogenkamp, Michel A.; Buijs, Mark J.; Zaura, Egija; ten Cate, Jacob (Bob) M.; van der Veen, Monique H.

    2016-01-01

    Background Some dental plaque fluoresces red. The factors involved in this fluorescence are yet unknown. Objective The aim of this study was to assess systematically the effect of age, thickness, and cariogenicity on the extent of red fluorescence produced by in vitro microcosm biofilms. Design The effects of biofilm age and thickness on red fluorescence were tested in a constant depth film fermentor (CDFF) by growing biofilms of variable thicknesses that received a constant supply of defined mucin medium (DMM) and eight pulses of sucrose/day. The influence of cariogenicity on red fluorescence was tested by growing biofilm on dentin disks receiving DMM, supplemented with three or eight pulses of sucrose/day. The biofilms were analyzed at different time points after inoculation, up to 24 days. Emission spectra were measured using a fluorescence spectrophotometer (λexc405 nm) and the biofilms were photographed with a fluorescence camera. The composition of the biofilms was assessed using 454-pyrosequecing of the 16S rDNA gene. Results From day 7 onward, the biofilms emitted increasing intensities of red fluorescence as evidenced by the combined red fluorescence peaks. The red fluorescence intensity correlated with biofilm thickness but not in a linear way. Biofilm fluorescence also correlated with the imposed cariogenicity, evidenced by the induced dentin mineral loss. Increasing the biofilm age or increasing the sucrose pulsing frequency led to a shift in the microbial composition. These shifts in composition were accompanied by an increase in red fluorescence. Conclusions The current study shows that a thicker, older, or more cariogenic biofilm results in a higher intensity of red fluorescence. PMID:27060056

  13. Protein adsorption on poly(N-isopropylacrylamide)-modified silicon surfaces: effects of grafted layer thickness and protein size.

    PubMed

    Yu, Qian; Zhang, Yanxia; Chen, Hong; Wu, Zhaoqiang; Huang, He; Cheng, Chi

    2010-04-01

    In this work, we investigated the protein adsorption on the end-tethered thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) brushes with varying grafted layer thickness prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) on initiator-immobilized silicon surfaces. The thickness of a grafted layer was modulated by adjusting reaction time and/or solvent composition. The surface properties as a function of thickness were investigated by water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM). The influence of PNIPAAm-grafted layer thickness on human serum albumin (HSA) adsorption in phosphate-buffered saline (PBS) (pH 7.4) at different temperature was evaluated using a radiolabeling method. In a lower thickness range (<15 nm), protein adsorption on PNIPAAm-grafted layer shows a thermoresponsive change in a certain extent, but the variation is not remarkable. However, it is interesting to observe that these surfaces exhibit good protein-resistant property. For the surface with a PNIPAAm thickness of 13.4 nm, the HSA adsorption level measured at room temperature was approximately 7 ng/cm2, corresponding to a reduction of 97% compared to the unmodified silicon surface. For thicker PNIPAAm-grafted surface with thickness of 38.1 nm, the adsorption results of three proteins (HSA, fibrinogen, and lysozyme) with different sizes and charges indicate that the PNIPAAm-modified surface exhibits a size-sensitive property of protein adsorption. PMID:20045297

  14. Multi-watt 589nm fiber laser source

    SciTech Connect

    DAWSON, J W; DROBSHOFF, A D; BEACH, R J; MESSERLY, M J; PAYNE, S A; BROWN, A; PENNINGTON, D M; BAMFORD, D J; SHARPE, S J; COOK, D J

    2006-01-19

    We have demonstrated 3.5W of 589nm light from a fiber laser using periodically poled stoichiometric Lithium Tantalate (PPSLT) as the frequency conversion crystal. The system employs 938nm and 1583nm fiber lasers, which were sum-frequency mixed in PPSLT to generate 589nm light. The 938nm fiber laser consists of a single frequency diode laser master oscillator (200mW), which was amplified in two stages to >15W using cladding pumped Nd{sup 3+} fiber amplifiers. The fiber amplifiers operate at 938nm and minimize amplified spontaneous emission at 1088nm by employing a specialty fiber design, which maximizes the core size relative to the cladding diameter. This design allows the 3-level laser system to operate at high inversion, thus making it competitive with the competing 1088nm 4-level laser transition. At 15W, the 938nm laser has an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >15:1). The 1583nm fiber laser consists of a Koheras 1583nm fiber DFB laser that is pre-amplified to 100mW, phase modulated and then amplified to 14W in a commercial IPG fiber amplifier. As a part of our research efforts we are also investigating pulsed laser formats and power scaling of the 589nm system. We will discuss the fiber laser design and operation as well as our results in power scaling at 589nm.

  15. Infrared Luminescence at 1010 nm and 1500 nm in LiNbO3:Er3+ Excitted by Short Pulse Radiation at 980 nm

    NASA Astrophysics Data System (ADS)

    Kokanyan, E. P.; Demirkhanyan, G. G.; Steveler, E.; Rinnert, H.; Aillerie, M.

    Luminescence of LiNbO3:Er3+ crystal at a wavelength of 1010 nm and 1500 nm under pulsed excitation of different power at a wavelength of 980 nm are experimentally and theoretically studied. It is revealed, that the main part of the absorbed energy gives rise to the luminescence at 1500 nm. Considered concentrations of Er3+ impurity ions allow to exclude cooperative processes in the impurity subsystem. The experimental results are interpreted in the framework of a three electronic levels system, assuming that the population of the higher lasing level 4I13/2 in the crystal under study is caused by relaxation processes from the excited level. It is shown that for obtaining of a laser radiation at about 1500 nm one can effectively use a pulse-pumping at 980 nm with a power density in a range of 50 ÷ 60 MW/cm2.

  16. Thickness and Elasticity of Gram-Negative Murein Sacculi Measured by Atomic Force Microscopy

    PubMed Central

    Yao, X.; Jericho, M.; Pink, D.; Beveridge, T.

    1999-01-01

    Atomic force microscopy was used to measure the thickness of air-dried, collapsed murein sacculi from Escherichia coli K-12 and Pseudomonas aeruginosa PAO1. Air-dried sacculi from E. coli had a thickness of 3.0 nm, whereas those from P. aeruginosa were 1.5 nm thick. When rehydrated, the sacculi of both bacteria swelled to double their anhydrous thickness. Computer simulation of a section of a model single-layer peptidoglycan network in an aqueous solution with a Debye shielding length of 0.3 nm gave a mass distribution full width at half height of 2.4 nm, in essential agreement with these results. When E. coli sacculi were suspended over a narrow groove that had been etched into a silicon surface and the tip of the atomic force microscope used to depress and stretch the peptidoglycan, an elastic modulus of 2.5 × 107 N/m2 was determined for hydrated sacculi; they were perfectly elastic, springing back to their original position when the tip was removed. Dried sacculi were more rigid with a modulus of 3 × 108 to 4 × 108 N/m2 and at times could be broken by the atomic force microscope tip. Sacculi aligned over the groove with their long axis at right angles to the channel axis were more deformable than those with their long axis parallel to the groove axis, as would be expected if the peptidoglycan strands in the sacculus were oriented at right angles to the long cell axis of this gram-negative rod. Polar caps were not found to be more rigid structures but collapsed to the same thickness as the cylindrical portions of the sacculi. The elasticity of intact E. coli sacculi is such that, if the peptidoglycan strands are aligned in unison, the interstrand spacing should increase by 12% with every 1 atm increase in (turgor) pressure. Assuming an unstressed hydrated interstrand spacing of 1.3 nm (R. E. Burge, A. G. Fowler, and D. A. Reaveley, J. Mol. Biol. 117:927–953, 1977) and an internal turgor pressure of 3 to 5 atm (or 304 to 507 kPa) (A. L. Koch, Adv. Microbial

  17. A differential mechanical profilometer for thickness measurement

    SciTech Connect

    Alves, J. Maia; Brito, M.C.; Serra, J.M.; Vallera, A.M.

    2004-12-01

    A low cost differential profilometer based on standard commercial displacement transducers is fully described. Unlike most common profilometers this device can be used to measure the thickness profile of samples having both surfaces irregular. A sensitivity of about 0.2 {mu}m, independent of the sample thickness is achieved.

  18. Monitoring Coating Thickness During Plasma Spraying

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.

    1990-01-01

    High-resolution video measures thickness accurately without interfering with process. Camera views cylindrical part through filter during plasma spraying. Lamp blacklights part, creating high-contrast silhouette on video monitor. Width analyzer counts number of lines in image of part after each pass of spray gun. Layer-by-layer measurements ensure adequate coat built up without danger of exceeding required thickness.

  19. Eggshell thickness in mourning dove populations

    USGS Publications Warehouse

    Kreitzer, J.F.

    1971-01-01

    Eggs (n = 452) of the mourning dove (Zenaidura macroura) were collected from 9 states in 1969 and 11 states in 1970, and shell thickness was compared with that of eggs (n = 97) collected from 24 states during the years 1861 to 1935. Mean shell thickness did not differ significantly in the test groups.

  20. Cloud Thickness from Offbeam Returns - Thor Lidar

    NASA Technical Reports Server (NTRS)

    Cahalan, R.; Kolasinski, J.; McGill, M.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Physical thickness of a cloud layer, and sometimes multiple cloud layers, can be estimated from the time delay of off-beam returns from a pulsed laser source illuminating one side of the cloud layer. In particular, the time delay of light returning from the outer diffuse halo of light surrounding the beam entry point, relative to the time delay at beam center, determines the cloud physical thickness. The delay combined with the pulse stretch gives the optical thickness. The halo method works best for thick cloud layers, typically optical thickness exceeding 2, and thus compliments conventional lidar which cannot penetrate thick clouds. Cloud layer top and base have been measured independently over the ARM/SGP site using conventional laser ranging (lidar) and the top minus base thickness are compared with a cloud top halo estimate obtained from the NASA/Goddard THOR System (THOR = THickness from Offbeam Returns). THOR flies on the NASA P3, and measures the halo timings from several km above cloud top, at the same time providing conventional lidar cloud top height. The ARM/SGP micropulse lidar provides cloud base height for validation.

  1. EVA mouthguards: how thick should they be?

    PubMed

    Westerman, Bill; Stringfellow, Peter M; Eccleston, John A

    2002-02-01

    A major consideration in the performance of mouthguards is their ability to absorb energy and reduce transmitted forces when impacted. This is especially important to participants in contact sports such as hockey or football. The thickness of mouthguard materials is directly related to energy absorption and inversely related to transmitted forces when impacted. However, wearer comfort is also an important factor in their use. Thicker mouthguards are not user-friendly. While thickness of material over incisal edges and cusps of teeth is critical, just how thick should a mouthguard be and especially in these two areas? Transmitted forces through different thicknesses of the most commonly used mouthguard material, ethylene vinyl acetate (EVA) (Shore A Hardness of 80) were compared when impacted with identical forces which were capable of damaging the oro-facial complex. The constant impact force used in the tests was produced by a pendulum and had an energy of 4.4 joules and a velocity of 3 meters per second. Improvements in energy absorption and reductions in transmitted forces were observed with increasing thickness. However, these improvements lessened when the mouthguard material thickness was greater than 4 mm. The results show that the optimal thickness for EVA mouthguard material with a Shore A Hardness of 80 is around 4 mm. Increased thickness, while improving performance marginally, results in less wearer comfort and acceptance. PMID:11841462

  2. Scattering From A Thick Dichroic Microwave Reflector

    NASA Technical Reports Server (NTRS)

    Chen, Jacqueline C.

    1994-01-01

    Thick Frequency Selective Surface with Rectangular Apertures, TFSSRA, computer program developed to calculate scattering parameters of thick frequency-selective surface with rectangular apertures on skew grid at oblique angle of incidence. Integral equation transformed into matrix equation, which is then solved. Written in FORTRAN 77 with single precision.

  3. Measurement of absolute optical thickness of mask glass by wavelength-tuning Fourier analysis.

    PubMed

    Kim, Yangjin; Hbino, Kenichi; Sugita, Naohiko; Mitsuishi, Mamoru

    2015-07-01

    Optical thickness is a fundamental characteristic of an optical component. A measurement method combining discrete Fourier-transform (DFT) analysis and a phase-shifting technique gives an appropriate value for the absolute optical thickness of a transparent plate. However, there is a systematic error caused by the nonlinearity of the phase-shifting technique. In this research the absolute optical-thickness distribution of mask blank glass was measured using DFT and wavelength-tuning Fizeau interferometry without using sensitive phase-shifting techniques. The error occurring during the DFT analysis was compensated for by using the unwrapping correlation. The experimental results indicated that the absolute optical thickness of mask glass was measured with an accuracy of 5 nm. PMID:26125394

  4. Thickness dependence of the charge-density-wave transition temperature in VSe{sub 2}

    SciTech Connect

    Yang, Jiyong; Liu, Yan; Du, Haifeng; Ning, Wei; Zheng, Guolin; Jin, Chiming; Han, Yuyan; Wang, Ning; Tian, Mingliang Zhang, Yuheng; Wang, Weike; Yang, Zhaorong

    2014-08-11

    A set of three-dimensional charge-density-wave (3D CDW) VSe{sub 2} nano-flakes with different thicknesses were obtained by the scotch tape-based micro-mechanical exfoliation method. Resistivity measurements showed that the 3D CDW transition temperature T{sub p} decreases systematically from 105 K in bulk to 81.8 K in the 11.6 nm thick flake. The Hall resistivity ρ{sub xy} of all the flakes showed a linear dependent behavior against the magnetic field with a residual electron concentration of the order of ∼10{sup 21} cm{sup −3} at 5 K. The electron concentration n increases slightly as the thickness d decreases, possibly due to the CDW gap is reduced with the decrease of the thickness.

  5. On-Line Measurement of Lubricant Film Thickness Using Ultrasonic Reflection Coefficients

    SciTech Connect

    Drinkwater, B.W.; Dwyer-Joyce, R.S.; Harper, P.

    2004-02-26

    The ultrasonic reflectivity of a lubricant layer between two solid bodies depends on the ultrasonic frequency, the acoustic properties of the liquid and solid, and the layer thickness. In this paper, ultrasonic reflectivity measurements are used as a method for determining the thickness of lubricating films in bearing systems. An ultrasonic transducer is positioned on the outside of a bearing shell such that the wave is focused on the lubricant film layer. For a particular lubricant film the reflected pulse is processed to give a reflection coefficient spectrum. The lubricant film thickness is then obtained from either the layer stiffness or the resonant frequency. The method has been validated using static fluid wedges and the elastohydrodynamic film formed between a ball sliding on a flat. Film thickness values in the range 50-500 nm were recorded which agreed well with theoretical film formation predictions.

  6. Control of lateral thickness gradients of Mo-Si multilayer on curved substrates using genetic algorithm.

    PubMed

    Yu, Bo; Jin, Chunshui; Yao, Shun; Li, Chun; Wang, Hui; Zhou, Feng; Guo, Benyin; Xie, Yao; Liu, Yu; Wang, Liping

    2015-09-01

    An inversion method based on a genetic algorithm has been developed to control the lateral thickness gradients of a Mo-Si multilayer deposited on curved substrates by planar magnetron sputtering. At first, the sputtering distribution of the target is inversed from coating thickness profiles of flat substrates at different heights. Then, the speed profiles of substrates sweeping across the target are optimized according to the desired coating thickness profiles of the primary and secondary mirrors in a two-bounce projection system. The measured coating thickness profiles show that the non-compensable added figure error is below 0.1 nm rms, and the wavelength uniformity across each mirror surface is within ±0.2% P-V. The inversion method introduced here exhibits its convenience in obtaining the sputtering distribution of the target and efficiency in coating iterations during process development. PMID:26368686

  7. Thickness dependent charge transport in ferroelectric BaTiO3 heterojunctions

    NASA Astrophysics Data System (ADS)

    Singh, Pooja; Rout, P. K.; Singh, Manju; Rakshit, R. K.; Dogra, Anjana

    2015-09-01

    We have investigated the effect of ferroelectric barium titanate (BaTiO3) film thickness on the charge transport mechanism in pulsed laser deposited epitaxial metal-ferroelectric semiconductor junctions. The current (I)-voltage (V) measurements across the junctions comprising of 20-500 nm thick BaTiO3 and conducting bottom electrode (Nb: SrTiO3 substrate or La2/3Ca1/3MnO3 buffer layer) demonstrate the space charge limited conduction. Further analysis indicates a reduction in the ratio of free to trapped carriers with increasing thickness in spite of decreasing trap density. Such behaviour arises the deepening of the shallow trap levels (<0.65 eV) below conduction band with increasing thickness. Moreover, the observed hysteresis in I-V curves implies a bipolar resistive switching behaviour, which can be explained in terms of charge trapping and de-trapping process.

  8. Fast dispersion encoded full range OCT for retinal imaging at 800 nm and 1060 nm

    NASA Astrophysics Data System (ADS)

    Hofer, Bernd; Považay, Boris; Unterhuber, Angelika; Wang, Ling; Hermann, Boris; Rey, Sara; Matz, Gerald; Drexler, Wolfgang

    2011-03-01

    The dispersion mismatch between sample and reference arm in frequency-domain OCT can be used to iteratively suppress complex conjugate artifacts and thereby increase the imaging range. We propose a fast dispersion encoded full range (DEFR) algorithm that detects multiple signal components per iteration. The influence of different dispersion levels on the reconstruction quality is analyzed for in vivo retinal tomograms at 800 nm. Best results have been achieved with about 30 mm SF11, with neglectable resolution decrease due to finite resolution of the spectrometer. Our fast DEFR algorithm achieves an average suppression ratio of 55 dB and converges within 5 to 10 iterations. The processing time on non-dedicated hardware was 5 to 10 seconds for tomograms with 512 depth scans and 4096 sampling points per depth scan. Application of DEFR to the more challenging 1060 nm wavelength region is demonstrated by introducing an additional optical fibre in the sample arm.

  9. Polarization properties of lidar scattering from clouds at 347 nm and 694 nm.

    PubMed

    Pal, S R; Carswell, A I

    1978-08-01

    The polarization characteristics of lidar scattering from cumulus and low-lying shower clouds have been measured with a system operating at 694 nm (red) and 347 nm (blue). The backscatter profiles of the polarization components as well as of the total intensity of the return are presented and discussed for the two wavelengths. The linear depolarization ratio delta, which can be used as a measure of the unpolarized multiple scattering, has been obtained at both wavelengths. This quantity has a very low value at cloud base for both wavelengths and increases with pulse penetration. The blue registers generally higher values of a within the cloud. The measured total intensity backscatter functions for both wavelengths are presented and discussed in relation to theoretical calculations of cloud models. PMID:20203781

  10. 100 nm half-pitch double exposure KrF lithography using binary masks

    NASA Astrophysics Data System (ADS)

    Geisler, S.; Bauer, J.; Haak, U.; Stolarek, D.; Schulz, K.; Wolf, H.; Meier, W.; Trojahn, M.; Matthus, E.

    2008-03-01

    In this paper we investigate the process margin for the 100nm half - pitch double exposure KrF lithography using binary masks for different illumination settings. The application of Double Exposure Lithography (DEL) would enlarge the capability of 248 nm exposure technique to smaller pitch e.g. for the integration of dedicated layers into 0.13 μm BiCMOS with critical dimension (CD) requirements exceeding the standard 248 nm lithography specification. The DEL was carried out with a KrF Scanner (Nikon S207D, NA Lens = 0.82) for a critical dimension (CD) of 100nm half pitch. The chemical amplified positive resists SL4800 or UV2000 (Rohm & Haas) with a thickness of 325nm were coated on a 70 nm AR10L (Rohm & Haas) bottom anti-reflective coating (BARC). With a single exposure and using binary masks it is not possible to resolve 100nm lines with a pitch of 200 nm, due to the refraction and the resolution limit. First we investigated the effect of focus variation. It is shown that the focus difference of 1st and 2nd exposure is one critical parameter of the DEL. This requires a good focus repeatability of the scanner. The depth of focus (DOF) of 360 nm with the coherence parameter σ = 0.4 was achieved for DEL with SL4800 resist. The influence of the better resist resolution of UV2000 on the process window will be shown (DOF = 460 nm). If we change the focus of one of the exposures the CD and DOF performance of spaces is reduced with simultaneous line position changing. Second we investigated the effect of different illumination shapes and settings. The results for conventional illumination with different values for σ and annular illumination with σ inner = 0.57 and σ outer = 0.85 will be shown. In summary, the results show that DEL has the potential to be a practical lithography enhancement method for device fabrication using high NA KrF tool generation.

  11. Novel spin-coating technology for 248-nm/193-nm DUV lithography and low-k spin on dielectrics of 200-mm/300-mm wafers

    NASA Astrophysics Data System (ADS)

    Gurer, Emir; Zhong, Tom X.; Lewellen, John W.; Lee, Ed C.

    2000-06-01

    An alternative coating technology was developed for 248 nm/193 nm DUV lithography and low-k spin on dielectric (SOD) materials used in the interconnect area. This is a 300 mm enabling technology which overcomes turbulent flow limitations above 2000 rpm and it prevents 40 - 60% reduction on the process latitudes of evaporation-related variables, common to 300 mm conventional coaters. Our new coating technology is fully enclosed and it is capable of controlling the solvent concentration above the resist film dynamically in the gas phase. This feature allows a direct control of the evaporation mass transfer which determines the quality of the final resist profiles. Following process advantages are reported in this paper: (1) Demonstrated that final resist film thickness can be routinely varied by 4000 angstrom at a fixed drying spin speed, thus minimizing the impact of turbulence wall for 300 mm wafers. (2) Evaporation control allows wider range of useful thickness from a fixed viscosity material. (3) Latitudes of evaporation-related process variables is about 40% larger than that of a conventional coater. (4) Highly uniform films of 0.05% were obtained for 8800 angstrom target thickness with tighter wafer-wafer profile control because of the enclosed nature of the technology. (5) Dynamic evaporation control facilitates resist consumption minimization. Preliminary results indicate feasibility of a 0.4 cc process of record (POR) for a 200 mm substrate. (6) Lower COO due to demonstrated relative insensitivity to environmental variables, robust resist consumption minimization and superior process capabilities. (7) Improved planarization and gap fill properties for the new generation photoresist/low-k SOD materials deposited using this enclosed coating technology.

  12. Non-Uniform Thickness Electroactive Device

    NASA Technical Reports Server (NTRS)

    Su, Ji (Inventor); Harrison, Joycelyn S. (Inventor)

    2006-01-01

    An electroactive device comprises at least two layers of material, wherein at least one layer is an electroactive material and wherein at least one layer is of non-uniform thickness. The device can be produced in various sizes, ranging from large structural actuators to microscale or nanoscale devices. The applied voltage to the device in combination with the non-uniform thickness of at least one of the layers (electroactive and/or non-electroactive) controls the contour of the actuated device. The effective electric field is a mathematical function of the local layer thickness. Therefore, the local strain and the local bending/ torsion curvature are also a mathematical function of the local thickness. Hence the thinnest portion of the actuator offers the largest bending and/or torsion response. Tailoring of the layer thicknesses can enable complex motions to be achieved.

  13. TUNABLE DIODE LASER MEASUREMENTS OF NO2 NEAR 670 NM AND 395 NM. (R823933)

    EPA Science Inventory

    Two single-mode diode lasers were used to record high-resolution absorption spectra of NO2 (dilute in Ar) near 670.2 and 394.5 nm over a range of temperatures (296 to 774 K) and total pressures (2.4 x 10(-2) to 1 atm). A commercial InGaAsP laser was tuned 1.3 cm(-1) at a repetiti...

  14. Analysis of multi-mode to single-mode conversion at 635 nm and 1550 nm

    NASA Astrophysics Data System (ADS)

    Zamora, Vanessa; Bogatzki, Angelina; Arndt-Staufenbiel, Norbert; Hofmann, Jens; Schröder, Henning

    2016-03-01

    We propose two low-cost and robust optical fiber systems based on the photonic lantern (PL) technology for operating at 635 nm and 1550 nm. The PL is an emerging technology that couples light from a multi-mode (MM) fiber to several single-mode (SM) fibers via a low-loss adiabatic transition. This bundle of SM fibers is observed as a MM fiber system whose spatial modes are the degenerate supermodes of the bundle. The adiabatic transition allows that those supermodes evolve into the modes of the MM fiber. Simulations of the MM fiber end structure and its taper transition have been performed via functional mode solver tools in order to understand the modal evolution in PLs. The modelled design consists of 7 SM fibers inserted into a low-index capillary. The material and geometry of the PLs are chosen such that the supermodes match to the spatial modes of the desired step-index MM fiber in a moderate loss transmission. The dispersion of materials is also considered. These parameters are studied in two PL systems in order to reach a spectral transmission from 450 nm to 1600 nm. Additionally, an analysis of the geometry and losses due to the mismatching of modes is presented. PLs are typically used in the fields of astrophotonics and space photonics. Recently, they are demonstrated as mode converters in telecommunications, especially focusing on spatial division multiplexing. In this study, we show the use of PLs as a promising interconnecting tool for the development of miniaturized spectrometers operating in a broad wavelength range.

  15. Electron-induced single event upsets in 28 nm and 45 nm bulk SRAMs

    DOE PAGESBeta

    Trippe, J. M.; Reed, R. A.; Austin, R. A.; Sierawski, B. D.; Weller, R. A.; Funkhouser, E. D.; King, M. P.; Narasimham, B.; Bartz, B.; Baumann, R.; et al

    2015-12-01

    In this study, we present experimental evidence of single electron-induced upsets in commercial 28 nm and 45 nm CMOS SRAMs from a monoenergetic electron beam. Upsets were observed in both technology nodes when the SRAM was operated in a low power state. The experimental cross section depends strongly on both bias and technology node feature size, consistent with previous work in which SRAMs were irradiated with low energy muons and protons. Accompanying simulations demonstrate that δ-rays produced by the primary electrons are responsible for the observed upsets. Additional simulations predict the on-orbit event rates for various Earth and Jovian environmentsmore » for a set of sensitive volumes representative of current technology nodes. The electron contribution to the total upset rate for Earth environments is significant for critical charges as high as 0.2 fC. This value is comparable to that of sub-22 nm bulk SRAMs. Similarly, for the Jovian environment, the electron-induced upset rate is larger than the proton-induced upset rate for critical charges as high as 0.3 fC.« less

  16. Electron-induced single event upsets in 28 nm and 45 nm bulk SRAMs

    SciTech Connect

    Trippe, J. M.; Reed, R. A.; Austin, R. A.; Sierawski, B. D.; Weller, R. A.; Funkhouser, E. D.; King, M. P.; Narasimham, B.; Bartz, B.; Baumann, R.; Schrimpf, R. D.; Labello, R.; Nichols, J.; Weeden-Wright, S. L.

    2015-12-01

    In this study, we present experimental evidence of single electron-induced upsets in commercial 28 nm and 45 nm CMOS SRAMs from a monoenergetic electron beam. Upsets were observed in both technology nodes when the SRAM was operated in a low power state. The experimental cross section depends strongly on both bias and technology node feature size, consistent with previous work in which SRAMs were irradiated with low energy muons and protons. Accompanying simulations demonstrate that δ-rays produced by the primary electrons are responsible for the observed upsets. Additional simulations predict the on-orbit event rates for various Earth and Jovian environments for a set of sensitive volumes representative of current technology nodes. The electron contribution to the total upset rate for Earth environments is significant for critical charges as high as 0.2 fC. This value is comparable to that of sub-22 nm bulk SRAMs. Similarly, for the Jovian environment, the electron-induced upset rate is larger than the proton-induced upset rate for critical charges as high as 0.3 fC.

  17. Demonstration of a high output power 1533nm optical parametric oscillator pumped at 1064nm

    NASA Astrophysics Data System (ADS)

    Foltynowicz, Robert J.; Wojcik, Michael D.

    2010-10-01

    A high output power, eye-safe, LIDAR transmitter based on a KTA optical parametric oscillator (OPO) was demonstrated. The OPO was based on a two crystal, NCPM, KTA ring cavity which was doubly resonant. A 7ns, 30Hz, flashlamp-pumped, Q-switched Nd:YAG laser was injection seeded and used to pump the OPO. The OPO converted the 1064 nm pump beam into a 1533 nm signal wave and 3475 nm idler wave. In addition to demonstrating a high power OPO system, we investigated the effects of seeding the pump laser on the OPO's conversion efficiency, oscillation threshold, maximum signal power, and beam quality. The power conversion efficiency between the signal and the injection seeded pump was 22% with an oscillation threshold of 104 MW/cm2 (500 mJ) and a maximum signal power of 6.44 W (215 mJ). The power conversion efficiency between the signal and the unseeded pump was 24% with an oscillation threshold of 77 MW/cm2 (367mJ) and a maximum signal power of 7 W (233 mJ). The beam quality of the signal beam was produced an M2 =15. When the pump laser was seeded, the full angle divergence improved by nearly a factor of five.

  18. Biostimulative effect of 809-nm diode laser and indocyanine green on p. aeruginosa instead of photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Aysan, Nuray; Topaloglu, Nermin; Yuksel, Sahru; Gulsoy, Murat

    2013-03-01

    Photodynamic therapy (PDT) is a safe and alternative antimicrobial treatment that consists of a chemical agent, called photosensitizer, which can be activated by light of an appropriate wavelength to produce reactive oxygen species (ROS). PDT can be used for photoinactivation of bacteria in an attempt to overcome the problem of bacterial multidrug resistance. In particular, it is an effective antimicrobial treatment against infected wounds that have antibiotic resistance and wound infections would otherwise lead to mortality and morbidity. The main purpose of this study was to demonstrate the importance of PDT dosimetry (light dose and concentration of photosensitizer). If the dosimetry of PDT was not optimized properly, photoinactivation of bacteria cannot be achieved and even worse biostimulation on pathogens could be observed. This study investigated whether there is a biostimulative effect due to free oxygen radicals of PDT when light dose and photosensitizer concentration are too low. In this study, the biostimulative effect on P. aeruginosa strain was observed instead of the PDT effect, when 84 J/cm2 of energy dose (809-nm diode laser) was applied with 20, 50, 100 and 150 μg/ml of ICG concentrations. The killing effect of PDT was observed with higher ICG concentrations, such as 200, 250 μg/ml of ICG. However the killing effect was not enough to destroy pathogen efficiently with these high concentrations of ICG.

  19. Dependence of the optimum parameters of femtosecond laser annealing of lead zirconate titanate films on their thickness

    NASA Astrophysics Data System (ADS)

    Elshin, A. S.; Abdullaev, D. A.; Mishina, E. D.

    2016-06-01

    The optimum parameters of laser annealing (crystallization) induced by repetitive pulses with a pulse duration of 100 fs and a wavelength of 800 nm, which falls in the transparency region of the film and, simultaneously, in the absorption region of the substrate, have been investigated experimentally as a function of the thickness of the ferroelectric film. It has been shown that, with an increase in the thickness of the ferroelectric film by 100 nm (in the range from 300 to 600 nm), the required power density of the laser beam increases, on the average, by 0.1 MW/cm2. The optimum exposure time of the laser beam with the desired power increases nonlinearly with an increase in the thickness of the film.

  20. A novel sub 20 nm single gate tunnel field effect transistor with intrinsic channel for ultra low power applications

    NASA Astrophysics Data System (ADS)

    Asthana, Pranav Kumar; Goswami, Yogesh; Ghosh, Bahniman

    2016-05-01

    We propose a nanoscale single gate ultra thin body intrinsic channel tunnel field effect transistor using the charge plasma concept for ultra low power applications. The characteristics of TFETs (having low leakage) are improved by junctionless TFETs through blending advantages of Junctionless FETs (with high on current). We further improved the characteristics, simultaneously simplifying the structure at a very low power rating using an InAs channel. We found that the proposed device structure has reduced short channel effects and parasitics and provides high speed operation even at a very low supply voltage with low leakage. Simulations resulted in IOFF of ∼ 9 × 10‑16 A/μm, ION of ∼20 μA/μm, ION/IOFF of ∼2 × 1010, threshold voltage of 0.057 V, subthreshold slope of 7 mV/dec and DIBL of 86 mV/V for PolyGate/HfO2/InAs TFET at a temperature of 300 K, gate length of 20 nm, oxide thickness of 2 nm, film thickness of 10 nm, low-k spacer thickness of 10 nm and VDD of 0.2 V.

  1. Gold Nanohole Array with Sub-1 nm Roughness by Annealing for Sensitivity Enhancement of Extraordinary Optical Transmission Biosensor

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Irannejad, Mehrdad; Yavuz, Mustafa; Cui, Bo

    2015-05-01

    Nanofabrication technology plays an important role in the performance of surface plasmonic devices such as extraordinary optical transmission (EOT) sensor. In this work, a double liftoff process was developed to fabricate a series of nanohole arrays of a hole diameter between 150 and 235 nm and a period of 500 nm in a 100-nm-thick gold film on a silica substrate. To improve the surface quality of the gold film, thermal annealing was conducted, by which an ultra-smooth gold film with root-mean-square (RMS) roughness of sub-1 nm was achieved, accompanied with a hole diameter shrinkage. The surface sensitivity of the nanohole arrays was measured using a monolayer of 16-mercaptohexadecanoic acid (16-MHA) molecule, and the surface sensitivity was increased by 2.5 to 3 times upon annealing the extraordinary optical transmission (EOT) sensor.

  2. Effect of Thickness on Surface Morphology of Silver Nanoparticle Layer During Furnace Sintering

    NASA Astrophysics Data System (ADS)

    Moon, Yoon Jae; Kang, Heuiseok; Kang, Kyungtae; Moon, Seung-Jae; Young hwang, Jun

    2015-04-01

    In printed electronics applications, specific resistances of conductive lines are critical to the performance of the devices. The specific resistance of a silver (Ag) nanoparticle electrode is affected by surface morphology of the layered nanoparticles which were sintered by the heat treatment after printing. In this work, the relationship between surface morphology and specific resistance was investigated with various sintering temperatures and various layer thicknesses of Ag nanoparticle ink. Ag nanoparticles with an average size of approximately 50 nm were spin-coated on Eagle XG glass substrates with various spin speed to change the layer thickness of Ag nanoparticles from 200 nm to 900 nm. Coated Ag nanoparticle layers were heated from 150°C to 450°C for 30 min in a furnace. The result showed that higher sintering temperature produces larger grains in an Ag layer and decreases specific resistance of the layer, but that the maximum allowable heating temperature is limited by the thickness of the layer. When grain size exceeded the thickness of the layer, the morphology of the Ag nanoparticles changed to submicron-sized islands and the Ag layers did not have electrical conductivity any more.

  3. Size Dependence in Hexagonal Mesoporous Germanium: Pore Wall Thickness versus Energy Gap and Photoluminescence

    SciTech Connect

    Armatas, G. S.; Kanatzidis, Mercouri G.

    2010-08-10

    A series of hexagonal mesoporous germanium semiconductors with tunable wall thickness is reported. These nanostructures possess uniform pores of 3.1-3.2 nm, wall thicknesses from 1.3 to 2.2 nm, and large internal BET surface area in the range of 404-451 m2/g. The porous Ge framework of these materials is assembled from the templated oxidative self-polymerization of (Ge9)4- Zintl clusters. Total X-ray scattering analysis supports a model of interconnected deltahedral (Ge9)-cluster forming the framework and X-ray photoelectron spectroscopy indicates nearly zero-valence Ge atoms. We show the controllable tuning of the pore wall thickness and its impact on the energy band gap which increases systematically with diminishing wall thickness. Furthermore, there is room temperature photoluminescence emission which shifts correspondingly from 672 to 640 nm. The emission signal can be quenched via energy transfer with organic molecules such as pyridine diffusing into the pores.

  4. Force sensing submicrometer thick cantilevers with ultra-thin piezoresistors by rapid thermal diffusion

    NASA Astrophysics Data System (ADS)

    Gel, M.; Shimoyama, I.

    2004-03-01

    One of the most important requirements for a cantilever-type sensor to obtain high force sensitivity is small thickness. By using current micromachining technology it is possible to produce cantilevers of submicrometer thickness. Where self-sensing piezoresistive cantilevers with submicrometer thickness are concerned, it is necessary to use a technology which can create ultra-thin (<100 nm) piezoresistors on a cantilever surface. This work demonstrates for the first time the application of a relatively simple, rapid thermal diffusion method by using spin-on glass film to fabricate sub-100 nm piezoresistors on an ultra-thin single-crystal silicon cantilever. Compared to other shallow junction fabrication methods, which involve implantation or deposition of a doped layer, this method is advantageous since no damage is created in the crystal structure and no toxic gas or hazardous material is used during the process. Besides, this technique can be applied by using low-cost rapid annealers, which can be readily found in most laboratories. By using this method, piezoresistive cantilevers with stiffness in the range of 0.001 N m-1 with sub-100 nm thick piezoresistors are fabricated, and a complete characterization of the fabricated cantilevers is performed.

  5. Superconducting properties and chemical composition of NbTiN thin films with different thickness

    SciTech Connect

    Zhang, L.; Peng, W.; You, L. X.; Wang, Z.

    2015-09-21

    In this research, we systematically investigated the superconducting properties and chemical composition of NbTiN thin films prepared on single-crystal MgO substrates. The NbTiN thin films with different thicknesses (4–100 nm) were deposited by reactive DC magnetron sputtering at ambient temperature. We measured and analyzed the crystal structure and thickness dependence of the chemical composition using X-ray diffraction and X-ray photoelectron spectroscopy depth profiles. The films exhibited excellent superconducting properties, with a high superconducting critical temperature of 10.1 K, low resistivity (ρ{sub 20} = 93 μΩ cm), and residual resistivity ratio of 1.12 achieved for 4-nm-thick ultrathin NbTiN films prepared at the deposition current of 2.4 A. The stoichiometry and electrical properties of the films varied gradually between the initial and upper layers. A minimum ρ{sub 20} of 78 μΩ cm and a maximum residual resistivity ratio of 1.15 were observed for 12-nm-thick films, which significantly differ from the properties of NbN films with the same NaCl structure.

  6. Multi-pulse LIBDE of fused silica at different thicknesses of the organic absorber layer

    NASA Astrophysics Data System (ADS)

    Pan, Yunxiang; Ehrhardt, Martin; Lorenz, Pierre; Han, Bing; Hopp, Bela; Vass, Csaba; Ni, Xiaowu; Zimmer, Klaus

    2015-12-01

    Laser-induced etching techniques feature several unique characteristics that enable ultraprecise machining of transparent materials. However, LIBDE (laser-induced back side dry etching) and LIBWE (laser-induced back side wet etching) are preferentially studied due to experimental feasibilities either using a very thin or a bulk absorber at the rear side of the transparent material. This study aims to fill the gap by examining the thickness dependence of the absorbing material. Multi-pulse-LIBDE (MP-LIBDE) of fused silica using different thick photoresist absorber layers (dL = 0.2-11.7 μm) was performed with a KrF excimer laser (λ = 248 nm, tp ≈ 20 ns). The influence of several experimental parameters, such as laser fluence, pulse number, film thickness, on the ablation morphology and the etching rate were investigated. Especially at moderate fluences (F = 0.7-1.5 J/cm2) MP-LIBDE and LIBWE show several similar process characteristics such as the etching rate dependence on the laser fluence and the pulse number with a typical etching rate of approx. 12 nm at 1 J/cm2. However, the specific etching rate values depend on the absorber layer thickness, for instance. The morphology of the etched surface is smooth with a roughness of below 5 nm rms. Further, the modification of the surface has been observed and will be discussed in relation to the multi-pulse laser etching mechanism.

  7. Thickness dependent structural, magnetic and magneto-transport properties of epitaxial Nd0.50Sr0.50MnO3 thin films

    NASA Astrophysics Data System (ADS)

    Kumar, Pawan; Singh, Hari Krishna

    2016-05-01

    We report the thickness-dependent structural, magnetic and magneto-transport properties in epitaxial Nd0.50Sr0.50MnO3 thin films (10 to 300nm) prepared by DC magnetron sputtering technique on single crystalline (001) oriented substrate LaAlO3. X-ray diffraction pattern reveals the epitaxial growth of all the films and the out-of-plane lattice parameter of films were found to increase with thickness. As thickness of the film increases the paramagnetic insulator (PMI) to ferromagnetic metal (FMM) transition temperature (TC), charge ordered transition temperature (TCO) and magnetic moment were found to increase with a strong bifurcation in ZFC-FC magnetization. The asymmetry in the coercivity seen in field dependent magnetization loops (M-H loops) suggests the presence of exchange bias (EB) effect. While temperature dependent resistivity of films show the semiconducting nature for thickness 10-200nm in temperature range from 5-300K, the film of thickness 300nm shows the insulator to metal transition with transition temperature (TIM) at 175K. Temperature dependent low field magnetoresistance (LFMR) measured at 4kOe found to decrease with thickness and for high field magnetoresistance (HFMR) at 40kOe and 60kOe also show similar dependence and a crossover at intermediate temperature range in the magnitude of MR between 10nm and 200nm films at constant field. Colossal increase in magnetoresistance observed for 10nm film at low temperature.

  8. Assessing change in mouthguard thickness according to the thickness of the original mouthguard sheet.

    PubMed

    Mizuhashi, Fumi; Koide, Kaoru; Takahashi, Mutsumi

    2014-12-01

    The aim of this study was to examine changes in thickness and differences in rate of change of mouthguard thickness according to the thickness of the original sheet used to form the mouthguard. The material used in this study was Sports Mouthguard (3.0, 3.8, and 5.0 mm thicknesses, ethylene vinyl acetate sheet). The sheets were heated until they hung 15 mm from the baseline and were then vacuum formed. The thickness of the mouthguard was measured, and the rate of change of thickness was calculated. The differences in thickness and rate of change of thickness at the labial surface of the central incisor and buccal surface of the first molar according to the thickness of sheet were analyzed by one-way anova, and that of the occlusal surface of the first molar was analyzed by the Kruskal-Wallis test. The results showed that the thickness of mouthguard increased as the thickness of sheet increased (P < 0.05 or P < 0.01). The thickness of the sheet did not affect the rate of change of thickness at the central incisor and occlusal surface of the first molar. Adequate thickness could be obtained using the original sheet with a thickness >3.8 mm at the buccal surface of the first molar and >3.0 mm at the occlusal surface of the first molar. At the central incisor, the necessary thickness of the original sheet was calculated as 5.6 mm. These results would be useful for selecting the appropriate mouthguard sheet material. PMID:24890333

  9. In vivo experiment study of nonablative photorejuvenation by using a 595-nm pulsed dye laser

    NASA Astrophysics Data System (ADS)

    Dang, Yongyan; Ren, Qiushi; Li, Wangrong; Liu, Huaxu; Liu, Yuxiu; Zhang, Jinsheng

    2005-01-01

    The pulsed dye laser (PDL) has a history of producing safe and effective clearance of dermal vascular lesions; however, non-ablative treatments of rhytids with 595nm PDL are seldom studied. The purpose of our research is to evaluate the changes of skin elasticity, histology and the amount of hydroxyproline after 595nm PDL non-ablative rejuvenation and to offer references for effective clinical treatments. Forty KM mice were used for this experiment. Laser parameters were as follows: an energy fluence of 8 to 12J/cm2, a pulse duration of 10ms, and a spot size of 7mm with 10% overlap. Skin elasticity was measured using Reviscometer RVM 600. Specimens were sectioned for hematoxylin-eosin and Van-Gieson staining, and dermal thickness was recorded in an ocular micrometer. The amount of hydroxyproline in the dermis was quantified by the biochemical method. No marked side effects such as blister and purpura were noted during laser treatments. New collagen synthesized with an improvement in the organization of collagen fibrils. The 12 J/cm2 group improved skin elasticity by 31.7%, dermal thickness by 25.3% and the amount of hydroxyproline by 55.9%. There were the good correlations between dermal thickness and the amount of hydroxyproline. Therefore 595nm PDL non-ablative photo-rejuvenation is a safe and effective method for wrinkle reduction. And the energy level of 12 J/cm2 has the greatest effect in improving skin mechanical properties and accelerating new collagen formation.

  10. Designing dual-trench alternating phase-shift masks for 140-nm and smaller features using 248-nm KrF and 193-nm ArF lithography

    NASA Astrophysics Data System (ADS)

    Petersen, John S.; Socha, Robert J.; Naderi, Alex R.; Baker, Catherine A.; Rizvi, Syed A.; Van Den Broeke, Douglas J.; Kachwala, Nishrin; Chen, J. Fung; Laidig, Thomas L.; Wampler, Kurt E.; Caldwell, Roger F.; Takeuchi, Susumu; Yamada, Yoshiro; Senoh, Takashi; McCallum, Martin

    1998-09-01

    One method for making the alternating phase-shift mask involves cutting a trench into the quartz of the mask using an anisotropic dry etch, followed by an isotropic etch to move the corners of the trench underneath the chrome to minimize problems caused by diffraction at the bottom corners of the phase-trench. This manufacturing method makes the addition of subresolution scattering bars and serifs problematic, because the amount of the undercut causes chrome lifting of these small features. Adding an additional anisotropically etched trench to both cut and uncut regions is helpful, but the etch does not move the trench corners under the chrome and result in a loss to intensity and image contrast. At 248 nm illumination and 4X magnification, our work shows that a combination of 240 nm dual-trench and 5 nm to 10 nm undercut produces images with equal intensity between shifted and unshifted regions without loss of image contrasts. This paper demonstrates optical proximity correction for doing 100 nm, 120 nm, 140 nm and 180 nm lines of varying pitch for a simple alternating phase-shift mask, with no dual-trench or undercut. Then the electromagnetic field simulator, TEMPEST, is used to find the best combination of dual-trench depth and amount of undercut for an alternating phase-shift mask. Phase measurement using 248 nm light and depth measurement of thirty-six unique combinations of dual-trench and phase-shift trench are shown. Based on modeling and experimental results, recommendations for making a fine tuned dual-trench 248 nm mask, as well as an extension of the dual-trench alternating phase-shift technique to 193 nm lithography, are made.

  11. Surface plasmon and photonic mode propagation in gold nanotubes with varying wall thickness

    SciTech Connect

    Kohl, Jesse; Fireman, Micha; O'Carroll, Deirdre M.

    2011-12-15

    Gold nanotube arrays are synthesized with a range of wall thicknesses (15 to >140 nm) and inner diameters of {approx}200 nm using a hard-template method. A red spectral shift (>0.39 eV) with decreasing wall thickness is observed in dark-field spectra of nanotube arrays and single nanowire/nanotube heterostructures. Finite-difference-time-domain simulations show that nanotubes in this size regime support propagating surface plasmon modes as well as surface plasmon ring resonances at visible wavelengths (the latter is observed only for excitation directions normal to the nanotube long axis with transverse polarization). The energy of the surface plasmon modes decreases with decreasing wall thickness and is attributed to an increase in mode coupling between propagating modes in the nanotube core and outer surface and the circumference dependence of ring resonances. Surface plasmon mode propagation lengths for thicker-walled tubes increase by a factor of {approx}2 at longer wavelengths (>700 nm), where ohmic losses in the metal are low, but thinner-walled tubes (30 nm) exhibit a more significant increase in surface plasmon propagation length (by a factor of more than four) at longer wavelengths. Additionally, nanotubes in this size regime support a photonic mode in their core, which does not change in energy with changing wall thickness. However, photonic mode propagation length is found to decrease for optically thin walls. Finally, correlations are made between the experimentally observed changes in dark-field spectra and the changes in surface plasmon mode properties observed in simulations for the various gold nanotube wall thicknesses and excitation conditions.

  12. Optimization of barrier layer thickness in MgSe/CdSe quantum wells for intersubband devices in the near infrared region

    SciTech Connect

    Chen, Guopeng; Shen, Aidong; Tamargo, Maria C.

    2015-10-28

    The authors report the optimization of MgSe barrier thickness in CdSe/MgSe multiple quantum well structures and its effect on structural, optical qualities and intersubband (ISB) transition characteristics. Three samples with the MgSe thicknesses of 2 nm, 3 nm, and 4 nm were grown on InP substrates by molecular beam epitaxy. X-ray diffraction and photoluminescence measurements showed that the thinner the MgSe barrier thickness the better the structural quality. However, ISB absorption was only observed in the sample with a MgSe thickness of 3 nm. Failing to observe ISB absorption in the sample with a thicker MgSe barrier (≥4 nm) is due to the deteriorated material quality while the missing of ISB transition in the sample with thinner barrier (≤2 nm) is due to the tunneling of electrons out of the CdSe wells. The optimized MgSe barrier thickness of around 3 nm is found to be able to suppress the electron tunneling while maintaining a good material quality of the overall structure.

  13. Thickness-dependent blue shift in the excitonic peak of conformally grown ZnO:Al on ion-beam fabricated self-organized Si ripples

    SciTech Connect

    Basu, T.; Kumar, M.; Som, T.; Nandy, S.; Satpati, B.; Saini, C. P.; Kanjilal, A.

    2015-09-14

    Al-doped ZnO (AZO) thin films of thicknesses 5,10, 15, 20, and 30 nm were deposited on 500 eV argon ion-beam fabricated nanoscale self-organized rippled-Si substrates at room temperature and are compared with similar films deposited on pristine-Si substrates (without ripples). It is observed that morphology of self-organized AZO films is driven by the underlying substrate morphology. For instance, for pristine-Si substrates, a granular morphology evolves for all AZO films. On the other hand, for rippled-Si substrates, morphologies having chain-like arrangement (anisotropic in nature) are observed up to a thickness of 20 nm, while a granular morphology evolves (isotropic in nature) for 30 nm-thick film. Photoluminescence studies reveal that excitonic peaks corresponding to 5–15 nm-thick AZO films, grown on rippled-Si templates, show a blue shift of 8 nm and 3 nm, respectively, whereas the peak shift is negligible for 20-nm thick film (with respect to their pristine counter parts). The observed blue shifts are substantiated by diffuse reflectance study and attributed to quantum confinement effect, associated with the size of the AZO grains and their spatial arrangements driven by the anisotropic morphology of underlying rippled-Si templates. The present findings will be useful for making tunable AZO-based light-emitting devices.

  14. Thickness Dependent Nanostructural, Morphological, Optical and Impedometric Analyses of Zinc Oxide-Gold Hybrids: Nanoparticle to Thin Film

    PubMed Central

    Perumal, Veeradasan; Hashim, Uda; Gopinath, Subash C. B.; Haarindraprasad, R.; Liu, Wei-Wen; Poopalan, P.; Balakrishnan, S. R.; Thivina, V.; Ruslinda, A. R.

    2015-01-01

    The creation of an appropriate thin film is important for the development of novel sensing surfaces, which will ultimately enhance the properties and output of high-performance sensors. In this study, we have fabricated and characterized zinc oxide (ZnO) thin films on silicon substrates, which were hybridized with gold nanoparticles (AuNPs) to obtain ZnO-Aux (x = 10, 20, 30, 40 and 50 nm) hybrid structures with different thicknesses. Nanoscale imaging by field emission scanning electron microscopy revealed increasing film uniformity and coverage with the Au deposition thickness. Transmission electron microscopy analysis indicated that the AuNPs exhibit an increasing average diameter (5–10 nm). The face center cubic Au were found to co-exist with wurtzite ZnO nanostructure. Atomic force microscopy observations revealed that as the Au content increased, the overall crystallite size increased, which was supported by X-ray diffraction measurements. The structural characterizations indicated that the Au on the ZnO crystal lattice exists without any impurities in a preferred orientation (002). When the ZnO thickness increased from 10 to 40 nm, transmittance and an optical bandgap value decreased. Interestingly, with 50 nm thickness, the band gap value was increased, which might be due to the Burstein-Moss effect. Photoluminescence studies revealed that the overall structural defect (green emission) improved significantly as the Au deposition increased. The impedance measurements shows a decreasing value of impedance arc with increasing Au thicknesses (0 to 40 nm). In contrast, the 50 nm AuNP impedance arc shows an increased value compared to lower sputtering thicknesses, which indicated the presence of larger sized AuNPs that form a continuous film, and its ohmic characteristics changed to rectifying characteristics. This improved hybrid thin film (ZnO/Au) is suitable for a wide range of sensing applications. PMID:26694656

  15. Thickness Dependent Nanostructural, Morphological, Optical and Impedometric Analyses of Zinc Oxide-Gold Hybrids: Nanoparticle to Thin Film.

    PubMed

    Perumal, Veeradasan; Hashim, Uda; Gopinath, Subash C B; Haarindraprasad, R; Liu, Wei-Wen; Poopalan, P; Balakrishnan, S R; Thivina, V; Ruslinda, A R

    2015-01-01

    The creation of an appropriate thin film is important for the development of novel sensing surfaces, which will ultimately enhance the properties and output of high-performance sensors. In this study, we have fabricated and characterized zinc oxide (ZnO) thin films on silicon substrates, which were hybridized with gold nanoparticles (AuNPs) to obtain ZnO-Aux (x = 10, 20, 30, 40 and 50 nm) hybrid structures with different thicknesses. Nanoscale imaging by field emission scanning electron microscopy revealed increasing film uniformity and coverage with the Au deposition thickness. Transmission electron microscopy analysis indicated that the AuNPs exhibit an increasing average diameter (5-10 nm). The face center cubic Au were found to co-exist with wurtzite ZnO nanostructure. Atomic force microscopy observations revealed that as the Au content increased, the overall crystallite size increased, which was supported by X-ray diffraction measurements. The structural characterizations indicated that the Au on the ZnO crystal lattice exists without any impurities in a preferred orientation (002). When the ZnO thickness increased from 10 to 40 nm, transmittance and an optical bandgap value decreased. Interestingly, with 50 nm thickness, the band gap value was increased, which might be due to the Burstein-Moss effect. Photoluminescence studies revealed that the overall structural defect (green emission) improved significantly as the Au deposition increased. The impedance measurements shows a decreasing value of impedance arc with increasing Au thicknesses (0 to 40 nm). In contrast, the 50 nm AuNP impedance arc shows an increased value compared to lower sputtering thicknesses, which indicated the presence of larger sized AuNPs that form a continuous film, and its ohmic characteristics changed to rectifying characteristics. This improved hybrid thin film (ZnO/Au) is suitable for a wide range of sensing applications. PMID:26694656

  16. Device characteristics of amorphous ZnSnLiO thin film transistors with various channel layer thicknesses

    NASA Astrophysics Data System (ADS)

    Wang, Hailong; Li, Bin; Zhang, Wenqi; Wu, Huaihao; Zhou, Dongzhan; Yao, Zhigang; Yi, Lixin; Zhang, Xiqing; Wang, Yongsheng

    2016-08-01

    The preparation and characteristics of ZnSnLiO thin film transistors were studied in this work. The ZnSnLiO films, as the channel layers with thickness varied from 20 to 60 nm, were deposited on SiO2/p-type Si substrates by radio frequency magnetron sputtering. The effect of channel layer thickness on the device characteristics of ZnSnLiO TFTs has been investigated to establish optimal channel layer thickness. The transistor with 40-nm-thick ZnSnLiO film shows the best performance with a field-effect mobility of 47 cm2/V s, a threshold voltage of 4.9 V, and an on/off ratio of 7.2 × 106.

  17. Nanostructued core-shell Sn nanowires @ CNTs with controllable thickness of CNT shells for lithium ion battery

    NASA Astrophysics Data System (ADS)

    Zhong, Yu; Li, Xifei; Zhang, Yong; Li, Ruying; Cai, Mei; Sun, Xueliang

    2015-03-01

    Core-shell structure of Sn nanowires encapsulated in amorphous carbon nanotubes (Sn@CNTs) with controlled thickness of CNT shells was in situ prepared via chemical vapor deposition (CVD) method. The thickness of CNT shells was accurately controlled from 4 to 99 nm by using different growth time, flow rate of hydrocarbon gas (C2H4) and synthesis temperature. The microstructure and composition of the coaxial Sn@CNTs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM) techniques. Moreover, the Sn@CNTs were studied as anode materials for Li-ion batteries and showed excellent cycle performance. The capacity was affected by the thickness of outer CNT shells: thick CNT shells contributed to a better retention while thin CNT shells led to a higher capacity. The thin CNT shell of 6 nm presented the highest capacity around 630 mAh g-1.

  18. Refractive index change during exposure for 193-nm chemically amplified resists

    NASA Astrophysics Data System (ADS)

    Oh, Hye-Keun; Sohn, Young-Soo; Sung, Moon-Gyu; Lee, Young-Mi; Lee, Eun-Mi; Byun, Sung Hwan; An, Ilsin; Lee, Kun-Sang; Park, In-Ho

    1999-06-01

    Some of the important areas to be improved for lithography simulation are getting correct exposure parameters and determining the change of refractive index. It is known that the real and imaginary refractive indices are changed during exposure. We obtained these refractive index changes during exposure for 193 nm chemically amplified resists. The variations of the transmittance as well as the resist thickness were measured during ArF excimer laser exposure. We found that the refractive index change is directly related to the concentration of the photo acid generator and de-protected resin. It is important to know the exact values of acid concentration from the exposure parameters since a small difference in acid concentration magnifies the variation in the amplified de-protection during post exposure bake. We developed and used a method to extract Dill ABC exposure parameters for 193 nm chemically amplified resist from the refractive index change upon exposure.

  19. Sub-10 nm nano-gap device for single-cluster transport measurements

    SciTech Connect

    Rousseau, J. Morel, R.; Vila, L.; Brenac, A.; Marty, A.; Notin, L.; Beigné, C.

    2014-02-17

    We present a versatile procedure for the fabrication of single electron transistor (SET) devices with nanometer-sized clusters and embedded back gate electrode. The process uses sputtering gas-aggregation for the growth of clusters and e-beam lithography with double angle shadow-edge deposition to obtain electrodes separated by nano-gaps with width below 10 nm. The nano-gap width is easily controlled only by geometrical factors such as deposited thin film thickness and evaporation angles. The usefulness of this technique is demonstrated by measuring the SET behavior of a device with a 4 nm cobalt cluster embedded in alumina, where the Coulomb blockade and incremental cluster charging can be readily identified without resorting to the differential conductivity.

  20. Subsurface imaging of silicon nanowire circuits and iron oxide nanoparticles with sub-10 nm spatial resolution.

    PubMed

    Perrino, A P; Ryu, Y K; Amo, C A; Morales, M P; Garcia, R

    2016-07-01

    Non-destructive subsurface characterization of nanoscale structures and devices is of significant interest in nanolithography and nanomanufacturing. In those areas, the accurate location of the buried structures and their nanomechanical properties are relevant for optimization of the nanofabrication process and the functionality of the system. Here we demonstrate the capabilities of bimodal and trimodal force microscopy for imaging silicon nanowire devices buried under an ultrathin polymer film. We resolve the morphology and periodicities of silicon nanowire pairs. We report a spatial resolution in the sub-10 nm range for nanostructures buried under a 70 nm thick polymer film. By using numerical simulations we explain the role of the excited modes in the subsurface imaging process. Independent of the bimodal or trimodal atomic force microscopy approach, the fundamental mode is the most suitable for tracking the topography while the higher modes modulate the interaction of the tip with the buried nanostructures and provide subsurface contrast. PMID:27232523

  1. Subsurface imaging of silicon nanowire circuits and iron oxide nanoparticles with sub-10 nm spatial resolution

    NASA Astrophysics Data System (ADS)

    Perrino, A. P.; Ryu, Y. K.; Amo, C. A.; Morales, M. P.; Garcia, R.

    2016-07-01

    Non-destructive subsurface characterization of nanoscale structures and devices is of significant interest in nanolithography and nanomanufacturing. In those areas, the accurate location of the buried structures and their nanomechanical properties are relevant for optimization of the nanofabrication process and the functionality of the system. Here we demonstrate the capabilities of bimodal and trimodal force microscopy for imaging silicon nanowire devices buried under an ultrathin polymer film. We resolve the morphology and periodicities of silicon nanowire pairs. We report a spatial resolution in the sub-10 nm range for nanostructures buried under a 70 nm thick polymer film. By using numerical simulations we explain the role of the excited modes in the subsurface imaging process. Independent of the bimodal or trimodal atomic force microscopy approach, the fundamental mode is the most suitable for tracking the topography while the higher modes modulate the interaction of the tip with the buried nanostructures and provide subsurface contrast.

  2. 193 nm Excimer laser processing of Si/Ge/Si(100) micropatterns

    NASA Astrophysics Data System (ADS)

    Gontad, F.; Conde, J. C.; Chiussi, S.; Serra, C.; González, P.

    2016-01-01

    193 nm Excimer laser assisted growth and crystallization of amorphous Si/Ge bilayer patterns with circular structures of 3 μm diameter and around 25 nm total thickness, is presented. Amorphous patterns were grown by Laser induced Chemical Vapor Deposition, using nanostencils as shadow masks and then irradiated with the same laser to induce structural and compositional modifications for producing crystalline SiGe alloys through fast melting/solidification cycles. Compositional and structural analyses demonstrated that pulses of 240 mJ/cm2 lead to graded SiGe alloys with Si rich discs of 2 μm diameter on top, a buried Ge layer, and Ge rich SiGe rings surrounding each feature, as predicted by previous numerical simulation.

  3. Near-field fluorescence imaging with 32 nm resolution based on microfabricated cantilevered probes

    NASA Astrophysics Data System (ADS)

    Eckert, Rolf; Freyland, J. Moritz; Gersen, Henkjan; Heinzelmann, Harry; Schürmann, Gregor; Noell, Wilfried; Staufer, Urs; de Rooij, Nico F.

    2000-12-01

    High-resolution near-field optical imaging with microfabricated probes is demonstrated. The probes are made from solid quartz tips fabricated at the end of silicon cantilevers and covered with a 60-nm-thick aluminum film. Transmission electron micrographs indicate a continuous aluminum layer at the tip apex. A specially designed instrument combines the advantages of near-field optical and beam-deflection force microscopy. Near-field optical data of latex bead projection patterns in transmission and of single fluorophores have been obtained in constant-height imaging mode. An artifact-free optical resolution of 31.7±3.6 nm has been deduced from full width at half maximum values of single molecule images.

  4. Development of airborne oil thickness measurements.

    PubMed

    Brown, Carl E; Fingas, Mervin F

    2003-01-01

    A laboratory sensor has now been developed to measure the absolute thickness of oil on water slicks. This prototype oil slick thickness measurement system is known as the laser-ultrasonic remote sensing of oil thickness (LURSOT) sensor. This laser opto-acoustic sensor is the initial step in the ultimate goal of providing an airborne sensor with the ability to remotely measure oil-on-water slick thickness. The LURSOT sensor employs three lasers to produce and measure the time-of-flight of ultrasonic waves in oil and hence provide a direct measurement of oil slick thickness. The successful application of this technology to the measurement of oil slick thickness will benefit the scientific community as a whole by providing information about the dynamics of oil slick spreading and the spill responder by providing a measurement of the effectiveness of spill countermeasures such as dispersant application and in situ burning. This paper will provide a review of early developments and discuss the current state-of-the-art in the field of oil slick thickness measurement. PMID:12899892

  5. Correlation between skin, bone, and cerebrospinal fluid layer thickness and optical coefficients measured by multidistance frequency-domain near-infrared spectroscopy in term and preterm infants

    NASA Astrophysics Data System (ADS)

    Demel, Anja; Feilke, Katharina; Wolf, Martin; Poets, Christian F.; Franz, Axel R.

    2014-01-01

    Near-infrared spectroscopy (NIRS) is increasingly used in neonatal intensive care. We investigated the impact of skin, bone, and cerebrospinal fluid (CSF) layer thickness in term and preterm infants on absorption-(μa) and/or reduced scattering coefficients (μs‧) measured by multidistance frequency-domain (FD)-NIRS. Transcranial ultrasound was performed to measure the layer thicknesses. Correlations were only statistically significant for μa at 692 nm with bone thickness and μs‧ at 834 nm with skin thickness. There is no evidence that skin, bone, or CSF thickness have an important effect on μa and μs‧. Layer thicknesses of skin, bone, and CSF in the range studied do not seem to affect cerebral oxygenation measurements by multidistance FD-NIRS significantly.

  6. Effects of total thickness on (001) texture, surface morphology, and magnetic properties of [Fe/Pt]{sub n} multilayer films by monatomic layer deposition

    SciTech Connect

    Yu, Y. S.; George, T. A.; Yue, L. P.; Sellmyer, D. J.; Li, W. L.; Fei, W. D.; Li Haibo; Liu Mei

    2010-10-15

    Atomic-scale [Fe/Pt]{sub n} multilayer films with different total thickness were prepared on thermally oxidized Si (100) substrates at room temperature by monatomic layer deposition using dc-magnetron and rf-magnetron sputtering. Effects of the total thickness on (001) texture, surface morphology, and magnetic properties of the postannealed films have been investigated. It is found that the particlelike structure films with perfect (001) texture and perpendicular magnetic anisotropy are obtained with a thickness of less than or equal to 6.5 nm. After 500 deg. C annealing, the films with thickness of 6.5 and 11.9 nm show very smooth surface. In addition, with increasing total thickness of the films, (001) texture and perpendicular magnetic anisotropy of the annealed films deteriorate, and the films become continuous in structure. The total thickness of the films also affects the exchange-coupling interaction among FePt magnetic grains and the magnetization reversal process.

  7. Extreme ultraviolet source at 6.7 nm based on a low-density plasma

    SciTech Connect

    Higashiguchi, Takeshi; Yugami, Noboru; Otsuka, Takamitsu; Jiang, Weihua; Endo, Akira; Li Bowen; Kilbane, Deirdre; Dunne, Padraig; O'Sullivan, Gerry

    2011-11-07

    We demonstrate an efficient extreme ultraviolet (EUV) source for operation at {lambda} = 6.7 nm by optimizing the optical thickness of gadolinium (Gd) plasmas. Using low initial density Gd targets and dual laser pulse irradiation, we observed a maximum EUV conversion efficiency (CE) of 0.54% for 0.6% bandwidth (BW) (1.8% for 2% BW), which is 1.6 times larger than the 0.33% (0.6% BW) CE produced from a solid density target. Enhancement of the EUV CE by use of a low-density plasma is attributed to the reduction of self-absorption effects.

  8. Effects of the 755-nm Alexandrite laser on fine dark facial hair: review of 90 cases.

    PubMed

    Uyar, Belkiz; Saklamaz, Ali

    2012-05-01

    Laser hair removal is a relatively effective method for thick hair. Despite the risk for induction of fine hair growth, application of laser for fine dark hair is sometimes inevitable. We investigate the effects of 755-nm Alexandrite laser on fine dark facial hair and evaluate the induction rates of fine hair growth and case satisfaction. In the present study, the thickening rate of hairs (33.33%) was found to be higher than the previously published rates. However, reduction of hair density can be obtained when the laser sessions are continued. PMID:22229689

  9. Nonlinear ultrasonic imaging of thermal fatigue cracks of several tens nm gap in glass plates

    NASA Astrophysics Data System (ADS)

    Hertl, M.; Kawashima, K.; Sekino, K.; Yasui, H.; Aida, T.

    2015-10-01

    Thermal fatigue crack of which gap distance is several tens nm in glass plate is imaged by using an immersion higher harmonic imaging technique. Some parts of the thermal fatigue crack are clearly imaged by the third harmonic amplitude of the 3.5 MHz burst wave by angular incidence. For through-transmission mode across the crack face, the seventh harmonic of a through-thickness resonant frequency also visualizes the thermal fatigue crack. If spatial resolution will reach to a few micron meters, the technique could be applied for detection of disbonds in bonded wafers.

  10. Plasma assisted molecular beam epitaxy growth and effect of varying buffer thickness on the formation of ultra-thin In{sub 0.17}Al{sub 0.83}N/GaN heterostructure on Si(111)

    SciTech Connect

    Chowdhury, Subhra; Biswas, Dhrubes

    2015-02-23

    This work reports on the detailed plasma-assisted molecular beam epitaxy (PAMBE) growth of ultra-thin In{sub 0.17}Al{sub 0.83}N/GaN heterostructures on Si(111) substrate with three different buffer thickness (600 nm, 400 nm, and 200 nm). Growth through critical optimization of growth conditions is followed by the investigation of impact of varying buffer thickness on the formation of ultra-thin 1.5 nm, In{sub 0.17}Al{sub 0.83}N–1.25 nm, GaN–1.5 nm, In{sub 0.17}Al{sub 0.83}N heterostructure, in terms of threading dislocation (TD) density. Analysis reveals a drastic reduction of TD density from the order 10{sup 10 }cm{sup −2} to 10{sup 8 }cm{sup −2} with increasing buffer thickness resulting smooth ultra-thin active region for thick buffer structure. Increasing strain with decreasing buffer thickness is studied through reciprocal space mapping analysis. Surface morphology through atomic force microscopy analysis also supports our study by observing an increase of pits and root mean square value (0.89 nm, 1.2 nm, and 1.45 nm) with decreasing buffer thickness which are resulted due to the internal strain and TDs.

  11. Automatic cortical thickness analysis on rodent brain

    NASA Astrophysics Data System (ADS)

    Lee, Joohwi; Ehlers, Cindy; Crews, Fulton; Niethammer, Marc; Budin, Francois; Paniagua, Beatriz; Sulik, Kathy; Johns, Josephine; Styner, Martin; Oguz, Ipek

    2011-03-01

    Localized difference in the cortex is one of the most useful morphometric traits in human and animal brain studies. There are many tools and methods already developed to automatically measure and analyze cortical thickness for the human brain. However, these tools cannot be directly applied to rodent brains due to the different scales; even adult rodent brains are 50 to 100 times smaller than humans. This paper describes an algorithm for automatically measuring the cortical thickness of mouse and rat brains. The algorithm consists of three steps: segmentation, thickness measurement, and statistical analysis among experimental groups. The segmentation step provides the neocortex separation from other brain structures and thus is a preprocessing step for the thickness measurement. In the thickness measurement step, the thickness is computed by solving a Laplacian PDE and a transport equation. The Laplacian PDE first creates streamlines as an analogy of cortical columns; the transport equation computes the length of the streamlines. The result is stored as a thickness map over the neocortex surface. For the statistical analysis, it is important to sample thickness at corresponding points. This is achieved by the particle correspondence algorithm which minimizes entropy between dynamically moving sample points called particles. Since the computational cost of the correspondence algorithm may limit the number of corresponding points, we use thin-plate spline based interpolation to increase the number of corresponding sample points. As a driving application, we measured the thickness difference to assess the effects of adolescent intermittent ethanol exposure that persist into adulthood and performed t-test between the control and exposed rat groups. We found significantly differing regions in both hemispheres.

  12. Investigation of Ionospheric Slab Thickness behaviour over Rome during high solar activity period

    NASA Astrophysics Data System (ADS)

    Trivedi, Richa; Gwal, Ashok Kumar; Jain, Sudhir

    The subject of the present study is to analyze the characteristic variations of the ionospheric slab thickness at Rome (41°N, 12°E, LT= (UT+1h), DIP=57°.4) for the period August, 2011 to July, 2012. The work deals with diurnal, seasonal, solar and magnetic activity variations of slab thickness. We observed that the seasonal mean value of slab thickness is higher during summer months than equinox and winter months and the mean diurnal variations of the slab thickness characterised with night-time values that are substantially higher than the day-time values during winter (night-to-day ratio between 1.01), but higher day-time and lower night-time values during summer (night-to-day ratio of 0.65). The slab thickness decreases with increase in solar flux value for mid-latitude. The results have been compared with the earlier ones and discussed in terms of possible source mechanism responsible for the variation of slab thickness at mid-latitude region. Keywords: F2 layer critical frequency (foF2); F2-layer electron density (NmF2); Slab thickness (τ); Solar Flux.

  13. Crystallization of confined water pools with radii greater than 1 nm in AOT reverse micelles.

    PubMed

    Suzuki, Akira; Yui, Hiroharu

    2014-07-01

    Freezing of water pools inside aerosol sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles has been investigated. Previous freezing experiments suffer from collision and fusion of AOT micelles and resultant loss of water from the water pool by shedding out during the cooling process. These phenomena have restricted the formation of ice to only when the radius of the water pool (Rw) is below 1 nm, and only amorphous ice has been observed. To overcome the size limitation, a combination of rapid cooling and a custom-made cell allowing thin sample loading is applied for instantaneous and homogeneous freezing. The freezing process is monitored with attenuated total reflection infrared spectroscopy (ATR-IR) measurements. A cooling rate of ca. -100 K/min and a sample thickness of ca. 50 μm overcomes the limitations mentioned above and allows the crystallization of water pools with larger radii (Rw > 1 nm). The corresponding ATR-IR spectra of the frozen water pools with Rw < 2.0 nm show similar features to the spectrum of metastable cubic ice (Ic). Further increase of the radius of the water pool (Rw > 2.0 nm), unfortunately, drastically decreased the integrated area of the ν(OH) band observed just after freezing, indicating the breakup of the micellar structure and shedding out of the water pool. In addition, it was revealed that Ic ice can also be formed in flexible organic self-assembled AOT reverse micelles for at least Rw ≤ ca. 2 nm, as well as in inorganic and solid materials with a pore radius of ca. 2 nm. The dependence of the phase transition temperature on the curvature of the reverse micelles is discussed from the viewpoint of the Gibbs-Thomson effect. PMID:24885023

  14. Landau-Lifshitz-Gilbert micromagnetic simulation on spin transfer torque efficiency of sub-30 nm perpendicular magnetic tunnel junctions with etching damage

    NASA Astrophysics Data System (ADS)

    Ito, Kenchi; Ohuchida, Satoshi; Muraguchi, Masakazu; Endoh, Tetsuo

    2015-04-01

    The threshold current density Jc0, effective anisotropy field Heff, and the spin transfer torque (STT) efficiency of magnetic tunnel junctions with perpendicular anisotropy (p-MTJs) with the free layer diameter d from 10 to 30 nm was evaluated when etching degraded the saturation magnetization Ms and/or anisotropic energy Ku of the ferromagnetic layers with thickness of 1 to 3 nm around the pillar, using Landau-Lifshitz-Gilbert (LLG) micro-magnetic simulation. The STT efficiency for MTJs with only Ms reduction increased with a decrease in d, which reproduces the experimental trend. Jc0 and Heff for MTJs with only Ku reduction dramatically decreased even when the thickness of the damaged region is only 1 nm. The thickness of the damaged region had a large influence on Jc0 and Heff for MTJs with either Ms or Ku reduction.

  15. Mitigation of Electrothermal Instabilities with Thick Insulating Coatings

    NASA Astrophysics Data System (ADS)

    Peterson, Kyle; Awe, Thomas; Yu, Edmund; Sinars, Daniel; Cuneo, Michael

    2013-10-01

    We will show results of recent experiments on Sandia's Z facility that demonstrate a dramatic reduction in instability growth when thick insulating coatings are used to mitigate electrothermal instability growth in magnetically driven imploding liners. These results also provide further evidence that the inherent surface roughness as a result of target fabrication is not the dominant seed for the growth of Magneto-Rayleigh-Taylor (MRT) instabilities in liners with carefully machined smooth surfaces (~100 nm surface RMS or better), but rather electrothermal instabilities that form early in the electrical current pulse as Joule heating melts and vaporizes the liner surface. More importantly, these results suggest a mechanism for possibly reducing the integral MRT instability growth substantially in magnetically driven inertial confinement fusion concepts such as MagLIF. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. Quantifying bone thickness, light transmission, and contrast interrelationships in transcranial photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Lediju Bell, Muyinatu A.; Ostrowski, Anastasia K.; Li, Ke; Kaanzides, Peter; Boctor, Emad

    2015-03-01

    We previously introduced photoacoustic imaging to detect blood vessels surrounded by bone and thereby eliminate the deadly risk of carotid artery injury during endonasal, transsphenoidal surgeries. Light would be transmitted through an optical fiber attached to the surgical drill, while a transcranial probe placed on the temporal region of the skull receives photoacoustic signals. This work quantifies changes in photoacoustic image contrast as the sphenoid bone is drilled. Frontal bone from a human adult cadaver skull was cut into seven 3 cm x 3 cm chips and sanded to thicknesses ranging 1-4 mm. For 700-940 nm wavelengths, the average optical transmission through these specimens increased from 19% to 44% as bone thickness decreased, with measurements agreeing with Monte Carlo simulations within 5%. These skull specimens were individually placed in the optical pathway of a 3.5 mm diameter, cylindrical, vessel-mimicking photoacoustic target, as the laser wavelength was varied between 700-940 nm. The mean optical insertion loss and photoacoustic image contrast loss due to the bone specimens were 56-80% and 46-79%, respectively, with the majority of change observed when the bone was <=2 mm thick. The decrease in contrast is directly proportional to insertion loss over this thickness range by factors of 0.8-1.1 when multiple wavelengths are considered. Results suggest that this proportional relationship may be used to determine the amount of bone that remains to be drilled when the thickness is 2 mm or less.

  17. Influence of emissive layer thickness on electrical characteristics of polyfluorene copolymer based polymer light emitting diodes

    NASA Astrophysics Data System (ADS)

    Das, D.; Gopikrishna, P.; Singh, A.; Dey, A.; Iyer, P. K.

    2016-04-01

    Polymer light emitting diodes (PLEDs) with a device configuration of ITO/PEDOT:PSS/PFONPN01 [Poly [2,7-(9,9’-dioctylfluorene)-co-N-phenyl-1,8-naphthalimide (99:01)]/LiF/Al have been fabricated by varying the emissive layer (EML) thickness (40/65/80/130 nm) and the influence of EML thickness on the electrical characteristics of PLED has been studied. PLED can be modelled as a simple combination of resistors and capacitors. The impedance spectroscopy analysis showed that the devices with different EML thickness had different values of parallel resistance (RP) and the parallel capacitance (CP). The impedance of the devices is found to increase with increasing EML thickness resulting in an increase in the driving voltage. The device with an emissive layer thickness of 80nm, spin coated from a solution of concentration 15 mg/mL is found to give the best device performance with a maximum brightness value of 5226 cd/m2.

  18. Quantification of thickness and wrinkling of exfoliated two-dimensional zeolite nanosheets

    PubMed Central

    Kumar, Prashant; Agrawal, Kumar Varoon; Tsapatsis, Michael; Mkhoyan, K. Andre

    2015-01-01

    Some two-dimensional (2D) exfoliated zeolites are single- or near single-unit cell thick silicates that can function as molecular sieves. Although they have already found uses as catalysts, adsorbents and membranes precise determination of their thickness and wrinkling is critical as these properties influence their functionality. Here we demonstrate a method to accurately determine the thickness and wrinkles of a 2D zeolite nanosheet by comprehensive 3D mapping of its reciprocal lattice. Since the intensity modulation of a diffraction spot on tilting is a fingerprint of the thickness, and changes in the spot shape are a measure of wrinkling, this mapping is achieved using a large-angle tilt-series of electron diffraction patterns. Application of the method to a 2D zeolite with MFI structure reveals that the exfoliated MFI nanosheet is 1.5 unit cells (3.0 nm) thick and wrinkled anisotropically with up to 0.8 nm average surface roughness. PMID:25958985

  19. Rifting Thick Lithosphere - Canning Basin, Western Australia

    NASA Astrophysics Data System (ADS)

    Czarnota, Karol; White, Nicky

    2016-04-01

    The subsidence histories and architecture of most, but not all, rift basins are elegantly explained by extension of ~120 km thick lithosphere followed by thermal re-thickening of the lithospheric mantle to its pre-rift thickness. Although this well-established model underpins most basin analysis, it is unclear whether the model explains the subsidence of rift basins developed over substantially thick lithosphere (as imaged by seismic tomography beneath substantial portions of the continents). The Canning Basin of Western Australia is an example where a rift basin putatively overlies lithosphere ≥180 km thick, imaged using shear wave tomography. Subsidence modelling in this study shows that the entire subsidence history of the <300 km wide and <6 km thick western Canning Basin is adequately explained by mild Ordovician extension (β≈1.2) of ~120 km thick lithosphere followed by post-rift thermal subsidence. This is consistent with the established model, described above, albeit with perturbations due to transient dynamic topography support which are expressed as basin-wide unconformities. In contrast the <150 km wide and ~15 km thick Fitzroy Trough of the eastern Canning Basin reveals an almost continuous period of normal faulting between the Ordovician and Carboniferous (β<2.0) followed by negligible post-rift thermal subsidence. These features cannot be readily explained by the established model of rift basin development. We attribute the difference in basin architecture between the western and eastern Canning Basin to rifting of thick lithosphere beneath the eastern part, verified by the presence of ~20 Ma diamond-bearing lamproites intruded into the basin depocentre. In order to account for the observed subsidence, at standard crustal densities, the lithospheric mantle is required to be depleted in density by 50-70 kg m-3, which is in line with estimates derived from modelling rare-earth element concentrations of the ~20 Ma lamproites and global isostatic

  20. Turbine airfoil with outer wall thickness indicators

    DOEpatents

    Marra, John J; James, Allister W; Merrill, Gary B

    2013-08-06

    A turbine airfoil usable in a turbine engine and including a depth indicator for determining outer wall blade thickness. The airfoil may include an outer wall having a plurality of grooves in the outer surface of the outer wall. The grooves may have a depth that represents a desired outer surface and wall thickness of the outer wall. The material forming an outer surface of the outer wall may be removed to be flush with an innermost point in each groove, thereby reducing the wall thickness and increasing efficiency. The plurality of grooves may be positioned in a radially outer region of the airfoil proximate to the tip.

  1. Frictional sliding at a compressed polycrystalline 50 nm grain size Al-Al interface

    NASA Astrophysics Data System (ADS)

    Hammerberg, J. E.; Ravelo, R. J.; Germann, T. C.

    2015-03-01

    We present the results of large-scale NEMD simulations for a polycrystalline Al-Al interface sliding at a relative velocity of 60 m/s and a pressure of 15 GPa with a boundary temperature of 300K. The sample consisted of annealed grains, 125 grains on either side of the initial sliding interface, with dimensions of 2x(236) nm in the normal direction and 236 nm in the periodic sliding and transverse directions. Simulation times were of order 20 ns and the sample had 1.8B atoms interacting with an Al-EAM potential. The initial grain structure evolves to a complex dynamic steady state grain morphology that is very different from the initial grain structure and is characterized by large plastic strains and strain rates in a deformation region of thickness 150 nm at the interface in the normal direction. The steady state shows a sequence of grain growth and refinement and a highly strained graded microstructure. This behavior is similar to that seen in simulations for 13 and 20 nm grains and a mesoscale model that takes into account the large plastic strains and strain rates, and the size of the deformation region is able to reproduce the values of the frictional force per unit area. This work was performed under the auspices of the U.S. Dept. of Energy under Contract DE-AC52-06NA25396. The support of the LANL ASC-PEM program is gratefully acknowledged.

  2. Segmentation of 830- and 1310-nm LASIK corneal optical coherence tomography images

    NASA Astrophysics Data System (ADS)

    Li, Yan; Shekhar, Raj; Huang, David

    2002-05-01

    Optical coherence tomography (OCT) provides a non-contact and non-invasive means to visualize the corneal anatomy at micron scale resolution. We obtained corneal images from an arc-scanning (converging) OCT system operating at a wavelength of 830nm and a fan-shaped-scanning high-speed OCT system with an operating wavelength of 1310nm. Different scan protocols (arc/fan) and data acquisition rates, as well as wavelength dependent bio-tissue backscatter contrast and optical absorption, make the images acquired using the two systems different. We developed image-processing algorithms to automatically detect the air-tear interface, epithelium-Bowman's layer interface, laser in-situ keratomileusis (LASIK) flap interface, and the cornea-aqueous interface in both kinds of images. The overall segmentation scheme for 830nm and 1310nm OCT images was similar, although different strategies were adopted for specific processing approaches. Ultrasound pachymetry measurements of the corneal thickness and Placido-ring based corneal topography measurements of the corneal curvature were made on the same day as the OCT examination. Anterior/posterior corneal surface curvature measurement with OCT was also investigated. Results showed that automated segmentation of OCT images could evaluate anatomic outcome of LASIK surgery.

  3. 808 nm driven Nd3+-sensitized upconversion nanostructures for photodynamic therapy and simultaneous fluorescence imaging.

    PubMed

    Wang, Dan; Xue, Bin; Kong, Xianggui; Tu, Langping; Liu, Xiaomin; Zhang, Youlin; Chang, Yulei; Luo, Yongshi; Zhao, Huiying; Zhang, Hong

    2015-01-01

    The in vivo biological applications of upconversion nanoparticles (UCNPs) prefer excitation at 700-850 nm, instead of 980 nm, due to the absorption of water. Recent approaches in constructing robust Nd(3+) doped UCNPs with 808 nm excitation properties rely on a thick Nd(3+) sensitized shell. However, for the very important and popular Förster resonance energy transfer (FRET)-based applications, such as photodynamic therapy (PDT) or switchable biosensors, this type of structure has restrictions resulting in a poor energy transfer. In this work, we have designed a NaYF4:Yb/Ho@NaYF4:Nd@NaYF4 core-shell-shell nanostructure. We have proven that this optimal structure balances the robustness of the upconversion emission and the FRET efficiency for FRET-based bioapplications. A proof of the concept was demonstrated for photodynamic therapy and simultaneous fluorescence imaging of HeLa cells triggered by 808 nm light, where low heating and a high PDT efficacy were achieved. PMID:25406514

  4. Comparison of lidar calibration at 1064-nm channel using the water-phase and cirrus clouds

    NASA Astrophysics Data System (ADS)

    Wu, Yonghua; Chaw, Shuki; Gross, Barry; Moshary, Fred; Ahmed, Sam

    2009-09-01

    Lidar calibration at the 1064-nm channel is explored by using the low-level water-phase cloud and high cirrus cloud. Based on a known constant of lidar ratio in the optically thick water cloud, the lidar calibration constant is estimated by integrating lidar returns in the cloud. By using wavelength independence of cirrus cloud backscatter, the lidar constant is analyzed with the two-wavelength signals ratio at 532-nm and 1064-nm after correcting aerosol transmittance from sunphotometer measurement. Calibration constants by these two separate methods are compared on the same day and show consistency with the relative difference of less than 30% in general. We further verify the calibration constant by regressing lidar signals with calibrated ceilometer data in the low planetary boundary layer (PBL). Moreover, the calibration result is tested by applying it to estimate aerosol backscatter at 1064-nm and Angstrom exponent. In the end, normalized daily averages of lidar constants over two-month period are presented.

  5. Conjugated Cofactor Enables Efficient Temperature-Independent Electronic Transport Across ∼6 nm Long Halorhodopsin.

    PubMed

    Mukhopadhyay, Sabyasachi; Dutta, Sansa; Pecht, Israel; Sheves, Mordechai; Cahen, David

    2015-09-01

    We observe temperature-independent electron transport, characteristic of tunneling across a ∼6 nm thick Halorhodopsin (phR) monolayer. phR contains both retinal and a carotenoid, bacterioruberin, as cofactors, in a trimeric protein-chromophore complex. This finding is unusual because for conjugated oligo-imine molecular wires a transition from temperature-independent to -dependent electron transport, ETp, was reported at ∼4 nm wire length. In the ∼6 nm long phR, the ∼4 nm 50-carbon conjugated bacterioruberin is bound parallel to the α-helices of the peptide backbone. This places bacterioruberin's ends proximal to the two electrodes that contact the protein; thus, coupling to these electrodes may facilitate the activation-less current across the contacts. Oxidation of bacterioruberin eliminates its conjugation, causing the ETp to become temperature dependent (>180 K). Remarkably, even elimination of the retinal-protein covalent bond, with the fully conjugated bacterioruberin still present, leads to temperature-dependent ETp (>180 K). These results suggest that ETp via phR is cooperatively affected by both retinal and bacterioruberin cofactors. PMID:26301971

  6. Thin film contamination effects on laser-induced damage of fused silica surfaces at 355 nm

    SciTech Connect

    Burnham, A. K.; Cordillot, C.; Fornier, A.; Genin, F. Y.; Rubenchick, A. M.; Schirmann, D.; Yoshiyama, J.

    1998-07-28

    Fused silica windows were artificially contaminated to estimate the resistance of target chamber debris shields against laser damage during NIF operation. Uniform contamination thin films (1 to 5 nm thick) were prepared by sputtering various materials (Au, Al, Cu, and B4C). The loss of transmission of the samples was first measured. They were then tested at 355 nm in air with an 8-ns Nd:YAG laser. The damage morphologies were characterized by Nomarski optical microscopy and SEM. Both theory and experiments showed that metal contamination for films as thin as 1 nm leads to a substantial loss of transmission. The laser damage resistance dropped very uniformly across the entire surface (e.g. 6 J/cm2 for 5 nm of Cu). The damage morphology characterization showed that contrary to clean silica, metal coated samples did not produce pits on the surface. B4C coated silica, on the other hand, led to a higher density of such damage pits. A model for light absorption in the thin film was coupled with a simple heat deposition and diffusion model to perform preliminary theoretical estimates of damage thresholds. The estimates of the loss due to light absorption and reflection pointed out significant .differences between metals (e.g. Al and Au). The damage threshold predictions were in qualitative agreement with experimental measurements.

  7. Spin wave eigenmodes in single and coupled sub-150 nm rectangular permalloy dots

    SciTech Connect

    Carlotti, G. Madami, M.; Tacchi, S.; Gubbiotti, G.; Dey, H.; Csaba, G.; Porod, W.

    2015-05-07

    We present the results of a Brillouin light scattering investigation of thermally excited spin wave eigenmodes in square arrays of either isolated rectangular dots of permalloy or twins of dipolarly coupled elements, placed side-by-side or head-to-tail. The nanodots, fabricated by e-beam lithography and lift-off, are 20 nm thick and have the major size D in the range between 90 nm and 150 nm. The experimental spectra show the presence of two main peaks, corresponding to modes localized either at the edges or in the center of the dots. Their frequency dependence on the dot size and on the interaction with adjacent elements has been measured and successfully interpreted on the basis of dynamical micromagnetic simulations. The latter enabled us also to describe the spatial profile of the eigenmodes, putting in evidence the effects induced by the dipolar interaction between coupled dots. In particular, in twinned dots the demagnetizing field is appreciably modified in proximity of the “internal edges” if compared to the “external” ones, leading to a splitting of the edge mode. These results can be relevant for the exploitation of sub-150 nm magnetic dots in new applications, such as magnonic metamaterials, bit-patterned storage media, and nano-magnetic logic devices.

  8. First principles study on the interfacial properties of NM/graphdiyne (NM = Pd, Pt, Rh and Ir): The implications for NM growing

    NASA Astrophysics Data System (ADS)

    Lu, Zhansheng; Li, Shuo; Lv, Peng; He, Chaozheng; Ma, Dongwei; Yang, Zongxian

    2016-01-01

    Based on the dispersion-corrected density functional calculations (DFT-D), we systematically studied the adsorption of noble metals (NM), Pd, Pt, Rh and Ir, on graphdiyne (GDY). We present a systematic study on the geometry, embedded adsorption energy and electronic structure of four different adatoms adsorbed on the GDY. The strong interaction between the NM adatoms and the GDY substrate is found with the NM embedded in the 18C-hexagon of the GDY. We investigated the mobility of the NM adatoms on the GDY, and found that the mobility barrier energy increases along with the increasing of the embedded adsorption energy. We present the NM adatoms growth of high concentrations on the GDY. Upon the analysis of the electronic structure and the frontier molecular orbitals, Rh and Ir adatoms of low concentrations (about 1.37 at%) on the GDY have the potential to be applied as single metal catalysts or gas molecule sensors.

  9. Picosecond laser texturization of mc-silicon for photovoltaics: A comparison between 1064 nm, 532 nm and 355 nm radiation wavelengths

    NASA Astrophysics Data System (ADS)

    Binetti, Simona; Le Donne, Alessia; Rolfi, Andrea; Jäggi, Beat; Neuenschwander, Beat; Busto, Chiara; Frigeri, Cesare; Scorticati, Davide; Longoni, Luca; Pellegrino, Sergio

    2016-05-01

    Self-organized surface structures were produced by picosecond laser pulses on multi-crystalline silicon for photovoltaic applications. Three different laser wavelengths were employed (i.e. 1064 nm, 532 nm and 355 nm) and the resulting morphologies were observed to effectively reduce the reflectivity of the samples after laser irradiation. Besides, a comparative study of the laser induced subsurface damage generated by the three different wavelengths was performed by confocal micro-Raman, photoluminescence and transmission electron microscopy. The results of both the structural and optical characterization showed that the mc-Si texturing performed with the laser at 355 nm provides surface reflectivity between 11% and 8% over the spectral range from 400 nm to 1 μm, while inducing the lowest subsurface damage, located above the depletion region of the p-n junction.

  10. Sea Ice Thickness Variability in Fram Strait

    NASA Astrophysics Data System (ADS)

    Gerland, S.; Renner, A.; Haas, C.; Nicolaus, M.; Granskog, M.; Hansen, E.; Hendricks, S.; Hudson, S. R.; Beckers, J.; Goodwin, H.

    2011-12-01

    On this poster, we show results from airborne electromagnetic (EM) sea ice thickness measurements demonstrating the temporal and spatial complexity of the ice thickness distribution in Fram Strait between Greenland and Svalbard. Knowledge about the spatial and temporal sea ice thickness distribution in the Arctic Ocean is necessary to assess the state of the sea-ice cover, and to understand relevant processes and changes. Since 2003, the Norwegian Polar Institute (NPI) has been conducting systematic in situ monitoring of sea ice thickness in the western Fram Strait, using both ground and airborne techniques. Fram Strait is a key region for large-scale ice dynamics in the Arctic. It represents the main export route for sea ice from the Arctic and the only deep strait connecting the interior Arctic Ocean and the rest of the world oceans. The ice thickness distribution in this region is the result of a combination of dynamic and thermodynamic sea ice processes. Transects for airborne EM observations were flown by NPI in spring 2005, 2008, and late summer 2010, and by the Alfred Wegener Institute in spring 2009. The regional ice thickness distributions are supplemented with ground measurements including snow thickness observations taken on ice stations during ship expeditions in spring 2005, 2007, and 2008 and annually in late summer from 2003 to 2011. From all these observations, we can show the differing characteristics of the thickness distributions in spring (2005, 2008, 2009) and late summer (2010) when the ice thickness is at its annual maximum (end of the freezing period) and minimum (end of the melting period), respectively. The ice thickness distribution can also vary spatially over short distances in north-south direction. Features such as the East Greenland Polynya, which varies in size for a given time from year to year, contribute to the spatial and temporal variability on the Greenlandic Shelf. In spring 2005, a gradient is visible across Fram Strait from

  11. Thickness-shear and thickness-twist vibrations of an AT-cut quartz mesa resonator.

    PubMed

    He, Huijing; Liu, Jinxi; Yang, Jiashi

    2011-10-01

    We study thickness-shear and thickness-twist vibrations of an AT-cut quartz plate mesa resonator with stepped thickness. The equations of anisotropic elasticity are used with the omission of the small elastic constant c(56). An analytical solution is obtained using Fourier series from which the resonant frequencies, mode shapes, and energy trapping are calculated and examined. The solution shows that a mesa resonator exhibits strong energy trapping of thickness-shear and thickness-twist modes, and that the trapping is sensitive to some of the structural parameters of the resonator. PMID:21989869

  12. Characterization of post mortem arterial tissue using time-resolved photoacoustic spectroscopy at 436, 461 and 532 nm.

    PubMed

    Beard, P C; Mills, T N

    1997-01-01

    Time-resolved photoacoustic spectroscopy has been used to characterize post mortem arterial tissue for the purpose of discriminating between normal and atheromatous areas of tissue. Ultrasonic thermoelastic waves were generated in post mortem human aorta by the absorption of nanosecond laser pulses at 436, 461 and 532 nm produced by a frequency doubled Q-switched Nd:YAG laser in conjunction with a gas filled Raman cell. A PVDF membrane hydrophone was used to detect the thermoelastic waves. At 436 nm, differences in the photoacoustic signatures of normal tissue and atherorma were found to be highly variable. At 461 nm, there was a clear and reproducible difference between the photacoustic response of atheroma and normal tissue as a result of increased optical attenuation in atheroma. At 532 nm, the generation of subsurface thermoelastic waves provided a means of determining the structure and thickness of the tissue sample. It is suggested that pulsed photoacoustic spectroscopy at 461 and 532 nm may find application in characterizing arterial tissue in situ by providing information about both the composition and thickness of the vessel wall. PMID:9015817

  13. Development of a unique laboratory standard: Indium gallium arsenide detector for the 500-1700 nm spectral region

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A planar (5 mm diameter) indium gallium arsenide detector having a high (greater than 50 pct) quantum efficiency from the visible into the infrared spectrum (500 to 1700 nm) was fabricated. Quantum efficiencies as high as 37 pct at 510 nm, 58 pct at 820 nm and 62 pct at 1300 nm and 1550 nm were measured. A planar InP/InGaAs detector structure was also fabricated using vapor phase epitaxy to grow device structures with 0, 0.2, 0.4 and 0.6 micrometer thick InP caps. Quantum efficiency was studied as a function of cap thickness. Conventional detector structures were also used by completely etching off the InP cap after zinc diffusion. Calibrated quantum efficiencies were measured. Best results were obtained with devices whose caps were completely removed by etching. Certain problems still remain with these detectors including non-uniform shunt resistance, reproducibility, contact resistance and narrow band anti-reflection coatings.

  14. Characterization of AlInN/AlN/GaN Heterostructures with Different AlN Buffer Thickness

    NASA Astrophysics Data System (ADS)

    Çörekçi, S.; Dugan, S.; Öztürk, M. K.; Çetin, S. Ş.; Çakmak, M.; Özçelik, S.; Özbay, E.

    2016-05-01

    Two AlInN/AlN/GaN heterostructures with 280-nm- and 400-nm-thick AlN buffer grown on sapphire substrates by metal-organic chemical vapor deposition (MOCVD) have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and Hall-effect measurements. The symmetric (0002) plane with respect to the asymmetric (10bar{1} 2) plane in the 280-nm-thick AlN buffer has a higher crystal quality, as opposed to the 400-nm-thick buffer. The thinner buffer improves the crystallinity of both (0002) and (10bar{1} 2) planes in the GaN layers, it also provides a sizeable reduction in dislocation density of GaN. Furthermore, the lower buffer thickness leads to a good quality surface with an rms roughness of 0.30 nm and a dark spot density of 4.0 × 108 cm-2. The optical and transport properties of the AlInN/AlN/GaN structure with the relatively thin buffer are compatible with the enhancement in its structural quality, as verified by XRD and AFM results.

  15. Characterization of AlInN/AlN/GaN Heterostructures with Different AlN Buffer Thickness

    NASA Astrophysics Data System (ADS)

    Çörekçi, S.; Dugan, S.; Öztürk, M. K.; Çetin, S. Ş.; Çakmak, M.; Özçelik, S.; Özbay, E.

    2016-07-01

    Two AlInN/AlN/GaN heterostructures with 280-nm- and 400-nm-thick AlN buffer grown on sapphire substrates by metal-organic chemical vapor deposition (MOCVD) have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and Hall-effect measurements. The symmetric (0002) plane with respect to the asymmetric (10bar{1}2) plane in the 280-nm-thick AlN buffer has a higher crystal quality, as opposed to the 400-nm-thick buffer. The thinner buffer improves the crystallinity of both (0002) and (10bar{1}2) planes in the GaN layers, it also provides a sizeable reduction in dislocation density of GaN. Furthermore, the lower buffer thickness leads to a good quality surface with an rms roughness of 0.30 nm and a dark spot density of 4.0 × 108 cm-2. The optical and transport properties of the AlInN/AlN/GaN structure with the relatively thin buffer are compatible with the enhancement in its structural quality, as verified by XRD and AFM results.

  16. Evolution of damping in ferromagnetic/nonmagnetic thin film bilayers as a function of nonmagnetic layer thickness

    NASA Astrophysics Data System (ADS)

    Azzawi, S.; Ganguly, A.; Tokaç, M.; Rowan-Robinson, R. M.; Sinha, J.; Hindmarch, A. T.; Barman, A.; Atkinson, D.

    2016-02-01

    The evolution of damping in Co/Pt, Co/Au, and Ni81Fe19 /Pt bilayers was studied with increasing nonmagnetic (NM) heavy-metal layer thicknesses in the range 0.2 nm ≤tNM≤10 nm , where tNM is the NM layer thickness. Magnetization precession was measured in the time domain using time-resolved magneto-optical Kerr effect magnetometry. Fitting of the data with a damped sinusoidal function was undertaken in order to extract the phenomenological Gilbert damping coefficient α . For Pt-capped Co and Ni81Fe19 layers a large and complex dependence of α on the Pt layer thickness was observed, while for Au capping no significant dependence was observed. It is suggested that this difference is related to the different localized spin-orbit interaction related to intermixing and to d -d hybridization of Pt and Au at the interface with Co or Ni81Fe19 . Also it was shown that damping is affected by the crystal structure differences in FM thin films and at the interface, which can modify the spin-diffusion length and the effective spin-mixing conductance. In addition to the intrinsic damping an extrinsic contribution plays an important role in the enhancement of damping when the Pt capping layer is discontinuous. The dependence of damping on the nonmagnetic layer thickness is complex but shows qualitative agreement with recent theoretical predictions.

  17. Cycloolefin/cyanoacrylate (COCA) copolymers for 193-nm and 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Dammel, Ralph R.; Sakamuri, Raj; Lee, Sang-Ho; Rahman, Dalil; Kudo, Takanori; Romano, Andrew R.; Rhodes, Larry F.; Lipian, John-Henry; Hacker, Cheryl; Barnes, Dennis A.

    2002-07-01

    The copolymerization reaction between methyl cyanoacrylate (MCA) and a variety of cycloolefins (CO) was investigated. Cycololefin/cyanoacrylate (COCA) copolymers were obtained in good yields and with lithographically interesting molecular weights for all cycoolefins studied. Anionic MCA homopolymerization could be largely suppressed using acetic acid. Based on NMR data, the copolymerization may tend to a 1:1 CO:MCA incorporation ratio but further work with better suppression of the anionic component is needed to confirm this. Lithographic tests on copolymers of appropriately substituted norbornenes and MCA showed semi-dense and isolated line performance down to 90 nm.

  18. ON-DISK COUNTERPARTS OF TYPE II SPICULES IN THE Ca II 854.2 nm AND Halpha LINES

    SciTech Connect

    Rouppe van der Voort, L.; Leenaarts, J.; Carlsson, M.; Vissers, G.; De Pontieu, B. E-mail: mats.carlsson@astro.uio.n E-mail: jorritl@astro.uio.n

    2009-11-01

    Recently, a second type of spicules was discovered at the solar limb with the Solar Optical Telescope onboard the Japanese Hinode spacecraft. These previously unrecognized type II spicules are thin chromospheric jets that are shorter lived (10-60 s) and that show much higher apparent upward velocities (of order 50-100 km s{sup -1}) than the classical spicules. Since they have been implicated in providing hot plasma to coronal loops, their formation, evolution, and properties are important ingredients for a better understanding of the mass and energy balance of the low solar atmosphere. Here, we report on the discovery of the disk counterparts of type II spicules using spectral imaging data in the Ca II 854.2 nm and Halpha lines with the CRisp Imaging SpectroPolarimeter at the Swedish Solar Telescope in La Palma. We find rapid blueward excursions in the line profiles of both chromospheric lines that correspond to thin, jet-like features that show apparent velocities of order 50 km s{sup -1}. These blueward excursions seem to form a separate absorbing component with Doppler shifts of order 20 and 50 km s{sup -1} for the Ca II 854.2 nm and Halpha line, respectively. We show that the appearance, lifetimes, longitudinal and transverse velocities, and occurrence rate of these rapid blue excursions on the disk are very similar to those of the type II spicules at the limb. A detailed study of the spectral line profiles in these events suggests that plasma is accelerated along the jet, and plasma is being heated throughout the short lifetime of the event.

  19. Movable-mask reactive ion etch process for thickness control in devices

    NASA Astrophysics Data System (ADS)

    Sandstrom, R. L.; Pezeshki, B.; Agahi, F.; Martel, R.; Crockett, J. G.

    1996-10-01

    By moving the substrate relative to a shadow mask in a reactive ion etching system, we are able to precisely tailor the thickness of critical layers. To minimize disturbing the plasma, all the mechanical components are kept below the anode. The system is highly reproducible, and can be programmed to yield arbitrary vertical profiles along one horizontal axis. Using silicon-on-insulator substrates, the resonance wavelength was modified as a function of position with better than 1 nm control in the vertical dimension. This technique should prove useful for optical devices where the thickness of the layers controls the device characteristics.

  20. Resistive switching in a few nanometers thick tantalum oxide film formed by a metal oxidation

    SciTech Connect

    Ohno, Takeo; Samukawa, Seiji

    2015-04-27

    Resistive switching in a Cu/Ta{sub 2}O{sub 5}/Pt structure that consisted of a few nanometer-thick Ta{sub 2}O{sub 5} film was demonstrated. The Ta{sub 2}O{sub 5} film with thicknesses of 2–5 nm was formed with a combination of Ta metal film deposition and neutral oxygen particle irradiation at room temperature. The device exhibited a bipolar resistive switching with a threshold voltage of 0.2 V and multilevel switching operation.

  1. Measurement of optical thickness variation of BK7 plate by wavelength tuning interferometry.

    PubMed

    Kim, Yangjin; Hibino, Kenichi; Sugita, Naohiko; Mitsuishi, Mamoru

    2015-08-24

    This paper presents the derivation of a 17-sample phase-shifting algorithm that can compensate the miscalibration and first-order nonlinearity of phase shift error, coupling error, and bias modulation of the intensity and satisfy the fringe contrast maximum condition. The phase error of measurements performed using the 17-sample algorithm is discussed and compared with those of measurements obtained using other algorithms. Finally, the optical thickness variation of a BK7 optically transparent plate obtained using a wavelength tuning Fizeau interferometer and the 17-sample algorithm are presented. The experimental results indicate that the optical thickness variation measurement accuracy for the BK7 plate was 3 nm. PMID:26368260

  2. APPLIED ORIGAMI. Origami of thick panels.

    PubMed

    Chen, Yan; Peng, Rui; You, Zhong

    2015-07-24

    Origami patterns, including the rigid origami patterns in which flat inflexible sheets are joined by creases, are primarily created for zero-thickness sheets. In order to apply them to fold structures such as roofs, solar panels, and space mirrors, for which thickness cannot be disregarded, various methods have been suggested. However, they generally involve adding materials to or offsetting panels away from the idealized sheet without altering the kinematic model used to simulate folding. We develop a comprehensive kinematic synthesis for rigid origami of thick panels that differs from the existing kinematic model but is capable of reproducing motions identical to that of zero-thickness origami. The approach, proven to be effective for typical origami, can be readily applied to fold real engineering structures. PMID:26206928

  3. A Thick Target for Synchrotrons and Betatrons

    DOE R&D Accomplishments Database

    McMillan, E. M.

    1950-09-19

    If a wide x-ray beam from an electron synchrotron or betatron is desired, in radiographic work with large objects for example, the usually very thin target may be replaced by a thick one, provided the resulting distortion of the x-ray spectrum due to multiple radiative processes is permissible. It is difficult to make the circulating electron beam traverse a thick target directly because of the small spacing between successive turns. Mounting a very thin beryllium, or other low-z material, fin on the edge of the thick target so that the fin projects into the beam will cause the beam to lose sufficient energy, and therefore radium, to strike the thick target the next time around. Sample design calculations are given.

  4. Avian eggshell thickness: Variability and sampling

    USGS Publications Warehouse

    Klaas, E.E.; Ohlendorf, H.M.; Heath, R.G.

    1974-01-01

    Measurements of shell thickness of the eggs of five species were subjected to nested analyses of variance. The analyses separated variation into two or three levels for which variances and percentages of the total variation were derived. The results show that differences among measurements of the same egg contribute little to the sample variance whereas differences among eggs within clutches contribute nearly as much as differences among clutches. It is more efficient and less costly to collect entire clutches of eggs in most studies of shell thickness. Using entire clutches, sample sizes needed to detect differences of 10 percent in shell thickness (at given significance levels and power) were estimated to be eight to 11 clutches for the species studied. For differences of five percent, 26 to 38 clutches are required. Guidelines are presented which may assist other workers in evaluating the efficiency of their sampling designs, and in estimating sample sizes for detecting differences in eggshell thickness in wild birds.

  5. Non-contact thickness measurement using UTG

    NASA Technical Reports Server (NTRS)

    Bui, Hoa T. (Inventor)

    1996-01-01

    A measurement structure for determining the thickness of a specimen without mechanical contact but instead employing ultrasonic waves including an ultrasonic transducer and an ultrasonic delay line connected to the transducer by a retainer or collar. The specimen, whose thickness is to be measured, is positioned below the delay line. On the upper surface of the specimen a medium such as a drop of water is disposed which functions to couple the ultrasonic waves from the delay line to the specimen. A receiver device, which may be an ultrasonic thickness gauge, receives reflected ultrasonic waves reflected from the upper and lower surface of the specimen and determines the thickness of the specimen based on the time spacing of the reflected waves.

  6. Vacuum casting of thick polymeric films

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Moacanin, J.

    1979-01-01

    Bubble formation and layering, which often plague vacuum-evaporated films, are prevented by properly regulating process parameters. Vacuum casting may be applicable to forming thick films of other polymer/solvent solutions.

  7. Determination of thickness and composition of high-k dielectrics using high-energy electrons

    SciTech Connect

    Grande, P. L.; Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS ; Vos, M.; Venkatachalam, D. K.; Elliman, R. G.; Nandi, S. K.; Research School of Astronomy and Astrophysics, The Australian National University, Canberra ACT 2611; Department of Physics, University of Chittagong, Chittagong 4331

    2013-08-12

    We demonstrate the application of high-energy elastic electron backscattering to the analysis of thin (2–20 nm) HfO{sub 2} overlayers on oxidized Si substrates. The film composition and thickness are determined directly from elastic scattering peaks characteristic of each element. The stoichiometry of the films is determined with an accuracy of 5%–10%. The experimental results are corroborated by medium energy ions scattering and Rutherford backscattering spectrometry measurements, and clearly demonstrate the applicability of the technique for thin-film analysis. Significantly, the presented technique opens new possibilities for nm depth profiling with high spatial resolution in scanning electron microscopes.

  8. Thick crystalline films on foreign substrates

    DOEpatents

    Smith, Henry I.; Atwater, Harry A.; Geis, Michael W.

    1986-01-01

    To achieve a uniform texture, large crystalline grains or, in some cases, a single crystalline orientation in a thick (>1 .mu.m) film on a foreign substrate, the film is formed so as to be thin (<1 .mu.m) in a certain section. Zone-melting recrystallization is initiated in the thin section and then extended into the thick section. The method may employ planar constriction patterns of orientation filter patterns.

  9. Thick crystalline films on foreign substrates

    DOEpatents

    Smith, H.I.; Atwater, H.A.; Geis, M.W.

    1986-03-18

    To achieve a uniform texture, large crystalline grains or, in some cases, a single crystalline orientation in a thick (>1 [mu]m) film on a foreign substrate, the film is formed so as to be thin (<1 [mu]m) in a certain section. Zone-melting recrystallization is initiated in the thin section and then extended into the thick section. The method may employ planar constriction patterns of orientation filter patterns. 2 figs.

  10. Microwave mixing with niobium variable thickness bridges

    NASA Technical Reports Server (NTRS)

    Wang, L.-K.; Callegari, A.; Deaver, B. S., Jr.

    1977-01-01

    Niobium thin-film bridges 300-A thick, 1-micron wide, and 0.5-micron long joining two bulk films 5000-A thick and having normal resistance of the order of 1 ohm have been fabricated and used for microwave mixing at 10 GHz. They exhibit Josephson, bolometric, and multiple-flux-flow mixing and have useful response at 100-200 GHz. The data show in a direct way limitations imposed by flux flow and heating.

  11. Optically thick line widths in pyrotechnic flares

    NASA Technical Reports Server (NTRS)

    Douda, B. E.; Exton, R. J.

    1975-01-01

    Experimentally determined sodium line widths for pyrotechnic flares are compared with simple analytical, optically-thick-line-shape calculations. Three ambient pressure levels are considered (760, 150 and 30 torr) for three different flare compositions. The measured line widths range from 1.3 to 481 A. The analytic procedure emphasizes the Lorentz line shape as observed under optically-thick conditions. Calculated widths are in good agreement with the measured values over the entire range.

  12. Suppression of high-order-harmonic intensities observed in aligned CO2 molecules with 1300-nm and 800-nm pulses

    NASA Astrophysics Data System (ADS)

    Kato, Kosaku; Minemoto, Shinichirou; Sakai, Hirofumi

    2011-08-01

    High-order-harmonic generation from aligned N2, O2, and CO2 molecules is investigated by 1300-nm and 800-nm pulses. The harmonic intensities of 1300-nm pulses from aligned molecules show harmonic photon energy dependence similar to those of 800-nm pulses. Suppression of harmonic intensity from aligned CO2 molecules is observed for both 1300- and 800-nm pulses over the same harmonic photon energy range. As the dominant mechanism for the harmonic intensity suppression from aligned CO2 molecules, the present results support the two-center interference picture rather than the dynamical interference picture.

  13. Flux-calibration of medium-resolution spectra from 300 nm to 2500 nm

    NASA Astrophysics Data System (ADS)

    Moehler, Sabine; Modigliani, Andrea; Freudling, Wolfram; Giammichele, Noemi; Gianninas, Alexandros; Gonneau, Anais; Kausch, Wolfgang; Lançon, Ariane; Noll, Stefan; Rauch, Thomas; Vinther, Jakob

    2014-08-01

    While the near-infrared wavelength regime is becoming more and more important for astrophysics there are few spectrophotometric standard star data available to flux calibrate such data. On the other hand flux calibrating high-resolution spectra is a challenge even in the optical wavelength range, because the available flux standard data are often too coarsely sampled. We describe a method to obtain reference spectra derived from stellar model atmospheres, which allow users to derive response curves from 300 nm to 2500 nm also for high-resolution spectra. We verified that they provide an appropriate description of the observed standard star spectra by checking for residuals in line cores and line overlap regions in the ratios of observed spectra to model spectra. The finally selected model spectra are then empirically corrected for remaining mismatches and photometrically calibrated using independent observations. In addition we have defined an automatic method to correct for moderate telluric absorption using telluric model spectra with very high spectral resolution, that can easily be adapted to the observed data. This procedure eliminates the need to observe telluric standard stars, as long as some knowledge on the target spectrum exists.

  14. Single virus particle mass detection using microresonators with nanoscale thickness

    NASA Astrophysics Data System (ADS)

    Gupta, A.; Akin, D.; Bashir, R.

    2004-03-01

    In this letter, we present the microfabrication and application of arrays of silicon cantilever beams as microresonator sensors with nanoscale thickness to detect the mass of individual virus particles. The dimensions of the fabricated cantilever beams were in the range of 4-5 μm in length, 1-2 μm in width and 20-30 nm in thickness. The virus particles we used in the study were vaccinia virus, which is a member of the Poxviridae family and forms the basis of the smallpox vaccine. The frequency spectra of the cantilever beams, due to thermal and ambient noise, were measured using a laser Doppler vibrometer under ambient conditions. The change in resonant frequency as a function of the virus particle mass binding on the cantilever beam surface forms the basis of the detection scheme. We have demonstrated the detection of a single vaccinia virus particle with an average mass of 9.5 fg. These devices can be very useful as components of biosensors for the detection of airborne virus particles.

  15. Holographic recording properties in thick films of ULSH-500 photopolymer

    NASA Astrophysics Data System (ADS)

    Waldman, David A.; Li, H.-Y. S.; Cetin, Erdem A.

    1998-06-01

    The photopolymer holographic recording materials, ULSH-500, based upon cationic ring-opening polymerization, has been further optimized for recording in an increased film thickness of 200 micrometers . The dynamic range attained, at least M/# equals 16, is substantially greater than previously reported, while concurrently the inherent low transverse shrinkage and high sensitivity characteristics of the material have been retained. Dynamic range or cumulative grating strength, (Sigma) (eta) i0.5, has been determined from co-locationally recorded peristrophic and angle multiplexed plane-wave gratings which exhibit low diffraction efficiencies between about 0.1 and 0.2%. Good Bragg selectivity consistent with the imaged thickness and sinc2 function behavior is observed for the multiplexed holograms, and both the angular response and the diffraction efficiency are stable without the need for post-imaging fixing procedures. Sensitivity is in the range of 1 to 10 cm/mJ, and the refractive index modulation achievable during consumption of the accessible dynamic range is n1 equals 1.3 X 10-2 at the read wavelength of 514.5 nm.

  16. Laser-accelerated proton conversion efficiency thickness scaling

    SciTech Connect

    Hey, D. S.; Foord, M. E.; Key, M. H.; LePape, S. L.; Mackinnon, A. J.; Patel, P. K.; Ping, Y.; Akli, K. U.; Stephens, R. B.; Bartal, T.; Beg, F. N.; Fedosejevs, R.; Friesen, H.; Tiedje, H. F.; Tsui, Y. Y.

    2009-12-15

    The conversion efficiency from laser energy into proton kinetic energy is measured with the 0.6 ps, 9x10{sup 19} W/cm{sup 2} Titan laser at the Jupiter Laser Facility as a function of target thickness in Au foils. For targets thicker than 20 {mu}m, the conversion efficiency scales approximately as 1/L, where L is the target thickness. This is explained by the domination of hot electron collisional losses over adiabatic cooling. In thinner targets, the two effects become comparable, causing the conversion efficiency to scale weaker than 1/L; the measured conversion efficiency is constant within the scatter in the data for targets between 5 and 15 {mu}m, with a peak conversion efficiency of 4% into protons with energy greater than 3 MeV. Depletion of the hydrocarbon contaminant layer is eliminated as an explanation for this plateau by using targets coated with 200 nm of ErH{sub 3} on the rear surface. The proton acceleration is modeled with the hybrid-particle in cell code LSP, which reproduced the conversion efficiency scaling observed in the data.

  17. Confinement in thickness-controlled GaAs polytype nanodots.

    PubMed

    Vainorius, Neimantas; Lehmann, Sebastian; Jacobsson, Daniel; Samuelson, Lars; Dick, Kimberly A; Pistol, Mats-Erik

    2015-04-01

    Polytype nanodots are arguably the simplest nanodots than can be made, but their technological control was, up to now, challenging. We have developed a technique to produce nanowires containing exactly one polytype nanodot in GaAs with thickness control. These nanodots have been investigated by photoluminescence, which has been cross-correlated with transmission electron microscopy. We find that short (4-20 nm) zincblende GaAs segments/dots in wurtzite GaAs confine electrons and that the inverse system confines holes. By varying the thickness of the nanodots we find strong quantum confinement effects which allows us to extract the effective mass of the carriers. The holes at the top of the valence band have an effective mass of approximately 0.45 m0 in wurtzite GaAs. The thinnest wurtzite nanodot corresponds to a twin plane in zincblende GaAs and gives efficient photoluminescence. It binds an exciton with a binding energy of roughly 50 meV, including central cell corrections. PMID:25761051

  18. Through-Thickness Flow Profile Determination of Confined Lubricant

    NASA Astrophysics Data System (ADS)

    Wong, Janet; Ponjavic, Aleks

    2013-03-01

    The knowledge of the through-thickness flow profile of lubricants confined between two rubbing surfaces is necessary for the friction prediction of lubricated engineering systems. While it is crucial to materials selection and engineering design, little work on the direct measurement of lubricant flow has been performed in elastohydrodynamic lubrication (EHL) regime as the nanoscopic film thickness bars the use of conventional techniques. Photobleached-fluorescence imaging was applied to obtain the first experimental flow profile of a ~100 nm lubricant film within an EHL contact. Mapping of flow profiles was also carried out across the contact. The investigated lubricants show multiple flow phenomena. They do not follow the predicted Couette flow, often assumed in tribology theory. Two distinct flow conditions were observed: transition from Couette flow to a non-linear velocity profile; and shear banding, or dilation. Both conditions were shown to depend on position and normal stress experienced by the lubricant. Causes, such as pressure gradient and limiting shear stress, and the effect on traction, will be discussed. This work is supported by EPSRC Platform Grant (EP/G026114/1)

  19. Ice Thickness in the Northwest Passage

    NASA Astrophysics Data System (ADS)

    Haas, C.; Howell, S.

    2015-12-01

    Recently the feasibility of commercial shipping in the ice-prone Northwest Passage has attracted a lot of attention. However, very little ice thickness information actually exists. We present results of the first-ever airborne electromagnetic ice thickness surveys over the NWP carried out in April and May 2011 and 2015 over first-year and multiyear ice. Results show modal thicknesses between 1.8 and 2.0 m in all regions. Mean thicknesses over 3 m and thick, deformed ice were observed over some multiyear ice regimes shown to originate from the Arctic Ocean. Thick ice features more than 100 m wide and thicker than 4 m occurred frequently. There are few other data to compare with to evaluate if the ice of the Northwest Passage has transitioned as other parts of the Arctic have. Although likely thinner than some 20 or more years ago, ice conditions must still be considered severe, and the Canadian Arctic Archipelao may well be considered the last ice refuge of the Arctic. These results have important implications for the prediction of ice break-up and summer ice conditions, and the assessment of sea ice hazards during the summer shipping season.

  20. Solid Surface Combustion Experiment: Thick Fuel Results

    NASA Technical Reports Server (NTRS)

    Altenkirch, Robert A.; Bhattacharjee, Subrata; West, Jeff; Tang, Lin; Sacksteder, Kurt; Delichatsios, Michael A.

    1997-01-01

    The results of experiments for spread over polymethylmethacrylate, PMMA, samples in the microgravity environment of the Space Shuttle are described. The results are coupled with modelling in an effort to describe the physics of the spread process for thick fuels in a quiescent, microgravity environment and uncover differences between thin and thick fuels. A quenching phenomenon not present for thin fuels is delineated, namely the fact that for thick fuels the possibility exists that, absent an opposing flow of sufficient strength to press the flame close enough to the fuel surface to allow the heated layer in the solid to develop, the heated layer fails to become 'fully developed.' The result is that the flame slows, which in turn causes an increase in the relative radiative loss from the flame, leading eventually to extinction. This potential inability of a thick fuel to develop a steady spread rate is not present for a thin fuel because the heated layer is the fuel thickness, which reaches a uniform temperature across the thickness relatively rapidly.

  1. Elastic stability of thick auxetic plates

    NASA Astrophysics Data System (ADS)

    Lim, Teik-Cheng

    2014-04-01

    Auxetic materials and structures exhibit a negative Poisson’s ratio while thick plates encounter shear deformation, which is not accounted for in classical plate theory. This paper investigates the effect of a negative Poisson’s ratio on thick plates that are subjected to buckling loads, taking into consideration the shear deformation using Mindlin plate theory. Using a highly accurate shear correction factor that allows for the effect of Poisson’s ratio, the elastic stability of circular and square plates are evaluated in terms of dimensionless parameters, namely the Mindlin-to-Kirchhoff critical buckling load ratio and Mindlin critical buckling load factors. Results for thick square plates reveal that both parameters increase as the Poisson’s ratio becomes more negative. In the case of thick circular plates, the Mindlin-to-Kirchhoff critical buckling load ratios and the Mindlin critical buckling load factors increase and decrease, respectively, as the Poisson’s ratio becomes more negative. The results obtained herein show that thick auxetic plates behave as thin conventional plates, and therefore suggest that the classical plate theory can be used to evaluate the elastic stability of thick plates if the Poisson’s ratio of the plate material is sufficiently negative. The results also suggest that materials with highly negative Poisson’s ratios are recommended for square plates, but not circular plates, that are subjected to buckling loads.

  2. Thickness-dependent white electroluminescence from diamond/CeF3/SiO2 multilayered films

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoping; Liu, Ping; Wang, Lijun; Li, Jian

    2014-03-01

    Diamond/CeF3/SiO2 multilayered films electroluminescent (EL) devices were made, and we found that the EL spectrum at room temperature depends on the CeF3 layer thickness. The EL spectrum shows that the main peaks are located at 527 nm, 593 nm, and 742 nm when the CeF3 layer thickness is less than 0.5 μm, but when the CeF3 layer thickness is greater than 0.5 μm, the electroluminescence spectrum obviously exhibits three bands, which are centered at 310-380 nm (ultraviolet emission), 520-580 nm (green-yellow emission), and 700-735 nm (red emission). The white EL brightness of the device (for thicker CeF3 layer) reaches a maximum of 15 cd/m2 at a forward applied voltage of 225 V, which can be distinguished at the sunlight in the light by the naked eye.

  3. Composite Fermion Spin Polarization Energy with Finite Layer Thickness

    NASA Astrophysics Data System (ADS)

    Shayegan, Mansour; Liu, Yang; Hasdemir, Sukret; Pfeiffer, Loren; West, Ken; Baldwin, Kirk

    2014-03-01

    We study the spin polarization transitions of fractional quantum Hall (FQH) states in the filling range 1 < ν < 2 in symmetric quantum wells (QWs), as a function of density. Our results reveal a strong well-width dependence of the critical density nC and ratio between the Zeeman energy (EZ) normalized to the Coulomb energy (e2 / 4 πɛlB), above which a certain FQH state becomes spin polarized. For example, the ν = 7 / 5 FQH state becomes spin polarized at about 3 times higher density or 1.7 times larger EZ in the 31-nm-wide QW than in the 65-nm-wide QW. This well-width dependence of the spin polarization stems from by the finite electron layer thickness in these QWs and the resulting softening of the Coulomb interaction. We acknowledge support through the DOE BES (DE-FG02-00-ER45841) for measurements, and the Gordon and Betty Moore Foundation (Grant GBMF2719), Keck Foundation, and the NSF (DMR-0904117, DMR-1305691 and MRSEC DMR-0819860) for sample fabrication. Work at Arg.

  4. Dependence of Gold Nanoparticle Radiosensitization on Functionalizing Layer Thickness.

    PubMed

    Spaas, Cedric; Dok, Rüveyda; Deschaume, Olivier; De Roo, Bert; Vervaele, Mattias; Seo, Jin Won; Bartic, Carmen; Hoet, Peter; Van den Heuvel, Frank; Nuyts, Sandra; Locquet, Jean-Pierre

    2016-04-01

    Gold nanoparticles functionalized with polyethylene glycol of different chain lengths are used to determine the influence of the capping layer thickness on the radiosensitizing effect of the particles. The size variations in organic coating, built up with polyethylene glycol polymers of molecular weight 1-20 kDa, allow an evaluation of the decrease in dose enhancement percentages caused by the gold nanoparticles at different radial distances from their surface. With localized eradication of malignant cells as a primary focus, radiosensitization is most effective after internalization in the nucleus. For this reason, we performed controlled radiation experiments, with doses up to 20 Gy and particle diameters in a range of 5-30 nm, and studied the relaxation pattern of supercoiled DNA. Subsequent gel electrophoresis of the suspensions was performed to evaluate the molecular damage and consecutively quantify the gold nanoparticle sensitization. In conclusion, on average up to 58.4% of the radiosensitizing efficiency was lost when the radial dimensions of the functionalizing layer were increased from 4.1 to 15.3 nm. These results serve as an experimental supplement for biophysical simulations and demonstrate the influence of an important parameter in the development of nanomaterials for targeted therapies in cancer radiotherapy. PMID:26950059

  5. Supercontinuum laser based optical characterization of Intralipid® phantoms in the 500-2250 nm range.

    PubMed

    Aernouts, Ben; Zamora-Rojas, Eduardo; Van Beers, Robbe; Watté, Rodrigo; Wang, Ling; Tsuta, Mizuki; Lammertyn, Jeroen; Saeys, Wouter

    2013-12-30

    A supercontinuum laser based double integrating sphere setup in combination with an unscattered transmittance measurement setup was developed and carefully validated for optical characterization of turbid samples in the 500-2250 nm wavelength range. A set of 57 liquid optical phantoms, covering a wide range of absorption and scattering properties, were prepared and measured at two sample thicknesses. The estimated bulk optical properties matched well for both thicknesses, and with theory and literature, without significant crosstalk between absorption and scattering. Equations were derived for the bulk scattering properties μ(s), μ(s)' and g of Intralipid® 20% which can be used to calculate the bulk scattering properties of intralipid-dilutions in the 500-2250 nm range. PMID:24514839

  6. Thickness dependent metal-insulator transition and dimensional crossover for weak localization in Si{sub 0.02}Zn{sub 0.98}O thin films grown by pulsed laser deposition

    SciTech Connect

    Das, Amit K. Ajimsha, R. S.; Kukreja, L. M.

    2014-05-21

    Metal to insulator transition was observed in Si{sub 0.02}Zn{sub 0.98}O (SZO) films, grown by pulsed laser deposition on sapphire substrates, as the thicknesses of the films were reduced from ∼40 to 15 nm. The SZO film with thickness of ∼40 nm showed typical metallic behavior in temperature dependent resistivity measurements. On the contrary, the SZO film with thickness of ∼15 nm was found to exhibit strong localization where the transport at low temperature was dominated by variable range hopping conduction. In the intermediate thickness regime, quantum corrections were important and a dimensional crossover from 3D to 2D weak localization occurred in the SZO film with thickness of 20 nm.

  7. Metamaterial near-field sensor for deep-subwavelength thickness measurements and sensitive refractometry in the terahertz frequency range

    SciTech Connect

    Reinhard, Benjamin; Schmitt, Klemens M.; Neu, Jens; Wollrab, Viktoria; Beigang, Rene; Rahm, Marco

    2012-05-28

    We present a metamaterial-based terahertz (THz) sensor for thickness measurements of subwavelength-thin materials and refractometry of liquids and liquid mixtures. The sensor operates in reflection geometry and exploits the frequency shift of a sharp Fano resonance minimum in the presence of dielectric materials. We obtained a minimum thickness resolution of 12.5 nm (1/16 000 times the wavelength of the THz radiation) and a refractive index sensitivity of 0.43 THz per refractive index unit. We support the experimental results by an analytical model that describes the dependence of the resonance frequency on the sample material thickness and the refractive index.

  8. Effect of the quantum well thickness on the performance of InGaN photovoltaic cells

    SciTech Connect

    Redaelli, L.; Mukhtarova, A.; Valdueza-Felip, S.; Ajay, A.; Durand, C.; Eymery, J.; Monroy, E.; Faure-Vincent, J.

    2014-09-29

    We report on the influence of the quantum well thickness on the effective band gap and conversion efficiency of In{sub 0.12}Ga{sub 0.88}N/GaN multiple quantum well solar cells. The band-to-band transition can be redshifted from 395 to 474 nm by increasing the well thickness from 1.3 to 5.4 nm, as demonstrated by cathodoluminescence measurements. However, the redshift of the absorption edge is much less pronounced in absorption: in thicker wells, transitions to higher energy levels dominate. Besides, partial strain relaxation in thicker wells leads to the formation of defects, hence degrading the overall solar cell performance.

  9. Oil film thickness measurement using airborne laser-induced water Raman backscatter

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.

    1980-01-01

    The use of laser-induced water Raman backscatter for remote thin oil film detection and thickness measurement is reported here for the first time. A 337.1-nm nitrogen laser was used to excite the 3400-cm-1 OH stretch band of natural ocean water beneath the oil slick from an altitude of 150 m. The signal strength of the 381-nm water Raman backscatter was always observed to depress when the oil was encountered and then return to its original undepressed value after complete aircraft traversal of the floating slick. After removal of background and oil fluorescence contributions, the ratio of the depressed-to-undepressed airborne water Raman signal intensities, together with laboratory measured oil extinction coefficients, is used to calculate the oil film thickness.

  10. Novel high refractive index fluids for 193nm immersion lithography

    NASA Astrophysics Data System (ADS)

    Santillan, Julius; Otoguro, Akihiko; Itani, Toshiro; Fujii, Kiyoshi; Kagayama, Akifumi; Nakano, Takashi; Nakayama, Norio; Tamatani, Hiroaki; Fukuda, Shin

    2006-03-01

    Despite the early skepticism towards the use of 193-nm immersion lithography as the next step in satisfying Moore's law, it continuous to meet expectations on its feasibility in achieving 65-nm nodes and possibly beyond. And with implementation underway, interest in extending its capability for smaller pattern sizes such as the 32-nm node continues to grow. In this paper, we will discuss the optical, physical and lithographic properties of newly developed high index fluids of low absorption coefficient, 'Babylon' and 'Delphi'. As evaluated in a spectroscopic ellipsometer in the 193.39nm wavelength, the 'Babylon' and 'Delphi' high index fluids were evaluated to have a refractive index of 1.64 and 1.63 with an absorption coefficient of 0.05/cm and 0.08/cm, respectively. Lithographic evaluation results using a 193-nm 2-beam interferometric exposure tool show the imaging capability of both high index fluids to be 32-nm half pitch lines and spaces.

  11. Temperature characteristic of 808nm VCSELs with large aperture

    NASA Astrophysics Data System (ADS)

    Feng, Yuan; Feng, Dawei; Hao, Yongqin; Wang, Yong; Yan, Changling; Lu, Peng; Li, Yang

    2015-03-01

    In order to study the output characteristics of 808nm vertical cavity surface emitting laser(VCSEL) with large aperture at different temperature, 808nm VCSEL with 500μm emitting diameter are fabricated with Reticular Electrode Structure(RES). Lasing wavelength, optical power and the threshold current are measured by changing the temperature of heat sink. And an output power of 0.42W is achieved at 1.3A at room temperature under continuous wave operation. The central wavelength is 803.32nm, and the full width at half maximum is 0.16nm, the temperature shift is 0.06nm/°, the thermal resistance is 0.098°/mW. The testing results show that 808nm VCSEL with large aperture is good temperature characteristic.

  12. Versatile 1 W narrow band 976 nm and 1064 nm light sources

    NASA Astrophysics Data System (ADS)

    Mohrdiek, S.; Pfeiffer, H.-U.; Zibik, E. A.; Sverdlov, B.; Pliska, T.; Lichtenstein, N.

    2011-02-01

    We report on development of novel curved waveguide (CWG) laser devices, where the emission wavelength centered at ~976 nm is stabilized to a 20 dB bandwidth of less than 100 picometer by using fiber Bragg gratings (FBG). Radiation from the curved waveguide laser is coupled using an anamorphic fiber lens into a single mode polarization maintaining fiber containing the FBG, the latter acting as a front reflector. The high power gain chip is based on Oclaro's InGaAs/AlGaAs quantum well laser. Use of the curved waveguide geometry allows to eliminate residual reflections in the optical path of the cavity, which is formed by the rear chip facet and the FBG. It is well known that additional reflections lead to significant deterioration of the spectral and power stability. The devices, assembled in telecom type housings, provide up to 1 W of low-noise and kink-free CW power. In addition pulse operation in nanosecond range is also investigated. The spectral stabilization time to the wavelength of the FBG is limited by the external cavity roundtrip of ~2 ns. A side mode suppression ratio of about 40 dB and higher is achieved for pulsed and CW operation. Results are also presented for a device at 1064 nm. Numerous applications can be envisioned for these devices. For instance devices with high power and ultranarrow spectral bandwidth allow greater flexibility in the choice of parameters for frequency conversion applications. In pulsed mode the device can be used in the special sensing applications where spectral stability is crucial.

  13. A new domino failure mechanism in deep sub-100-nm technologies and its solution

    NASA Astrophysics Data System (ADS)

    Yang, Ge; Kang, Sung-Mo

    2004-03-01

    The domino circuit failure is due to competing requirements of the keeper and the NMOS logic transistors that cannot be satisfied simultaneously in order to achieve the noise margin and performance objectives. Domino keeper transistor has to be upsized to compensate for the subthreshold leakage and gate leakage currents that discharge the dynamic node in deep sub-100nm technologies. Domino multiplexer can fail when the fan-in number is greater than 14 for the noise margin of 0.1 Vdd, where the noise margin is defined as the input voltage that causes 10% voltage drop at the dynamic node of Domino. In simulation, 45nm BSIM4 models were used with the power supply voltage of 0.8V. To solve this problem, we propose a dual gate oxide thickness (Tox) implementation for high fan-in Domino. With proper dual gate oxide thickness assignment, subthreshold leakage and gate leakage that discharge the dynamic node are suppressed with the keeper size reduced. Proposed circuit not only prevents the possible failure in high fan-in Domino, but also reduces the delay and power consumption due to decreased contention between the keeper and NMOS logic tree. For 14-bit domino multiplexer, proposed circuit is 56% faster with 66% less power consumption and without area penalty, compared to single Tox domino.

  14. Preparation and characterization of Irgacure 784 doped photopolymers for holographic data storage at 532 nm

    NASA Astrophysics Data System (ADS)

    Lin, S. H.; Hsiao, Y.-N.; Hsu, K. Y.

    2009-02-01

    This paper presents the development of a thick photopolymer for holographic data storage at a wavelength of 532 nm. Irgacure 784, one kind of the titanocene photoinitiators, has been selected and doped to synthesize the photopolymers in this research. Using a two-step thermo-polymerization procedure two photopolymer samples have been fabricated, Irgacure 784 doped poly(methyl methacrylate) (PMMA) and Irgacure 784 doped epoxy resin. Samples of 2 mm thick have been fabricated. Holographic measurements show that Irgacure 784 doped epoxy resin is very sensitive at 532 nm and that it is capable of supporting holographic data storage at a ultra-fast recording rate of 760 Mb s-1. Mass spectrum measurement, solid state 1H-NMR spectrum measurement, and thermogravity analyses (TGA) have been performed. The results reveal the physical mechanism of holographic recording in these samples, providing a guideline for a design strategy and fabrication technique to produce a low-shrinkage recording material for holographic data storage in the tera-byte information age.

  15. Near-infrared transillumination at 1310-nm for the imaging of early dental decay

    NASA Astrophysics Data System (ADS)

    Jones, Robert S.; Huynh, Gigi D.; Jones, Graham C.; Fried, Daniel

    2003-09-01

    New imaging technologies are needed for the early detection of dental caries (decay) in the interproximal contact sites between teeth. Previous measurements have demonstrated that dental enamel is highly transparent in the near-IR at 1300-nm. In this study, a near-IR imaging system operating at 1300-nm was used to acquire images through tooth sections of varying thickness and whole teeth in order to demonstrate the utility of a near-IR dental transillumination system for the imaging of early dental caries (decay). Simulated lesions, which model the optical scattering of natural dental caries, were placed in plano-parallel dental enamel sections. The contrast ratio between the simulated lesions and surrounding sound enamel was calculated from analysis of acquired projection images. The results show significant contrast between the lesion and the enamel (>0.35) and a spatial line profile that clearly resolves the lesion in samples as thick as 6.75-mm. This study clearly demonstrates that a near-IR transillumination system has considerable potential for the imaging of early dental decay.

  16. Dependence of BiFeO3 thickness on exchange bias in BiFeO3/ Co2FeAl multiferroic structures

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Zhang, D. L.; Wang, Y. H.; Miao, J.; Xu, X. G.; Jiang, Y.

    2011-01-01

    We have grown BiFeO3 (BFO) thin films with different thickness on Si/SiO2/Ti/Pt(111) substrates by pulsed laser deposition. Half-metallic Co2FeAl (CFA) films with a thickness of 5 nm were then grown on the BFO films by magnetron sputtering. Through the magnetic hysteresis loops of the BFO/CFA heterostructure, we observe a direct correlation between the thickness of the BFO film and exchange bias (EB) field. The EB field exhibits fluctuation behavior with a cyclical BFO thickness of 60 nm, which is close to the spiral modulation wavelength (62 nm) of BFO. It indicates the influence of spiral modulation on the EB in the BFO/CFA multiferroic structure.

  17. Ultrastructurally-smooth thick partitioning and volume stitching for larger-scale connectomics

    PubMed Central

    Hayworth, Kenneth J.; Xu, C. Shan; Lu, Zhiyuan; Knott, Graham W.; Fetter, Richard D.; Tapia, Juan Carlos; Lichtman, Jeff W.; Hess, Harald F.

    2015-01-01

    FIB-SEM has become an essential tool for studying neural tissue at resolutions below 10×10×10 nm, producing datasets superior for automatic connectome tracing. We present a technical advance, ultrathick sectioning, which reliably subdivides embedded tissue samples into chunks (20 µm thick) optimally sized and mounted for efficient, parallel FIB-SEM imaging. These chunks are imaged separately and then ‘volume stitched’ back together, producing a final 3D dataset suitable for connectome tracing. PMID:25686390

  18. Electrochromism of DC magnetron-sputtered TiO2: Role of film thickness

    NASA Astrophysics Data System (ADS)

    Sorar, Idris; Pehlivan, Esat; Niklasson, Gunnar A.; Granqvist, Claes G.

    2014-11-01

    Titanium dioxide films were prepared by reactive DC magnetron sputtering and the role of the film thickness d on the electrochromism was analyzed for 100 < d < 400 nm. The best properties were obtained for the thickest films, which yielded a mid-luminous transmittance modulation of 58% and a corresponding coloration efficiency of 26.3 cm2/C. The films were amorphous according to X-ray diffraction measurements and showed traces of adsorbed water as revealed by infrared spectroscopy.

  19. Unique Challenges Accompany Thick-Shell CdSe/nCdS (n > 10) Nanocrystal Synthesis

    SciTech Connect

    Guo, Y; Marchuk, K; Abraham, R; Sampat, S; Abraham, R.; Fang, N; Malko, AV; Vela, J

    2011-12-23

    Thick-shell CdSe/nCdS (n {ge} 10) nanocrystals were recently reported that show remarkably suppressed fluorescence intermittency or 'blinking' at the single-particle level as well as slow rates of Auger decay. Unfortunately, whereas CdSe/nCdS nanocrystal synthesis is well-developed up to n {le} 6 CdS monolayers (MLs), reproducible syntheses for n {ge} 10 MLs are less understood. Known procedures sometimes result in homogeneous CdS nucleation instead of heterogeneous, epitaxial CdS nucleation on CdSe, leading to broad and multimodal particle size distributions. Critically, obtained core/shell sizes are often below those desired. This article describes synthetic conditions specific to thick-shell growth (n {ge} 10 and n {ge} 20 MLs) on both small (sub2 nm) and large (>4.5 nm) CdSe cores. We find added secondary amine and low concentration of CdSe cores and molecular precursors give desired core/shell sizes. Amine-induced, partial etching of CdSe cores results in apparent shell-thicknesses slightly beyond those desired, especially for very-thick shells (n {ge} 20 MLs). Thermal ripening and fast precursor injection lead to undesired homogeneous CdS nucleation and incomplete shell growth. Core/shells derived from small CdSe (1.9 nm) have longer PL lifetimes and more pronounced blinking at single-particle level compared with those derived from large CdSe (4.7 nm). We expect our new synthetic approach will lead to a larger throughput of these materials, increasing their availability for fundamental studies and applications.

  20. 40nm tunable multi-wavelength fiber laser

    NASA Astrophysics Data System (ADS)

    Jia, Qingsong; Wang, Tianshu; Zhang, Peng; Dong, Keyan; Jiang, Huilin

    2014-12-01

    A Brillouin-Erbium multi-wavelength tunable fiber laser at C-band is demostrated. A 10 km long singlemode fiber(SMF), a 6 m long Erbium-doped fiber, two couplers, a wavelength division multiplexer, a isolator, an optical circulator, a 980nm pump laser and a narrow linewidth tunable laser are included in the structure. A segment of 10 km-long single-mode fiber (SMF) between the two ports of a 1×2 coupler is used as Brillouin gain. Ebiumdoped fiber amplifier (EDFA) consists of a segment of 6m er-doped fiber pumped by 980nm laser dioder . A narrow linewidth tunable laser from 1527 to 1607 nm as Brillouin bump, At the Brillouin pump power of 8mW and the 980 nm pump power of 400 mw, 16 output channels with 0.08 nm spacing and tuning range of 40 nm from 1527 nm to 1567 nm are achieved. We realize the tunable output of wavelength by adjusting the 980 nm pump power and the Brillouin pump wavelength. Stability of the multiwavelength fiber laser is also observed.

  1. 7nm logic optical lithography with OPC-Lite

    NASA Astrophysics Data System (ADS)

    Smayling, Michael C.; Tsujita, Koichiro; Yaegashi, Hidetami; Axelrad, Valery; Nakayama, Ryo; Oyama, Kenichi; Yamauchi, Shohei; Ishii, Hiroyuki; Mikami, Koji

    2015-03-01

    The CMOS logic 22nm node was the last one done with single patterning. It used a highly regular layout style with Gridded Design Rules (GDR). Smaller nodes have required the same regular layout style but with multiple patterning for critical layers. A "line/cut" approach is being used to achieve good pattern fidelity and process margin.[1] As shown in Fig. 1, even with "line" patterns, pitch division will eventually be necessary. For the "cut" pattern, Design-Source-Mask Optimization (DSMO) has been demonstrated to be effective at the 20nm node and below.[2,3,4] Single patterning was found to be suitable down to 16nm, while double patterning extended optical lithography for cuts to the 10-12nm nodes. Design optimization avoided the need for triple patterning. Lines can be patterned with 193nm immersion with no complex OPC. The final line dimensions can be achieved by applying pitch division by two or four.[5] In this study, we extend the scaling using simplified OPC to the 7nm node for critical FEOL and BEOL layers. The test block is a reasonably complex logic function with ~100k gates of combinatorial logic and flip-flops, scaled from previous experiments. Simulation results show that for cuts at 7nm logic dimensions, the gate layer can be done with single patterning whose minimum pitch is 53nm, possibly some of the 1x metal layers can be done with double patterning whose minimum pitch is 53nm, and the contact layer will require triple patterning whose minimum pitch is 68nm. These pitches are less than the resolution limit of ArF NA=1.35 (72nm). However these patterns can be separated by a combination of innovative SMO for less than optical resolution limit and a process trick of hole-repair technique. An example of triple patterning coloring is shown in Fig 3. Fin and local interconnect are created by lines and trims. The number of trim patterns are 3 times (min. pitch=90nm) and twice (min. pitch=120nm), respectively. The small number of masks, large pitches, and

  2. Polarization-dependent aluminum metasurface operating at 450 nm.

    PubMed

    Højlund-Nielsen, Emil; Zhu, Xiaolong; Carstensen, Marcus S; Sørensen, Michael K; Vannahme, Christoph; Asger Mortensen, N; Kristensen, Anders

    2015-11-01

    We report on a polarization-dependent plasmonic aluminum-based high-density metasurface operating at blue wavelengths. The fabricated sub-wavelength structures, tailored in size and geometry, possess strong, localized, plasmonic resonances able to control linear polarization. Best performance is achieved by rotating an elongated rectangular structure of length 180 nm and width 110 nm inside a square lattice of period 250 nm. In the case of 45 degrees rotation of the structure with respect to the lattice, the normal-incidence reflectance drops around the resonance wavelength of 457 nm from about 60 percent to below 2 percent. PMID:26561151

  3. Properties of AlF3 and LaF3 films at 193nm

    NASA Astrophysics Data System (ADS)

    Xue, Chunrong; Shao, Jianda

    2010-10-01

    In order to develop low loss, high-performance 193nm Fluoride HR mirrors and anti-reflection coatings, LaF3 and AlF3 materials, used for a single-layer coating, were deposited by a molybdenum boat evaporation process. Various microstructures that formed under different substrate temperatures and with deposition rates were investigated. The relation between these microstructures (including cross section morphology, surface roughness and crystalline structure), the optical properties (including refractive index and optical loss) and mechanical properties (stress) were investigated. Furthermore, AlF3 used as a low-index material and LaF3 used as a high-index material were designed and deposited for multilayer coatings. Transmittance, reflectance, stress, and the laser-induced damage threshold (LIDT) were studied. It is shown that AlF3 and LaF3 thin films, deposited on the substrate at a temperature of 300 °C, obtained good quality thin films with high transmittance and little optical loss at 193 nm. For multilayer coatings, the absorption mainly comes from LaF3. Based on these studies, The thickness of 193nm films was controled by a 1/3 baffle with pre-coating technology. the LaF3/AlF3 AR coantings and HR mirrors at 193nm were designed and deposited. Under the present experimental conditions, the reflectance of LaF3/AlF3 HR mirror is up to 96%, and its transmittance is 1.5%. the LaF3/AlF3 AR coanting's residual reflectance is less than 0.14%, and single-sided transmittance is 93.85%. To get a high-performance 193nm AR coating, super-polished substrate is the best choice.

  4. Dependence of 20-nm C/H CD windows on critical process parameters

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Su; Gu, Pei-Yi; Tsai, Ming-Jinn

    2010-04-01

    20 nm contact hole (C/H) patterning is applicable for sub-22 nm technology node applications. Dependence of C/H CD window on critical process parameters is important for process stability and repeatability. Post applied baking (PAB) condition, resist thickness, develop time, and dry etch rate are considered to be the most important process parameters for e-beam chain scission resist ZEP520A C/H patterning. In this paper, PAB temperatures (TPAB) are investigated at temperatures between lower than glass transition temperature (TG) and much higher than TF. Effects of these process parameters on 20 nm +/-10% C/H CD window for various pattern densities and e-beam doses are studied. The critical process parameters are determined by their effects on CD window size, C/H sidewall profile, proximity effect immunity, ΔCD/ΔDose slope, and etch selectivity. Experimental results are summarized below. Thinnest ZEP520A film has the largest 20nm +/-10% CD window on D-D plot for various L/S ratios and doses. The dosage window of smaller C/H CD is larger. The proximity effect is negligible for 50 nm ZEP520A baked at 200°C/300 sec. No apparent effect is found in CD window on D-D plot for develop time as short as 30 sec. PAB condition is most critical than the other process parameters in determining resist density and polymerization which affect e-beam scattering and chain scission in resist film and therefore affects CD resolution and window. PAB condition of 140°C/60 sec is most desirable in terms of CD window on D-D plot, C/H sidewall profile, dry etch rate and proximity effect.

  5. Anomalous thickness dependence of quality factor in TiN film resonators grown on functionalized Si substrates

    NASA Astrophysics Data System (ADS)

    Xu, Peng; Kohler, Tim; Lock, Evgeniya; Rosen, Yaniv; Ramanayaka, Aruna; Guchhait, Samaresh; Osborn, Kevin

    Various properties affect the quality factor of superconducting resonators at millikelvin temperatures including the presence of nanoscale interfacial dielectric films and residual quasiparticles. Superconducting titanium nitride is polycrystalline such that growth phases may also affect the resonator quality. Here, we functionalize Si substrates in different hydrophobic and hydrophilic plasma environments, sputter titanium nitride on top and pattern the latter films into resonators. For each functionalization we study the quality factor dependence on the superconducting film thickness, where the thicknesses are changed only between 25 and 50 nm. As expected, most functionalizations reveal very little quality factor dependence on superconducting film thickness. However, other functionalizations dramatically, and even anomalously, increase or decrease the quality with thickness. For example, oxygen plasma functionalization causes the quality factor to increase by a factor of more than ten at single photon power with increased thickness. We report on the progress towards finding the intrinsic reason for strong quality factor dependences on surface functionalization.

  6. Generation and use of high power 213 nm and 266 nm laser radiation and tunable 210-400 nm laser radiation with BBO crystal matrix array

    DOEpatents

    Gruen, Dieter M.

    2000-01-01

    A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.

  7. Do fire disturbances account for missing C in snow dominated headwater catchments in NM?

    NASA Astrophysics Data System (ADS)

    Perdrial, J. N.; Brooks, P. D.; Swetnam, T.; Lohse, K. A.; Rasmussen, C.; Harpold, A. A.; Litvak, M. E.; Broxton, P. D.; Mitra, B.; Condon, K.; Huckle, D. M.; Vazquez, A.; Lybrand, R. A.; Holleran, M.; Orem, C. A.; Meixner, T.; Chorover, J.

    2013-12-01

    How do fires affect the potential for long term carbon (C) sequestration in the forests of western North America? We quantified current C fluxes (net ecosystem exchange [NEE] and dissolved & particulate stream and ground water fluxes) and pools (above and below ground biomass, [AGB, BGB], soil C) in three catchments of the Jemez River Basin Critical Zone Observatory. Our estimates revealed that study systems are dominated by gaseous fluxes (ranging from 3,200 to 3,900 kg ha-1 yr-1over three years) with only small losses to streams as dissolved or particulate C (5 to 30 kg ha-1 yr-1) or to GW (1-6 kg ha-1 yr-1) rendering these systems substantial sinks for atmospheric C. Our estimates for biomass (20,000 - 240,000 kg ha-1) and soil C (80.000 and 160.000 kg ha-1) are comparable to stocks of similar soil and vegetation types (Lal 2005; North et al. 2009) and at current uptake rates only ~ 50-100 years are necessary for accumulation. Since old soil C accumulated over a longer period of time, current uptake rates are either higher than past ones and/or disturbances reduced the stocks in the past. Logging is documented in these systems but cannot explain the bulk of unaccounted C. Wildfires in contrast have occurred repeatedly in the past and impacted the C budget by reducing stocks (e.g. ~ 8% of AGB, ) during each fire. Additionally, uptake rates after fire are reduced until vegetation regrowth, with microbial respiration and thus carbon loss dominating in the interim. Post-fire debris flows (estimate 800 - 1140 kg C ha-1 after a recent fire in NM) present an additional sink. Together, our results are used to test the hypothesis that recurring wildfires strongly impact the C-balance of seasonally snow-covered forests in the SW US leading to oscillation between sources and sinks for C. Lal R (2005). Forest Ecol Manag 220 (1-3):242-258. North M, Hurteau M, Innes J (2009). Ecol Appl 19 (6):1385-1396.

  8. Utilisation of chip thickness models in grinding

    NASA Astrophysics Data System (ADS)

    Singleton, Roger

    Grinding is now a well established process utilised for both stock removal and finish applications. Although significant research is performed in this field, grinding still experiences problems with burn and high forces which can lead to poor quality components and damage to equipment. This generally occurs in grinding when the process deviates from its safe working conditions. In milling, chip thickness parameters are utilised to predict and maintain process outputs leading to improved control of the process. This thesis looks to further the knowledge of the relationship between chip thickness and the grinding process outputs to provide an increased predictive and maintenance modelling capability. Machining trials were undertaken using different chip thickness parameters to understand how these affect the process outputs. The chip thickness parameters were maintained at different grinding wheel diameters for a constant productivity process to determine the impact of chip thickness at a constant material removal rate.. Additional testing using a modified pin on disc test rig was performed to provide further information on process variables. The different chip thickness parameters provide control of different process outputs in the grinding process. These relationships can be described using contact layer theory and heat flux partitioning. The contact layer is defined as the immediate layer beneath the contact arc at the wheel workpiece interface. The size of the layer governs the force experienced during the process. The rate of contact layer removal directly impacts the net power required from the system. It was also found that the specific grinding energy of a process is more dependent on the productivity of a grinding process

  9. Partial and full-thickness neuroretinal transplants.

    PubMed

    Ghosh, F; Juliusson, B; Arnér, K; Ehinger, B

    1999-01-01

    Adult and embryonic rabbit retinal sheets were transplanted into the subretinal space of adult rabbits. The transplants were either full-thickness with intact layering, or gelatin embedded and vibratome sectioned with the inner retina removed. The full-thickness grafts were positioned subretinally by means of a glass capillary in which they were partially folded. The vibratome sectioned ones were placed using a plastic injector in which the gelatin embedded graft was flat. The embryonic full-thickness grafts were followed clinically up to 3 months, and the other 3 transplant types up to 1 month postoperatively, after which the retina was sectioned and stained for light microscopy. Surgical complications were more common in eyes receiving vibratome sectioned grafts with 10 out of 34 eyes displaying blood in the vitreous. Four of these eyes also developed total retinal detachment. Out of 17 eyes receiving full-thickness grafts, only one displayed these complications. Histologically, 11 out of 13 embryonic full-thickness transplants revealed straight, laminated transplants with correct polarity, and with all normal retinal layers present. In these transplants, fusion with the host increased in time. Of the adult full-thickness transplants, only 1 out of 4 survived, and this graft showed signs of degeneration. The vibratome sectioned adult transplants in a few cases survived the first two postoperative weeks. In these grafts, both inner and outer retina were present, indicating an incomplete vibratome sectioning. With longer postoperative times, the number of surviving transplants in this group diminished considerably. All vibratome sectioned embryonic transplants developed into rosettes and sometimes also into laminated sections with reversed polarity. It can be concluded that in rabbits, the surgical technique used for vibratome sectioned transplants requires a larger sclerotomy and retinotomy, since they have to be kept flat in the transplanting instrument due to

  10. Diffraction efficiency of 200-nm-period critical-angle transmission gratings in the soft x-ray and extreme ultraviolet wavelength bands.

    PubMed

    Heilmann, Ralf K; Ahn, Minseung; Bruccoleri, Alex; Chang, Chih-Hao; Gullikson, Eric M; Mukherjee, Pran; Schattenburg, Mark L

    2011-04-01

    We report on measurements of the diffraction efficiency of 200-nm-period freestanding blazed transmission gratings for wavelengths in the 0.96 to 19.4 nm range. These critical-angle transmission (CAT) gratings achieve highly efficient blazing over a broad band via total external reflection off the sidewalls of smooth, tens of nanometer thin ultrahigh aspect-ratio silicon grating bars and thus combine the advantages of blazed x-ray reflection gratings with those of more conventional x-ray transmission gratings. Prototype gratings with maximum depths of 3.2 and 6 μm were investigated at two different blaze angles. In these initial CAT gratings the grating bars are monolithically connected to a cross support mesh that only leaves less than half of the grating area unobstructed. Because of our initial fabrication approach, the support mesh bars feature a strongly trapezoidal cross section that leads to varying CAT grating depths and partial absorption of diffracted orders. While theory predicts broadband absolute diffraction efficiencies as high as 60% for ideal CAT gratings without a support mesh, experimental results show efficiencies in the range of ∼50-100% of theoretical predictions when taking the effects of the support mesh into account. Future minimization of the support mesh therefore promises broadband CAT grating absolute diffraction efficiencies of 50% or higher. PMID:21460902

  11. Diffraction efficiency of 200-nm-period critical-angle transmission gratings in the soft x-ray and extreme ultraviolet wavelength bands

    SciTech Connect

    Heilmann, Ralf K.; Ahn, Minseung; Bruccoleri, Alex; Chang, Chih-Hao; Gullikson, Eric M.; Mukherjee, Pran; Schattenburg, Mark L.

    2011-04-01

    We report on measurements of the diffraction efficiency of 200-nm-period freestanding blazed transmission gratings for wavelengths in the 0.96 to 19.4 nm range. These critical-angle transmission (CAT) gratings achieve highly efficient blazing over a broad band via total external reflection off the sidewalls of smooth, tens of nanometer thin ultrahigh aspect-ratio silicon grating bars and thus combine the advantages of blazed x-ray reflection gratings with those of more conventional x-ray transmission gratings. Prototype gratings with maximum depths of 3.2 and 6 {mu}m were investigated at two different blaze angles. In these initial CAT gratings the grating bars are monolithically connected to a cross support mesh that only leaves less than half of the grating area unobstructed. Because of our initial fabrication approach, the support mesh bars feature a strongly trapezoidal cross section that leads to varying CAT grating depths and partial absorption of diffracted orders. While theory predicts broadband absolute diffraction efficiencies as high as 60% for ideal CAT gratings without a support mesh, experimental results show efficiencies in the range of {approx}50-100% of theoretical predictions when taking the effects of the support mesh into account. Future minimization of the support mesh therefore promises broadband CAT grating absolute diffraction efficiencies of 50% or higher.

  12. Snow thickness retrieval over thick Arctic sea ice using SMOS satellite data

    NASA Astrophysics Data System (ADS)

    Maaß, N.; Kaleschke, L.; Tian-Kunze, X.; Drusch, M.

    2013-07-01

    The microwave interferometric radiometer of the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission measures at a frequency of 1.4 GHz in the L-band. In contrast to other microwave satellites, low frequency measurements in L-band have a large penetration depth in sea ice and thus contain information on the ice thickness. Previous ice thickness retrievals have neglected a snow layer on top of the ice. Here, we implement a snow layer in our emission model and investigate how snow influences L-band brightness temperatures and whether it is possible to retrieve snow thickness over thick Arctic sea ice from SMOS data. We find that the brightness temperatures above snow-covered sea ice are higher than above bare sea ice and that horizontal polarisation is more affected by the snow layer than vertical polarisation. In accordance with our theoretical investigations, the root mean square deviation between simulated and observed horizontally polarised brightness temperatures decreases from 20.0 K to 4.4 K, when we include the snow layer in the simulations. Under cold Arctic conditions we find brightness temperatures to increase with increasing snow thickness. Because dry snow is almost transparent in L-band, this brightness temperature's dependence on snow thickness origins from the thermal insulation of snow and its dependence on the snow layer thickness. This temperature effect allows us to retrieve snow thickness over thick sea ice. For the best simulation scenario and snow thicknesses up to 35 cm, the average snow thickness retrieved from horizontally polarised SMOS brightness temperatures agrees within 0.7 cm with the average snow thickness measured during the IceBridge flight campaign in the Arctic in spring 2012. The corresponding root mean square deviation is 6.3 cm, and the correlation coefficient is r2 = 0.55.

  13. Snow thickness retrieval over thick Arctic sea ice using SMOS satellite data

    NASA Astrophysics Data System (ADS)

    Maaß, N.; Kaleschke, L.; Tian-Kunze, X.; Drusch, M.

    2013-12-01

    The microwave interferometric radiometer of the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission measures at a frequency of 1.4 GHz in the L-band. In contrast to other microwave satellites, low frequency measurements in L-band have a large penetration depth in sea ice and thus contain information on the ice thickness. Previous ice thickness retrievals have neglected a snow layer on top of the ice. Here, we implement a snow layer in our emission model and investigate how snow influences L-band brightness temperatures and whether it is possible to retrieve snow thickness over thick Arctic sea ice from SMOS data. We find that the brightness temperatures above snow-covered sea ice are higher than above bare sea ice and that horizontal polarisation is more affected by the snow layer than vertical polarisation. In accordance with our theoretical investigations, the root mean square deviation between simulated and observed horizontally polarised brightness temperatures decreases from 20.9 K to 4.7 K, when we include the snow layer in the simulations. Although dry snow is almost transparent in L-band, we find brightness temperatures to increase with increasing snow thickness under cold Arctic conditions. The brightness temperatures' dependence on snow thickness can be explained by the thermal insulation of snow and its dependence on the snow layer thickness. This temperature effect allows us to retrieve snow thickness over thick sea ice. For the best simulation scenario and snow thicknesses up to 35 cm, the average snow thickness retrieved from horizontally polarised SMOS brightness temperatures agrees within 0.1 cm with the average snow thickness measured during the IceBridge flight campaign in the Arctic in spring 2012. The corresponding root mean square deviation is 5.5 cm, and the coefficient of determination is r2 = 0.58.

  14. Thickness quantization in a reorientation transition

    NASA Astrophysics Data System (ADS)

    Venus, David; He, Gengming; Winch, Harrison; Belanger, Randy

    The reorientation transition of an ultrathin film from perpendicular to in-plane magnetization is driven by a competition between shape and surface anisotropy. It is accompanied by a ''stripe'' domain structure that evolves as the reorientation progresses. Often, an n layer film has stable perpendicular magnetization and an n+1 layer film has stable in-plane magnetization. If the domain walls are not pinned, the long-range stripe domain pattern averages over this structure so that the transition occurs at a non-integer layer thickness. We report in situ experimental measurements of the magnetic susceptibility (via MOKE) of the reorientation transition in Fe/2 ML Ni/W(110) films as a function of thickness as they are deposited at room temperature. In addition to a peak at the reorientation transition, we observe a strong precursor due to thickness quantization in atomic layers. This peak is described quantitatively by the response of small islands of thickness 3 layers with in-plane anisotropy in a sea of 2 layers Fe with perpendicular anisotropy. The fitted parameters give an estimate of the island size at which the response disappears. This size corresponds to a domain wall thickness, so that the islands become locally in-plane, demonstrating the self-consistency of the model.

  15. Structural, electrical and magnetic properties of evaporated permalloy thin films: effect of substrate and thickness

    NASA Astrophysics Data System (ADS)

    Guittoum, A.; Bourzami, A.; Layadi, A.; Schmerber, G.

    2012-05-01

    We have studied the effects of the substrate and the thickness on the structural, electrical and magnetic properties of permalloy thin films Ni81Fe19 (Py). Series of Py thin films were evaporated on four various substrates: glass, kapton, Si(1 0 0) and Si(1 1 1). The thickness ranges from 13 nm to 190 nm. We show that evaporated permalloy on kapton and Si(1 1 1) present a strong ⟨1 1 1⟩ preferred orientation for samples thicker than 85 nm; however, the films grown on glass and Si(1 0 0) present a weak (1 1 1) texture for most of these samples. Generally, the lattice constant for Py/glass, Py/Si(1 0 0) and Py/Si(1 1 1) samples is found to be smaller than the bulk value (abulk), while for the Py/kapton, it is larger than abulk. There is an overall increase of the grain sizes (100 Å-480 Å) with thickness for Py/Si(1 1 1), Py/Si(1 0 0) and Py/glass. For the Py/kapton samples, the grain sizes (about 130 Å) seem to be independent of the thickness. The resistivity, ρ, decreases with increasing thickness for all samples. The highest values of ρ were observed in the Py/kapton thin films, diffusion at the grain boundaries might be in part responsible for these high values. The magnetization easy axis is found to be in the film plane for all samples. For all series, the two thinner films seem to exhibit a perpendicular magnetocrystalline anisotropy. The coercive field, HC//, values range from 1 Oe to 67 Oe. A peak in the HC// vs. t curve is observed for Py/Si while for Py on glass and Py/kapton, HC// seems to be constant. We also observed that for the thicker Py/Si(1 1 1) samples, the coercivity decreases as the grain sizes increase.

  16. Combined influence of cholesterol and synthetic amphiphillic peptides upon bilayer thickness in model membranes.

    PubMed Central

    Nezil, F A; Bloom, M

    1992-01-01

    Deuterium (2H) NMR was used to study bilayer hydrophobic thickness and mechanical properties when cholesterol and/or synthetic amphiphillic polypeptides were added to deuterated POPC lipid bilayer membranes in the liquid-crystalline (fluid) phase. Smoothed acyl chain orientational order profiles were used to calculate bilayer hydrophobic thickness. Addition of 30 mol% cholesterol to POPC at 25 degrees C increased the bilayer thickness from 2.58 to 2.99 nm. The peptides were chosen to span the bilayers with more or less mismatch between the hydrophobic peptide length and membrane hydrophobic thickness. The average thickness of the pure lipid bilayers was significantly perturbed upon addition of peptide only in cases of large mismatch, being increased (decreased) when the peptide hydrophobic length was greater (less) than that of the pure bilayer, consistent with the "mattress" model of protein lipid interactions (Mouritsen, O.G., and M. Bloom. 1984. Biophys. J. 46:141-153). The experimental results were also used to examine the combined influence of the polypeptides and cholesterol on the orientational order profile and thickness expansivity of the membranes. A detailed model for the spatial distribution of POPC and cholesterol molecules in the bilayers was proposed to reconcile the general features of these measurements with micromechanical measurements of area expansivity in closely related systems. Experiments to test the model were proposed. PMID:1600079

  17. Temperature- and thickness-dependent elastic moduli of polymer thin films.

    PubMed

    Ao, Zhimin; Li, Sean

    2011-01-01

    The mechanical properties of polymer ultrathin films are usually different from those of their counterparts in bulk. Understanding the effect of thickness on the mechanical properties of these films is crucial for their applications. However, it is a great challenge to measure their elastic modulus experimentally with in situ heating. In this study, a thermodynamic model for temperature- (T) and thickness (h)-dependent elastic moduli of polymer thin films Ef(T,h) is developed with verification by the reported experimental data on polystyrene (PS) thin films. For the PS thin films on a passivated substrate, Ef(T,h) decreases with the decreasing film thickness, when h is less than 60 nm at ambient temperature. However, the onset thickness (h*), at which thickness Ef(T,h) deviates from the bulk value, can be modulated by T. h* becomes larger at higher T because of the depression of the quenching depth, which determines the thickness of the surface layer δ. PMID:21711747

  18. Thickness and microstructure effects in the optical and electrical properties of silver thin films

    SciTech Connect

    Ding, Guowen Clavero, César; Schweigert, Daniel; Le, Minh

    2015-11-15

    The optical and electrical response of metal thin films approaching thicknesses in the range of the electron mean free path is highly affected by electronic scattering with the interfaces and defects. Here, we present a theoretical and experimental study on how thickness and microstructure affect the properties of Ag thin films. We are able to successfully model the electrical resistivity and IR optical response using a thickness dependent electronic scattering time. Remarkably, the product of electronic scattering time and resistivity remains constant regardless of the thickness (τx ρ = C), with a value of 59 ± 2 μΩ cm ⋅ fs for Ag films in the investigated range from 3 to 74 nm. Our findings enable us to develop a theoretically framework that allows calculating the optical response of metal thin films in the IR by using their measured thickness and resistivity. An excellent agreement is found between experimental measurements and predicted values. This study also shows the theoretical lower limit for emissivity in Ag thin films according to their microstructure and thickness. Application of the model presented here will allow rapid characterization of the IR optical response of metal thin films, with important application in a broad spectrum of fundamental and industrial applications, including optical coatings, low-emissivity windows and semiconductor industry.

  19. Temperature- and thickness-dependent elastic moduli of polymer thin films

    PubMed Central

    2011-01-01

    The mechanical properties of polymer ultrathin films are usually different from those of their counterparts in bulk. Understanding the effect of thickness on the mechanical properties of these films is crucial for their applications. However, it is a great challenge to measure their elastic modulus experimentally with in situ heating. In this study, a thermodynamic model for temperature- (T) and thickness (h)-dependent elastic moduli of polymer thin films Ef(T,h) is developed with verification by the reported experimental data on polystyrene (PS) thin films. For the PS thin films on a passivated substrate, Ef(T,h) decreases with the decreasing film thickness, when h is less than 60 nm at ambient temperature. However, the onset thickness (h*), at which thickness Ef(T,h) deviates from the bulk value, can be modulated by T. h* becomes larger at higher T because of the depression of the quenching depth, which determines the thickness of the surface layer δ. PMID:21711747

  20. Visualizing depth and thickness of a local blood region in skin tissue using diffuse reflectance images.

    PubMed

    Nishidate, Izumi; Maeda, Takaaki; Aizu, Yoshihisa; Niizeki, Kyuichi

    2007-01-01

    A method is proposed for visualizing the depth and thickness distribution of a local blood region in skin tissue using diffuse reflectance images at three isosbestic wavelengths of hemoglobin: 420, 585, and 800 nm. Monte Carlo simulation of light transport specifies a relation among optical densities, depth, and thickness of the region under given concentrations of melanin in epidermis and blood in dermis. Experiments with tissue-like agar gel phantoms indicate that a simple circular blood region embedded in scattering media can be visualized with errors of 6% for the depth and 22% for the thickness to the given values. In-vivo measurements on human veins demonstrate that results from the proposed method agree within errors of 30 and 19% for the depth and thickness, respectively, with values obtained from the same veins by the conventional ultrasound technique. Numerical investigation with the Monte Carlo simulation of light transport in the skin tissue is also performed to discuss effects of deviation in scattering coefficients of skin tissue and absorption coefficients of the local blood region from the typical values of the results. The depth of the local blood region is over- or underestimated as the scattering coefficients of epidermis and dermis decrease or increase, respectively, while the thickness of the region agrees well with the given values below 1.2 mm. Decreases or increases of hematocrit value give over- or underestimation of the thickness, but they have almost no influence on the depth. PMID:17994894