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Printability and inspectability of programmed pit defects on teh masks in EUV lithography

Description: Printability and inspectability of phase defects in ELlVL mask originated from substrate pit were investigated. For this purpose, PDMs with programmed pits on substrate were fabricated using different ML sources from several suppliers. Simulations with 32-nm HP L/S show that substrate pits with below {approx}20 nm in depth would not be printed on the wafer if they could be smoothed by ML process down to {approx}1 nm in depth on ML surface. Through the investigation of inspectability for programmed pits, minimum pit sizes detected by KLA6xx, AIT, and M7360 depend on ML smoothing performance. Furthermore, printability results for pit defects also correlate with smoothed pit sizes. AIT results for pattemed mask with 32-nm HP L/S represents that minimum printable size of pits could be {approx}28.3 nm of SEVD. In addition, printability of pits became more printable as defocus moves to (-) directions. Consequently, printability of phase defects strongly depends on their locations with respect to those of absorber patterns. This indicates that defect compensation by pattern shift could be a key technique to realize zero printable phase defects in EUVL masks.
Date: March 12, 2010
Creator: Kang, I.-Y.; Seo, H.-S.; Ahn, B.-S.; Lee, D.-G.; Kim, D.; Huh, S. et al.
Partner: UNT Libraries Government Documents Department

Mesoscopic structure conditions the emergence of cooperation on social networks

Description: We study the evolutionary Prisoner's Dilemma on two social networks substrates obtained from actual relational data. We find very different cooperation levels on each of them that cannot be easily understood in terms of global statistical properties of both networks. We claim that the result can be understood at the mesoscopic scale, by studying the community structure of the networks. We explain the dependence of the cooperation level on the temptation parameter in terms of the internal structure of the communities and their interconnections. We then test our results on community-structured, specifically designed artificial networks, finding a good agreement with the observations in both real substrates. Our results support the conclusion that studies of evolutionary games on model networks and their interpretation in terms of global properties may not be sufficient to study specific, real social systems. Further, the study allows us to define new quantitative parameters that summarize the mesoscopic structure of any network. In addition, the community perspective may be helpful to interpret the origin and behavior of existing networks as well as to design structures that show resilient cooperative behavior.
Date: December 1, 2008
Creator: Lozano, S.; Arenas, A. & Sanchez, A.
Partner: UNT Libraries Government Documents Department

Redox non-innoence permits catalytic nitrene carbonylation by (dadi)Ti=NAd (Ad = adamantyl)

Description: This article describes (dadi)Ti(X/L) species that manifest redox non-innocence (RNI), including a rare instance in which carbon monoxide does not affect redox activity at the metal, and does not bind, thus permitting its use as a substrate in catalysis.
Date: March 3, 2017
Creator: Heins, Spencer P.; Wolczanski, Peter T.; Cundari, Thomas R. & MacMillan, Samantha N.
Partner: UNT College of Arts and Sciences

Platinum(II)-Catalyzed Ethylene Hydrophenylation: Switching Selectivity between Alkyl- and Vinylbenzene Production

Description: Article discussing platinum(II)-catalyzed ethylene hydrophenylation and the influence of dipyridyl chelate ring size on catalyst activity and longevity.
Date: April 23, 2013
Creator: McKeown, Bradley A.; Gonzalez, Hector Emanuel; Friedfeld, Max R.; Brosnahan, Anna M.; Gunnoe, T. Brent; Cundari, Thomas R., 1964- et al.
Partner: UNT College of Arts and Sciences

Reactions of a Ru(II) Phenyl Complex with Substrates that Possess C-N or C-O Multiple Bonds: C-C Bond Formation, N-H Bond Cleavage, and Decarbonylation Reactions

Description: Article on the reactions of an Ru(II) phenyl complex with substrates that possess C-N or C-O multiple bonds and C-C bond formation, N-H bond cleavage, and decarbonylation reactions.
Date: February 8, 2006
Creator: Lee, John P.; Pittard, Karl A.; DeYonker, Nathan J.; Cundari, Thomas R., 1964-; Gunnoe, T. Brent & Petersen, Jeffrey L.
Partner: UNT College of Arts and Sciences

Long term biosustainability in a high energy, low diversity crustal biome

Description: Geochemical, microbiological, and molecular analyses of alkaline saline groundwater at 2.8 kilometers depth in Archaean metabasalt revealed a microbial biome dominated by a single phylotype affiliated with thermophilic sulfate reducers belonging to Firmicutes. These sulfate reducers were sustained by geologically produced sulfate and hydrogen at concentrations sufficient to maintain activities for millions of years with no apparent reliance on photosynthetically derived substrates.
Date: October 1, 2006
Creator: Lin, L-H.; Wang, P-L.; Rumble, D.; Lippmann-Pipke, J.; SherwoodLollar, B.; Boice, E. et al.
Partner: UNT Libraries Government Documents Department

Enantioselective Catalysis of the Aza-Cope Rearrangement by a Chiral Supramolecular Assembly

Description: The chiral supramolecular catalyst Ga{sub 4}L{sub 6} [L = 1,5-bis(2,3-dihydroxybenzoylamino)naphthalene] is a molecular tetrahedron that catalyzes the 3-aza-Cope rearrangement of allyl enammonium cations. This catalysis is accomplished by preorganizing the substrate in a reactive conformation within the host. This work demonstrates that through the use of enantiopure assembly, its chiral cavity is capable of catalyzing the 3-aza-Cope rearrangement enantioselectively, with yields of 21-74% and enantiomeric excesses from 6 to 64% at 50 C. At lower temperatures, the enantioselectivity improved, reaching 78% ee at 5 C. This is the highest enantioselectivity to date induced by the chiral cavity of a supramolecular assembly.
Date: July 29, 2009
Creator: Brown, Casey J.; Bergman, Robert G. & Raymond, Kenneth N.
Partner: UNT Libraries Government Documents Department

Quasi-Freestanding multilayer graphene films on the carbon face of SiC

Description: The electronic band structure of as-grown and doped graphene grown on the carbon face of SiC is studied by high-resolution angle-resolved photoemission spectroscopy, where we observe both rotations between adjacent layers and AB-stacking. The band structure of quasi-freestanding AB-bilayers is directly compared with bilayer graphene grown on the Si-face of SiC to study the impact of the substrate on the electronic properties of epitaxial graphene. Our results show that the C-face films are nearly freestanding from an electronic point of view, due to the rotations between graphene layers.
Date: June 30, 2010
Creator: Siegel, D. A.; Hwang, C. G.; Fedorov, A. V. & Lanzara, A.
Partner: UNT Libraries Government Documents Department

Reactions of TpRu(CO) (NCMe) (Me) (Tp = Hydridotris(pyrazolyl)borate) with Heteroaromatic Substrates: Stoichiometric and Catalytic C-H Activation

Description: Article discussing reactions of TpRu(CO)(NCMe)(Me) (Tp = Hydridotris(pyrazolyl)borate) with heteroaromatic substrates and stoichiometric and catalytic C-H activation.
Date: October 15, 2004
Creator: Pittard, Karl A.; Lee, John P.; Cundari, Thomas R., 1964-; Gunnoe, T. Brent & Petersen, Jeffrey L.
Partner: UNT College of Arts and Sciences

Performance Limits of Low Bandgap Thermophotovoltaic Antimonide-Based Cells for Low Temperature Radiators

Description: This paper assesses the performance of antimonide-based thermophotovoltaic cells fabricated by different technologies. In particular, the paper compares the performance of lattice matched quaternary (GaInAsSb) cells epitaxially grown on GaSb substrates to the performance of ternary (GaInSb) and binary (GaSb) cells fabricated by Zn diffusion on bulk substrates. The focus of the paper is to delineate the key performance advantages of the highest performance-to-date of the quaternary cells to the performance of the alternative ternary and binary antimonide-based diffusion technology. The performance characteristics of the cells considered are obtained from PC-1D simulations using appropriate material parameters.
Date: August 29, 2000
Creator: Borrego, J.M.; Wang, C.A.; Dutta, P.S.; rajagopalan, G.; Bhat, I.B.; Gutmann, R.J. et al.
Partner: UNT Libraries Government Documents Department

Asymmetric Intramolecular Alkylation of Chiral Aromatic Imines via Catalytic C-H Bond Activation

Description: The asymmetric intramolecular alkylation of chiral aromatic aldimines, in which differentially substituted alkenes are tethered meta to the imine, was investigated. High enantioselectivities were obtained for imines prepared from aminoindane derivatives, which function as directing groups for the rhodium-catalyzed C-H bond activation. Initial demonstration of catalytic asymmetric intramolecular alkylation also was achieved by employing a sterically hindered achiral imine substrate and catalytic amounts of a chiral amine.
Date: April 16, 2007
Creator: Watzke, Anja; Wilson, Rebecca; O'Malley, Steven; Bergman, Robert & Ellman, Jonathan
Partner: UNT Libraries Government Documents Department

Sculpting the shape of semiconductor heteroepitaxial islands: fromdots to rods

Description: In the Ge on Si model heteroepitaxial system, metal patterns on the silicon surface provide unprecedented control over the morphology of highly ordered Ge islands. Island shape including nanorods and truncated pyramids is set by the metal species and substrate orientation. Analysis of island faceting elucidates the prominent role of the metal in promoting growth of preferred facet orientations while investigations of island composition and structure reveal the importance of Si-Ge intermixing in island evolution. These effects reflect a remarkable combination of metal-mediated growth phenomena that may be exploited to tailor the functionality of island arrays in heteroepitaxial systems.
Date: June 20, 2006
Creator: Robinson, J.T.; Walko, D.A.; Arms, D.A.; Tinberg, D.S.; Evans,P.G.; Cao, Y. et al.
Partner: UNT Libraries Government Documents Department

Self-Organized Vertical Superlattices in Epitaxial GaInAsSb

Description: Self-organized superlattices are observed in GaInAsSb epilayers grown nominally lattice matched to vicinal GaSb substrates. The natural superlattice (NSL) is detected at the onset of growth; is continuous over the lateral extent of over several microns; and persists vertically throughout several microns of the epilayer. Furthermore, the NSL is inclined by an additional 4{sup o} with respect to the vicinal (001) GaSb substrate. The tilted NSL intersects the surface of the epilayer, and the NSL period is geometrically correlated with surface undulations. While the principle driving force for this type of phase separation arises from solution thermodyamics, the mechanism for the self-organized microstructure is related to local strains associated with surface undulations. By using a substrate with surface undulations, the tilted NSL can be induced in layers with alloy compositions that normally do not exhibit this self-organized microstructure under typical growth conditions. These results underscore the complex interactions between compositional modulations and morphological perturbations.
Date: February 9, 2004
Creator: Wand, CA; Vineis, CJ & Calawa, DR
Partner: UNT Libraries Government Documents Department

Ohmic Contacts to n-type GaSb and n-type GaInAsSb

Description: An investigation with the objective of improving n-type ohmic contacts to GaSb-based devices is described. This study involves a series of n-GaInAsSb and n-GaSb samples with varying doping, grown on both n-GaSb and semi-insulating GaAs substrates. These samples were fabricated into mesa-etched TLM structures, and the specific contact resistivity and sheet resistance of these layers as a function of majority electron concentration were measured. Extremely low specific contact resistivities of about 2 x 10{sup -6} {Omega}-cm{sup 2} and sheet resistances of about 4 {Omega}/{open_square} are found for n-type GaInAsSb doped at about 3 x 10{sup 18} cm{sup -3}.
Date: June 16, 2003
Creator: Huang, R.K.; Wang, C.A.; Harris, C.T.; Connors, M.K. & Shiau, D.A.
Partner: UNT Libraries Government Documents Department

Extensions of the Stoney Formula for Substrate Curvature to Configurations with Thin Substrates or Large Deformations

Description: Two main assumptions which underlie the Stoney formula relating substrate curvature to mis-match strain in a bonded thin film are that the film is very thin compared to the substrate, and the deformations are infinitesimally small. Expressions for the curvature-strain relastionship are derived for cases in which thses assumptions are relaxed, thereby providing a biasis for interpretation of experimental observations for a broader class of film-substrate configurations.
Date: April 26, 1999
Creator: Chason, E.; Floro, J.A. & Freund, L.B.
Partner: UNT Libraries Government Documents Department

Facile and Regioselective C H Bond Activation of Aromatic Substrates by an Fe (II) Complex Involving a Spin-Forbidden Pathway

Description: Article discussing facile and regioselective C H bond activation of aromatic substrates by an Fe(II) complex involving a spin-forbidden pathway.
Date: February 27, 2013
Creator: Kalman, Steven E.; Petit, Alban; Gunnoe, T. Brent; Ess, Daniel H.; Cundari, Thomas R., 1964- & Sabat, Michal
Partner: UNT College of Arts and Sciences

A Laboratory Study of the Asiatic Clam (Corbicula fluminea Müller) as Influenced by Substrate, Food Source and Water Type

Description: Growth of Corbicula fluminea was monitored in the laboratory. Three experiments were conducted. Experiment I utilized three substrates and one food type. Experiment II utilized three substrates and two food types. Experiments I and II were conducted to determine if substrate type or food type effected growth. Experiment III used no substrates, one food type and was conducted to determine growth response to different types of water. Clams were maintained in three substrates: sand, gravel and clay. Clams were also maintained without substrate. Growth was monitored by measuring shell length (mm) and recording the weight (mg) of clams over a period of thirty days. At the end of the test period data were evaluated for normality and homogeneity.
Date: May 1995
Creator: Halbrook, Courtney (Courtney Ann)
Partner: UNT Libraries

Spin-on-glass coatings for the generation of super-polishedsubstrates for extreme ultraviolet optics

Description: Substrates intended for use as extreme ultraviolet (EUV) optics have extremely stringent requirements in terms of finish. These requirements can dramatically increase the cost and fabrication time, especially when non-conventional shapes, such as toroids, are required. Here we present a spin-on-glass resist process capable of generating super-polished parts from inexpensive substrates. The method has been used to render diamond-turned substrates compatible for use as EUV optics. Toroidal diamond-turned optics with starting rms roughness in the 3.3 to 3.7 nm range have been smoothed to the 0.4 to 0.6 nm range. EUV reflectometry characterization of these optics has demonstrated reflectivities of approximately 63%.
Date: January 1, 2005
Creator: Salmassi, Farhad; Naulleau, Patrick P. & Gullikson, Eric M.
Partner: UNT Libraries Government Documents Department

Aza Cope Rearrangement of Propargyl Enammonium Cations Catalyzed By a Self-Assembled `Nanozyme

Description: The tetrahedral [Ga{sub 4}L{sub 6}]{sup 12-} assembly (L = N,N-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene) encapsulates a variety of cations, including propargyl enammonium cations capable of undergoing the aza Cope rearrangement. For propargyl enammonium substrates that are encapsulated in the [Ga{sub 4}L{sub 6}]{sup 12-} assembly, rate accelerations of up to 184 are observed when compared to the background reaction. After rearrangement, the product iminium ion is released into solution and hydrolyzed allowing for catalytic turnover. The activation parameters for the catalyzed and uncatalyzed reaction were determined, revealing that a lowered entropy of activation is responsible for the observed rate enhancements. The catalyzed reaction exhibits saturation kinetics; the rate data obey the Michaelis-Menten model of enzyme kinetics, and competitive inhibition using a non-reactive guest has been demonstrated.
Date: February 27, 2008
Creator: Hastings, Courntey J.; Fiedler, Dorothea; Bergman, Robert G. & Raymond, Kenneth N.
Partner: UNT Libraries Government Documents Department

Characterization of Arthrobacter Globiformis Aspartate Transcarbamylase Concentrations of Substrates

Description: This thesis consists of one major section with two subsections. The first subsection investigates the activity of Arthrobacter globiformis aspartate transcarbamylase's specific activity with increasing concentrations of the enzyme's substrate. Dihydroorotase (DHOase) activity was also measured with increasing concentrations of the substrate dihydroorotate. The second subsection collected data in order to classify the enzyme, resulting in a classification into the category of class A ATCases with bifunctional ATCase-DHOase complexes. The thesis provides evidence to broaden understanding of the ATCase and DHOase enzymes for members of the family that Arthrobacter belongs to.
Date: December 2012
Creator: Wright, Jackie
Partner: UNT Libraries