bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Various Organic Coatings on Glasses
Authors: Lee Donghun , Condrate Robert A. 
Published: April 2011

AbstractOrganic compounds such as oleic acid, polymethyl methacrylate (PMMA) and polyacrylate (PAA) were coated on slide and silica glass powders. The resulting interaction mechanism was determined by the leaching properties of the glass, and the bond strength of each ion on the glass with coated organics. Soluble components such as sodium and calcium play important roles in the interaction properties of the organics with glass surfaces. The effects of solvent are also discussed.
Roughness Characterization by Optical Spectroscopy of CoSi2 Thin Films
Authors: Bocelli S. , Guizzetti G. , Marabelli F. , Hatziconstantinidou S. , Petersson C.S. 
Published: April 2011

AbstractSpecular and diffuse reflectance and spectroscopic ellipsometry were used to characterize a series of Cosi2 films obtained by heat treatment on a Co/Ti bilayer. The surface quality is strongly affected by etching procedures. The intrinsic optical properties of the CoSi2 film exhibit a small dependence on the growth technique.
An Investigation Of Vacancy Population During Arsenic Activation In Silicon
Authors: Dokumaci O. , Gossmann H.-J. , Jones K. S. , Law M. E. 
Published: April 2011

AbstractRecent experimental investigations have shown that electrical deactivation of arsenic in silicon creates excess silicon interstitials. This study investigated the possibility of excess vacancy generation during arsenic activation. We used Sb doping superlattice structures containing six 10 nm wide Sb doped spikes separated by 100 nm. It was found that antimony diffusion was not enhanced as active arsenic concentration increased, indicating there is no observable vacancy injection out of the arsenic layer during the activation process. Plan-view transmission electron microscopy study of the samples revealed dislocation loops before the activation anneal. Although the loops completely dissolved during the activation anneal, they do not seem to be sufficient enough to absorb all the vacancies generated by the activated arsenic. When germanium was present at the surface instead of arsenic, antimony diffusion was enhanced.
Gettering of FE By Aluminum In P-Type Cz Silicon
Authors: Ahn S. H. , Zhao S. , Smith A. L. , Chalfoun L. L. , Platero M. , Nakashima H. , Kimerling L. C. 
Published: April 2011

AbstractIn this study, we investigate the gettering process of Fe in p-type Cz silicon after iron has been introduced at the solubility limit at 1000°C. Deep Level Transient Spectroscopy (DLTS) was used to measure [FeB], a fingerprint of [Fei], at the center of samples. The minority carrier diffusion length and lifetime were calculated from Electron Beam Induced Current (EBIC) measurements. The fact that [FeB] is proportional to the negative second power of the minority carrier diffusion length at the high [FeB] regime confirms that FeB donors are the dominant recombination centers limiting solar cell performance with high Fe contamination. By quenching after heat treatment, we can maintain and measure the kinetics and thermodynamics of gettering exclusively. The getter/silicon interface was studied by comparison of the gettering rates of molten Al at 620°C, 700°C, and 800°C, and iron silicide at 700°C. We model Fe gettering with respect to temperature, time, solubility and precipitate nuclei density. In the early stage of Fe gettering, the process is dominated by precipitate formation around oxygen precipitate nuclei. The precipitate density is estimated to be on the order of 5×108cm−3. In later stages, Fe outdiffusion contributes to the [Fei] reduction. The early stage precipitation limits [Fei] reduction after short time to the solubility at the gettering temperature.
Optical Nmr From Single Quantum Dots
Authors: Brown S. W. , Kennedy T. A. , Gammon D. 
Published: April 2011

AbstractWe have observed nuclear magnetic resonance (NMR) signatures from constituent Ga and As nuclei in single GaAs quantum dots formed by interface fluctuations in GaAs/AlGaAs quantum wells. Orientation of the nuclear spin system by optical pumping causes an Overhauser shift in the excitonic energy levels proportional to the degree of nuclear orientation. NMR was detected by monitoring changes in the combined Overhauser plus Zeeman splitting of an exciton localized in a single quantum dot as the RF frequency was swept through a nuclear resonance. The NMR signals originate from ∼105 nuclei in the quantum dot — (20 nm)3 volume - representing an increase in sensitivity of five orders of magnitude over previous optical NMR measurements and thirteen orders of magnitude over conventional NMR. The data were fit to Lorentzian lineshapes, giving 75As linewidths on the order of 20 kHz.
Ctivation Energies Of Interstitial Oxygen Diffusion In Silicon Containing Hydrogen
Authors: Wijaranakula W. 
Published: April 2011

AbstractThe activation energies of interstitial oxygen diffusion in silicon containing hydrogen were derived from the results obtained from thermal donor generation experiments using numerical fitting based upon the classical nucleation rate theory and the time-dependent reduction of interstitial oxygen concentration resulting from oxygen aggregation. By using a new thermal equilibrium concentration of hydrogen at a pressure of 1 atm of 2×1021 exp(- 1.75 eV/kT), and the expression for the dependence of hydrogen thermal equilibrium concentration on the partial pressure P given as P0.65 times the hydrogen thermal equilibrium concentration at a pressure of 1 atm, the correlation between the activation energies of interstitial oxygen diffusion and hydrogen saturation is observed to be linearlogarithmic. In the hydrogen saturation range between 103 and 106, the activation energies of interstitial oxygen diffusion are estimated to be between 0.03 and 0.21 eV lower than the normal value of 2.53 eV. This implies that enhanced oxygen diffusion may occur primarily under hydrogen saturation conditions.
An Anomalous Deep Center (EC-0.31 Ev) in Semi-Insulating GaAs
Authors: Fang Z-Q. , Look D. C. 
Published: April 2011

AbstractA prominent deep center in semi-insulating GaAs, T5 at Ec×0.31 eV, has been studied by thermally stimulated current (TSC) spectroscopy using variation of illumination energy, intensity, and time. Unlike the case for most of TSC traps, the steady-state (long illumination time) peak intensity of T5 varies with light intensity. With the additional evidence that T5 seems to be related to both AsGa and VAs, it is possible that a photoinduced interaction AsGa.-VAs→VGa,-Asi-VAs is taking place.
Deep Level Transient Spectroscopy Study Of High-Temperature Aluminum Implanted 6H-SiC
Authors: Stotski Yuri A. , Usov Igor O. , Suvorov Alexander V. 
Published: April 2011

AbstractDeep levels in 6H-SiC wafers implanted with Al+ ions at high-temperature were studied using current deep level transient spectroscopy (iDLTS). Aluminum was implanted at a temperature of 1800 °C with an energy of 40 keV and a dose of 2 × 1016 cm−2 into n-type epitaxial layers with different carrier concentration. Four levels were found, at Ec−0.12, Ec−0.13, Ec−1.06 and Ev+0.35 eV. It was established that modification of the carrier concentration in original ntype 6H-SiC epitaxial layers affects the deep levels concentration. The relationship between the thickness of the space charge region and the relative deep level concentration was considered.
Stabilization of Hydrogen‐Free Cvd‐ Sio2 Films
Authors: Uchida Y. , Takei S. , Matsumura M. 
Published: April 2011

AbstractAnnealing effects have been investigated for the SiO2 films deposited from a Tetra‐Iso‐Cyanate‐Silane and Tertiary‐Alkyl‐Amine gas mixture in order to stabilize its desirable hydrogen‐free property. It was found that O3 annealing eliminates effectively the NCO‐group from the deposited film, resulting in the improved water resistance characteristics, and that HF changes the Si‐NCO bonds to Si‐F bonds resulting also in improved film properties.
Very Thin Films of High Dielectric Constant Materials
Authors: Beach David B. , Vallet Catherine E. , Paranthaman Mariappan 
Published: April 2011

AbstractAn all‐alkoxide route to SrBi2Ta2O9 (SBT) thin films and powders was developed. While stoichiometric gels transformed to single‐phase SBT, excess bismuth was required to obtain single‐phase SBT films on Pt substrates. An annealing temperature of 800 °C in O2 for 2 minutes was required to crystallize the films. Electrical measurements of SBT films produced under these conditions showed that films less than 2000 Å in thickness were shorted, while films of 3000 to 5000 Λ had a dielectric constant of~ 300. RBS measurements of a bismuth titanate film on Pt indicated that Pt diffuses into the dielectric layer when annealed at 700 °C in O2 for 1 minute, suggesting that interfacial reaction of these layered bismuth materials may be significant.
Novel Mocvd Processes for Nanoscale Oxide Thin Films
Authors: Li Tingkai , Zawadzkp Pete , Stall Richard A. , Zhu Yongfei , Desu Seshu B. 
Published: April 2011

AbstractNanoscale oxide thin films such as Ba1‐xSrxTiO3 (BST), SrBi2Ta2O9 (SBT), and PbZr1‐xTixO3 (PZT) that have a high dielectric constant and excellent ferroelectric properties have been receiving greatly increased attention, especially for high density memories in next generation integrated circuits. However, with increasing deposition temperature the surface roughness of the films increases, which results in high leakage current, and when the thickness of oxide films is decreased, the apparent bulk‐like properties of thin films tend to worsen due to the increased influence of the interface. To solve these problems, novel MOCVD techniques, plasma enhanced deposition, and a two step process, were developed for high quality oxide thin films.
Optical Characterization of Europium-Doped Calcium Fluoride Thin Films Grown on Silicon by Molecular Beam Epitaxy
Authors: Fang X.M. , Liu W.K. , Shan W. , Chatterjee T. , Mccann P.J. , Santos M.B. , Song J.J. 
Published: April 2011

AbstractPhotoluminescence measurements have been made on Eu-doped CaF2 thin films grown on Si(100) substrates. The dependence of the integrated intensity of both the zero-phonon line and the vibronic sideband on temperature and Eu concentration has been studied in the range of 10 – 300 K and 0.14 – 7.48 at. %, respectively. An anti-Stokes feature is visible in the emission spectra at 75 K, indicating a significant occupation of the excited vibrational states of Eu2+ by phonons before the transition at temperatures above 75 K. The integrated intensity of the vibronic sideband increases slightly as temperature increases. The solubility of Eu in CaF2 thin films grown on Si(100) is found to be somewhere around 4.05 at. % as confirmed by the increase of the line width of x-ray rocking curves and the decrease in the integrated intensity of the zero-phonon line with Eu concentration.
Photoresist Polymer Mask Formed From Aqueous Phase Via Polymerization In A Two Dimensional Surfactant Template
Authors: Newman P. D. , Newman G. K. , Harwell J. H. 
Published: April 2011

AbstractAn environmental friendly, aqueous based, thin film technology is investigated that is quite versatile in forming a variety of polymer substrates. The polymer substrates are potentially capable of being utilized as high resolution resists for semiconductor chip production. This process is based on polymerization of monomers partitioned within a two dimensional surfactant template adsorbed on the surface of a silicon wafer. The surfactant template (bilayer) serves to localize the polymerization reaction at the liquid‐solid interface and thereby resulting in the coverage of the silicon wafer with a nano‐thin polymer film. On a polished silicon wafer with a 4 nm silicon oxide layer, film thickness up to 130 nm have been obtained for polystyrene and for poly(methyl methacrylate) (PMMA) which is also used as a standard photoresist mask in electron beam lithography.
Cavities for Intersubband Transitions
Authors: Berger V. , Duboz J-Y , Ducloux E. , Lafon F. , Pavel I. , Boucaud P. , Gauthier-Lafaye O. , Julien F. , Tchelnokov A. , Planel R. 
Published: April 2011

ABSTRACTThe different possible geometries for intersubband transitions in microcavities are discussed. A consequence of the selection rule governing intersubband transition is the vanishing interaction with the electromagnetic field inside a usual vertical cavity. The geometry of vertical planar cavities which has been used extensively with interband transitions is therefore useless in the case of intersubband transitions. Different solutions are reviewed to overcome this problem. The breakdown of the selection rule in a vertical cavity is first discussed. This can be done with the use of vertical quantum wells, or thanks to intracavity diffraction gratings. Second, the use of in plane cavities is discussed. Two solutions are here envisaged: Whispering gallery modes in microdisk cavities, and efficient etched air/GaAs Bragg mirrors. Concerning the latter attractive solution, the losses by diffraction into the substrate are evaluated theoretically and experimentally. The solution of the Maxwell equations by a finite element method in this three dimensional system shows the great importance of diffraction. These results are confirmed by waveguided Fourier transform spectroscopy. To overcome this difficulty, we propose the use of lower refractive index substrates, such as oxidized AlAs.
Theoretical Studies of Electronic Intersubband Transitions in n-Type Doped Quantum Wells for Infrared Photodetector Applications
Authors: Huang Danhong , Manasreh M. O. 
Published: April 2011

ABSTRACTA self-consistent (8 × 8)-k · P model based on the Kohn-Sham density-functional formalism is used to calculate the quasi-particle wave functions and energy levels in n-type doped quantum wells. The self-energy from electron-electron, electron-impurity, and electron-phonon scattering was included in the calculation. The electronic intersubband absorption was calculated using a generalized self-consistent-field method including the vertex correction. The theoretical approach was applied to explain the variation of the intersubband transition peak energies as the temperature or the electron density is changed. Good agreement between the theory and experiment was achieved. The present theoretical model was also applied to design two-colors quantum well infrared photodetectors and was found to agree with the experimental measurements. Based on the numerical calculation, an approach to realize the three-colors infrared photodetectors in the triple-coupled quantum wells was proposed.
Inelastic Light Scattering in Zinc Germanium Diphosphide Crystals
Authors: Bairamov B. H. , Negoduyko V. K. , Rud Yurri V. , Toporov V. V. , Voitenko V. A. , Schunemann P. G. , Fernelius N. , Ohmer M. C. , Jackson H. E. 
Published: April 2011

ABSTRACTThe inelastic light scattering spectra of chalcopyrite structure ZnGeP2 crystals grown by an improved low temperature crystallization from the nonstoichiometric solution of this compound in the liquid Bi or liquid Tl solutions as well as grown by high temperature Bridgman technique has been investigated together with the optical absorption and electron transport measurements.
Sputter Deposition of Semiconductor Superlattices for Thermoelectric Applications
Authors: Wagner Andrew V. , Foreman Ronald J. , Farmer Joseph C. , Barbee Troy W. 
Published: April 2011

ABSTRACTTheoretical dramatic improvement of the thermoelectric properties of materials by using quantum confinement in novel semiconductor nanostructures has lead to considerable interest in the thermoelectric community. Therefore, we are exploring the critical materials issues for fabrication of quantum confined structures by magnetron sputtering in the lead telluride and bismuth telluride families of materials. We have synthesized modulated structures from thermoelectric materials with bilayer periods of as little as 3.2 nm and shown that they are stable at deposition temperatures high enough to grow quality films. Issues critical to high quality film growth have been investigated such as nucleation and growth conditions and their effect on crystal orientation and growth morphology. These investigations show that nucleating the film at a temperature below the growth temperature of optimum electronic properties produces high quality films. Our work with sputter deposition, which is inherently a high rate deposition process, builds the technological base necessary to develop economical production of these advanced materials. High deposition rate is critical since, even if efficiencies comparable with CFC based refrigeration systems can be achieved, large quantities of quantum confined materials will be necessary for cost-competitive uses.
InSb Detectors and Focal Plane Arrays on GaAs, Si, and Al203 Substrates
Authors: Michel E. , Mohseni H. , Wojkowski J. , Sandven J. , Xu J. , Razeghi M. , Vu P. , Bredthauer R. , Mitchel W. , Ahoujja M. 
Published: April 2011

ABSTRACTIn this paper, we report on the growth and fabrication of InSb detectors and Focal Plane Arrays (FPA's) on (100) Si, Al203, and (100) and (111) GaAs substrates for infrared (IR) imaging. Several advantages result from using GaAs, Si, or Al203. First, InSb FPA's on these materials do not require thinning as with detectors fabricated from bulk InSb. In addition, these substrates are available in larger sizes, are semi-insulating (GaAs and sapphire), and are less expensive than InSb.Optimum growth conditions have been determined and discrete devices have been fabricated on each substrate material. The structural, electrical, and optical properties were verified using x-ray, Hall, photoresponse, and photoluminescence (PL) measurements. Measured x-ray Full Widths at Half Maximum (FWHM) were as low as 55 and 100 arcsec for InSb epilayers on GaAs and Si, respectively. Hall mobilities were as high as 128,000, 95,000 and 72,000 cm2/V-sec at 200 K, 77 K, and room temperature, respectively. In addition, 77 K PL linewidths were as low as 18, 20, and 30 meV on GaAs, Si, and sapphire substrates respectively, well below the 48 meV value previously reported in the literature.In collaboration with Lockheed Martin Fairchild Systems (LMFS), IR thermal imaging has been obtained from InSb FPA's on GaAs and Si substrates. This is the first successful IR thermal imaging from heteroepitaxially grown InSb. Because of the high quality substrates, larger areas, and higher yields, this technology is very promising for challenging traditional InSb FPA hybrid technology.
Atomic-Scale Simulations of Structural Properties of Ceramics
Authors: Keffer D. J. , Streitz F. H. , Mintmire J. W. 
Published: April 2011

AbstractWe have recently developed a novel computational method for molecular dynamics simulations of metal oxide ceramics. This approach explicitly includes variable charge transfer between anions and cations. This method has been used to model the structural properties of bulk and surface alumina and aluminum systems including tensile failure of the bulk systems, as well as to model the rupture under tensile stress of an interface between a (0001) face of a-alumina and a (111) face of aluminum. We have applied this method to perform atomic-scale simulations of nanoindentation of ceramic and model rigid tips onto metal and ceramic substrates.
A Theoretical and Experimental Study of the Chemical Bonding in AgGaS2
Authors: Continenza Alessandra , de Pascale Teresa M. , Meloni Franco , Serra Marina , Shaukat Ali , Burzlaff Hans , Spengler Roland 
Published: April 2011

AbstractAgGaS2 is a technologically important semiconductor for its large birefringence coefficient. In this work we compare the theoretical ab-initio all-electron FLAPW results with very refined experimental data obtained with accurate X-ray analysis. In particular we focus our attention to the electronic distribution along the significative bonding directions connecting the three different atoms. Furthermore, the charge density contours around Ag provide a clear evidence of the contribution of its d orbitals to the chemical bond.
Synthesis of Ferroelectric Strontium Bismuth Tantalate Films from Metal Alkoxide Precursors
Authors: Zhuang Wei-Wei , Liu Lumei , Wu Naijuan , Hao Zhidong , Hoffman David M. , Ignatiev Alex , Jacobson Allan J. , Perry Scott S. 
Published: April 2011

AbstractFerroelectric SrBi2Ta2O9 (SBT) films were prepared by the spin coating technique on platinum, quartz and YBa2Cu3O7-x/LaA1O3 substrates from a methoxyethanol solution of bismuth isopropoxide (Bi(OCH(CH3)2)3) and strontium tantalum isopropoxide (SrTa2(OCH(CH3)2)12). X-Ray diffraction studies showed some crystallization occurred after annealing the films under oxygen flow at 600 °C and excellent crystallinity was achieved after annealing at 750 °C for 0.5 h. Electron microprobe analysis gave a composition close to that expected for SBT, and atomic force microscopy gave a root mean square surface roughness of 101 A. An hysteresis measurement (1 kHz) gave remnant polarization (2Pr), saturation polarization (Ps) and coercive field (Ec) values of 14.5 μC/cm2, 14.5 μ/cm2 and 59 kV/cm, respectively.
Zeolite Sensor for Nitrogen Monoxide Detection at High Temperature
Authors: Tsuchiya Hiroshi , Sasaki Isao , Harano Azuchi , Okubo Tatsuya , Sadakata Masayoshi 
Published: April 2011

ABSTRACTDevelopment of new NOx sensors, which would be sensitive, selective, inexpensive and stable at elevated temperature, will greatly contribute to the reduction of the air pollution. In this paper, synthesis and performance of zeolite film applied for gas sensing are reported.Zeolite thin films (Cu ion-exchanged ZSM-5) were synthesized on the gold electrode of AT-cut quartz platelet by hydrothermal synthesis. In order to probe the target molecule (NO) selectively, Na in as synthesized ZSM-5 film was ion-exchanged with Cu. The films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The synthesis condition for orientation to (0×0) face, on which the straight pores of ZSM-5 are opening, was optimized.The bulk type quartz oscillator coated with Cu-ZSM-5 thin layer was tested as NO sensor in a flowing stream of He. This sensing system could be operated at high temperature because of the thermal stability of the ZSM-5 film and the gold electrode. As a result, NO was successfully detected at 348 K.
High Surface Area Silicon Carbide Doped with Zirconium for use as Heterogeneous Catalyst Support
Authors: Ledoux Marc J. , Pham-Huu Cuong , Bouchy Christophe , Gallo Pascal Del , Estournes Claude , Crouzet Claude , Heinrich Baudouin 
Published: April 2011

ABSTRACTHigh surface area (> 100 m2 · g−1) SiC doped with zirconium was prepared by the gas-solid reaction. The material was made up of three phases: β-SiC, covered by ZrO2 and an amorphous phase composed of Si, Zr and O. The characterization of the sample was performed by means of powder X-ray diffraction (XRD), surface area and porosity measurements by the BET method, scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Preliminary catalytic tests, the standard n-C7 isomerization on supported MoOxCy showed that this new support was at least as effective as pure SiC.