bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deposition of Cu Films for Laser Mirror by Partially Ionized Beam Deposition
Authors: Koh Seok-Keun , Yoon Young-Soo , Kim Ki-Hwan , Jang Hong-Gui , Jung Hyung-Jin 
Published: April 2011

AbstractPartially ionized beam deposition of Cu thin films on glass at room temperature were carried out to fabricate Cu laser mirrors with good structural and reflectance properties. At a constant film thickness of 600 Å, the grain size of as-grown Cu films increased with acceleration voltage, and there was no indication of defects such as cracks and/or large pores in the film surface as shown in scanning electron microscopy images. Root-mean-square(Rms) surface roughnesses of the films with thicknesses of 600 Å were measured by atomic force microscopy. RmS surface roughness increased when acceleration voltage increased from 0 kV to 2 kV, but decreased at the acceleration voltage of 3 kV. RmS surface roughness of the film grown at 4 kV, however, increased again. At the acceleration voltage of 3 kV, reflectance of the films increased with the film thickness until 600 Å and decreased at the film thickness of 800 Å. The reflectance results showed that the Cu film deposited at 3 kV had higher reflectance than that of others. Our results suggest that it is possible to grow the Cu film with good structural and optical properties on glass substrate at room temperature by partially ionized beam deposition.
Formation of Buried Two-Dimensional Electron Gas in Gaas by Si Ion Doping Using Mbe-Fib Combined System
Authors: YANAGISAWA J. , Nakayama H. , Wakaya F. , Yuba Y. , Gamo K. 
Published: April 2011

Abstract0.1 and 30 keV Si2+ focused ion beams (FIB) were implanted in two types of GaAs, one of which is semi-insulating (s.i.) GaAs, while the other is grown by molecular beam epitaxy (MBE). Successive regrowth over the implanted surface was performed using MBE-FIB combined system, and the resistance was measured. It was found that for 100 eV Si2+ FIB implantation, the sample was nonconductive without a post annealing at 800°C. After the post annealing, however, the sample became conductive, and the resistance was the same order in magnitude as the sample fabricated using 30 keV Si + FIB irradiation. This suggests a potential of selective formation of Si δ-like doped layers in GaAs and GaAs/AlGaAs using a low-energy FIB.
Pulsed Laser Deposition of Epitaxial Sr(RuxSn1-x)O3 Thin Film Electrodes and KNbO3/Sr(RuxSnl-x)O3 Bilayers
Authors: Christen H.-M. , Boatner L. A. , Englisht L. Q. , Géa L. A. , Marrero P. J. , Norton D. P. 
Published: April 2011

AbstractSr(RuxSnl-x)O3 is proposed as a new conducting oxide for use in epitaxial multilayer structures. The Sr(Ru0.48Sn0.52)O3 composition exhibits an excellent lattice match with (100)-oriented KTaO3, and films of this composition grown by pulsed laser deposition on KTaO3, SrTiO3, and LaAIO3 substrates have been analyzed by X-ray diffraction, Rutherford backscattering/ion channeling, and resistivity measurements. Epitaxial KNbO3/Sr(Ru0 48Sn0.52)O3 bilayers have been successfully grown.
Green Light Generated by Frequency-Doubling in LiNbO3 and LiTaO3 Thin Films
Authors: Kingston J. J. , Armani-Leplingard F. , Fork D. K. , Anderson G. B. 
Published: April 2011

AbstractThin films of LiNbO3 and LiTaO3 are grown by off-axis magnetron sputtering on A12O3 and LiTaO3 substrates. When stoichiometry is precisely controlled, the films display excellent crystallographic and morphologic properties and have optical losses that are acceptable for frequency-doubling. LiNbO3/A12O3 samples have rocking curve widths as low as Δω = 76 arc sec and rms surface roughnesses less than 1 nm. Rocking curves performed with a resolution of 12 arc sec in 2θ indicate that there is very little tilt to the grains. Most of the width of the standard rocking curve is associated with variations in the interplanar spacing. The LiTaO3 films have similar characteristics. LiNbO3/LiTaO3 samples have rocking curve widths as low as Δω = 28 arc sec. Again, there is very little tilt misalignment to the grains, and the best samples have rms surface roughnesses less than 1 nm. The LiNbO3/LiTaO3 samples are typically 650 nm thick and many have optical losses less than 5 dB/cm. The LiNbO3/A12O3 samples, typically 250 nm thick, have losses of 5–7 dB/cm. The higher modal intensity at the surface of the thinner films increases surface scattering losses.We have generated green light by frequency doubling in LiTaO3 and LiNbO3 thin-film planar waveguides. Phase matching was achieved by both modal dispersion and quasi-phase matching.
Sputtered and Reactively Grown Epitaxial GdAIO3Films as Buffer Layers for C-Oriented YBa2Cu3O7-δFilms on R-Sapphire
Authors: Senz S. , Sieber H. , Zakharov N. D. , Lorenz M. , Hochmuth H. , Hesse D. 
Published: April 2011

AbstractThin films of the orthorhombic perovskite GdAlO3were grown on R-plane sapphire single crystals. Two different film growth methods were used,viz.(i) a chemical reaction of a Gd-O plasma with the sapphire crystals, and (ii) the reactive radio frequency (r.f.) sputtering of a GdAlO3target. Subsequently, YBa2Cu3O7-δ(YBCO) films were deposited onto the GdAlO3buffer by pulsed laser deposition (PLD). The GdAlO3and YBCO films were investigated by Xray diffraction pole figure analysis and transmission electron microscopy (TEM), including highresolution transmission electron microscopy of cross sections. Independent of the deposition method the GdAlO3films grew according to the nearly equivalent orientation relationshipsThe GdAlO3grains are additionally tilted by angles up to ± 3° around the sapphire [11.1] axis. On top of these buffer layers the YBCO films grew with c-orientation and with an in-plane rotation of 45°. YBCO films of 200 nm thickness on GdAlO3buffer layers with a thickness of 10 to 20 nm showed a Tc> 87 K and a jc(77 K) > 3×106A/cm2.
Computer Simulation, Design, and Characterization of a Nozzle for More Effective Delivery of Oxidizing Gases
Authors: Kraisinger C. J. , Fusina D. M. , Schlom D. G. 
Published: April 2011

AbstractFor the in situ growth of cuprate superconductors and related oxides by vacuum deposition methods it is desired to achieve as high a flux of oxidizing species as possible at the growing surface and as little as possible elsewhere within the reaction chamber. The well known gas flow equations derived by Knudsen, Clausing, and others which apply to the molecular flow regime were implemented in a computer algorithm to simulate the gas flow upon a substrate from hypothetical nozzles of several different geometries. The optimal design for a particular MBE chamber and substrate size was determined and such a nozzle was fabricated and characterized. A dysprosium-coated quartz crystal monitor was used to determine the oxidant flux. The measured result matches predictions of the computer model within a factor of three. The computer algorithm was also used to model the spatial distribution of ozone gas through a nozzle of another reported geometry, where measurements of the resulting flux had been made. The shape of the calculated flux distribution agrees to within a few percent and the absolute values of flux reported agree within a factor of two.
C-Axis Oriented Lithium Niobate Films on (001) Magnesium Oxide by Pulsed Laser Deposition
Authors: Lacey J. L. , Schlom D. G. 
Published: April 2011

AbstractFor the first time, epitaxial c-axis oriented lithium niobate (LiNbO3) films were grown on MgO (001) substrates. This orientation is relevant to the monolithic integration of LiNbO3 with GaAs for waveguiding, frequency doubling, and other opto-electronic applications. The epitaxial orientation relationship is (001 ) LiNbO3 parallel to (001) MgO and [100] LiNbO3 parallel to [110] MgO. Four equivalent in-plane orientations were observed, such that the lithium or niobium atoms along the [100] axis of LiNbO3 are bonded to the oxygen atoms on diagonal comers of the MgO unit cell. These epitaxial films were prepared by off-axis pulsed laser deposition at substrate temperatures of 775–800 °C in a 15–50 mTorr mixture of 5% O3 in O2.
Surface Band Gaps and Superexchange Interaction in Transition Metal Oxides
Authors: Pothuizen J. J. M. , Cohen O. , Sawatzky G. A. 
Published: April 2011

AbstractIn this paper, we discuss the change in the band gap of charge transfer insulators for different surface terminations. We have calculated the Madelung potential of the unreconstructed (100) surfaces of the rocksalt structured TM-O compounds (TM = Mn, Fe, Co and Ni). We also considered possible step defects on a (100) surface. The presented results are calculated in both the purely ionic case (TM2+O2−) and in the strong ligand p - cation 4s, phybridization (TM1+O1−) case. In both cases the charge transfer gap, Δ, for the surface is reduced compared to the bulk value. As a consequence of this reduction there is a large increase of the surface superexchange interaction, Jsur, and a decrease of the band gap.
Preparation and Electrical Properties of (Zr, Sn)TiO4 Dielectric Thin Films by Laser Ablation
Authors: Nakagawara Osamu , Tabata Hitoshi , Toyota Yuji , Kobayashi Masato , Yoshino Yukio , Katayama Yuzo , Kawai Tomoji 
Published: April 2011

Abstract(Zr, Sn)TiO4 is considered as a promising dielectric material for microwave devices owing to the temperature stability of capacitance and excellent microwave properties. Preferential (111)-oriented (ZrSn)TiO4 thin film was obtained by an ArF laser ablation. Properties of the crystallized film were as follows; the temperature coefficient of capacitance TCC was 17.6ppm/°C at 3MHz and the dielectric constant εr, 38 in the microwave range of 1GHz˜10GHz. It has turned out that the crystallization of this material is quite effective for improving dielectrical properties. Surface morphologies were observed by atomic force microscope(AFM). Grains grew on the crystallized film at 1 μm × 1 μm size.
Rem and Tem Studies of Thin Film Growth Dynamics on si Surfaces
Authors: Minoda Hiroki , Tanishiro Yasumasa , Yagi Katsumichi 
Published: April 2011

AbstracA study of surfactant-mediated epitaxy of Ge on Si(111) surfaces was carried out by in-situ transmission electron microscopy (TEM) and reflection electron microscopy (REM). Formation of 3D islands on the Si(111)-In surfaces was suppressed because of a change of critical nucleation size of the 3D islands. It was also found that formation of misfit dislocations at the interface between Si and Ge films was promoted by predeposition of In.
Observation of Vacancy Clustering in Si Crystals During in Situ Electron Irradiation in a High Voltage Electron Microscope
Authors: Fedina L. , Landuyt J. Van , Vanhellemont J. , Aseev A. 
Published: April 2011

AbstractThe formation of vacancy clusters in various Si crystals covered with SiO2 and Si3N4 films has been studied by means of high-voltage and high-resolution electron microscopy using electron beam energies of 1000 and 400 keV, respectively, and at temperatures between 20 and 250°C. Small vacancy clusters of about 2-5 nm in the form of Frank dislocation loops and stacking fault tetrahedra were observed by irradiating the thinnest areas (< 20 nm) of the investigated silicon specimens. Vacancy clustering seems to be more complicated in the thicker parts (> 20 nm) of irradiated crystals. We assume that in these areas vacancy clusters may be formed only in Si layers near the interfaces Si-SiO2 or Si-Si3N4 and they may interact with interstitials without full recombination of the defects. This leads to the appearance of a new form of interstitial clusters such as {111}-defects as well as the usual interstitial {113}-defects associated with vacancy clusters during prolonged irradiation in the HVEM.
In-situ Hrem Heating Experiments at Very High Temperatures
Authors: Kamino T. , Saka H. 
Published: April 2011

AbstractA specimen-heating holder which allows an observation of reactions of more than one materials, in a controlled manner, at such a high temperature as 1723K has been developed. Facet-unfacet transformation and reconstruction of Au-deposited Si surfaces have been observed at very high temperatures at near-atomic resolution.
Initial Stage of Oxidation on Si(111)-7×7 Surface Investigated by Scanning Tunneling Microscope
Authors: Ha Jeong Sook , Park Kang-Ho , Park Seong-Ju , Lee El-Hang 
Published: April 2011

AbstractThe initial oxidation of Si(111)-7×7 surface has been investigated by taking the STM images of samples dosed with oxygen at room temperature and high temperatures between 500°C and 750 °C. In particular, different site selectivities between two oxygen-induced features, bright and dark sites, were observed and explained in terms of the difference in potential energy curves. In addition to such a strong site selectivity under low oxygen partial pressure (l×10-9 torr), heavy surface etching by oxygen was observed at higher O2 partial pressures and temperatures resulting in the high density of monolayer-deep etch marks on terraces.
An In-Situ Tem Study of the Dynamic Behavior of Domain Walls in a Free-Standing Lead Titanate Thin Film Under External Stress
Authors: Ren S. B. , Lu C. J. , Shen H. M. , Wang Y. N. 
Published: April 2011

AbstractThe evolution of domain structure with external stress in a free-standing PbTiO3 ferroelectric thin film of ˜100nm in thickness is observed by in-situ TEM technique. The thin film is composed of granular grains of ˜100nm in diameter, most of them appear to be single-domained whereas others are multi-domained showing domains of different sizes(5˜20nm). For some single-domained grains new domains appear during tension. For multi-domained grains, rearrangement of domain walls and coarsening of domains have been observed during tension. In many cases the domain walls disappear under high stress, i.e., a multi-domained grain changes into a single-domained grain. However, it is also observed that a large portion of single-domained grains appear not to respond to external stress. The dynamic behavior of domain walls in very thin ferroelectric thin films may help to understand the switching of these very thin films.
Stark Effects on Band Gap and Surface Phonons of Semiconductor Quantum Dots in Dielectric Hosts
Authors: Mu R. , Ueda A. , Tung Y -S. , Henderson D. O. , Zhu Jane G. , Budai John D. , White W. C. 
Published: April 2011

AbstractWe have investigated quantum-confined Stark effect (QCSE) on GaAs and CdSe nanocrystals and the electric field effect on surface phonons of GaAs nanocrystals isolated in sapphire substrates. For a strongly quantum-confined system, GaAs quantum dots illustrated no exciton energy shift. When the excitons are weakly confined in CdSe, a ∼ 2 meV red-shift was observed. On the other hand, the results of the electric field effect on surface phonon are dramatic both phonon oscilator strength and freqnency. As the strength of the electric field increases, the total intensity of the surface phonon decreases. At the same time, an additional peak was also observed at 277 cm-1, which is about 3 cm-1 above the center frequency of the surface phonon mode of GaAs nanocrystals embedded in a sapphire host.
Femtosecond Nonlinear Transmission Study of Free-Standing Porous Silicon Films
Authors: Klimov V. , Mcbranch D. , Karavanskii V. 
Published: April 2011

AbstractLarge photo-induced absorption signals were observed in free standing porous silicon films in the spectral range from 1.1 to 2.5 eV using a femtosecond pump and probe technique. The measured nonlinear signal has a very fast component with relaxation constants from 800 fs to tens of picoseconds superimposed on the slow-relaxing thermal background. The spectral structure and relaxation dynamics of the short-lived component of transient absorption show the presence of molecular-like Si complexes with well defined energy levels and spectrally uniform picosecond relaxation dynamics.
Effect of γ-Irradiation on Photoluminescence of Porous Silicon
Authors: Astrova E. V. , Emtsev V. V. , Lebedev A. A. , Poloskin D. S. , Remenyuk A. D. , Rud' Yu. V. , Vitman R. F. 
Published: April 2011

AbstractProperties of Porous Silicon (PS) subjected to gamma irradiation in an air ambient and in vacuum have been studied. Gamma-irradiation was carried out in usual room atmosphere, and in evacuated tubes. The samples of porous silicon were investigated by means of photoluminescence (PL) and infrared (IR) absorption. For the samples irradiated under atmospheric conditions, the PL intensity increases by several times as the dose increases up to 1019photons/cm2 and after that point it starts to go down. For a dose of ˜9.1019photons/cm2 the PL intensity falls by a factor of ˜50. The position of the spectrum maximum does not change, but the half-width of the spectrum increases by 2 or 3 times. In the case of gamma-irradiation in vacuum the PL intensity gradually decreases with increasing dose. IR absorption measurements showed variations of the intensity of Si-H and Si-O bands with the irradiation dose. Enhancement of PL at lower doses has been explained by irradiation assisted oxidation of PS at atmospheric conditions and its degradation at higher doses by suppresion of the light-emitting centers.
Phase Transformation of Germanium Ultrafine Particles at High Temperature
Authors: Nozaki S. , Sato S. , Ono H. , Morisaki H. , Iwase M. 
Published: April 2011

AbstractGermanium (Ge) films were deposited on substrates whose temperature was kept at room (Ge-RT) or liquid nitrogen temperature (Ge-LNT) by the cluster-beam evaporation technique. The Raman spectra of both films with a double peak suggest that the crystal structure is not the ordinary diamond but the tetragonal one. The critical temperature for the phase transformation from the tetragonal into the diamond structure is found much higher than that for the Ge nanostructures deposited by the gas-evaporation technique. The Ge-LNT sample exhibits photooxidation and photoluminescence (PL) when it is exposed to the UV light. Their PL and optical absorption characteristics are strongly influenced by a combination of the photo-oxidation and thermal annealing treatments.
Synthesis of Size-Classified Silicon Nanocrystals
Authors: Camata Renato P. , Atwater Harry A. , Vahala Kerry J. , Flagan Richard C. 
Published: April 2011

AbstractWe report the synthesis of size-classified silicon nanocrystals by applying differential mobility analysis to an originally polydisperse aerosol of ultrafine silicon crystallites. Using the described technique, the average nanocrystal size can be tuned by simply adjusting an electric field. Samples of uncoagulated silicon nanocrystals have been obtained and size control has been achieved within 15–20% in the 2–10 nm size regime.
Optical and Structural Characterization of Arsenide/ Phosphide Interfaces Formed by Flow Modulation Epitaxy
Authors: Emerson D. T. , Smart J. A. , Whittingham K. L. , Chumbes E. M. , Shealy J. R. 
Published: April 2011

AbstractBulk GaAsP, 20Å-500Å GaAsP/GaInP single quantum wells and 70 Å period GaAsP/GaInP superlattices were deposited on GaAs substrates by Flow Modulation Epitaxy. In these structures, the disordered GaInP is lattice matched while the GaAsP is in tension with the As mole fraction varying from 0.6 to 1. The structures were studied using asymmetric x-ray diffraction, 1K photoluminescence, Raman scattering, transmission electron microscopy and atomic force microscopy. Raman and x-ray diffraction are used to assess the structural quality of the superlattices, especially with regard to the presence/absence of superlattice x-ray satellites and disorder activated longitudinal acoustic phonons. A model including the effects of composition, strain, and confinement on longitudinal optic phonons is described and used to estimate the composition, using Raman scattering, in the thin, pseudomorphic GaAsP layers in the superlattices. Photoluminescence is used to assess the composition of the interfacial layers in the single quantum wells and to determine transition energies in the superlattices. In addition, analysis of the heterostructure luminescence, including prediction of the energy band alignment as calculated with the model solid theory corrected for strain, is found to suggest the presence of a type II band alignment in the heterostructures for some values of GaAsP composition. Finally, Raman scattering and x-ray diffraction are used to compare arsenide to phosphide interfaces in GaAs and InP-based heterostructures.
Determining Thin Film Density by Energy-Dispersive X-Ray Reflectivity: Application to a Spin-on-Glass Dielectric
Authors: Wallace W. E. , Wu W. L. 
Published: April 2011

AbstractA novel method for determining thin film density by energy dispersive x-ray reflectivity is demonstrated for a polymer-derived spin-on-glass dielectric intended for microelectronics applications. The effects of sample misalignment limit the accuracy of x-ray reflectivity as typically practiced. These effects may be properly accounted for by measuring the critical angle for reflection at many different x-ray wavelengths simultaneously. From this measurement, thin film density can be ascertained with much improved accuracy. The results of the x-ray reflectivity measurement are compared to those derived from MeV ion scattering.
Dislocation Formation in Trench-Based Dynamic Random Access Memory (DRAM) Chips
Authors: Ho H. , Hammerl E. , Stengl R. , Benedict J. 
Published: April 2011

AbstractThis paper reports on our studies of dislocation formation in trench capacitor DRAM structures. Experimental results on process dependence and layout dependence of dislocation formation in cell layouts with minimum feature sizes from 0.5 μm to 0.25 μm are compared to two-dimensional stress simulations. It is shown that the nucleation and spatial distribution of dislocations can be explained by considering stress fields which are influenced by the overlay of deep trench and shallow trench isolation structures.
Determination of Bulk Mismatch Values in Heterostructures” by TEM/CBED
Authors: Armigliato A. , Balboni R. , Frabboni S. 
Published: April 2011

AbstractUsing isotropic elasticity theory it is possible to determine the bulk mismatch in thinned, cross-sectioned heterostructures, where a relaxation occurs along the thinning direction. This is accomplished by measuring, in the central disk of a single Convergent Beam Electron Diffraction (CBED) pattern, the position of the High Order Laue Zone lines, which are sensitive to lattice parameters along different crystallographic directions. The results obtained in both uniform and graded Sil-xGex/Si heterostructures are in good agreement with bulk values deduced from independent techniques.
Measurement of Young's Modulus and Poisson's Ratio of Free-Standing Ag/Cu Multilayered Thin Films
Authors: Huang Haibo , Spaepen Frans 
Published: April 2011

AbstractStrain measurement by laser diffraction was used in tensile testing of free-standing Ag/Cu multilayered thin films with repeat lengths between 3 nm and 3 μm. The mean value, for all the films, of the Young modulus was 83.1± 1.2 GPa, and of the Poisson ratio was 0.377±0.015. No variation with bilayer repeat length, and hence no “supermodulus” effect, was observed.
Kinetic Studies of Nanoscale Crystallization in Electronic Materials
Authors: Hayzelden C. , Batstone J. L. 
Published: April 2011

AbstractWe report a kinetic analysis of low-temperature NiSi2-mediated crystallization of amorphous Si by in situ transmission electron microscopy. The initiation of crystallization by formation of crystalline Si on buried NiSi2 precipitates is shown to have an activation energy of 2.8±0.7eV. Crystallization of the amorphous Si via migrating precipitates of NiSi2 occurs with an activation energy of 2.0±0.2eV. The significance of these activation energies is discussed in terms of possible atomistic mechanisms of crystalline Si initiation and subsequent growth. Amorphous Si is reported to crystallize at temperatures as low as 450°C.