bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intercluster Interaction of TiO2 Nanoclusters Using Variable-Charge Interatomic Potentials
Authors: Ogata Shuji , Iyetomi Hiroshi , Tsuruta Kenji , Shimojo Fuyuki , Kalia Rajiv K. , Nakano Aiichiro , Vashishta Priya 
Published: April 2011

ABSTRACTA new interatomic potential has been developed for molecular-dynamics simulations of TiO2 based on the formalism of Streitz and Mintmire [J. Adhesion Sci. Technol. 8, 853 (1994)], in which atomic charges vary dynamically according to the generalized electronegativity-equalization principle. The present potential reproduces various quantities of rutile crystal including vibrational density of states, static dielectric constants, melting temperature, elastic moduli, and surface relaxation. Calculated cohesive-energy and dielectric constants for anatase crystal agree well with experimental data. The potential is applied to TiO2 nanoclusters (size 60-80Å) for both anatase and rutile phases to analyze their equilibrium configuration and spacecharge distribution. Stable double-charge layer is found in the surface region of a spherical nanocluster for both rutile and anatase, resulting in enhanced Coulomb-repulsion between the nanoclusters at close proximity.
First Observation of Atomic Long Range Ordering in Metal-Oxide Based ZnMgO Wide Bandgap Heterostructures
Authors: Vispute R. D. , Choopun S. , Li Y. H. , Chalk D. M. , Ogale S. B. , Sharma R. P. , Venkatesan T. , Iliadis A. 
Published: April 2011

AbstractWe report the first observation of atomic long range ordering in the metal-oxide based wide bandgap (3.68 eV) ZnMgO alloy semiconductor thin films grown on sapphire (0001) by pulsed laser deposition. The ZnMgO system has the hexagonal wurtzite structure. The atomic ordering was deduced from the observations of forbidden x-ray diffraction peaks in the wurtzite structure. We show that under optimum thin film growth conditions, Zn and Mg preferentially occupy hcp sublattice. The relative intensity of the superlattice peak was largest for the Mg content in the range of 10%, which is about 50% of the solubility of Mg in ZnO. The observation of long range order in ZnMgO alloy semiconductor is quite important in the context of understanding issues related to the growth kinetics, surface reconstruction, and phase stability of metal-oxide based heterostructures and devices.
Correlation of Ingap(001) Surface Structure During Growth and CuptB-Type Bulk Ordering
Authors: Zorn M. , Kurpas P. , Bhattacharya A. , Weyers M. , Zettler J.-T. , Richter W. 
Published: April 2011

AbstractThe mechanism causing the CuPtB-type ordering of InGaP grown lattice matched to GaAs was investigated by in-situ reflectance anisotropy spectroscopy (RAS/RDS). Experiments were performed during InGaP growth in metal-organic vapour phase epitaxy (MOVPE). From the experiments it can be concluded that bulk ordering only occurs when InGaP growth is performed under phosphorus-rich (2×1)-like surface conditions. Bulk ordering completely disappears under growth conditions which cause a less-phosphorus-rich (2×4)-like surface dimer configuration.
High Resolution Analysis of Embedded Quantum Dots
Authors: Harvey A. J. , Davock H. J. , Goodhew P. J. 
Published: April 2011

AbstractA key piece of information in the understanding of quantum dot behaviour is the composition of the dot after any capping and/or annealing processes. It is important to know the composition and uniformity of the dots after they have been embedded in a semiconducting matrix, which usually contains one or more of the elements in the dot. This is a classically difficult analytical problem for any TEM technique. This problem has been approached by developing a model of the interaction between the electron probe and any dot/wettinglayer/matrix configuration. This model predicts the shape of an analytical line scan for any particular configuration and includes the effect of beam broadening on the analysis of dots at different depths within the thin section. The results are compared with STEM analyses of InAs dots in a GaAs matrix.
Inas Nanostructures in a Silicon Matrix: Growth and Properties
Authors: Cirlin G. E. , Egorov V. A. , Petrov V. N. , Golubok A. O. , Komyak N. I. , Polyakov N. K. , Samsonenko Yu. B. , Denisov D. V. , Volovik B. V. , Ustinov V. M. , Alferov Zh. I. , Ledentsov N. N. , Heitz R. , Bimberg D. , Zakharov N. D. , Werner P. , Gösele U. 
Published: April 2011

AbstractUnder certain growth conditions InAs/Si heteroepitaxial growth proceeds via Stranski-Krastanow or Volmer-Weber growth modes depending on the growth parameters. Critical thickness at which three dimensional InAs islands start to appear at the Si(100) surface is within the range of 0.7 - 4.0 monolayers (substrate temperature range is 350°C - 430 °C). Their size depends critically on the growth conditions and is between 5 nm and 80 nm (uncapped islands). Critical lateral size of the coherent (Si capped) dislocation-free island is equal to 2 - 5 nm depending on the island height. Islands having larger size are dislocated. Optical properties of InAs nanoscale islands capped with Si reveal a luminescence band in the 1.3 μm region.
Mbe Growth, Structural and Optical Characterization of Inas/Ingaaias Self-Organized Quantum Dots
Authors: Ustinov V. M. , Zhukov A. E. , Kovsh A. R. , Maleev N. A. , Mikhrin S. S. , Musikhin Y. G. , Tsatsul'nikov A. F. , Volovik B. V. , Bedarev D. A. , Maximov M. V. , Livshits D. A. , Bert N. A. , Kop'ev P. S. , Alferov Zh. I. , Ledentsov N. N. , Bimberg D. 
Published: April 2011

AbstractInAs quantum dots (QD) have been shown to extend the optical emission range for III-V heterostructures pseudomorphically grown on GaAs substrates. One of the ways to achieve 1.3 micron emission from the InAs QDs is to overgrow them with an In-containing alloy layer. In the present work we study structural and optical properties of InAs/In(Ga,Al)As QD structures grown by MBE on GaAs substrates using transmission electron microscopy (TEM), photoluminescence (PL), and electroluminescence (EL). We show that the main reason for the increase in the PL wavelength is the phase separation of the In(Ga,Al)As alloy stimulated by the InAs islands and the effective matrix bandgap plays a minor role. As the result of the local composition modulation, the effective volume of a QD is increased due to the enhancement of In concentration in the vicinity of the InAs island. We study how the effective thickness of InAs and InGaAs affect the crystal perfection and PL peak energy. Using the AlGaAs as a matrix also led to the noticeable red shift of the quantum dot PL line as compared to the GaAs matrix. Possible reasons for this unexpected phenomenon are discussed. Characteristics of the GaAs-based vertical cavity surface emitting structures and high power CW RT edge-emitting lasers for the 1.3 micron range using these QDs are be presented.
Growth Temperature Dependence of Size Distribution of Selfassembled Inas Quantum Dots on Gaas(001): From Diffusion- to Strain-Limited Growth
Authors: Yuan J. , Lian G. D. , Li Z. Y. , Ritchie D. A. , Thompson R. M. , Shields A. J. , Farrer I. , Brown L. M. 
Published: April 2011

AbstractWe have investigated the molecular beam epitaxy (MBE) growth of buried InAs quantum dots on GaAs (001) surface, as a function of deposition temperature, by transmission electron microscopy (TEM) and photoluminescence (PL). We found that the dot growth at low temperature is controlled by diffusion-limited aggregation. As the growth temperature increases, this growth mode is modified by misfit strain, resulting in a narrowing of the size distribution. However, we did not find any evidence for a thermodynamically optimized size. In addition, we found that the optical properties of the quantum dots does not correlate directly with the geometric size of the quantum dots, indicating a complex internal structure for quantum dots grown at high growth temperature.
Photoreflectance Investigation of Inas/Gaas Self-Assembled Quantum Dots Grown by Almbe
Authors: Geddol M. , Ferrinm R. , Guizzetti G. , Patrini M. , Franchi S. , Frigeri P. 
Published: April 2011

AbstractPhotoreflectance measurements have been performed in the 0.8–1.5 eV photon energy range and at temperatures from 80 to 300 K on stacked layers of InAs/GaAs self-assembled quantum dots (QDs) grown by Atomic-Layer Molecular Beam Epitaxy. The spectral features due to the QD optical response were analyzed by using lineshape models characteristic of modulation spectroscopy of confined systems. The dependence of the ground state transition energy on the number of stacked QD layers is investigated and it is shown that Coulomb interaction can account for the observed different behavior of the ensemble optical response of QD families characterized by different morphologies and coexisting in the same sample.
Soft X-Rays for Deep Sub-100 Nm Lithography, with and Without Masks
Authors: Smith Henry I. , Carter D. J. D. , Ferrera J. , Gil D. , Goodberlet J. , Hastings J. T. , Lim M. H. , Meinhold M. , Menon R. , Moon E. E. , Ross C. A. , Savas T. , Walsh M. , Zhang F. 
Published: April 2011

AbstractThe development of micro- and nanofabrication, their applications, and their dependent industries has progressed to a point where a bifurcation of technology development will likely occur. On the one hand, the semiconductor industry (at least in the USA) has decided to develop EUV and SCALPEL to meet its future needs. Even if the semiconductor industry is successful in this (which is by no means certain) such tools will not be useful in most other segments of industry and research that will employ nanolithography. As examples, MEMS, integrated optics, biological research, magnetic information storage, quantum-effect research, and multiple applications not yet envisioned will not employ the lithography tools of the semiconductor industry, either because they are too expensive, insufficiently flexible, or lacking in accuracy and spatial-phase coherence. Of course, direct-write electron-beam lithography can meet many of these non-semiconductor-industry needs, but in other cases a technique of higher throughput or broader process-latitude is necessary. Our experience at MIT in applying low-cost proximity x-ray nanolithography to a wide variety of applications leads us to conclude that this technology can provide an alternative path of a bifurcation. A new projection lithography technique, zone-plate-array lithography (ZPAL), does not require a mask, can operate from UV to EUV to x-rays, and has the potential to reach the limits of the lithographic process.
Polymer-Inorganic High Contrast and High Sensitivity Resists for Nanolithography
Authors: Wu Hengpeng , Wang Jianzhao , Gonsalves Kenneth E. 
Published: April 2011

AbstractPolyhedral oligosilsesquioxane methacrylate (POSSMA)/methyl methacrylate(MMA)/tert-butyl methacrylate(TBMA)/tert-butyl acrylate(TBA) copolymers were synthesized by solution polymerization. Their preliminary lithography-related properties were studied. It is shown that the mass ratio of MMA/POSSMA=85.8/14.2 leads to an X-ray resist with a high contrast of 23.5 without sacrificing the sensitivity(1350 mJ/cm2) which remains comparable to that of standard PMMA. By careful manipulation of components and compositions, this generic type of polymer could potentially be utilized as a DUV or e-beam resist as well.
Resist Materials Providing Small Line-Edge Roughness
Authors: Namatsu Hideo , Yamaguchi Toru , Kurihara Kenji 
Published: April 2011

AbstractOur research focuses on the line-edge roughness of resist patterns and how to reduce it in order to establish nanolithography as a practical tool. Commercially available e-beam resists exhibit a line-edge roughness of 3 nm (σ) or more. It is caused mainly by polymer aggregates in the resist. During development, they are extracted through dissolution of the surrounding polymer matrix. That is, the aggregates themselves dissolve more slowly than the surrounding matrix; and those that remain embedded in the resist produce line-edge roughness. To reduce the roughness, the effect of the aggregates must be suppressed. One way of doing this is to use a resist containing small aggregates. A good candidate is hydrogen silsesquioxane, which has a three-dimensional framework. Another way is to use a resist in which the aggregates are linked together, which makes them difficult to extract during development. A good example is an acrylate-type resist with a cross-linker mixed in.
Lithographic Materials Technologies: 193 nm Imaging and Beyond
Authors: Reichmanis Elsa , Nalamasu Omkaram , Houlihan Francis M. , Gabor Allen H. , Neisser Mark O. , Bowden Murrae J. 
Published: April 2011

AbstractAdvances in microlithographic resist materials have been a key enabler of the unabated productivity gains in the electronics industry and are continuing to help push the ultimate limits of optical lithography. The challenges posed by the introduction of new optical lithography technologies that use smaller wavelengths have been successfully met by the materials community through the design of chemically amplified resist technologies and 193 nm resist materials based on aliphatic polymers and dissolution inhibitors. With continued advances in resist materials, exposure systems and resolution enhancement and mask technologies, optical lithography will be capable of patterning ≤ 0.1 μm design rule devices in future fabs.
A kinetic Monte Carlo Model of Silicon CVD Growth from a Mixed H2/siH4 Gas Source
Authors: Fearn M. , Sayed M. , Jefferson J. H. , Robbins D. J. 
Published: April 2011

AbstractWe report the development of an atomistic scale Kinetic Monte Carlo model of silicon CVD growth. By employing a variable time step algorithm, simulations have been performed over a range of time scales, enabling direct comparison with experimental data. The validity of using the kinetic theory of gases for evaluating steady state incoming particle fluxes within the model is demonstrated by comparison with computational fluid dynamics simulations. The model is applied to study hydrogen desorption rates from Si(001) and the dependence of silicon growth rate on substrate temperature, with results found to be in good agreement with experimental data. An experimentally observed decrease of growth rate with increasing H2 partial pressure is also reproduced by the model and shown to be caused by a decrease in silane adsorption on a hydrogen-rich surface.
Molecular Dynamics Simulations of Solid Phase Epitaxy of Si:Growth Mechanism and Defect Formation
Authors: Motooka T. , Munetoh S. , Nisihira K. , Moriguchi K. , Shintani A. 
Published: April 2011

AbstractWe have investigated crystal growth and defect formation processes during solid phase epitaxy (SPE) of Si in the [001] direction based on molecular dynamics (MD) simulations using the Tersoff potential. From the Arrhenius plot of the growth rates obtained by MD simulations, we have found that the activation energy of SPE at lower temperatures is in good agreement with the experimental value, approximately 2.7 eV, while it becomes lower at higher temperatures. This can be attributed to the difference in the amorphous/crystalline (a/c) interface structure. In the low temperature region, the a/c interface is essentially (001) and the rate-limiting step is two-dimensional nucleation on the (001) a/c interface. On the other hand, the a/c interface becomes rough due to (111) facets formation in the high temperature region and the rate-limiting step is presumably a diffusion process of Si to be trapped at the kink sites associated with these facets. Defect formation is found to be initiated by 5-membered rings created at the a/c interface. These mismatched configurations at the interface give rise to (111) stacking faults during further SPE growth.
Multimillion-Atom Simulations of Atomic-Level Surface Stresses and Pressure Distribution on InAs/GaAs Mesas
Authors: Su Xiaotao , Kalia Rajiv K. , Madhukar Anupam , Nakano Aiichiro , Vashishta Priya 
Published: April 2011

AbstractLarge-scale molecular dynamics simulations are performed to investigate the atomiclevel stresses on InAs/GaAs mesas. The simulations are based on an interatomic-potential scheme for InAs/GaAs systems which depends on the local chemical composition. Multiresolution techniques are used to speed up the simulations. InAs/GaAs square mesas with { 101 }-type sidewalls are studied. The atomic-level pressure distribution and surface atomic stresses on the sidewalls with 12, 10, 8 and 6 monolayers of InAs overlayers have been calculated.
Nanostructure Fabrication Using Electron Beam
Authors: Matsui Shinji 
Published: April 2011

AbstractNanofabrication strategies developed by using electron beam (EB) are described. Ten-nm structures of organic positive and negative resist patterns have been achieved by using a commercially available EB lithography system. As one of the applications of EB nanolithography to nanodevices, an electrically variable shallow junction MOSFET (EJ-MOS) is described. As a novel approach, material-wave nanotechnology using de Broglie wave has been developed. Line and dot patterns with 100-nm periodicity were exposed on a PMMA resist by EB holography with a thermal field-emitter gun and an electron biprism. This technique allows us to produce nanoscale periodic patterns. Furthermore, the possibility of nanostructure fabrication by atomic-beam holography has been demonstrated by using a laser-trap technique and a computer-generated hologram made by EB lithography.
The Novel Technique of Nanometer-Size Fabrication by Using Conventional Photolithography
Authors: Hashioka Shingi , Matsumura Hideki 
Published: April 2011

AbstractA novel method to prepare nanometer-size patterns by using currently available massproduction technology is proposed. In this study, a contact pattern-mask with nanometersize slit is fabricated by combination of photolithography and anodic oxidation of metal. The slit width of the pattern-mask can be controlled in the order of nano-meters by anodic voltage during oxidation of side-wall of the metal. 10nm width trench is formed in Si substrate by using such nanometer slit-mask. It is suggested that the technique can be utilized as fabrication process of the nano-scale devices.
Fabrication of Isolated Nanoparticle Circuitry Via Lensless Optical Tweezing (“L. O. T. s”)
Authors: Dearing M. T. , Spalding G. C. 
Published: April 2011

AbstractWe propose a novel method for trapping a nanometer-scale particle into a stable structure useful for a variety of interesting electrical measurements. The particle to be trapped can be dielectric or metallic, magnetic or non-magnetic. Our methodology was developed, in part, to ensure the absence of extraneous nanoparticles in the region of the device under test; it also allows a possible feedback mechanism to indicate when a nanoparticle has been successfully trapped. In particular, we irradiate a substrate containing a tiny etch-pit hole. On the transmission side of the substrate, the diffracted or evanescent optical fields should contain large enough gradients to localize a nanoparticle to the region of the hole.
Molecular Scale Electronics. Critical Nanolithography Issues of Synthesis and Addressing
Authors: Huang S. , Mickelson E. T. , Rawlett A. M. , Asplund C. L. , Cassell A. M. , Kozaki M. , Burgin T. P. , Jones l. , Tour J. M. , Myrick M. L. , Van Patten P. G. , Chen J. , Zhou C.-W. , Muller C. J. , Deshpande M. R. , Reed M. A. , Bumm L. A. , Cygan M. T. , Dunbar T. D. , Weiss P. S. , Allara D. L. 
Published: April 2011

AbstractAs we rapidly approach the point at which solid-state electronic devices cease to be made any smaller, molecular scale electronics offers, perhaps, the best chance for a continued miniaturization of computational devices. We must, however, completely re-think our approach to lithography. Presented in this paper are our solution-phase and solid-support based syntheses of molecular wires of precise length and dimensions, and our methods of addressing these wires via molecular “alligator clips” to gold and platinum electrodes of macroscale dimensions.
Resist Materials and Nanolithography
Authors: Dobisz Elizabeth A. 
Published: April 2011

AbstractThe work focuses on lithographic processes and materials for sub-50 nm lithography. Lithographic results of polymethyl methacrylates of molecular weights of 50,000, 100,000, 496,000, and 950, 000 are compared. It was found that the molecular weight and developer concentration do not affect smallest linewidth, within experimental error. However, the molecular weight does affect the line-to-line resolution in dense gratings of 40–60 nm in contrast and developer induced swelling. 40 nm period gratings are shown. The work next examines the use of chemically amplified resists for nanofabrication, with a focus on SAL-601. Sub-50 nm lines are defined with latitude of an order of magnitude in dose and a factor of two in post exposure bake time. The results are modeled with a diffusion reaction kinetic model and an approach to optimize resolution and reproducibility is presented. Challenges to attaining the ultimate resolution and line-to-line resolution in polymeric resists include contrast, mechanical stability, swelling, and adhesion. Metal binding self assembled monolayers (SAMs) are presented a class of resists, that circumvent the latter three complications. Work at the Naval Research Laboratory on SAM resists is outlined.
Liquid Phase Diffusion Bonding for Thermoelectric Material Pb-Sn-Te
Authors: Shinohara Y. , Hashimoto M. , Imai Y. , Isoda Y. , Nishida I. A. 
Published: April 2011

ABSTRACTLiquid phase diffusion bonding was applied to the development of the joined thermoelectric material Pb-Sn-Te, which was expected to be superior to the monolithic Pb-Sn-Te. A Sn sheet 50μm thick was used for the inserted material. The sheet was sandwiched between Pb-Sn-Te segments with different hole concentrations, and subsequently the bonding was performed under 2MPa at 700K for 15min in Ar. The Sn sheet was changed to a SnTe interfacial layer of less than 10μm in thickness. The interfacial layer showed high toughness, and good ohmic and thermal contact up to 550K. Liquid phase diffusion bonding was an excellent technique for joining of thermoelectric material Pb-Sn-Te.
Optimisation of Adhesion at Transition Metal-Oxide Interfaces by Processing at Well-Chosen Oxygen Activity
Authors: Backhaus-Ricoult M. 
Published: April 2011

ABSTRACTTransition metal-oxide interfaces suffer within their thermodynamic stability range Gibbs' adsorption and show important changes in chemical composition with oxygen activity. As a consequence, specific free interfacial energy and adhesion energy also vary with oxygen activity. Adhesion at a given non-reactive transition metal-oxide interface can then be optimised by establishing the proper oxygen activity during processing or by a post-treatment at the interface.In the present work, the approach of Gibbs' adsorption is extended to crystalline, anisotropic (special) transition metal-oxide interfaces. It is demonstrated that interfacial energy varies with oxygen activity. The variation in energy is studied for different adsorption energies, temperatures and interfacial planes.