bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inductively-Coupled Plasma Nitriding of Fused Silica
Authors: Vethanayagam T. K. , Johnson P. F. 
Published: March 2011

AbstractPlasma nitriding of fused silica has been performed over a temperature range of 750°C to 1300°C in a nitrogen-hydrogen plasma generated by an inductively coupled RF discharge. The plasma is used as both thermal and chemical source. The effects of various process parameters such as surface temperature, gas pressure and treatment time on total nitrogen content have been studied. The advantages and the drawbacks of this direct plasma nitriding technique are briefly discussed.
Corona-Discharge-Induced Stress Relaxation in Silicon Dioxide Films on Silicon
Authors: Landsberger L. M. , Tiller W. A. 
Published: March 2011

AbstractVariations in refractive index (density) with growth temperature are taken as a rough measure of residual compressive stress in dry SiO2 films. This paper presents experimental data regarding the relaxation of these stresses by a low-temperature (600–900°C) oxygen corona discharge process. For an initial oxide layer of 1100 Å thickness grown at 800°C, relaxation is complete after a corona treatment of 10 minutes at -lμA. The dose of O− ions required is found to be about 1–1.5% of the total oxygen atoms in the initial layer. The difference in dose between oxide on (111) and (100) Si is found to be proportional to the respective density changes from the initial oxide to fully relaxed oxide.
Micromachining of Silicon Mechanical Structures
Authors: Kaminsky G. 
Published: March 2011

ABSTRACTRefined processing procedures for producing geometrically highly precise silicon structures are described. The structures are fabricated by the high-precision micromachining of silicon utilizing wet chemical orientation and/or concentration dependent, etching techniques. Very exact processing procedures required to reproducibly achieve good high quality structures with excellent large and small scale uniformity are detailed. Relief structures having features as small as 0.2μm have been produced. Some of the structures and devices attainable will be described including: (1) very high Q torsional oscillators useful as powerful probes of the mechanical properties of a variety of physical systems, (2) unstrained focusing x-ray mirrors, and (3) μm dimension mechanical “shadow masks” with multiple slit features having knife-edge acuity of much better than 1μm over an area ˜1cm2 and useful for noncontaminative, in situ patterning of thin films deposited in MBE or other vacuum deposition techniques.
Ion Beam Machining of Micromechanical Structures
Authors: Davies S. T. , Bowen D. K. 
Published: March 2011

ABSTRACTThe needs of high precision engineering currently call for dimensional tolerances of the order of 0.1μm and surface roughness of order 0.01μm, often in hard, brittle materials or materials of relatively poor machinability. The development of argon ion beam machining for milling, drilling and turning or lathing is reported as a means of satisfying these requirements. Highly controllable material removal is achieved for the fabrication of micromechanical structures, profiling of surfaces and fine surface finishing. Surface evolution at submicron precision is demonstrated, with particular reference to the production of both circular and non-circular sections in an “ion beam lathe”.
Quantum Interference Effect in Narrow n+-GaAs Wires
Authors: Ishibashi Koji , Nagata Koh , Ishida Shuichi , Gamo Kenji , Aoyagi Yoshinobu , Kawabe Mitsuo , Murase Kazuo , Namba Susumu 
Published: March 2011

ABSTRACTOur experimental results about aperiodic magnetoconductance in narrow n+-GaAs wire are described. These wires are fabricated in an MOCVD grown n+-GaAs film by electron beam lithography and the dry etching technique. It is found that the aperiodic structure arises from the quantum interference which is important in small structures (<1in). The experimental results are compared to the recent theory.
Determination of the Threshold Energy of Noble Gas Defects in Silicon Created by Ion Beam Etching
Authors: Sawyer W. D. , Weber J. 
Published: March 2011

ABSTRACTUsing photoluminescence we investigate defects introduced into silicon by ion beam etching. The luminescence spectra show the presence of various defects known from radiation damage studies. Ion-beam milling with different noble gas ions produces a family of defects which gives rise to almost identical photoluminescence spectra. The intensity of the Ar noble gas defect luminescence is studied for different ion-beam energies (200–2000eV) and crystal orientations. The threshold energy to create this defect leads to a model of the defect structure.
Thermal Reactions of Bisazides in Resists Containing Double Bonds
Authors: Pryde C. A. 
Published: March 2011

ABSTRACTDerivatives of 2,6-bis(4-azidobenzylidene) cyclohexanone are frequently used as photosensitizers in photoresists. These compounds are generally considered to be quite thermally stable. However, there have been reports of thermal degradation occurring at temperatures as low as 60'C.Experiments done here suggest that the thermal stability of the azide is adversely affected by the presence of unsaturated material in the formulation. Data from IR spectroscopy show that, by itself, 2,6-bis(4-azidobenzylidene) 4-methylcyclohexanone is thermally stable in a polyamic acid film at 75–80° C. However, addition of a monomeric aminoacrylate to the formulation results in a significant decay in the absorption of the azide moiety in just a few hours at these same temperatures. This decay is attributed to reaction of the sensitizer with the acrylate double bonds. In a thick film, which might require a 1–2 hour prebake, this thermal addition could result in a significant degree of crosslinking and thus to decreased contrast in the final pattern.
Reactive Ion Etching and Lithographic Characterization of a New Organosilicon Resist
Authors: Tarascon R. G. , Shugard A. , Reichmanis E. 
Published: March 2011

ABSTRACTWe describe the use of a novel organosilicon novolac as a base resin component of bi-level resist systems for both photo and electron-beam lithography. The lithographic evaluation of the new material demonstrates submicron resolution and high aspect ratio images with little linewidth loss after reactive ion etching (RIE). The optimization of the RIE conditions will be also discussed.
Microporous Amorphous Superlattices
Authors: Deckman H. W. , Abeles B. , Dunsmuir J. H. , Roxlo C. B. , Tiedje T. 
Published: March 2011

ABSTRACTLithographic fabrication techniques have been extended to the molecular dimension by using the layer pattern in deposited amorphous superlattices as an etching template for the creation of slot structures. Fabrication considerations are discussed for the formation of 10–50Å slots structures suitable for studying shape selective chemistry with fluoresence spectroscopy.
Exploring Magnetic properties of Epitaxial Films and Superlattices
Authors: Erskine J. L. , Onellion M. F. , Thompson M. A. 
Published: March 2011

ABSTRACTRecent advances in spin-sensitive spectroscopie techniques combined with the rapidly expanding capabilities to synthesize novel materials utilizing molecular beam epitaxy (MBE) are stimulating new interest in magnetism and magnetic materials. Epitaxial growth offers opportunities to stabilize and study crystal phases of elemental magnetic materials which do not naturally occur in nature, and to vary the crystal parameters and composition of epitaxial films in precisely controlled ways. Multilayer superlattice films can also be fabricated using MBE. These structures offer unprecedented new opportunities to explore the relationship between crystal structure and various magnetic properties such as spontaneous magnetization, the Curie temperature and magnetic anisotropy in well characterized systems. The present paper reviews some of the more recent work on thin film magnetic systems including structure analysis of film quality, new techniques for probing the electronic and magnetic properties of the films and the important role large scale numerical calculations are beginning to play in guiding the choice of magnetic systems for study.
Anomalous Dispersion Corrections to Surface and Interface Exafs Measurements Made Using Glancing Angles
Authors: Chen Huaiyu , Heald Steve M. , Tranquada John M. 
Published: March 2011

ABSTRACTEXAFS studies using glancing angle fluorescence on the interface of the Cu-Al thin film system show that the sputtering process generates a different interface structure than for an evaporated one. To obtain quantitative information, the anomalous dispersion effects have to be considered. Simple model calculations are presented for the correction factor which yield good results for Au thin film data. Extension of this model to bilayer systems is discussed.
Simulation of Atomistic Crystal Growth from the Vapor Phase
Authors: Taylor Paul A. , Dodson Brian W. 
Published: March 2011

ABSTRACTWe are in the process of studying strained-layer growth of two-dimensional Lennard-Jones lattices. To do so, we have developed three techniques, based on the Monte Carlo method and molecular dynamics, of simulating atomistic crystal growth from the vapor phase. The Monte Carlo method efficiently simulates the effects of long time-scale processes on the growth of strained-layer systems, but omits the transient dynamics of particle adsorption. The second technique, using molecular dynamics, gives results suggesting that epitaxial growth of strained-layer systems can occur on the picosecond timescales. However, this technique cannot capture the influence of the long time-scale processes on the growth process. In view of the shortcomings of the previous two techniques, A hybrid technique incorporating both the Monte Carlo method and molecular dynamics, has been developed. In principle, this technique models the transient dynamics of adsorption as well as the long term evolution of the system. This technique, however, is limited by artifacts that may only be eliminated by use of unwarrented amounts of supercomputer time.
Interdiffusion of Al and Ga in (Al,Ga)As/GaAs Quantum Wells
Authors: Schlesinger T. E. , Lee Jyh-Chwen , Kuech T. F. 
Published: March 2011

ABSTRACTWe have employed photoluminescence spectroscopy to determine the interdiffusion of Al and Ga in (Al,Ga)As/GaAs quantum wells. The luminescence due to the n=l electron to heavy hole transition in these wells before and after anneal was measured. A variational calculation was employed to determine the expected position of this luminescence peak both before and after the anneal. A single diffusion coefficient, D, was used to model the interdiffusion of the Al and Ga and from the shifted position of the luminescence peaks under various anneal conditions of time and temperature its value was determined. These measurements were performed as a function of temperature to yield ΔE where D = D0e -ΔE/KT. This diffusion coefficient was also studied as a function of the initial Al composition in the cladding layers which ranged from 0.3 to 1.0.
Characterization of the a-SN/CDTE(110) Interface by Angle-Resolved X-Ray Photoemission
Authors: Lin Tzer-Shen , Partin William J. , Chung Yip-Wah 
Published: March 2011

ABSTRACTStoichiometric and atomically clean CdTe(110) surfaces have been prepared by suitable chemical etching, followed by argon sputtering, and sample annealing in ultra-high vacuum. Cubic (α) -tin was grown on CdTe(110) by tin evaporation from a tungsten filament at a substrate temperature of 30 °C. Angle-resolved X-ray photoelectron spectroscopy (ARXPS) was used to determine the a-Sn growth mechanism and the composition profile of this semiconductor heterostructure nondestructively. From our analyses, we conclude that a-Sn grows on CdTe(110) at 30 °C by a layer by layer mechanism and forms an abrupt junction with CdTe(110).
Transition from Schottky Limit to Bardeen Limit in the Schottky Barrier Formation of al on n- and p-GaAs(110) Interfaces
Authors: Chin K. K. , Cao R. , Kendelewicz T. , Miyano K. , Williams M. D. , Doniach S. , Lindau I. , Spicer W. E. 
Published: March 2011

ABSTRACTSchottky barrier formation at room temperature (RT) and low temperature (LT) is studied by photoemission. In the low Al coverage regime (from 0.001 to about 1 ML), it is found that, compared to RT pinning behavior, the n-GaAs(110) surface band bending is attenuated, while the p-GaAs(110) surface band bending is enhanced. This striking phenomenon indicates that, by lowering the substrate temperature, one reduces the disturbance of the GaAs(110) surface, and the surface Fermi level of the n- and p-GaAs(110) tends to go to the same position, the so-called Schottky limit that characterizes a perfect defect-free interface. However, as the coverage increases (up to 30 ML), a new mechanism (in the framework of the unified defect model, it is the formation of defect levels due to the energy released as the adsorbed Al atoms start to form clusters and replace Ga) associated with a disturbed surface becomes dominant. Thus, the LT Fermi level positions of n- and p-GaAs move towards the RT positions, the so-called Bardeen limit. This demonstrates that, by controlling the surface disturbance, one can modify the Schottky barrier formation process, going from the Schottky limit which does not have pinning centers to the Bardeen limit which suggests the existence of pinning centers.
Monte Carlo Simulation of the Growth of ZnSe by MBE
Authors: Venkatasubramanian R. , Otsuka N. , Datta S. , Kolodziejski L. A. , Gunshor R. L. 
Published: March 2011

ABSTRACTA Monte Carlo study of the growth of ZnSe by Molecular beam epitaxy is presented. The study is focused on the role of surface kinetic reactions on the structural quality of the epilayers. Two different models for the incorporation of Se molecules, one with a highly reactive physisorbed state and the other with a relatively nonreactive physisorbed state are employed for simulations. It is shown that the structural quality of the epilayers is very sensitive to the flux ratio if the physisorbed state is relatively nonreactive. It is also shown that if the physisorbed state is highly reactive, good quality epilayers are obtained over a wide range of flux ratio.
Modulated Amorphous Alloy Films
Authors: Chien C. L. , Liou S. H. , Natan M. 
Published: March 2011

ABSTRACTWe have made modulated solids consisting of several hundred layers of a-Fe80Zr20/a-Ni30Nb70 in which the layer thicknesses are a few nanometers. The modulating nature of the sample and the flat growth of the layers are confirmed by cross sectional TEM. The layers of a-Ni30Nb70 are non-magnetic and serve as inert layers separating the magnetic a-Fe80Zr20 layers. By varying the thickness of the a-FegoZr20 layers, the thickness dependence of the magnetic properties has been studied. The sign of the magnetic surface anisotropy constant has been determined.
Rf Magnetron Sputter Deposition and Characterization of Aluminum Nitride thin Films
Authors: Krupanidhi Saluru B. 
Published: March 2011

ABSTRACTHighly crystalline and resistive thin films of aluminum nitride have been rf magnetron sputter deposited. The films were characterized in terms of structure, electrical and optical properties. A perfect c-axis orientation along (002) direction was obtained, in the reactive sputtered films from a metal target, keeping the substrates as low as 350°C. The structural and electrical properties were observed to be sensitive to deposition conditions. It has also been observed that the combination of higher powers and low sputtering pressures, exposed the films to high energy neutral ion bombardment. A correlation between deposition parameters and the physical properties is presented.
Structure of Copper-Hafnium Multilayers
Authors: Clemens B. M. , Stec J. P. , Heald S. M. , Tranquada J. M. 
Published: March 2011

ABSTRACTThe structure of copper-hafnium multilayers has been studied as a function of composition modulation wavelength by x-ray diffraction and EXAFS. Sputter deposited samples were produced with composition modulation wavelengths of 1/2, 5, 7, 10, 14, and 20 close packed planes of each constituent per layer. The structure evolved anisotropically from amorphous to crystalline with increasing composition modulation wavelength, with crystalline order first appearing in the growth direction in the 7 mono-layer sample. Structural coherence in the growth direction was not observed to extend beyond one elemental layer in any sample, and evidence for a disordered interfacial layer was observed by EXAFS for all samples. Small angle x-ray diffraction showed strong composition modulation for all but the 1/2 monolayer sample. The amorphous interface is the result of reaction during deposition similar to the solid state reaction observed in other systems such as nickel-zirconium.
TI-X Alloy Composition Modulated Layered Structures
Authors: Jankowski A. F. , Adams R. O. , Williams L. 
Published: March 2011

ABSTRACTThe binary alloy series of Ti-X metallic, composition modulated layered structures has been fabricated via magnetron sputtering. The Ti-X systems (where X is Ta, Mo, or V) explored are exemplary of solid solution systems, such as the supermodulus systems of Cu-Ni, Ag-Pd, Au-Ni, and Cu-Pd (which all feature fee crystalline compatibility). In the present case, the beta-phase of Ti sought in these Ti-X systems suggests bec crystalline compatibility, with interlayer misfit strains not exceeding 10%.The Ti-X series examined, matches elements of high and low atomic number. (Z of Ti, V, Mo, and Ta are 22, 23, 42, and 73, respectively.) Difficulties which arise in a conventional tungsten basket - alumina crucible physical vapor deposition process, i.e. obtaining thr vaporization temperatures for Ti, V, Mo and Ta of 1235, 1332, 1822, and 2240 °C at 130 mPa, respectively, are overcome by magnetron sputtering. Thin films produced by alternate deposition of Ti with V, Mo, or Ta, are desired with individually unique, regular repeating layer thicknesses which range from 1.5 to 15 nm.An initial characterization of the Ti-X composition modulated alloys has been conducted using X-ray diffraction. The pole figure constructions of the various composition wavelengths give a qualitative look at the strain accomodation within the thin films and possible manifestations in mechanical properties.
Superconducting Properties of v/cr Artificial Metallic Superlattices
Authors: Davis B. M. , Zheng J. Q. , Ma M. R. , Jin B. Y. , Hilliard J. E. , Ketterson J. B. 
Published: March 2011

ABSTRACTWe have studied the superconducting properties of V/Cr superlattices. Superlattices of V100Crx, V150Crx, and V200Crx, with x varying between 3 and 80 atomic planes have been prepared. The films have a strong (110) texture and were grown on sapphire substrates at 250°C in an ultra-high vacuum system. The zero field transition temperature of the V150Crx and V200Crx, but not the V100Crx films have been adequately modeled using Werthamer's theory for proximity effect coupled films. The films have a dimensional crossover in the parallel upper critical field when the thickness of the Cr layers is about 60 atomic planes.
Phase Transitions in the Picosecond Time Domain
Authors: Elsayed-Ali Hani E. , Mourou Gerard A. 
Published: March 2011

ABSTRACTThe physical processes occurring during the initial stages of ultrafast laser heating of metals are described. Femtosecond laser irradiation is used to create nonequilibrium heating in metals. In such a nonequilibrium state, the electron temperature can be heated up to a few thousand degrees above the lattice temperature. Electron-lattice relaxation is time-resolved in copper and found to be 1 – 4 ps depending on the laser heating ffuence. The technique of time-resolved electron diffraction (a lattice structural and temperature probe) is described. Utilization of this technique for lattice temperature measurement of thin metal films is demonstrated.
High Temperature Stability of Amorphous TaxCu1-x Diffusion Barriers on GaAs
Authors: Oh J. E. , Pouch J. J. , Ingram D. C. , Alterovitz S. A. , Woollam J. A. 
Published: March 2011

ABSTRACTThe x value of the most thermally stable co-sputtered TaxCu1-x alloy films are found to correlate with measured maximum temperature coefficients of resistance as a function of alloy composition. To investigate the possible application of these materials as diffusion barriers for the Au-GaAs system, vacuum annealing and infrared rapid thermal annealing are made over a wide temperature range. Resistivity changes, X-ray diffraction, Auger electron spectroscopy, and Rutherford backscattering measurements are performed to find the metallurgical stabilities of these materials at elevated temperatures.For high x values, the reaction temperature for TaxCu1-x, in contact with GaAs lies between 500 and 700°C. For Au in contact with TaxCu1-x the TaxCu1-x/GaAs reaction occurs at about 600°C. Amorphous Ta93Cu7 exhibits uniform mixing with surrounding elements, whereas Ta80Cu20 exhibits phase separation.
Propagation of Acoustic Phonons in Amorphous Superlattices
Authors: Santos P. V. , Ley L. , Mebert J. , Koblinger J. 
Published: March 2011

ABSTRACTWe have investigated the Raman and the phonon transmission spectra of a-Si:H/a-SiNx:H super lattices. At low wavenumbers, the Raman spectrum shows sharp peaks corresponding to the excitation of modes from the folded branches of the dispersion relation for longitudinal acoustic phonons propagating perpendicular to the layers. Energy gaps in the folded phonon dispersion occur at the center and at the boundary of the mini-Brillouin zone due to the differences in the acoustic impedances of the layers. The size of the lowest gaps was determined by light scattering. The phonon transmission spectra show transmission minima that we attribute to the frequency gaps in the dispersion of transversal acoustic phonons. The position and width of these minima are compared with the dispersion obtained from the Raman data.
Structure of Amorphous Semiconductor Interfaces Determined from in Situ Optical Reflectivity Measurements
Authors: Yang L. , Abeles B. 
Published: March 2011

ABSTRACTThe optical reflectivity at 6328Å of a-Si:H, a-Ge:H, a-Si:H/a-SiNx:H and a-Si :H/a-SiOx:H interfaces can be explained by a model of chemically abrupt interfaces that are macroscopica!ly rough on a scale of 10–20Å.
Photoemission Study of the a-Si-H/a-SiOx:H and a-Si:H/a-SiN:H Interface Formation
Authors: Eberhardt W. , Abeles B. , Yang L. , Stasiewski H. , Sondericker D. 
Published: March 2011

ABSTRACTWe report a study of the interface formation between a-Si:H and a-SiOx:H or a-SiN:H in the coverage regime from a submonolayer to a few layers. The films were grown by plasma assisted CVD and characterized by photoemission. Our studies show that the growth mechanism is different for a-SiOx:H on a-Si:H than for a-Si:H on a a-Si:Ox:H. The growth of the a-SiNx:H/a-Si:H interface on the other hand is independent of the direction.
Optical Properties and Interface Study of a-Si:H/a-C:H Superlattices
Authors: Fangqing Zhang , Deyan He , Xixiang Xu , Jinzhong Cui , Guosheng Sun , Guanghua Chen , Yuliang He 
Published: March 2011

ABSTRACTExperimental results on a-Si:H/a-C:H superlattices, including the blue-shift of the optical band gap, the light-induced conductivity effect, the interface structure and the interfacial defects, are presented. Differences between our glow-discharge and sputter-prepared a-Si:H/a-C:H super lat t ices are described.