bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Rate Dry Etching of GaN, AIN and InN in ECR Cl2/CH4/H2/Ar Plasmas
Authors: Vartuli C. B. , Pearton S. J. , Abernathy C. R. , Shul R. J. , Kilcoyne S. P. , Crawford M. Hagerott , Howard A. J. , Parmeter J. E. 
Published: April 2011

ABSTRACTEtch rates for binary nitrides in ECR Cl2/CH4/H2/Ar are reported as a function of temperature, rf-bias, microwave power, pressure and relative gas proportions. GaN etch rates remain relatively constant from 30 to 125 °C and then increase to a maximum of 2340 Å-min−1 at 170 °C. The AIN etch rate decreases throughout the temperature range studied with a maximum of 960 Å-min−1 at 30 °C. When CH4 is removed from the plasma chemistry, the GaN and InN etch rates are slightly lower, with less dramatic changes with temperature. The surface composition of the III–V nitrides remains unchanged over the temperatures studied. The GaN and InN rates increase significantly with rf power, and the fastest rates for all three binaries are obtained at 2 mTorr. Surface morphology is smooth for GaN over a wide range of conditions, whereas InN surfaces are more sensitive to plasma parameters.
Lateral Diffusion Limitations of Ingaas/Gaas for Nanostructure Fabrication
Authors: Redinbo Gregory F. , Craighead Harold G. 
Published: April 2011

ABSTRACTWe have investigated the technique of implantation enhanced interdiffusion (IEI) for optical nanostructure fabrication in strained InxGal-xAs/GaAs quantum wells. Implantation masks with widths from 40 nm to 40 μm were fabricated on the surface of InxGal-xAs/GaAs (x+0.1, 0.2) 3.5 nm quantum well material which was implanted with 100 kV As+ with doses ranging from 5 × 1012 to 8.5× 1013 ions/cm2. After mask removal and a high temperature anneal, cathodoluminescence (CL) spectroscopy was used to investigate the optical properties of the resulting structures. We have measured electron-heavy hole recombination energy shifts due to quantum well interdiffusion of up to 60 meV for the highest doses used here with broad area implants. However, while quantum well emission under large (40 μm) masks is preserved, smaller masks show an emission blue shift not due to ions penetrating through the mask. A simple model of the width dependence of this shift yields an enhanced lateral diffusion length of approximately 1 μm which is many times larger than the lateral straggle of the implanted As+. We conclude that lateral diffusion effects may impose a limit on nanostructure fabrication in the InxGal-xAs/GaAs system with this technique.
Metal-Parylene Interconnection Systems
Authors: Dabral S. , Zhang X. , Wang B. , Yang G.-R. , Lu T.-M , McDonald J.F. 
Published: April 2011

AbstractThis paper reports the results of a study to integrate a metal-parylene interconnection system. The advantages and issues are highlighted. Fabrication steps for packaging geometries as well as proposed fabrication steps for VLSI applications are discussed. The relevant material properties for interconnection system design have been compiled.
High Temperature Alternating Copolymers As Dielectric Materials: Synthesis, Structure And Properties
Authors: Ree M. , Goh W.H. , Park J.-W. , Lee M.-H. , Rhee S.B. 
Published: April 2011

AbstractA new diamine monomer, N,N'-bis(4-aminophenyl)-2,5-(diisopropoxycarbony)benzene-l,4-dicarboxamide was synthesized. Using the diamine, several alternating copolyimide precursors were successfully synthesized by its condensation polymerization with dianhydrides. The structure and properties (mechanical properties and thermal expansivity) of alternating copolyimides imidized thermally were characterized, and compared with those of the corresponding randomcopolyimides prepared from the copoly(amic acid)s. The alternating copolyimides exhibited relatively higher chain order and in-plane orientation in films than the random copolyimides. The higher chain order and in-plane orientation led to the higher tensile modulus and lower thermal expansivity in the alternating copolyimides. Such effect of comonomer sequence was found to be highly pronounced in copolyimides consisting of comonomers which have a large difference in the chain rigidity. It was demonstrated in this study that the formation of alternating copolyimides is a suitable route to improve the performance of properties.
Low Dielectric Constant Thermostable Polymers
Authors: Sillion B. , Rabilloud G. , Garapon J. , Gain O. , Vallet J. 
Published: April 2011

AbstractThe dielectric properties of the heat-resistant heterocyclic polymers are governed by their chemical structure and the absence of unwanted dipoles. A polyphenylquinoxaline is taken as an example of the effect of the dipole symmetry. In the particular case of polyimides, it is obvious that the dehydrocyclization of the intermediate polyamic acid has to be completed to produce the lowest achievable permittivity. This is illustrated by the polycondensation in solution of the polyimides based on 4,4'-(9H-fluoren-9-ylidene)-bisbenzeneamine. In addition, the spatial conformation of the macromolecular chain can also play an important role. The chemistry of a polyimide prepared from 4,4'-(1,3-benzenedicarbonyl) bis(1,2-benzenedicarboxylic acid dianhydride) allows to discuss this topic. However, a dielectric constant of 2.7 seems to be the ultimate value achievable for dense films prepared with the most performing polymers. The introduction of homogeneously distributed micro-voids allows the preparation of dielectric films with a permittivity lower than 2.0. The modification of a polymer with tertiobutyl carbonate (t.BOC) groups is a promising approach because it offers a large processability window.
A Multilayer Approach to the Design of Fine Dispersed Metallic two Component Materials
Authors: Eisenmenger-Sittner C. , Behr R. , Bergauer A. , Hejl A. , Bauer W. 
Published: April 2011

ABSTRACTIn the common applications of multilayer materials a strict separation of the single layers as well as very sharply defined interlayer interfaces are highly desired. On the otherhand there exists a large class of materials which consist of small particles dispersed in a matrix with mechanically different properties.In this paper the theoretical concepts of producing this second class of materials via a multilayer deposition approach are presented. Although the focus is on the preparation ofsputter deposited immiscible metallic two component materials, the concepts presented arevalid for a greater variety of materials and deposition techniques.The phase distribution as well as the roughness evolution of a material consisting of oneisland- and one layer forming component is quantitatively described by considerations about the minimization of the surface free energy of the whole system. On the atomistic level the formation of critical nuclei on an arbitrarily shaped surface is briefly discussed and a connection to the thermodynamic minimization of the surface free energy is made.
Charge Transfer from PbS Quantum Dots to Insulating TiO2 Matrix
Authors: Könenkamp R. , Hoyer P. 
Published: April 2011

ABSTRACTWe report on the photoconductivity of thin films consisting of a porous nanocrystalline TiO2 matrix and quantum size PbS clusters adsorbed on the inner surfaces of theTiO2. The PbS clusters are typically a few nm in size and are not connected. Due to quantum confinement the bandgap of the clusters is widened to around 2 eV from the 0.41 eV value for PbS bulk. The clusters thus absorb in the visible spectrum. However, due to their spatial separation, photoconductance through the film requires carrier transfer through the TiO2 matrix. Our data show this to occur only for clusters <25 Å, for which the conduction band edge lies above the TiO2 conduction band edge. For larger clusters the band alignment at the TiO2/PbS interface appears to be unfavorable for carrier transfer; these clusters do not contributeto photoconduction.
Magnetic Properties and Structural Transformation in Copper-304 Stainless Steel Multilayer Materials
Authors: Parvin K. , Weathersby S.P. , Barbee T.W. , Weihs T.P. , Wall M.A. 
Published: April 2011

ABSTRACTMultilayer foils of Cu-304 stainless steel (304SS) with equal layer thicknesses in the range t=5.0-500 Å and total thicknesses 10-20 μm have been synthesized using magnetron sputtering at ambient substrate temperature. The x-ray diffraction data of as-deposited films show two structural regimes: small thickness (t=5-10 Å) which is characterized by epitaxial FCC growth of 304SS on copper, and large thickness (t=13.5-500 Å) which shows epitaxial FCC 304SS growth near the interface and BCC 304SS growth away from the interface. FCC structured films show very small magnetic moments at room temperature similar to bulk 304SS stable FCC phase. However, a strong magnetic moment is observed for thicker samples due to ferromagnetic metastable 304SS BCC phase. Two opposing transformations occur in the 304 layers as the samples are heated. The first transformation is from the metastable BCC 304SS to the stable FCC phase. This transformation produces a strong drop in magnetic moment and is clearly visible in the large period multilayers which contain high volume fractions of BCC 304SS. The second transformation is from the original FCC phase to a new stable BCC phase in the 304SS near the copper-304SS interfaces.The transformation is produced by diffusion of nickel from the 304SS into the surroundingcopper and the chemical destabilization of the FCC phase which starts near 400 ºC.This transformation produces a sharp increase in magnetic moment. The magnetic signal drops to zero near 675 ºC which is the Curie temperature of ferromagnetic BCC Fe.75 Cr25..
Absolute Calibration of Sims Depth Profiles of a-SiNx:H/a-Si:H and a-SiOx:H/a-Si:H Multilayers
Authors: Li Jianwei , Chabala Jan M. , Levi-Setti Riccardo 
Published: April 2011

ABSTRACTWe calibrated secondary ion mass spectrometry (SIMS) depth profiles of a-SiNx:H/a-Si:H and a-SiOx:H/a-Si:H multilayer samples by comparing them to high-spatial-resolution SIMS maps of cross sections through the layers. Both profiles and images were acquired with a focused scanning 45 keV Ga+ ion microprobe. During depth profiling an area gating technique was used to improve depth resolution. At the beginning of the profile the resolution was 8 nm. By cutting the multilayer films at a small angle through the layers, we obtained SIMS images of cross sections through thesemultilayer samples. The resolution along the expanded direction is about 10 nm. By comparing the depth profiles and the cross section images, we determined the ionbeam-induced atomic mixing in the samples, as a function of depth and the sputtering yield for each layer.
Structure of Magnetic Multilayers and Magnetoresistance
Authors: Shinjo Teruya 
Published: April 2011

ABSTRACTMagnetoresistance (MR) studies on non-coupled type multilayers are briefly surveyed. As a possible method to enhance MR effect, measurements with current in outof–plane directions are described. Non–coupled type multilayers were prepared on microstructured substrates with V–shaped grooves to measure the MR in a new geometry, with current at–an–angle–to–the–plane, and actually an enhanced MR ratio was observed.
Characterization of Asymmetric Polydiacetylene Ultrathin Films
Authors: Cheong D. W. , Shivshankar V. , Wang H. C. , Sung C. M. , Kumar J. , Tripathy S. K. 
Published: April 2011

ABSTRACTNonlinear optical (NLO) ultrathin films of a preforrned asymmetric polydiacetylene have been fabricated by Z-type Langmuir-Blodgett film deposition from the air-water interface. Induced in-plane orientation of the polydiacetylene backbone on the substrates has been confirmed by UV/Vis, FT-IR dichroism, and degenerate four wave mixing (DFWM) studies. All the measurements indicate that the backbone is prefe rentially oriented along the dipping direction. Second harmonic generation study suggests that the LB multilayers form an asymmetric structure (Z-type) due to the accumulation of 2-dimensional ordered monolayer and the dominant induced second order polarization is in the plane of the film. The film morphology and molecular orientation have been investigated by atomic force microscopy (AFM).
Solid State Reaction of Al and Zr in Al/Zr Multilayers: A Calorimetry Study
Authors: Blobaum K.J. , Weihs T.P. , Barbee T.W. , Wall M.A. 
Published: April 2011

ABSTRACTThe exothermic, solid state reaction of Al and Zr has been studied in thick AL/Zr multilayers using Differential Scanning Calorimetry and X-ray diffraction. The multilayersamples were magnetron sputter deposited into highly textured alternate layers of Al and Zr with nominal composition A13Zr. The samples used in this study were 47μm thick with a 427Å period. When samples were isochronally scanned from 25º to 725ºC, a large exotherm at ˜350ºC was followed by one or two smaller exotherms at ˜650ºC. The first exotherm is dominated by a diffusionbased reaction of Al and Zr that produces two phases in isochronal scans: amorphous AI-Zrand cubic A13Zr, and two additional phases in isothermal anneals: A12Zr and tetragonal AI3Zr. The exothermic heat from this multi-phase reaction is measured using isochronal scans and isothermal anneals, and the heat flow is analyzed using a l-D diffusion based model. An average activation energy and a diffusion constant are determined. In the isothermal scans, the total exothermic heat increases linearly with √ime, and layer thicknesses vary linearly with heat.
In-Situ Observation of Stress in Cu/Pd Multilayers
Authors: Ueda T. , Simenson G.F. , Nix W.D. , Clemens Bruce M. 
Published: April 2011

ABSTRACTStress evolution was studied during growth of Cu/Pd multilayers using an in-situ, laserbased wafer curvature technique which allowed measurement of stress changes associated with sub-monolayer thickness increases. The apparent stress in the Cu layers changes during growth, from compressive, for thickness less than about 0.5 nm, to tensile for thicknesses above this. The stress behavior in the Pd layers depends on the thickness of the underlying Cu layer. Pd deposited on thick (2 nm) Cu layers is under an apparent compressive stress, while Pd deposited on thin (< 1 nm) Cu layers is initially under a tensile stress but changes to a compressive stress at about 0.5 nm. The overall compressive stress maxima observed in multilayers at a bilayer period of 2 nm is explained by this in-situ behavior. The stress behavior in this system is consistent with either island growth of Cu, or thickness dependent alloying behavior, or both.
Crystallization in Metal-Metalloid Multilayers
Authors: Sinclair R. , Konno T. J. , Itoh T. , Zhu N. C. 
Published: April 2011

ABSTRACTWe have studied the reactions which occur in metal-metalloid multilayers made from elements which have binary eutectic phase diagrams. The metal mediates crystallization of the amorphous as-deposited metalloid by crystal nucleation inside the metal layer followed by rapid diffusion through the metal from amorphous to crystalline phases. The metalloid crystallization temperature is significantly reduced by this reaction. Systems showing this behavior are Al-Si, Ag-Si, Ag-Ge, Co-C, Ni-C and Fe-C. We believe, therefore, that it is a general phenomenon which we have now extended to the case of Ag-SiC.
Residual Stress, Mechanical Behavior and Electrical Properties of Cu/Nb Thin-Film Multilayers
Authors: Griffin A. J. , Embury J. D. , Hundley M. F. , Jervis T. R. , Kung H. H. , Scarborough W. K. , Walter K. C. , Wood J. , Nastasi M. 
Published: April 2011

ABSTRACTThe effect of compositional wavelength on the residual stress, electrical resistivities and mechanical properties of Cu/Nb thin-film multilayers sputtered onto single-crystal Si substrates was evaluated. Electrical resistivities were measured down to 4 °K using a standard four-point probe measurement system. A differential specimen-curvature technique was used to detennine residual stress, and a mechanical-properties microprobe was employed to obtain hardness and elastic modulus. Characterization techniques included profilometry, Ion-Beam Analysis (IBA) and Transmission Electron Microscopy (TEM). The hardness of the Cu-Nb multilayers increased with decreasing compositional wavelength so that the layered structures had hardness values in excess of either of the constituents and the hardness predicted by the rule of mixtures. A peak in the net residual compressive stress of the multilayers was observed at a compositional wavelength of 100 nm. No resistivity plateau was observed within the composition wavelength range studied.
Interfacial Reactions and Thermal Stability of Ultrahigh Vacuum Deposited Multilayered Mo/Si Structures
Authors: Liang J.M. , Chen L.J. 
Published: April 2011

ABSTRACTInterfacial reactions and thermal stability of ultrahigh vacuum deposited multilayered Mo/Si structures have been investigated by high resolution transmission electron microscopy in conjunction with fast Fourier transform and auto–correlation function analysis. For samples with nominal atomic ratios Mo:Si = 1:2 and 3:1, well defined multilayered Mo/Si structures were obtained after annealing at 250 °C for 30 min. On the other hand, distinct multilayered MoSi2/Si structure was formed only for Mo:Si = 1:2 samples after annealing at 650 °C for 1 h.Multiphases were observed to form simultaneously in samples annealed at 400–500 °C. After 650 °C annealing for 1 h, tetragonal MoSi2 was the only silicide phase observed for the Mo:Si = 1:2 samples, whereas both tetragonal and hexagonal MoSi2 were present in Mo:Si = 3:1 samples. The stability of the multilayered Mo/Si structures was found to depend critically on the atomic ratios of constituent elements, bilayer period and annealing conditions. The results are interpreted in terms of the delicate balance between intermixing of constituent atoms and silicide formation.
Production of Mo/si Multilayers At Increased Substrate Temperatures: The Effect On D-Spacing, Interface Roughness and Density.
Authors: Voorma H.-J. , Louis E. , Koster N.B. , Bijkerk F. , der M.J. van 
Published: April 2011

ABSTRACTTo obtain the optimal growth conditions of Mo/Si multilayer structures, produced with e-beam evaporation, the effect of using enhanced deposition temperatures is investigated in detail. We describe the variations of the structure for multilayers deposited at substrate temperatures ranging from 300 K to 550 K. A temperature of 490 K was found to be the optimum resulting in low interface roughness and moderate inter-diffusion. The decrease of the dspacing at the optimum substrate temperature, compared to coatings deposited at room temperature, is explained by a change in free volume of the Si layer.
Evolution of Co/Ge Films on Si(100) and Ge(100) Substrates
Authors: Carlow G.R. , Lowes T.D. , Grunwell M. , Zinke-Allmang M. 
Published: April 2011

ABSTRACTWe present results on the evolution of Co/Ge films on Si(100) substrates. Room temperature deposition of 18 nm thick Ge films followed by 5 nm thick Co films was done by Molecular Beam Epitaxy (MBE) and then post-deposited annealing was done at 700 C. Using combinations of Scanning electron microscopy, Auger electron spectroscopy and Rutherford backscattering spectroscopy, we determine that the Co and Ge are clustering on the Si surface at these annealing temperatures. During the clustering, the Co is diffusing into the Si substrate leaving a Ge-rich clustered morphology. To test the effect of the Si substrate on the evolution of the films, Co films were deposited on Ge(100) substrates and annealed at 700 C. Clustered morphologies are seen on the Ge substrates and Co in-diffusion is also occurring. The morphologies on the Ge substrates are significantly different from those on the Si substrates.
An Electrical Model for Multilayered n+/n and Heterostructure Planar Ohmic Contacts
Authors: Reeves Geoffrey K. , Leech Patrick W. , Harrison H. Barry 
Published: April 2011

ABSTRACTThe standard Transmission Line Model (TLM) is an electrical network that is commonly used to model planar two-layer (metal-semiconductor) ohmic contacts. More complex multilayered planar structures have led to the development of more complex models. A Tri-Layer Transmission Line Model (TLTLM) was recently proposed in order to more accurately represent an alloyed ohmic contact. The TLTLM also enables other layered planar contact structures such as non-alloyed n+/n, heterojunction and metal-silicide-silicon contacts to be analysed. In this paper, it is shown that when the TLTLM is combined with a modified TLM network, important device properties such as contact and parasitic resistance can be derived for device structures using several epilayers such as FET's. An example is given of the current distribution in an FET and the calculation of the parasitic resistance in the gate-drain channel and the contact resistance of the drain.
Elastic Properties of CVD Diamond Via Dynamic Resonance Measurements
Authors: D'Evelyn Mark P. , Slutz David E. , Williams Bradley E. 
Published: April 2011

ABSTRACTControl of the mechanical properties of CVD diamond is essential to achieve optimal performance in various applications. While several methods have been applied to the measurement of the Young's modulus of thick-film CVD diamond, in general these methods are not suitable for diamond characterization on a production scale. In addition, many of these methods cannot determine the shear modulus (or Poisson's ratio), which is necessary for a complete description of the elastic properties. We have developed a simple dynamic resonance method for determining both the Young's and shear modulus of free-standing CVD diamond in the shape of rectangular plates or round disks. The specimen is supported along nodal lines of flexural or torsional modes. Oscillations induced by impact from a falling ceramic bead are sensed by a microphone, and the resonant frequencies are determined by a signal analyzer. The Young's and shear modulus are calculated from the frequencies of the fundamental flexural and torsional modes, respectively, using quasi-analytic formulas. CVD diamond grown by several methods routinely achieves Young's and shear modulus values above 1000 GPa and 500 GPa, respectively, in good accord with theoretical values for pure polycrystalline diamond.
An Indentation Test for Measuring Adhesion Toughness of Thin Films Under High Residual Compression With Application to Diamond Films
Authors: Drory M. D. , Hutchinson J. W. 
Published: April 2011

ABSTRACTAdhesion measurement of brittle coatings on ductile substrates is examined with emphasis on diamond–coated metals. The experimental aspects of determining film adhesion is discussed through measurement of the interface toughness by a brale indentation method.
Shock Wave Synthesis of Diamond and other Phases
Authors: Decarli Paul S. 
Published: April 2011

ABSTRACTShock wave synthesis of diamond was an unexpected result of experiments designed to explore the effects of shock waves on a variety of materials. The initial announcement in 1959 was controversial; shock synthesis of diamond had been shown to be unlikely, on the basis of kinetic arguments. Jamieson confirmed the identification and suggested a diffusionless mechanism, c-axis compression of rhombohedral graphite. Subsequent work has provided strong evidence that shock wave synthesis of cubic diamond is a conventional thermally activated nucleation and growth process. Thermal inhomogeneities provide the requisite high temperatures; quenching via thermal equilibration is implicit in the process. Shock synthesis of adamantine BN phases appears to be quasi-martensitic; a martensitic mechanism may partially account for the Lonsdaleite (hexagonal diamond) observed in some meteorites and in some artificial shock products. Diamond is also formed as a detonation product in oxygen-deficient explosives. The polycrystalline product of shock synthesis is similar to natural carbonado. The association of carbonado with an ancient giant impact crater is noted.