bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Creation of Misfit Dislocations; A Study of InGaAs Alloys on GaAs Substrates
Authors: Goodhew Peter J , Kightley Philip 
Published: March 2011

ABSTRACTGrowth onto vicinal substrates causes 60° misfit dislocations to adopt line directions away from <110> in order for them to maintain their presence within the substrate to strained layer interface. Observations show that for the growth of an on-axis [001]wafer the dislocations have a line direction, within measurement error, exactly [110] or [-110] and two sets of orthogonal dislocations are generated. When grown onto a wafer that is cut off-axis toward [010] four sets of dislocations are generated. The two sets of dislocations in each direction converge to form low angle intersections from which edge dislocations are formed. These edge dislocations can become very long by the glide out of the interface plane of the component 60° dislocations. This ‘zipping-up’ to form the edge components only occurs in one direction from the low angle point of intersection and the edge segments are exclusively generated in the buffer layer. Their density and penetration are a function of thickness and composition of the mismatched epilayer. The mechanisms by which the dislocations adopt line directions away from <110> and why they zip-up from the intersection in only one direction are discussed.
Initial Stages of Molecular Beam Epitaxical Growth of Highly Strained Inxga1-XAs on Gaas (100)
Authors: Guha S. , Madhukar A. , Kapre R. , Rajkumar K. C. 
Published: March 2011

ABSTRACTWe have studied the initial stages of highly mismatched InxGa1-x As growth on GaAs (100) by transmission electron microscopy (TEM). We find direct evidence of (i) deformation in the substrate below each island to depths of about 150 A and (ii) strain relief in the islands at their lateral edges. Growth morphology as a function of growth temperature is studied and it is found that the tendency for islanding for x as high as 0.5 can be supressed to a large extent by a reduction in the growth temperature. We also present results of correlation between TEM determined different growth morphologies (brought about by different growth temperatures ) and the electrical characteristics of AlAs/InxGa1-xAs resonant tunneling diode structures grown on GaAs (100).
Molecular Dynamics Study of Pb Overlayer on Cu(100)
Authors: Karimi M. , Tibbits P. , Ila D. , Dalins I. , Vidali G. 
Published: March 2011

ABSTRACTIsothermal-isobaric Molecular Dynamics (MD) simulation of a submonolayer Pb film in c(2×2) ordered structure adsorbed on a Cu(100) substrate showed retention of order to high T. The Embedded Atom Method (EAM) calculated the energy of atoms of overlayer and substrate. The time-averaged squared modulus of the two dimensional structure factor for the Pb overlayer measured the order of the overlayer. The results are for increasing T only, and require verification by simulated cooling.
Elastic Energies of Coherent Germanium Islands on Silicon
Authors: Vanderbilt David , Wickham L. K. 
Published: March 2011

ABSTRACTMotivated by recent observations of coherent Ge island formation during growth of Ge on Si (100), we have carried out a theoretical study of the elastic energies associated with the evolution of a uniform strained overlayer as it segregates into coherent islands. In the context of a two-dimensional model, we have explored the conditions under which coherent islands may be energetically favored over both uniform epitaxial films and dislocated islands. We find that if the interface energy (for dislocated islands) is more than about 15% of the surface energy, then there is a range of island sizes for which the coherent island structure is preferred.
Effect of Nonhydrostatic Stress on Crystal Growth Kinetics
Authors: Aziz Michael J. , Sabin Paul C. , Lu Guo-Quan 
Published: March 2011

ABSTRACTThe effect of nonhydrostatic stresses on the solid phase epitaxial growth rate of crystalline Si(100) into self-implanted amorphous surface layers has been measured. Uniaxial stresses of up to 6 kbar (0.6 GPa) were attained by bending wafers over SiO2 rods and annealing at a temperature too low for plastic deformation to relieve the stress in the crystal, but high enough for solid phase epitaxial growth to proceed. The growth rate on the tensile side was greater than that on the compressive side of the wafer, in marked contrast to the enhancement observed from hydrostatic pressure. The phenomenology of an “activation strain”, the nonhydrostatic analogue of the activation volume, has been developed to characterize the results. Combined with the measurement of the activation volume, the measurement reported here permits us to characterize to first order the entire activation strain tensor corresponding to the transition state for solid phase epitaxy of Si(lOO). We conclude that the transition state for this process is “short and fat”; that is, the fluctuation to the transition state involves an expansion in the two in-plane directions and a contraction in the direction normal to the surface large enough to make the overall volume change negative. The symmetry of the measured activation strain tensor is inconsistent with all bulk point defect mechanisms for solid phase epitaxy. The relevance of the activation strain formalism to heteroepitaxy and vapor phase epitaxy is discussed.
Ion Induced Crystallization and Growth of Nanoscale Grains in Ceramics
Authors: Pannikkat A. R. , Børgesen P. , Lilienfeld D. A. , Lappalainen R. , Msaad H. , Raj R. 
Published: March 2011

ABSTRACTSelf supporting thin films of amorphous alumina and zirconia were irradiated with light and heavy ions at various temperatures(25–430°C). Irradiation was found to result in the formation of 10–30 nm large grains well below conventional crystallization temperatures. These grains were quite stable against subsequent thermal growth. Crystallization, grain size, and growth depended on ion species as well as on ‘stabilizing’ additives (yttria or Pt).
Manipulation of Nucleation Sites in Solid-State Crystallization of Amorphous Si Films
Authors: Kumomi Hideya , Yonehara Takao 
Published: March 2011

ABSTRACTNucleation sites are manipulated in amorphous Si films to control grain location and the size distribution during the solid-state crystallization. The principle of the method is theoretically investigated. Nucleation is suppressed and the sites are periodically formed in the plane of amorphous films by 2-step Si ion implantation. Thermal annealing causes preferential nucleation of single nuclei at the artificial sites and they grow laterally in the film. Consequently, 3 μm large grains were arranged in a matrix with a narrow size distribution.
Microstructural Evolution of AI/Ni and Ni/AI Bilayer Thin Films
Authors: Barnard J. A. , Haftek E. , Waknis A. , Tan M. 
Published: March 2011

ABSTRACTThe growth and microstructural evolution of Al/Ni and Ni/AI bilayer thin films have been investigated as a function of Al and Ni layer thickness and thermal treatment by transmission electron microscopy. Studies were also made of Al and Ni single layers of varying thickness. All films were grown by dc magnetron sputtering using carbon coated Cu TEM grids as substrates. For the bilayers, the Al thickness was fixed at either 3.5 or 7.0 nm while the Ni thickness was varied systematically from 3.2 to 12.8 nm. Deposition sequence significantly influenced bilayer microstructure even in as-deposited samples. Al/Ni bilayers generally exhibited a finer microstructure than Ni/AI. In the 3.5 nm Al/Ni bilayers no conclusive electron diffraction evidence was found for elemental Al while for the reverse sequence both Al and NiAl3 diffraction rings were found. In the 7.0 nm Al/Ni bilayers diffraction rings due to Al were observed. The reverse sequence again produced both Al and NiAl3 diffraction rings. Interestingly, diffraction rings due to the Ni layers were found for all samples but were consistently measured at positions corresponding to a 2.5–3.5% increase in interplanar spacing. Annealing at 385°C produced evidence for generalized grain growth and strong accentuation of the electron diffraction rings due to the NiAl3 phase. Again, deposition significantly influenced annealed bilayer microstructure. For the Al/Ni sequence annealing produced polycrystalline N1AI3 island-like structures, while for Ni/AI bilayers, annealing promoted the growth of small NiAl3 crystals uniformly distributed in the film.
Characterization of the Structure and Interfaces in Metallic Superlattices
Authors: Kim Jeha , Dutcher John R. , Lee Sukmock , Stegeman George I. , Falco Charles M. 
Published: March 2011

ABSTRACTUsing magnetically enhanced dc-triode sputtering we have grown metallic multilayers of Ag/Pd and Cu/Pd with modulation wavelengths A ranging from 10 Å to 120 Å. The Ag/Pd films were prepared with two different thickness ratios of silver to palladium (1:1 and 3:1) while the Cu/Pd films all were 1:1. We observed in the Ag/Pd films that the variation with A of the (111) lattice spacing dav in the growth direction is less than 0.5%, independent of the composition. However, these films exhibited enhancements in the Rayleigh sound velocity vR of up to 22% for the 1:1 samples and 13% for the 3:1 Ag/Pd samples respectively as A decreased. The Cu/Pd films showed a slight systematic dependence of dav on A, although its variation was only approximately 0.7%. A softening in vR of up to 7% for the Cu/Pd samples was observed.
A Microfabrication Approach to Mechanical Testing of Thin Films
Authors: Read David T. 
Published: March 2011

ABSTRACTAn approach to measuring the mechanical properties of thin films with in—plane and thickness dimensions comparable to those of films in VLSI electronic devices and in multi—chip modules is being developed. The guiding principles are to utilize as much as possible the technology of microelectronic fabrication and to make the design downward—scalable in size so that eventually the very smallest films and structures can be tested. The necessary components have been designed; we are in the process of building and testing them.The specimen and associated instrumention are fabricated by semiconductor techniques on a 50 mm—diameter silicon wafer. Piezoresistors arranged as strain—sensitive Wheatstone bridges are fabricated by diffusion. One bridge, located on a grip section, is the load cell. After opening contact windows and metallization, the thin—film specimen is deposited. Then the silicon wafer is patterned and etched, leaving the specimen hanging between two instrumented grip sections linked by flexible silicon springs. Relative displacement of the grip sections is imposed by either a micrometer or a micro—stepper motor and measured by a scanned laser beam and by additional strain—sensitive bridges.
Nondestructive Measurement of Interphase Processes Using Impedance Spectroscopy
Authors: Frankovic Richard , Troyk Philip R. , Anderson James E. 
Published: March 2011

ABSTRACTImpedance spectroscopy (IS) was used as a nondestructive technique to measure the interphase processes of encapsulated microelectronic substrates exposed to high relative humidity. The advantages of IS include: sensitivity of IS to chemical kinetics, ability of in-situ testing of encapsulated packages and non-destructive nature.Samples undergoing contamination under high relative humidity, produce frequency responses resembling those found for electrochemical cells. This suggests that the presence of hygroscopic residues induce surface water uptake resulting in the formation of surface electrochemical cells and decreased interphase impedance.Samples undergoing a process of “supercleaning” using argon plasma and exposed to high relative humidity, produce frequency responses that more closely approach responses characteristic of dry samples than do conventionally cleaned or contaminated samples.
Removing the Barriers to Next Generation'S Dielectric Films: In Situ Void-Free Planarized Films
Authors: Monkowski J.R. , Logan M.A. , Wright L.F. 
Published: March 2011

ABSTRACTIn the next generation of semiconductor devices, minimum dimensions will be smaller, aspect ratios (height to width) of devices features will be larger, and BPSG dielectrics will be challenged to deal with these changes. A new process, which integrates deposition, flow, and anneal of BPSG films, and allows void-free filling of high-aspect-ratio trenches with excellent surface planarization, is presented in this paper. Scanning electron micrographs are used to show the extent of film coverage and planarization. Additional characterization includes ion chromatography, ellipsometry, stress measurements, and breakdown field measurements.
Crosslinking and Ciiain-Scission of Photosensitive Polyimidesiloxane Under Deep UV Irradiation
Authors: Jeng S. , Xu M. , Kwok H. S. , Tang D. Y. , Acharya H. R. , Rosenfeld J. C. 
Published: March 2011

ABSTRACTPolyimides are considered as promising packaging materials in multi-layer interconnections and multi-chip modules because of their low dielectric constant and good planarizability. Photosensitive polyimidesiloxane (SIM2000XL) as a newly emerging polyimide is showing not only similar properties as conventional polyimides but also the advantages of process simplification and improved adhesion. Moreover, it is proposed that SIM2000XL can be an oxygen-plasma etching barrier in multi-level lithographic systems because of its high silicon content.We characterized the photosensitivity of SIM2000XL thin films under excimer laser (193 nm) exposure. The sensitivity of SIM2000XL was found to be about 20 mJ/cm2. After the SIM2000XL thin films were exposed through a photomask in the contact mode, development gave the usual negative patterns. However, the remained film thickness after exposure reached a maximum of about 65 % of the initial film thickness and decreased with further irradiation. This can be attributed to the competing processes of polymer crosslinkage and chain-scission. This phenomenon is important for applications of polymers in DUV lithography. A detailed study of these two competing processes are presented.
Curing and Alignment of Liquid Crystalline Epoxy Networks
Authors: Ober C. K. , Barclay G. G. , Papathomas K I. , Wang D. W. 
Published: March 2011

ABSTRACTLiquid crystalline epoxy networks have been prepared from glycidyl terminated polyether oligomers of varying molecular weight. These oligomers were prepared by functionalizing hydroxy terminated oligomers based on 4,4'- dihydroxy-α-methylstilbene and α,ω-dibromoalkanes with glycidyl groups. Curing of these oligomers was carried out either within their nematic mesophase or in their isotropic state. Different thermal properties were observed after curing under these two sets of conditions. Extremely low values of the coefficient of thermal expansion in the range of 15 to 60 ppm/°C were achieved. To produce aligned thermosets, orientation of the liquid crystalline phase was induced during the curing process by a magnetic field. Orientation of these networks was measured by wide angle x-ray diffraction (WAXD).
Characterization of Polymer Dielectrics for High-Density Electronic Packaging
Authors: Wang David W. , Tong Ho-Ming 
Published: March 2011

ABSTRACTBecause of rapid advances in semiconductor technology, polymer dielectrics are finding widespread use in high-density packaging to improve performance and processability. Notable among these materials are polyimides, benzocyclobutene resins, and fluoropolymer containing composites.Polyimides have been used extensively for chip passivation and first-level packaging. Benzocyclobutenes, processed as conventional thermosets, are being investigated as thin film dielectric for use in multichip modules. A silicon containing derivative can be used as a plasma etch stop. Polytetrafluoroethylene is used either as matrix or reinforcement in circuit boards to produce a low dielectric constant composite.Knowledge of materials properties is crucial to ensure the reliability and function of products incorporating these polymers. In this article, a few selected characterization techniques for the determination of important materials properties such as solvent diffusion, plasma etch rate, and thermomechanical characteristics will be discussed.
Effects of Processing Conditions on the Material Properties of Polyimide Thin Films
Authors: Pietila Doug , DeBra Lisa , Guan John , Lee Chung 
Published: March 2011

ABSTRACTThe effects of curing rate and solvent content prior to curing were examined for Hitachi PIX L110 polyimide thin films. DMA, TMA, DSC, and wafer bow measurements were used to elucidate in-plane storage modulus, Z-axis CTE, heat capacity, and residual stress dependencies on processing conditions and film position across the wafer. It was found that the residual stress and storage modulus are highly dependent on the processing conditions. Additionally, the heat capacity and storage modulus showed significant dependency on wafer position as well as processing conditions. The Z-axis CTE was found to deviate significantly from values published for the in-plane (xy) direction.
Impedance Spectroscopy of the Polymer Thick Film Resistor/Conductor Interface
Authors: Jussila S. , Stubb H. , Pienimaa S. 
Published: March 2011

ABSTRACTImpedance spectroscopy has been used to study the electric properties of screen—printed polymer thick film (PTF) resistors over the frequency range 10 Hz — 500 MHz. With a suitable test pattern it was possible to separate the impedance response of the resistor/conductor interface from that of the resistive element itself. This proved to be useful when analysing, whether the manufacturing parameters have more influence on the properties of the interface or the bulk resistor. The main varied manufacturing parameters were curing method, curing temperature and the resistor/conductor interface (pure copper vs. silver treated copper). Furthermore, the test components were kept for 600 hours in a humid environment (85ºC / 85% RH), and after this the impedance measurements were repeated. Analysis of the effects of these manufacturing and environmental conditions on the electrical properties of PTF resistors are presented.
Effect of RF Sputtering on T/H Susceptibility of Cr/Polyimide Adhesion
Authors: Kim D. G. , Oh T. S. , Molis S. , Kowalczyk S. , Kim J. 
Published: March 2011

ABSTRACTEffects of RF sputtering on the hydrothermal stability of Cr/polyimide interfaceshave been studied using FTIR, XPS, and peel test. It has been found that RF sputter-treatment of polyimnide surface prior to metal deposition leads to an enhancement of adhesion through chemical bonding of the metal with polyimide resulting in cohesive polyimide failure. The RF sputter treatment of polyimide, however, simultaneously modifies the polyimide underneath its surface. The adhesion strength of the Cr/polyimide interfaceis degraded significantly upon exposure to a temperature/humidity (T/H) environment. It is suggested this degradation results from the hydrolysis of polyimide. The hydrolysis is facilitated by the presence of modified unstable polyimide near the interface. This degradation of adhesion strength can be minimized by converting the unstablemodified polyimide to a more stable state by re-curing the Cr/polyimide interfacebefore exposure to T/H environment.
Novel Precursors for the Deposition of II-VI Semiconductor Films
Authors: Bochmann Manfred , Webb Kevin J. 
Published: March 2011

ABSTRACTHighly sterically hindered chalcogenolato complexes M(EC6H2R3-2,4,6)2 (M = Zn, Cd, Hg; E = S, Se, Te; R = Me, Pri, But) have been prepared. Compounds with R -= But are volatile under reduced pressure and are suitable as precursors for the deposition of II-VI films.
Growth and Characterization of Highly Oxygen-Doped GaAs
Authors: Goorsky M.S. , Kuech T.F. , Mooney P.M. , Cardone F. , Potemski R.M. 
Published: March 2011

ABSTRACTHigh levels (≃ 1018cm-3) of oxygen were introduced into GaAs by using dimethyl aluminum methoxide (DMAlM0) as an oxygen-bearing precursor during metalorganic vapor phase epitaxy. Layers co-doped with oxygen and intentionally added silicon, both to concentrations of ≃ 1018 cm-3, were depleted of free carriers and had no measurable luminescence. Deep levels were present in layers grown with lower oxygen incorporation, but the compensation mechanism due to oxygen incorporation is not apparently tied to a specific defect level. The material with the electronic deep levels also possessed deep luminescence energy lines. All layers exhibited excellent surface morphology. For comparison, other layers were grown by introducing low levels of 02 and trimethyl aluminum during GaAs growth. The surface morphology of these layers was usually hazy and the layers did not exhibit the same well defined electrical and optical characteristics as the layers grown with DMAlMO.
AlxGa1-xas Growth by OMVPE Using Trimethylamine Alane
Authors: Hobson W. S. , Abernathy C. R. , Pearton S. J. , Harris T. D. 
Published: March 2011

ABSTRACTWe have investigated the growth of AlxGal-xAs (0.1 ≤ x ≤ 1) by organometallic vapor phase epitaxy using trimethylamine alane (TMAA1) as the aluminum precursor. A low pressure (30 Torr) reactor was used with hydrogen as the carrier gas. At the high gas velocities (> 1 m · s-1) employed there was no visible deposition upstream of the substrate. AIGaAs epilayers with featureless surface morphology could be obtained over the entire range of composition. The layers exhibited very strong room-temperature photoluminescence and excellent compositional uniformity (x = 0.235 ± 0.002 over a 40 mm diameter). A comparison was made between the electrical and optical characteristics of AlGaAs grown with either trimethylgallium (TMGa) or triethylgallium (TEGa). The hole concentration of the layers grown using TMGa was significantly higher than that with TEGa (e.g., 6–7 × 1017cm-3vs. 1 × 1016cm-3) for the same TMAA1 and AsH3mole fractions. High-purity AlGaAs was achieved with TMAAl and TEGa at higher AsH3flow rates.
Deposition of GaN by Remote Plasma-Enhanced Chemical-Vapor Deposition (Remote PECVD)
Authors: Choi S.W. , Bachmann K.J. , Lucovsky G. 
Published: March 2011

ABSTRACTFilms of GaN have been grown on silicon by remote plasma-enhanced chemical-vapor deposition using trimethyl gallium and ammonia. The ammonia is rf plasma excited along with He, and the trimethyl gallium is introduced downstream from the plasma generation zone. The activation energy for the growth of GaN is 0.95±0.05 eV. This is tentatively assigned to the activation of NH groups, extracted from the plasma as primary precursors for the surface reaction with trimethyl gallium (TMG), or adsorbed fragments of this molecule. At high He flow rates, an abrupt increase in the growth rate is observed corresponding to a change in the reaction mechanism which is attributed to the formation of atomic nitrogen.
Calculation of Gallium-Arsenic-Metal Phase Diagrams
Authors: Scofield James D. , Davison J. E. , Smith S. R. 
Published: March 2011

ABSTRACTContact metallizations for space-based GaAs solar cells must survive at high temperatures for several minutes. Which metallizations will survive can be predicted by properly calculated phase diagrams instead of performing hundreds of reactions. A method for calculating the ternary temperature constitution phase diagrams Is briefly explained and the phase diagrams are calculated for two Ga-As-X alloy systems. The free energy functions of the liquid and solid phases are approximated by the regular solution theory. The phase diagrams of the three binary alloy systems which form the boundaries of the ternary alloy system are utilized to calculate the binary regular solution parameters. The free energy functions for the ternary liquid and solid phases are expressed In terms of the binary regular solution parameters. The temperature and composition of the liquidus and solidus boundaries for the ternary alloy systems are calculated from these free energy functions. Calculated results are presented for the Ga-As-Ag and the Ga-As-Ge systems.