bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical Studies of The Uniformity of Thermally Induced In-Plane Strain in Thin Gallium Arsenide Films
Authors: Taysing-Lara M. , Shen H. , Wraback M. , Pamulapati J. , Dutta M. 
Published: April 2011

ABSTRACTIn-plane anisotropic strain can be employed in the design of a new class of optoelectronic devices, such as high contrast, polarization sensitive spatial light modulators. One of the key issues involved in realizing these devices is obtaining a controllable and uniform in-plane strain. We have studied the uniformity of thermally induced in-plane strain in MOCVD grown GaAs lift-off thin films mounted on LiTaO3 or CaCO3 substrates. The experiment exploits the straininduced splitting of the excitonic interband transition at low temperature through absorption measurements using a Ti-Sapphire laser focused to a spot size less than 100 μm. The polarization vector of the incident light was oriented along an axis which enhances both features. From the energy positions of these transitions, the magnitude as well as the type of the in-plane strain was determined. Topographic scans performed over a 1.4mm X 1.4mm area for the sample bonded to CaCO3, and along a 2 mm line for that bonded to LiTaO3 revealed variations in strain of less than 5%.
Van Der Waals Epitaxy Versus Homoepitaxy of Low Temperature GaAs (111) Layers
Authors: Gray Jennifer L. , Rumaner L.E. , Yoo H.M. , Ohuchi F.S. 
Published: April 2011

ABSTRACTIn the design of GaAs devices, material selection for heteroepitaxy is limited due to the large amount of strain produced by lattice mismatch. To overcome this problem, a new growth method has been proposed called van der Waals Epitaxy (VDWE). This process attempts to decouple the interface through the growth of a van der Waals bonded crystal layer in-between the two materials with dissimilar lattice constants, thereby accommodating the lattice mismatch. Typical van der Waals materials such as GaSe, have hexagonal crystal structures and are grown with the c-axis perpendicular to the surface due to the nature of the bonding. These materials have a low surface energy and are not very reactive. In addition, they are only stable at relatively low temperatures. This poses two constraints to the growth of GaAs on GaSe. Initial experiments were done to investigate the possibility of growing GaAs (111) layers homoepitaxially at temperatures compatible with van der Waals crystals, with high crystallinity and a smooth surface. Twinned growth layers 1.7μm thick, were obtained at 350° C on a GaAs (111)B substrate using MBE. Further experiments looked at homoepitaxial growth on (111)A substrates and at slightly higher temperatures. These results were then compared to GaAs layers grown on GaSe layers in which nucleation occurs on a van der Waals surface as opposed to the covalently bonded GaAs substrate. The relative quality of the layers was analyzed using RHEED and TEM.
Liquid Phase Epitaxial Growth and Characterization of GaAs on InP Substrates
Authors: Kim Dong-Keun , Lee Hyung-Jong , Lee Byung-Teak 
Published: April 2011

ABSTRACTOptimum growth conditions were investigated to obtain high quality heteroepitaxial GaAs layers on InP substrates by liquid phase epitaxy (LPE). Addition of about 0.005wt% of Se to the Ga growth melt effectively suppressed dissolution of the InP substrates into the melt during the initial stage of the growth, resulting in a significantly improved surface morphology. The crystallinity and the surface morphology could be further improved by growing undoped GaAs layers on thin Se-doped buffer GaAs as well as using InP substrates patterned with grating structure. The transmission electron microscopy observation indicated that the misfit dislocations interact with each other at the grating region, resulting in a lower dislocation density in the upper GaAs layer. The (400) double crystal X-ray diffraction peaks of the undoped GaAs showed fullwidth- at-half-maximum of about 380 arcsec, which is comparable with the previously reported values using more sophisticated growth techniques.
MOVPE Growth and Doping of ZnTe Using Tertiarybutylphosphine as the Metalorganic Doping Precursor
Authors: Perkins N. R. , Dawson-Elli David F. , Kuech T.F. 
Published: April 2011

ABSTRACTZnTe has gained attention as a promising material for short wavelength optoelectronic applications. Unlike ZnSe, ZnTe can be doped p-type but not n-type. There are few reports detailing the growth and doping of ZnTe films through the MOVPE technique. We present growth and doping studies for ZnTe formed through low pressure MOVPE. Dimethylzinctriethylamine and diisopropyltelluride were chosen as the metalorganic precursors. Growth studies were carried out on both GaAs (100) and GaSb (100) substrates. Growth morphology was very sensitive to both the lattice mismatch and the initial surface preparation. This is particularly evident on the GaSb substrates. ZnTe growth temperatures ranged from 340 to 420°C, and growth rates of up to 1 μm/hour were achieved. ZnTe was found to be readily doped using tertiarybutylphosphine, with p-type concentrations ranging from 4×1016 cm−3 to 2x1019 cm−3, and corresponding room temperature hole mobilities between 55 and 12 cm2/V-sec. Tertiarybutylphosphine was also observed to significantly improve the surface morphology for growths on GaSb substrates.
Structure and Electronic Properties of Misfit Dislocations in ZnSe/GaAs(001) Heterojunctions
Authors: Chen Y. , Liu X. , Weber E. , Bourret E. D. , Olego D. J. , Dorman D. R. , Gaines J. M. , Tasker N. R. , Liliental-Weber Z. , Haller E. , Washburn J. 
Published: April 2011

ABSTRACTStudies of the structure and electrical properties of regular and irregular misfit dislocations in undoped and N-doped ZnSe epilayers grown on GaAs(001) substrates by transmission electron microscopy (TEM), cathodoluminescence (CL) are reported. In undoped ZnSe epilayers, two sets of misfit dislocation arrays were observed: a straight orthogonal array along [110] and, and an irregular array roughly along [100] and [010] directions. The CL observations suggest that the irregular dislocations trap carriers more efficiently than the dislocations along <110>, possibly due to the high density of kinks existing along the zig-zag irregular dislocations. These irregular dislocations can be eliminated by doping nitrogen in the ZnSe epilayer with [N]≥l×1018 cm−3.
Ordered Structures of Zn1-xFexSe Epilayers Grown on GaAs Substrates with ZnSe Buffer Layers
Authors: Wei H.-Y. , Beesabathina D. Prasad , Salamanca-Riba L. , Jonker B. T. 
Published: April 2011

ABSTRACTWe observed the coexistence of two types of ordered structures, Cu3Au and CuPt, in Zn0.4Fe0.6Se epilayers grown on ZnSe buffer layers on (001) GaAs substrates by transmission electron microscopy. In addition, the Cu3Au ordered structure exists with a multi-faceted domain shape. Energy dispersive x-ray spectra from these domains showed higher Fe concentration than in the disordered matrix. However, in Zn0.5Fe0.5Se epilayers, we only observed CuAu-I ordered multi-faceted domains. The samples with relatively high Fe concentration (x ≈0.6) also showed domains of FeSe with a hexagonal structure with triangular form coexisting with Cu3Au ordered domains. Strain-induced interdiffusion takes place between the buffer layer and the epilayer as evidenced by a rough interface between the alloy and the buffer layer.
Single Crystal Multilayer Coating on ZnSe and CdSe
Authors: Alov D.L. , Kolchin A.A. , Rybchenko S.I. 
Published: April 2011

ABSTRACTCVD is applied to grow the multilayer structure on CdSe proposed as a promising coating for IR-optics. The coating is composed of alternately grown CdS and CdSe single crystal layers. The proposed coating characteristics are expected to be much better than those of the coatings produced by the sputtering method.
Influence of Surface Step Density on the Growth of Mercury Cadmium Telluride by Molecular Beam Epitaxy
Authors: Colin T. , Minsås D. , Gjøen S. , Sizmann R. , Løvold S. 
Published: April 2011

ABSTRACTWe report for the first time the results of structural and optical characterizations performed on Mercury Cadmium Telluride (MCT) grown simultaneously by Molecular Beam Epitaxy (MBE) on (11 1)B 4°misoriented and (211)B CdZnTe substrates. These two Te-terminated surfaces differ only by the density and the nature of their surface steps. In MBE conditions we do not observe any difference of incorporation between the two orientations at low growth temperatures and only a slight difference in Te and Hg incorporations above 200°C. This study confirms that the growth mode is essentially the same on both orientations and the growth proceeds by step-flow. The higher step density on (211) surfaces allows broader tolerances on the substrate temperature for the growth of twin-free material. It also leads to higher crystalline quality for the lowest temperatures. These observations have been confirmed by magneto-absorption experiments on superlattices grown simultaneously on both orientations.
Atomic Scale Properties of Normal and Inverted MBE-Grown Interfaces as Revealed by Zeeman Studies
Authors: Grieshaber W. , Bodin C. , Cibert J. , Wasiela A. , Merle-D'Aubigne Y. , Gaj J. , Feuillet G. 
Published: April 2011

ABSTRACTThe enhanced Zeeman effect of excitons in asymmetric CdZnTe-CdTe-CdMnTe quantum wells is studied quantitatively to gain information separately on the profile of the normal and inverted interfaces. The normal interface appears as more “abrupt” than the inverted interface. This behaviour is well accounted for if we assume that during the growth a rapid Cd/Mn exchange takes place between the surface layer and the subsurface one.
Interface Reaction Kinetics for Permalloy-Tantalum Thin Film Couples
Authors: Kellock A.J. , Baglin J.E.E. , Coffey K.R. , Howard J.K. , Parker M.A. , Neiman D.L. 
Published: April 2011

ABSTRACTThermal interdiffusion mechanisms and kinetics have been studied for Ta-Permalloy (Ni80Fe20), Ta-Ni and Ta-Fe thin film couples, in the temperature range 300°C - 600°C. Interaction modes identified for the Ta-NiFe system include: fast diffusion of Ta into grain boundaries of NiFe, and nucleation and growth of Ni3Ta, with consequent depletion of Ni in the remaining NiFe, and eventual segregation of Fe.
Grain Boundary Diffusion in NiFe/Ag Bilayer Thin Films
Authors: Gall M. , Pellerin J.G. , Ho P.S. , Coffey K.R. , Howard J.K. 
Published: April 2011

ABSTRACTX-ray photoelectron spectroscopy (XPS) has been used to investigate grain boundary diffusion of Ag through 250 Å thick Ni80Fe20 (permalloy) films in the temperature range of 375 to 475°C. Grain boundary diffusivities were determined by modeling the accumulation of Ag on Ni80Fe20 surfaces as a function of time at fixed annealing temperature. The grain boundary diffusivity of Ag through Ni80Fe20 is characterized by a diffusion coefficient prefactor, D0,gb, of 0.9 cm2/sec and an activation energy, Ea,gb, of 2.2 eV. The Ni80Fe20 film microstructure has been investigated before and after annealing by atomic force microscopy and x-ray diffraction. The microstructure of Ni80Fe20 deposited on Ag underlayers remained relatively unchanged upon annealing.
Microstructural Development at Ti-Based Alloy/Coated SiC
Authors: Strangwood M. , Ponton C.B. , Delplancke M.P. , Vassileris V. , Winand R. 
Published: April 2011

ABSTRACTThe kinetics of formation of reaction layers at the interface between a Ti-based alloy (β-21s) and graphite blocks coated first, by CVD techniques, with a 100 μm layer of SiC and then either TiC or C were determined. The rate controlling step for reaction at 900°C and 10 MPa for up to 6 hours was found to be carbon diffusion through the reaction layer. The behaviour was found to be consistent with that of composite systems for prolonged heat treatment and the same growth behaviour was exhibited by both systems. Incubation times of 0.42 and 0.9 hours were determined for reaction layer growth in the TiC- and C-coated systems respectively. The reaction layer/Ti-alloy bond strength was good but all couples failed readily, especially if any C layers remained. The growth conditions of TiC coatings by reactive magnetron sputtering were determined for two different types of gas mixtures: CH4/Ar and C2H2/Ar. The composition and structure of the films were extensively studied.
Grain Growth Suppression and Enhancement by Interdiffusion in Thin Films
Authors: King Alexander H. , Harris Karen E. 
Published: April 2011

ABSTRACTGrain structure and grain growth in thin metallic films are important because of their effects on properties such as yield strength, electrical resistance and electromigration resistance. Since almost all thin films are used in contact with a substrate and many also have contacts with overlayers, it is important to consider how interactions with other materials affect the grain growth process. In this paper we consider the effects of diffusive interactions. We will show that interdiffusion often accompanies grain growth and that it can result in a number of novel grain boundary reactions, driven by a variety of effects. Using TEM techniques, we demonstrate cases of grain growth suppression and grain growth enhancement resulting from interdiffusion of solute atoms in gold thin films. The reasons for the observed effects will be considered with a view to providing a fundamental understanding of the types of systems that might be expected to exhibit the various phenomena.
Role of the Epitaxy Relations in the CoCrPt Thin Films with Bilayer V/Cr Underlayers
Authors: Glijer Pawel , Sivertsen John M , Judy Jack H 
Published: April 2011

ABSTRACTThe effects of grain-to-grain epitaxy conditions on the magnetic properties of high coercivity CoCr13Pt13 films with bilayer Cr/Cr, V/Cr and V/V underlayers were studied. V/Cr films were used in order to obtain underlayers that would differ from Cr only by a size of the lattice constant. Introduction of V instead of Cr as an underlayer changed the relative misfits between CoCrPt and the underlayer lattice and increased the amount of {0002} texture in the magnetic film. This effect led to a decrease in the in-plane coercivity. CoCrPt/V/Cr and CoCrPt/Cr/Cr films exhibited similar texture of the underlayer, the same microstructure and similar level of internal stress. Correspondingly the decrease in coercivity did not exceed 10% (from 2.7 kOe to 2.5 kOe). On the other hand CoCrPt/V/V film had more than 4 times smaller coercivity (0.6 kOe). In this case, change in the magnetic properties was caused not only by altered misfits but also by the change in microstructure, texture and state of stress in the film. Results obtained indicate that small changes in misfits between a magnetic layer and an underlayer can be effectively used to control coercivity only if other structural parameters remain unchanged.
GMR, Structural, and Magnetic Studies in NiFeCo/Ag Multilayer thin Films
Authors: Jarratt J.D. , Barnard J.A. 
Published: April 2011

ABSTRACTGiant Magnetoresistance (GMR), crystal structure, and magnetic properties have been investigated in a series of sputtered Ni66Fe16Co18/Ag multilayer films with induced uniaxial anisotropy. The film thickness ranges studied were 20 and 25 Å for NiFeCo, and 25 to 50 Å for Ag. GMR was only evident in the films after post-deposition annealing. This onset of GMR is thought to be due to the breaking up of the NiFeCo layers into ferromagnetic platelets or islands by the immiscible Ag diffusing perpendicular to the film plane along the grain boundaries. The magnitude and field sensitivity of the GMR was dependent on the annealing time and temperature. High angle x-ray diffraction (HXRD) was used to reveal the overall film structure and growth texture and low angle XRD (LXRD) was used to investigate the quality of the multilayer structures. M-H hysteresis loops revealed in-plane uniaxial anisotropy in as-deposited films which is eventually eliminated with annealing. The easy axis squareness experiences a pronounced decrease with lower temperature annealing, but then increases slightly with annealing temperature.
Pulsed Laser Deposition of Bi4Ti3O12 Thin Films on Indium Tin Oxide Coated Glass
Authors: Cho H-J. , Jo William , Noh T. W. 
Published: April 2011

ABSTRACTBi4Ti3O12 thin films have been grown on indium tin oxide coated glass by pulsed laser deposition. The films are rapidly thermal annealed at 650 °C in various kinds of ambients. X-ray diffraction and scanning electron microscopy are used to investigate crystallization and microstructures, respectively. Using Auger electron microscopy, chemical compositions and depth profiles are examined. Optical and current-voltage characteristics measurements of the films show that their transmittance and leakage current behaviors are strongly dependent upon the microstructures. O2 partial pressure in the rapid thermal annealing process is found to be an important parameter which determines crystallization, microstructures, and leakage current behaviors of the Bi4Ti3O12 thin films.
Improved Surface Roughness at Poly-Oxide/Poly-Si Interface by a Novel Oxidation Method
Authors: Jun M.C. , Kim J.W. , Kim K.B. , Ahn B.C. , Han M.K. 
Published: April 2011

ABSTRACTWe present a novel oxidation method to improve the surface roughness at the poly-oxide/poly-Si interface. Instead of directly oxidizing the poly-Si to the desired thickness of the SiO2, a thin oxide layer is thermally grown on the poly-Si layer and then an a-Si layer is deposited on the top of the oxide layer. The a-Si layer is used as a silicon-source during next step of oxidation. The a-Si layer is fully oxidized until the poly-oxide/poly-Si interface advances below the initial interface. For comparison, the poly-oxide/poly-Si interface is also obtained by the conventional oxidation method. The surface roughness at the interface is investigated using transmission electron microscopy (TEM) and atomic force microscopy (AFM). For the novel oxidation method with the 50 Å thick intermediate oxide, the rms surface roughness at the poly-oxide/poly-Si interface is 30 Å, whereas that is 120 Å for the conventional method.
Growth of Rock-Salt and Spinel Structured Oxides on α-Al2O3, c-ZrO2and MgO
Authors: Ramamurthy Sundar , Kotula Paul G. , Carter C. Barry 
Published: April 2011

ABSTRACTPulsed-laser deposition has been used to grow thin films of the rock-salt and spinel structured oxides NiO, CoO and C03O4on single-crystal substrates of α-Al2O3, MgO and C-Z1O2. The resultant microstructures were characterized in plan-view by transmission electron microscopy and by low-voltage scanning electron microscopy. In all the depositions, the parameters could be controlled to grow predominantly single-crystal films. In the NiO/(0001)α-Al2O3and CoO/(100)c-ZrO2systems, {111}-oriented films were observed which were found to be twinned close to 60° and 90° about <111> respectively. Growth of cobalt oxide films on (100) MgO at 800°C and 15 mTorr of oxygen produced {100}-oriented domains of C03O4meeting at antiphase boundaries. These observations and other recent studies re-emphasize the role of substrate crystallography in governing the orientation relationships in the overlayer.
The Effects of High Temperature Exposure on the Fracture of Thin Tantalum Nitride Films
Authors: Moody N. R. , Venkataraman S. K. , Nelson J. C , Worobey W , Gerberich Andw. W. 
Published: April 2011

ABSTRACTContinuous microscratch testing was used in this study to determine the effects of elevated temperature exposure on the adhesion and toughness of thin tantalum nitride films. These films were sputter-deposited at room temperature on sapphire substrates to a nominal thickness of 600 nm with some films heated to 600°C in vacuum while others were heated to 600°C in air. The films heated in vacuum exhibited no changes in composition or structure while the films heated in air completely transformed to tantalum pentoxide. Comparison of the results shows that the interfacial fracture toughness increases from 0.5 MPa-m1/2 for as-sputtered films to 0.8 MPa-m1/2 for films heated in air. However, the toughness increases to more than 3.0 MPa-m1/2 when the films are heated in vacuum. The increase in toughness values follows the reduction in deposition defect content where formation of an oxygen deficient tantalum oxide layer in air from the as-sputtered film increases interfacial toughness slightly while full densification of the tantalum nitride films in vacuum increases toughness to very high levels.
Local Texture and Electromigration in Fine Line Microelectronic Aluminum Metallization
Authors: Hurd J. L. , Rodbell K. P. , Knorr D. B. , Koligman N. L. 
Published: April 2011

ABSTRACTAluminum films 1 μm thick were deposited on oxidized silicon by sputtering and partially ionized beam evaporation to vary the crystallographic texture. These films were patterned into lines and subsequently annealed at 400 °C for 1 h. A strong correlation between the electromigration behavior and the blanket film texture (X-ray diffraction (XRD) / pole figures) has been reported previously for these films. In this work, an Electron Backscatter Diffraction (EBSD) a.k.a. Backscatter Kikuchi Diffraction (BKD) technique was employed using a scanning electron microscope (SEM) to interrogate individual grain orientations. BKD pole figures were acquired for lines ≥0.3 μm wide and for blanket (pad) regions. Identical, inverse pole figures were found for blanket films measured using both XRD and BKD (pads). Furthermore, the BKD (111) fiber texture shows a line width dependency, with narrow lines having a slightly improved texture over blanket (pad) regions. Local grain orientations were investigated near and within electromigration testing sites with characteristic void and hillock morphologies. The relationship of neighboring grain orientations to electromigration damage is shown.
Fabrication of Polycrystalline Si1−xGex Films on Oxide for Thin-Film Transistors
Authors: Tsai Julie A. , Tang Andrew J. , Reif Rafael 
Published: April 2011

ABSTRACTPolycrystalline-Si1−xGex films have been formed by various methods on oxide-coated Si substrates at temperatures ≤600°C. Compared to thermal growth, plasma deposition of poly-Si1−xGex promotes smoother films with smaller grains having a {200}-dominated texture. Poly-Si1−xGex Alms formed by plasma deposition of amorphous-Si1-xGex followed by a crystallization anneal have an even smoother surface with grain sizes enhanced by an order of magnitude and a weak {111} grain texture. Hydrogen incorporated in amorphous-Si1−xGex evolves completely during crystallization without disrupting the smooth surface morphology. The largest grain sizes (∶1.3μm) are achieved in poly-Si1−xGex films formed by Si+ ion implantation for amorphization with a subsequent recrystallization anneal.
Microstructures of Chemical-Vapour-Deposited Tin Films
Authors: Yoshikawa Noboru , Kikuchi Atsushi 
Published: April 2011

ABSTRACTA gas mixture consisting of TiCl4, H2 and N2 was fed into an externally-heated steel tube, and TiN was deposited on the inner wall by CVD. Microstuctures of the films were observed and their relationships with the preferred crystal orientations were studied. Distributions of the film growth rate and gas concentrations along the axial direction were calculated.By comparing the film microstructures with the calculated local deposition conditions, it is shown that formation of the films with (110) preferred orientation correlated with the conditions at high temperature and low partial pressure of TiCl4 on the substrate.