bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photo-Oxidation of Hydrogenated Amorphous Silicon-Carbon Alloys
Authors: John P. , Odeh I.M. , Qayyum A. , Wilson J.I.B. 
Published: March 2011

ABSTRACTHydrogenated amorphous silicon-carbon alloys, a-Si:C:H, have been deposited as thin films (d=0.1-0.5 micron) on crystalline silicon substrates from a capacitively coupled rf discharge in silane-propane mixtures. Variations in the stoichiometry of the films were achieved by altering the ratio of SiH4 to C3H8 flow rates at a sbstrate temperature in the range 240-260°C and total pressure between 30-70 mtorr. The silicon to carbon ratios were established by X-ray photoelectron spectroscopy, XPS, and the hydrogen content and distribution by infra-red spectroscopy.
Patterning of Gaas/AIGaAs Wafers by Focused Electron-Bear Induced Chlorine Etching and Subsequent Kbe Growth
Authors: Taneya M. , Sugimoto Y. , Hidaka H. , Akita K. 
Published: March 2011

ABSTRACTIn-situ patterning of AlxGa1-xAs (0≦x≦0.7) using a electron-beam (EB) and chlorine gas (Cl2) and the application to “In-Situ EB Lithography” are investigated. In this patterning method, an ultra-thin GaAs oxide is utilized as a resist film. The oxide resist prevents C12 gas etching of the underlying material and can be also patterned by an EB irradiation under a C12 pressure, which brings about selective etching of GaAs/AlGaAs layers. Etch rates of AlxGa1-xAs (0<x≦0.7) are 20-30 nm/min, which is almost equal to that of GaAs (20 nm/min). Using this technique of EB-induced patterning, a novel concept “In-Situ EB Lithography” is proposed, where the whole processes for EB lithography are successively conducted in a ultra-high vacuum multi-chamber system. An overgrown layer on a GaAs surface patterned by this “In-Situ EB Lithography” shows a good morphology.
Deep Structures Produced in III-V Materials by Combined Focused Ion Beam Irradiation and Dry Etching
Authors: Harriott L.R. , Wang Y.L. , Chin B.H. , Temkin H. 
Published: March 2011

ABSTRACTWe have developed a direct patterning process for InP based materials which uses ion exposure followed by dry etching to produce surface topography. The substrate is first implanted with a 20 keV Ga+ beam focused to 0.2 micron diameter. The surface pattern is then developed in the substrate by etching with or without a low energy (25 -100 eV) flood Ar+ ion beam in a C12(5×10-4 Torr) atmosphere at 180 to 2000 C. This process has been integrated in a common vacuum chamber with a gas source molecular beam epitaxy (GSMBE) system. In-situ patterning and high quality overgrowth has been demonstrated for low Ar+ ion energies during etching. In this paper, we will describe a model for the patterning mechanism and suggest how it may be exploited to achieve a complete vacuum lithography process compatible with epitaxial regrowth.
Nanosecond Thermal Processing for Ultra-High-Speed Device Technology
Authors: Sigmon Thomas W. , McCarthy Anthony M. , Weiner CA Kurt H. , Carey Paul G. 
Published: March 2011

ABSTRACTProgress in high-speed device technology is occurring by both scaling of conventional devices, such as MOSFETs and bipolars, and the development of new device structures which take advantage of multi-layer heterostructures. As scaling in lateral dimensions allows production of devices with dimensions approaching 0.lμm, vertical scaling has become a topic of concern. In this paper we focus on nanosecond thermal processing (NTP), anew area of process technology which uses a pulsed uv-laser to perform selective doping and epitaxy on nanosecond time scales. The rapid thermal cycles and precise control of impurity profiles inherent to the new technique addresses many of the problems faced in vertical scaling for silicon MOS and bipolar structures and in the fabrication of selective heteroepitaxial layers. Following a brief historical overview and description of the process, successful applications in the fabrication of submicron MOSFETs and narrow base bipolar transistors in silicon will be presented. Structural and electrical results will be presented for heteroepitaxial layers fabricated in the GexSi1-x and InxGa1-xAs material systems by the technique.
Selective Surface Modification of Fluorocarbon Resin Using Excimer Laser
Authors: Okoshi M. , Murahara M. , Toyoda K. 
Published: March 2011

ABSTRACTThe fluorocarbon resin (Teflon) which is a very stable material chemically, has chemical resistance. Because of this property, it has no affinity for oil or water. Therefore, we have tried selective area modification of the resin surface b-y using an excimer laser.Fluorocarbon resin is a polymer of C-F bonds. In our experiment, the resin surface was irradiated by an ArF excimer laser, of which the photon energy is higher than that of the C-F bond, to excite the strong C-F bonds. B radicals, the best combination for F atoms, were formed simultaneously. Consequently, F atoms of C-F bonds were pulled out by B radicals. B(CH3 )3 with absorption in agreement with the wavelength of the ArF laser were used as raw materials of the B radicals. By irradiating the gas by the ArF laser beam, the photodecomposed B radicals functioned by pulling out F atoms, and the other methyl radicals ( -CH3 ) substituted for F atoms. As the result, this resin surface turned out to be oleophilic exclusively on the areas exposed to the light.
Elevated Temperature Reactive Ion Etching of GaAs and AIGaAs in C2H6 / H2
Authors: Pearton S. J. , Hobson W. S. , Jones K. S. 
Published: March 2011

ABSTRACTThe temperature dependence of etch rate, surface morphology and atomic composition, and depth of hydrogen passivation of Si dopants in n-type GaAs and AIGaAs has been measured for reactive ion etching in C2H6 /H2. The etching of GaAs shows an increase of a factor of two between 150 and 250°C, decreasing at higher temperatures, while there is no temperature dependence for the etch rate of AlGaAs over the range 50-350°C. The As-to-Ga ratio in the nearsurface region of GaAs remains unchanged over the whole temperature range investigated and there is no polymer deposition. The etched surface morphology is smooth for both GaAs and AIGaAs for all temperatures while the depth of Si dopant passivation by hydrogen shows an increase with increasing substrate temperature during the etching treatment.
Laser Patterning and Electrical Properties of Submicron Lines of Y-Ba-Cu-O
Authors: Zheng J. P , Ying Q. Y. , Kim H. S. , Bhattacharya D. , Shaw D. T. , Kwok H.S. 
Published: March 2011

ABSTRACT0.6 µm-wide lines of high Tc Y-Ba-Cu-O have been fabricated by direct laser writing on mirror-like thin films which were grown by laser deposition without post annealing. Laser ablation etching had no effect on the Tc and Jc until the lines were < 1µm wide. The 0.6 µm-wide strip showed some degradation of Tc and Jc. The critical current densities for these patterned lines were measured to be ∼5×106 A/cm2 at 50 K.
Laser Induced Chemical Vapor Deposition of GaN
Authors: Kobayashi A. , Asai T. , Kawai S. , Chong P.J. 
Published: March 2011

ABSTRACTThin films of GaN were grown on the Al2O3 (0001) substrate by the laserinduced chemical vapor deposition technique. Morphology were different for the films grown with and without laser irradiation. Moreover, the density of nucleus and the growth rate in the case of the growth with the parallel irradiation were greater than those without irradiation. Differences were attributed to presence of photo-dissociated species in the case of the laser irradiation. Additional irradiation normal to the substrate decreased the rate, probably because of the accelerated desorption of the reactive adsorbed species.
Ordering and Energetics of Hg Overlayers on Cu(O01)
Authors: Hutchings C.W. , Dowben P.A. , Kime Y.J. , Li W. , Karimi M. , Moses C. , Vidali G. 
Published: March 2011

ABSTRACTThe growth, ordering, and energetics of Hg overlayers on Cu(O01) have been studied using atom beam scattering, LEED and angle-resolved photoemission. Two stable ordered phases have been identified: one phase is a c(2↑2) and the other phase is a higher density square lattice which has a coincidence c(4↑4) structure. A phase diagram has been determined using LEED and atom beam diffraction data for surface temperatures between 180 and 330 K. ABS data suggest out that there is a narrow coexistance region between these two phases. The isosteric heat of adsorption has been determined as a function of coverage.
In-Situ Transmission Electron Microscopy Studies of the Oxidation of Si (111) 7X7
Authors: Gibson J.M. 
Published: March 2011

ABSTRACTThe kinematical approximation is valid for High-Energy Transmission Electron Diffraction from monolayers in planview. We use this fact to study quantitatively the attack of Si (111) 7×7 by 02. Oxygen is found to bind in the bridging position of the adatom backbonds and render the structure very stable during subsequent 02 exposure. Electron-beam exposure during dosing additionally creates rapid disordering which is presumed to represent SiOx formation.
Temperature Dependent Current-Voltage Characteristics in Thin SiO2 Films
Authors: Zhao Jin , Ravindra N. M. 
Published: March 2011

ABSTRACTAn analysis of the Fowler-Nordheim tunneling (FNT) theory and its application to temperature dependent current-voltage characteristics, of very thin films of SiO2 on silicon, is presented. The final results are believed to provide the most complete examination of FN emission theory and predict the breakdown electric field in thin SiO2 films. The role of the roughness, at the Si-SiO2 interface, in determining the FNT current in these structures is also discussed.
Adsorption and Tribochemical Reactions
Authors: Mullins W. M. , Fischer T. E. 
Published: March 2011

ABSTRACTA model for chemisorption based on the Lewis theory is proposed and developed. The model reproduces the observed relationship between aqueous solubility and band gap for covalent oxides. A relationship is shown between the calculated free-energy of the surface reactions and the observed effect of water on the wear of these materials. This relationship is explained in terms of surface reaction rate and equilibrium. Similar calculations for the adsorption of -CH3functional groups are presented. The results are compared to water adsorption calculations and related to experimental wear test results for model fluids on covalent oxides. The effect of water on lubricant adsorption is discussed.
Atomically-Resolved Surface Photovoltage Probed by Optically-Excited Scanning Tunneling Microscopy
Authors: Hamers R.J. , Markert K. 
Published: March 2011

ABSTRACTScanning Tunneling Microscopy combined with optical excitation techniques is used to study non-equilibrium electronic properties of clean silicon surfaces with high spatial resolution. Tunneling potentiometry is performed to measure the excess carrier distributions via the surface photovoltage effect. Well-ordered regions of Si(111)-(7×7) show a uniform surface photovoltage effect, while strong decreases are observed near defects. The decreases in the photovoltage are attributed to an increase in the rate of recombination of electron-hole pairs in the vicinity of the defects.
Topography of Si(111): Clean Surface Preparation and Silicon Molecular Beam Epitaxy
Authors: Tung R. T. , Schrey F. , Eaglesham D. J. 
Published: March 2011

ABSTRACTLine defects at the interfaces of epitaxial silicide layers grown at room temperature on Si(111) are found to correspond to steps on the original surface. This has enabled the examination, by transmission electron microscopy, of the topography of large areas of the Si surface after various treatments. Methods for removal of surface oxide and carbide are compared. Silicon molecular beam epitaxy (MBE) is shown to occur via step-flow mechanism at high temperatures, and through nucleation and growth of islands on terraces at low temperatures.
Electronic and Atomic Properties of a-C:H/Semiconductor Interfaces
Authors: Wittmer M. , Ugolini D. , Oelhafen P. 
Published: March 2011

ABSTRACTWe have investigated the electronic and atomic properties of the interface between amorphous hydrogenated carbon (a-C:H) films and the semiconductor materials Si, Ge and GaAs with photoelectron spectroscopy, high resolution transmission electron microscopy and ion channeling technique. The different properties of the interfacial layers are summarized and compared to the adhesion quality of a-C:H films on these semiconductor materials.
Non-Equilibrium Molecular Dynamics Simulation of the Rapid Solidification of Metals
Authors: Richardson Cliff F. , Clancy Paulette 
Published: March 2011

ABSTRACTThe ultra-rapid melting and subsequent resolidification of Embedded Atom Method models of the fcc metals copper and gold are followed using a Non-Equilibrium Molecular Dynamics computer simulation method. Results for the resolidification of an exposed (100) face of copper at room temperature are in good agreement with recent experiments using a picosecond laser. At T = 0.5 Tm, the morphology of the solid/liquid interface is shown to be similar to a Lennard-Jones model. The morphology of the crystal-vapor interface at 92% of Tm shows a significant disordering of the topmost layers. Difficulties with the EAM model for gold are observed. Comparison of the Baskes et al. and Oh and Johnson embedding functions are discussed.
Structure and Properties of Inversion Domain Boundaries in β-Sic
Authors: Lambrecht W. R. L. , Lee C. H. , Segall B. 
Published: March 2011

ABSTRACTThe structure of inversion domain boundaries in β-SiC (i.e. boundaries between domains with inverted Si and C positions) is investigated by means of a Keating model. For the (110) boundary, the relaxation of the C-C and Si-Si bonds towards the ideal bond lengths which occur in the diamond structure can basically be achieved by a rotation of neighboring Si-C bonds. For the (001) boundary, it is achieved by varying the spacing between the domains. The electronic properties and total energy of formation of the relaxed (110) boundary are studied by means of linear muffin-tin orbital calculations. The interface localized states in the semiconducting gap are mainly due to the Si-Si bonds and lead to a semimetallic situation near the interface.
The Application of Glancing Angle Exafs to Study the Structure of Platinum-Nickel Multilayers
Authors: Lamble G.M. , Heald S.M. , Clemens B.M. 
Published: March 2011

ABSTRACTRecent reports have correlated the mechanical properties of multilayers with a structural expansion of the constituents. Whether this expansion is an interface or bulk effect remains in dispute. We apply the technique of glancing angle EXAFS to obtain information about the local structure and multilayer composition and use these results to shed light on certain aspects of this controversy. The experiments were performed on platinum-nickel multilayers of varying bilayer thickness. Measurements were made by fluorescence detection of EXAFS beyond both the Pt LIII and the Ni K edges. Considerable interlayer mixing is evident, as is the presence of order within the interface. We additionally find that the bulk metallic character is retained within the layers.
Atomic Scale Structure of Twin Boundary In Y-Ba-Cu-O Superconductors
Authors: Zhu Yimei , Suenaga M. , Xu Youwen , Kawasaki M. 
Published: March 2011

ABSTRACTHigh resolution electron microscopy of the twin boundary layers in YBa2(Cu1-xMx)3O7–8 for x=0 and 0.02 and M=Zn, Fe and Al showed that the boundary widths are ∼1 nm for the pure and the Zn substituted YBa2Cu3O7, 2.5∼3 nm for the Fe and Al substituted oxide. It was found that the lattice plane is shifted across the twin boundary by (1/3 ∼ 1/2)·2d(110) along the boundary. The broadening of the layer for the cases of Fe and Al is also thought to be associated with a reduction of the twin boundary energy, which also leads to an increased twin density.
Photoemission Characterization of Thin Film Nucleation on Inert Substrates
Authors: Haugstad G. , Raisanen A. , Caprile C. , Yu X. , Franciosi A. 
Published: March 2011

ABSTRACTSynchrotron radiation photoemission was used to characterize Sm and Mn thin film nucleation and growth on solid Xe substrates, in the 3×1014 - 2×1016 atoms/cm2 coverage range. Film growth is well approximated by a model in which the nucleation site density remains constant and hemi-ellipsoidal particles increase in size until coalescence is achieved. Site density and average cluster size are determined from the coverage-dependence of metal and Xe photoemission intensities. Size estimates are confirmed by experimental fingerprints of coalescence.
The Initial Stages of MBE Growth of InSb on GaAs(100) - A High Misfit Heterointerface
Authors: Kiely C.J. , Rockett A. , Chyi J-I. , Morkoc H. 
Published: March 2011

ABSTRACTThe initial stages of heteroepitaxy of InSb on GaAs(100) grown by MBE have been studied by transmission electron microscopy. Three dimensional InSb island growth occurs in which the majority of the 14.6% misfit strain is accommodated by a square array of a/2<011= edge-type misfit dislocations. The implications of each island having a well defined defect array before coalescence into a continuous epilayer are discussed. Some 600-type a/2<101= interfacial defects and associated threading dislocations are also observed in coalesced films and possible reasons for their existence are explained. A strong asymmetrical distribution of planar defects in the InSb islands is observed and the origin of the asymmetry is discussed. Finally some evidence for local intermixing in the vicinity of the interface is presented.
Large Area Silicon Avalanche Photodiodes: Photomultiplier Tube Alternate
Authors: Reiff G. , Squillante M.R. , Serreze H.B. , Entine G. , Huth Gerald C. 
Published: March 2011

ABSTRACTSilicon avalanche photodiodes have recently been shown to be a potential replacement for vacuum tube photomultipliers in many nuclear scintillation detector applications. The large active area, low noise, and ease of use of these solid-state photomultipliers makes them ideally suited to scintillation detector applications where overall size and ruggedness are a major concern. Historically, avalanche photodiodes have been limited for use in this capacity by small active areas, low internal gains, and poor optical sensitivity at the wavelengths at which most solid scintillator materials emit. Recent advances as the result of research aimed directly at the solution to these problems however, have successfully demonstrated one inch active area silicon avalanche photodiodes which produce a FWHM resolution of 9.5% for Cs137 at room temperature when coupled to a 1″ × 1″ NaI(Tl) scintillation crystal. Improvements to both material quality and device structure have advanced the state-of-the-art to make silicon avalanche photodiodes a viable alternative in scintillation gamma spectroscopy as well as for large area optical, beta, and low energy x-ray detectors.
Thick Surface Barrier Detectors Made of Ultra-High Purity P-Type Si Single Crystal
Authors: Shiraishi F. , Takami Y. , Hosoe M. , Ohsawa Y. , Sato H. 
Published: March 2011

ABSTRACTThe detector material used in this experimments is Ultra-High Purity p-type Si crystal. The material was single-crystalized through floating zone process from poly-crystal grown by thermal decomposition of highly refined mono-silane gas which had been purified by molecular sieves of specially prepared Zeolite powder.The resisitivity at room temperature is normally above 30 kΩ.cm, and the value of the highest grade ones exceeds 100kΩ.cm which corresponds to the Boron concentration of 1.5×l011 B/cm3.The potentiality of this material for detector use was investigated through Surface Barrier Detector fabrication. Detectors of above 4 mm thick and of excellent characteristics both at room temperature and at liq. N2 temperature could readily be fabricated. Owing to tie extremely high resisitivity, detectors can be made either partially depleted or totally depleted simply by properly selecting the wafer resisitivity and the thickness.In detector fabrication, the proper surface chemical treatment is very important, and seriously affects the leakage current and breakdown characteristics.Ultra-High Purity Si is promising as new detector material and has good potentiality to replace Si(Li) as followings:1) simple and easy detector fabrication,2) potentiality of thick detector fabrication (∼1cm),3) no precipitation problem of Li ions, and4) feasibility of thick ⊿E detector with thin entrance window on both faces.
Characterization of Single Crystal Mercuric Iodide (HgI2) Using Thick Detector Structures
Authors: Beyerle A. , Hull K. , Markakis J. , Schnepple W. , Van Den Berg L. 
Published: March 2011

ABSTRACTSingle crystal sections of HgI2 (about 1 cm thick) have been evaluated for charge carrier transport properties. Using these thick detector structures, surface effects produced during fabrication are reduced, enhancing the bulk property characteristics. The standard time-of-flight method was used to determine electron and hole mobilities. Lifetime measurements for electrons and holes were made by direct observation of the carrier decay where crystal transit times were long compared to lifetimes. Nonlinear charge carrier velocities have been observed during mobility measurements. These nonlinearities impair a partial charge collection technique [1,2,3] for spectra generation taken with thick detectors while having a lesser effect on the standard full charge collection approach. Partial charge collection methods have produced greater peak efficiencies than full charge collection, and investigations of crystal properties are being used to enhance this method.
State-of-the-Art X-Ray Detectors Fabricated on PCG Grown Mercuric Iodide Platelets.
Authors: Squillante M. R. , Lis S. , Hazlett T. , Entine G. 
Published: March 2011

ABSTRACTRecent developments on HgI2 detectors fabricated from platelets grown by the Polymer Controller Growth (PCG) technique have resulted in a better understanding of this remarkable process and provide increased hope for the future of room temperature operable, high resolution x-ray detectors. The benefits of PCG are higher purity using reagent grade materials, better control of stoichiometry, rapid growth, and simplified fabrication. This latter benefit is even more significant when the extreme fragility of HgI2 crystals is considered. The problems of device resolution crystal stability and uniformity, and control ot platelet growth were investigated under a NASA funded program. HgI2 devices fabricated from PCG platelets gave room temperature energy resolutions under 400 eV (FWHM) for the 5.9 eV Mn x-ray. Models for the polymer assisted transport are discussed along with an analysis of spectra obtained from PCG grown devices. Reproducibility has been demonstrated both for platelet growth and device performance.
Ohmic and Rectifying Contacts on High Resistivity P-Type Cadmium Telluride
Authors: Musa A. , Ponpon J.P. , Hage-Ali M. 
Published: March 2011

ABSTRACTOhmic and rectifying contacts on high resistivity etched P-type cadmium telluride have been studied in order to produce diode structures.For this,we have first investigated the properties of gold contacts obtained by chemical reactions of CdTe dippedin gold chloride.Both electrical characterization and structure have been analyzed as a function of the experimental conditions of the contact deposition.The results can be interpreted in terms of a current flow enhanced by tunnelling through the Au-CdTe junction and related to the structure of the interface a few tens of nanometer below the gold contact. In addition,several rectifying contacts have been investigated , in order to achieve a structure having low leakage current.