bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Thickness and Wavelength on the Mechanical Properties of a Compositionally Modulated Ceramic Thin Film
Authors: Oliver W. C. , List F. A. , McKee R. A. 
Published: March 2011

AbstractThe hardness and modulus of thin (<1 μm) ceramic films have been investigated using the differential mechanical properties microprobe (DMPM). The DMPM consists of a computer controlled ultra-low load indentation system with a special system that allows the elastic stiffness of the contact to be determined continuously during the indentation process. The films were deposited in a molecular beam epitaxy (MBE) system utilizing unique high temperature effusion cells. Two specimens have been studied. The first is a wedge shaped layer of amorphous Al2O3 on a silicon substrate. The thickness of the layer varies from 0 to 990 nm at the two extreme sides of a 3 in. silicon wafer. The effect of layer thickness on the hardness and modulus as measured with the DMPM has been quantified for this system. The second specimen is made up of 38 repetitions of alternating layers of crystalline TiO2 and amorphous Al2O3. The wavelength of the composition modulation and the thickness of the film varies uniformly from 0 to 38 nm and from 0 to 1460 nm respectively across the 3 in. diameter of the silicon substrate.
Studies of Si Surface Chemistry and Epitaxy Using Scanning Tunneling Microscopy and Spectroscopy
Authors: Avouris Phaedon , Wolkow Robert 
Published: March 2011

ABSTRACTWe apply scanning tunneling microscopy (STM) and spectroscopy (STS) to study the reaction of NH3 with Si(111)-(7×7), and the epitaxial growth of CaF2 on Si(11). By a combination of topographs and atom-resolved spectra we can follow the spatial distribution of the reaction and changes in electronic structure with atomic resolution. We find that there are strong site-selectivities for the NH3 reaction on the 7×7 surface. We also observe the initial stages of the CaF2 deposition and even are able to image insulating multi-layer CaF2 films.
Silane Adsorption and Decomposition on Si(111)-(7×17)
Authors: Gates S. M. , Greenlief C. M. , Beach D. B. 
Published: March 2011

ABSTRACTThe reactive sticking coefficient, SR, of SiH4 on the Si(111)-(7×7) surface has been studied as a function of hydrogen coverage (ΘH) in the surface temperature (TS) range 80–500°C. At 400°C, evidence is seen for two adsorption regimes which are proposed to correspond to minority and majority surface sites. On the minority sites (ΘH = 0 to 0.08), SR is approximately independent of TS. On the majority sites (ΘH > 0.08), SR is a complicated function of TS and ΘH. After SiH4 exposure, surface SiH is the dominant stable decomposition intermediate from 80 to 500°C, with detectable populations of SiH2 and SiH3 present at the lowest temperatures.
Chemisorption of HF on Silicon Surfaces
Authors: Joycea S. A. , Yarmoff J. A. , Johnson A. L. , Madey T. E. 
Published: March 2011

ABSTRACTWe have investigated the interaction of gaseous hydrofluoric acid (HF) with single crystal silicon surfaces using soft x-ray photoemission spectroscopy and Electron Stimulated Desorption Ion Angular Distributions (ESDIAD). Examination of the Si(2p) core level for surfaces saturated with HF shows the formation of silicon-fluoride bonds indicating the dissociative chemisorption of HF on both Si(111) and Si(100) surfaces. Inspection of the F(2s) and F(2p) valence levels at saturation coverage indicate that only one-half monolayer of fluorine bonds to the silicon. The primary ion desorbed by electron bombardment of these surfaces is F+ with only a minor contribution from H+. ESDIAD images from a saturation coverage of HF on stepped Si(100) surfaces reveal F+ desorption primarily along the direction of the terrace dimers. The ESDIAD patterns from HF adsorbed on Si(111) are characterized by strong normal F+ emission with a weak background component of off-normal emission. These results are consistent with the dissociative chemisorption of HF where the ion emission direction is determined by the Si-F bond directions.
Effects of Potassium on the Adsorption and Reactions of Nitric Oxide on Silicon Surface
Authors: Ying Z. C. , Ho W. 
Published: March 2011

ABSTRACTThe adsorption, thermoreactions, and photoreactions of NO coadsorbed with K on Si(111)7×7 at 90 K have been studied and compared with the results obtained from the Kfree surface. The experiments were performed under ultra-high vacuum conditions using high resolution electron energy loss spectroscopy, work function change measurements, and mass spectrometry. NO adsorbs both molecularly and dissociatively on the K-free surface. Two molecular N–O stretching modes are observed at 188 and 225 meV. The concentration of these NO molecules on the surface decreases as the K exposure increases and vanishes at high K exposures. A new N–O stretching mode, attributed to adsorption of NO molecules on K clusters, is observed at 157 meV. After thermal heating or photon irradiation, the surface is covered with atomic O and N. The surface is more oxidized in the presence of K. A steady decrease in the photodesorption cross section is observed as the K exposure increases and is attributed to K-induced band structure changes.
Metal Atom Routes to Metal-Based Clusters in Polymers
Authors: Andrews Mark P. , Galvin Mary E. , Heffner Sharon A. 
Published: March 2011

ABSTRACTPast syntheses of polymer composites have largely evolved from chemical reduction or thermal decomposition of organometallic or inorganic precursor molecules in polymers, or plasma and thermal co-deposition of metal vapors and carbonaceous free radicals. Our approach involves the site-specific capture of metal atoms deposited in vacuum to give isolated, high energy mononuclear organometallic centers within a polymer film. These centers can be converted at ambient or sub-ambient temperatures (ie, below the polymer glass transition temperature) to, for example, metal oxide microclusters.We describe the results of our studies of a prototypical system involving chromium atoms and their conversion to corundum-type oxide microclusters in arene-functionalized polymer films. Thus Cr was deposited into 150 K liquid tetrahydrofuran solutions of polystyrene or poly(styrene-isoprene-styrene) triblock, spun in vacuo as thin films on the surface of a rotating glass cryostat. Evidence from epr spectrscopy shows that the resulting polymer-anchored (inter/intra-chain) bis(arene)Cr sandwich complex is locally mobile in the macroscopically rigid film at room temperature. The Cr atom is discharged from the rings by subsequent reaction with oxygen diffused into the film. Although α Cr2O3is a classic twosublevel antiferromagnet that is not epr active above 308 K, we observe an intense signal even at 77 K in these films. Cr2O3microclusters are indicated, and these are confirmed by in situ measurements of the oxidation and aggregation process.The metal atom methodology has also been used to synthesize silver microsphere/polymer composites. With quadratic electrooptic phase modulation, these composites were found to show a third order susceptibility enhanced by coupling the dipolar surface plasmon mode of the particles with incident light.
Interaction of in Atom Spin-Orbit States with Si(100) Surfaces
Authors: Oostra Doeke J. , Smilgys Russell V. , Leone Stephen R. 
Published: March 2011

ABSTRACTScattering and desorption of In from Si(100) is investigated. Laser induced fluorescence is used to probe the desorbing and or scattered species. Auger Electron Spectroscopy is used to study the composition on the surface. The results show that at surface temperatures below 820 K a two dimensional layer of In desorbs by a half order mechanism. This is explained by assuming two dimensional In islands on the surface. Above 820 K, desorption takes place by a first order mechanism. The desorption para-meters appear to be spin-orbit state specific. The desorption energy for In 2P3/2 is 2.8 ± 0.4 eV and for In 2P½ 2.5 ± 0.2 eV. The difference is equal to the difference in the spin-orbit energy. So far no specular scattering of In is observed, suggesting that the sticking coefficients are unity.
Reactive Atom-Surface Scattering the Adsorption and Reaction of Atomic Oxygen on the Si(100) Surface
Authors: Engstrom J. R. , Nelson M. M. , Engel T. 
Published: March 2011

ABSTRACTThe adsorption and reaction of atomic oxygen on the Si(100) surface has been examined by employing supersonic beam techniques, X-ray photoelectron spectroscopy and mass spectrometry. Atomic oxygen adsorbs with a unit probability of adsorption on the clean Si(100) surface. The probability of adsorption decreases monotonically with increasing coverage. At surface temperatures above approximately 1000 K. the adsorption of atomic oxygen results in the gasification of the substrate, producing SiO(g). In comparison to molecular oxygen for this reaction, where two surface intermediates were implicated, only one surface intermediate is formed from the reaction of atomic oxygen with the Si surface.
Atom- and Radical-Surface Sticking Coefficients Measured Using Resonance Enhanced Multiphoton Ionization (REMPI)
Authors: Robertson Robert M. , Rossi Michel J. 
Published: March 2011

ABSTRACTSticking coefficients γ of neutral transient species at ambient temperature were measured using in situ Resonance Enhanced Multiphoton Ionization (REMPI) of the transients in a Knudsen cell. γ for I and CF3I‡ on a stainless steel surface were 0.16 and >0.5, respectively, whereas γ for CF3 on the same surface was measured to <0.01; γof SiH2 on a growing carbon containing amorphous silicon surface was 0.11; this value increased to 0.15 for interaction of SiH2 with a “pure” growing silicon-hydrogen surface, and γ of SiH2‡ on both types of surfaces was found to be >0.5.
Amorphous to Crystalline Structural Transition during Growth of Silicon by Plasma Enhanced Chemical vapor Deposition
Authors: Varhue W. J. , Krause S. , Dea J. , Jung C. O. 
Published: March 2011

ABSTRACTThe growth of thin Si films by RF glow discharge undergoes a transition from amorphous to microcrystalline as power density is increased. This results in a substantial change in the film's electrical conductivity and activation energy for electrical conduction. The RF glow discharge has been characterized in terms of plasma density, plasma potential and electron temperature with emissive Langmuir Probe measurements. The structural transition has been observed with a transmission electron microscope.
In Situ Characterization of thin film Growth by Ftir Irras
Authors: Butler J. E. , Koller K. B. , Schmidt W. A. 
Published: March 2011

ABSTRACTIn-situ analysis of low temperature Plasma Enhanced Chemical Vapor Deposition (PECVD) SiO2 films deposited on HgCdTe, Silicon, and Aluminum substrates was performed by double modulation Fourier Transform Infrared Reflection Absorption spectroscopy (FT-IRRAS). The sensitivity and selectivity of this technique are sufficient for an in-situ assessment of the film quality and reaction conditions at any stage of film growth. An oblique angle of incidence of ca. 557deg; was chosen to yield maximum sensitivity for the 1260 cm−1 LO mode of SiO2 on Si. The peak frequency and shape of the LO mode absorption band varied with the quality of the SiO2 films. This diagnostic technique can be applied readily to in-situ analysis of dielectric thin films formed under a variety of reaction conditions as long as the gaseous ambient is partially transmissive to the IR radiation.
Surface Reaction Mechanisms in the Metallisation and Etching of Semiconductor Materials.
Authors: Wee A , Murrell A J , French C L , Price R J , Jackman R B , Foord J S 
Published: March 2011

ABSTRACTSurface spectroscopic techniques have been used to investigate aluminium deposition form tri-methyl aluminium (TMA) on Si(100), and the etching of InP by chlorine. Thermal reactions and processes stimulated by UV lamps and ion beams are examined. The results are interpreted in the light of the adsorption states which are formed and the surface transformations of chemical states which are observed to occur.
Nucleation Barriers in Chemical Vapor Deposition of Triisobutylaluminum on Silicon
Authors: Mantell D. A. 
Published: March 2011

ABSTRACTThe nucleation of chemical vapor deposition (CVD) using triisobutylaluminum (TIBA) on Si (100) surfaces is observed in situ with x-ray photoelectron spectroscopy (XPS). Oxygen from oxide on the silicon inhibits the rate of nucleation by reacting with adsorbed TIBA and forming a thin layer of oxidized organometallic. This layer blocks active adsorption sites and prevents further deposition. On a surface without oxide, the TIBA molecules decompose liberating aluminum that can migrate and nucleate into islands opening sites for further adsorption and film growth. By removing the oxide (native or thermal) in selected areas of the surface, the barrier to nucleation is removed and aluminum deposition can occur in a predetermined pattern.
Mixed Metal Organometallic Clusters: Precursors for Intermetallic Powders
Authors: Gonsalves K. E. , Kembaiyan K. T. 
Published: March 2011

ABSTRACTntial catalytic applications [1]. Also, in non-catalytic areas, there is a move to build alloy powders from large metal clusters [2]. Therefore, we have initiated a program to develop intermetallic powders from mixedmetal organometallic precursors [3]. Here we report the synthesis and characterization of iron-cobalt intermetallic powders obtained from heteroorganometallic clusters [4]. Our objective therefore is to (1) provide a simple and effective means of synthesizing iron-cobalt intermetallics (2) vary the ratio of iron to cobalt in such intermetallics, and (3) provide a method to produce homogeneous products from iron-cobalt metalorganic precursors specifically synthesized for this purpose. The resulting intermetallics may have unique magnetic characteristics.
Excimer Laser Induced Photochemistry of Silane-Ammonia Mixtures
Authors: Jasinski J. M. , Beach D. B. , Estes R. D. 
Published: March 2011

ABSTRACTSteady-state and time resolved molecular beam sampling mass spectrometry have been used to study the ArF excimer laser induced photochemistry of silaneammonia mixtures at 193 nm. Under both steady state and single laser shot conditions, products as complicated as tetraaminosilane are formed promptly. A mechanism which accounts for the formation of all observed products is proposed and evaluated.
Defects and Their Control in SiO2 Films Prepared by D2 –Lamp Photochemical Vapor Deposition
Authors: Nonaka Hidehiko , Arai Kazuo , Ichimura Shingo 
Published: March 2011

ABSTRACTAmorphous silica films deposited from the mixture of gases (Si2 H6 and Si2F6) by deutrium-lamp CVD were studied by IR, vacuum UV, EPR and Auger electron (AE) spectrometries. The F-doping enhanced the film growth and removed defects in the film such as -H, -OH, and E' centers. A model on deposition and defect formation mechanisms was proposed based on the thermodynamic Stabilities of resultant HF in the reactions. The AES study showed that the film surface modified by activated oxygen had an increased hardness against electron beams.
Organometallic Chemical Vapor Deposition of Gaas Using Novel Organometallic Precursors
Authors: Jones R. A. , Cowley A. H. , Benac B. L. , Kidd K. B. , Ekerdt J. G. , Miller J. E. 
Published: March 2011

ABSTRACTThe goals of the research are the design and synthesis of a new class of precursor compounds for III/V compound semiconductor materials, growth of films with these precursors and developoment of an understanding of the relationships between precursor structure, film growth reactions and film properties. Conventional OMCVD of III/V compound materials has a number of inherent safety and processing problems associated with the group III alkyl and group V hydride sources. Our approach to these problems is the synthesis of a single precursor with a fixed III:V stoichiometry and a direct two center, two electron sigma III V bond., These, compounds have the general formula,[R2M(R 2 E)] 2 and R2M(R 2 E) 2M R2 (MM = Al, Ga, In; E=P, As; R, R = alkyl, aryl). The III V bond in these compounds is stronger than the other bonds and the minium deposition temperature can be controlled by employing subsituents that undergo facile hydrocarbon elimination.A typical example is the use of [Me 2Ga(µ t Bu 2 As)] 2 as the single source for GaAs films. The organometallic precursor is a solid crystalline powder which is maintained at 130°C to generate enough vapor for OMCVD. Typical film growth conditions involve the use of H2 or He as the carrier gas, substrate temperatures of 500 to 700°C, and a total system pressure of 0.0002 Torr. GaAs(100), Si(100) (As doped 30 off toward (011) and quartz have been used as substrates. Film composition has been established with XPS. The Ga 3d, As 3d, and C ls signals at 18.8, 40.9, and 284.6 eV, respectively, reveal the films to be 1:1 Ga:As and void of carbon. The carbon levels are less than 1000 ppm. X ray diffraction and SEM results suggest polycrystalline GaAs on quartz and epitaxial GaAs on GaAs(100) and Si(100). (2 K) photoluminescence measurements on GaAs, grown on semi insulating GaAs(100) and Si doped GaAs(0 100) at 570 C. produce PL signals indicating that crystalline domains are present, the measurements indicate degeneratively n doped material and show that good Ga:As ratios and low levels (ca. 1 ppm) of impurities are present. Growth rates:∼ 1.0 mm/hour.
Ion Beam Assisted Deposition of Metal Films
Authors: Gamo Kenji , Namba Susumu 
Published: March 2011

ABSTRACTThe chtaracteristics of ion beam assisted deposition are discussed and compared with those of photon beam assisted deposition. Effects of various deposition parameters including ion species, beam energy and substrate temperature are discussed. Deposited films usually include impurities such as C and O. Inclusion of oxygen takes place by enhanced oxidation by background oxygen and may be reduced by depositing in a clean vacuum. Promising applications of maskless ion beam assisted deposition are also discussed.
Focused Ion Beam-Induced Carbon Deposition
Authors: Harriott L. R. , Vasile M. J. 
Published: March 2011

ABSTRACTA process for repair of micron and submicron sized transparent defects on photomasks is described. Opaque films are deposited at the intersection of the flux of organic monomers from a gas jet and a 20 keV Ga ion beam. Focused ion beam-induced deposition differs from other ion-induced, electron beam and laser processes due to the very high ion current density and the sputtering of the material as it is being deposited. We have explored the deposition-sputtering rate competition for several precursor materials as a function of monomer flux and ion beam dose rate. Our results suggest a model for deposition which requires polymerization of the precursor through carbon-carbon double bonds to favor deposition over sputtering by creating high molecular weight material at the target.
Spin-on Silicon Oxide (Sox): Deposition and Properties
Authors: Smolinsky Gerald , Ryan Vivian 
Published: March 2011

ABSTRACTHigh quality SiO2 films are obtained by spin-coating wafers with a sol/gel of silicic acid in either a 2, 3, or 4-carbon linear-aliphatic alcohol. Some properties of the deposited film depend upon the solvent: such as density, tensile stress, and infrared spectrum. However, Rutherford-back-scattering analysis indicates the O:Si ratio (2.00±05) to be independent of the solvent. The infrared spectrum of the oxide exhibits Si-OSi absorption in the range 1070–1080 cm.−1 depending on the curing temperature and solvent system. (The weaker Si-OSi band is found at 804–810 cm.−1) In addition, low-temperature-cured (<500 °C) films show Si–OH absorption. Films hot-plate baked at 150–350 °C are stable but not fully cured. Films from propanol baked at 400 °C have a refractive index of 1.41–1.42 and a wet-etching rate in 30:1 BOE of ˜1250 Å/min. Films cured at 900 °C have a refractive index of 1.42–1.43, a wet-etching rate of ˜430 A/min, and are more dense by a factor of ˜1.25. Dry-etching with CHF3/O2 occurs at rates comparable to those of CVD oxides. Multiple applications lead to crack-free films as thick as 0.6–0.8 μ m. Deposition over aluminum-patterned topography results in a smoothing of the surface and suppression of hillock growth in the aluminum even after a 450 °C cure. SOX adheres to silicon, aluminum, and silicon dioxide. A boron-doped SOX is readily prepared.
Organometallic Precursors for III-V Semiconductors
Authors: Byrne Erin K. , Douglas Trevor , Theopold Klaus H. 
Published: March 2011

ABSTRACTOrganometallic molecules containing covalently linked gallium and arsenic or indium and phosphorus have been synthesized and characterized spectroscopically and by X-ray diffraction. These precursors can be transformed into the corresponding III-V materials in a chemical reaction proceeding at ambient temperature. The compound semiconductors prepared in this way are obtained as amorphous powders. During the reaction, quantum size effects may be observed by UV-VIS spectroscopy as the particles grow.
Electrical Properties of Hard Carbon Films
Authors: Varhue Walter , Pandelisev Kiril , Shinseki Brian 
Published: March 2011

ABSTRACTThe electrical resistivity, optical band gap and activation energy for electrical conduction have been determined as a function of preparation conditions. The operating conditions for the glow discharge reactor have been interpreted in terms of ion energy and reactive species production. The change in the electrical properties could not be explained as a percentage of [SP3] versus [SP2] bonding ratio. Rather, these two species are embedded in an amorphous medium which determines the materials electrical properties.
Deposition of Thin Alumina Films from Supercritical Water Jets
Authors: Brand J. I. , Miller D. R. 
Published: March 2011

ABSTRACTThin alumina films are grown on a silicon substrate, in vacuum, at a rate of about 10 Å per second, and at substrate temperatures below 1500C. Alumina is dissolved in supercritical water and the resulting solution expanded in a supersonic free jet, which is directed at the substrate. The films are characterized by ESCA and FTIR.
An Antimony Planar Diffusion Source
Authors: Wilson Jack , Gustaferro Robert , Bonny Alan , Maddox Ed 
Published: March 2011

ABSTRACTAntimony is a useful n-type dopant for buried layers, due to its low rate of lateral diffusion in subsequent processing steps. To date, no solid planar diffusion source has been available. Reported here is the development of such a source.The source is made by high temperature synthesis in a hot press. A mixture of antimony trioxide and silicon powders is placed in the press, and heated under pressure. The reactionresults in a solidified product. Wafers are sliced from this product to form the actual planar diffusion sources.The sources are used in a two-step doping process: a predeposition followed by a drive-in. Oxygen is required in both steps, due to the chemistry involved. Typical properties of the doped silicon are: sheet resistance, 10 Ω/square, junction depth, 4–6 microns, and antimony surface concentration. 3–8 × 1019/cm3.
Optical Properties of Finely-Structured Particulates
Authors: Sheng Ping , Zhou Min-Yao , Chen Zhe , Chui S. T. 
Published: March 2011

ABSTRACTWe show that rod-like particulates structured from interleaving layers of metal and insulator (or semiconductor) can exhibit novel infrared and far-infrared characteristics that are tunable through the variation of their geometric parameters. In particular, a dispersion of these particles can be made to absorb strongly at any prescribed far-infrared frequency by controlling their transverse dimensions and insulator fractions.