Robert F. Hicks

University of California, Los Angeles | UCLA · Department of Materials Science and Engineering

In this report, networks of carbon nanotubes (CNTs) are transformed into composite yarns by infusion, mechanical consolidation and polymerization of dicyclopentadiene (DCPD). The microstructures of the CNT yarn and its composite are characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and a...

In this report, networks of carbon nanotubes (CNTs) are transformed into composite yarns by infusion, mechanical consolidation and polymerization of dicyclopentadiene (DCPD). The microstructures of the CNT yarn and its composite are characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and a...

Wide angle X-Ray scattering was used to measure the progression of alignment when stretching carbon nanotube (CNT) sheets. The nanotubes were grown by an aerogel chemical vapor deposition process and drawn onto a drum rotating at a draw rate of 15 m/min to form a sheet. Samples were cut from this sheet at 0°, 10°, 25°, 45° and 90° with respect to t...

The treatment of polymer surfaces with atmospheric pressure and vacuum plasmas for enhanced adhesion is examined in this chapter. Poor wetting and adhesion can occur in microelectronic packages in key manufacturing steps such as applying epoxy molding compound to the substrate and applying epoxy underfill to the flip chip module. Low-pressure plasm...

A low-temperature, atmospheric pressure helium and oxygen plasma has been used for the surface preparation of aluminum 2024 prior to adhesive bonding. The plasma converted the aluminum from a water contact angle (WCA) of 79° to down to 38° within 5 s of exposure, while sanding reduced the WCA to only 51°. Characterization of the aluminum surface by...

Transitional metal oxides hold great potential for high capacity anodes. However, the low electron conductivity of such materials leads to poor cycling stability and inferior rate capability. We reported herein the use of a novel hydrogen plasma technology to improve the conductance of metal oxides, which leads great success in improving the rate p...

An atmospheric pressure helium and oxygen plasma has been used for the surface preparation of 410 stainless steel and carbon-fiber epoxy laminates prior to bonding to themselves or to each other. Lap shear results for stainless steel coupons and carbon-fiber epoxy laminates demonstrated an 80% and a 150% increase in bond strength, respectively, aft...

In order to avoid using polyvinyl alcohol (PVA), an eco-friendly sizing technology with atmospheric pressure plasma treatment and green sizing recipes has been developed and evaluated with respect to sizing properties and desizing efficiency. The results show that the eco-friendly sizing technology can endow cotton yarn with better sizing propertie...

Gold rush: Nanoporous palladium particles are decorated with gold clusters by galvanic replacement. The bimetallic pPd@Au nanocatalysts feature a well-defined nanoporous morphology coupled to a highly accessible surface area with segregated Au clusters, and are highly active in both benzyl alcohol oxidation and formic acid electro-oxidation. The am...

Carbon nanotube yarn and sheet were activated using radio frequency, atmospheric pressure, helium and oxygen plasmas. The nanotubes were exposed to the plasma afterglow, which contained 8.0 × 1016 cm−3 ground state O atoms, 8.0 × 1016 cm−3 metastable O2 (1Δg), and 1.0 × 1016 cm−3 ozone. X-ray photoelectron spectroscopy and infrared spectroscopy rev...

A review is presented on the surface preparation of polymers and composites using atmospheric pressure plasmas. This is a promising technique for replacing traditional methods of surface preparation by abrasion. With sufficient exposure to the plasma afterglow, polymer and composite surfaces are fully activated such that when bonded and cured with...

Adhesive bonding offers many advantages over mechanical fastening, but requires certification before it can be incorporated in primary structures for commercial aviation without disbond-arrestment features or redundant load paths. Surface preparation is widely recognized as the key step to producing robust and predictable adhesive bonds. Laser abla...

form only given. Atmospheric pressure plasma treatment is a key process for surface preparation prior to adhesive bonding of plastics and composites for use in the aerospace, automotive, medical device, and electronics industries. A review is presented on methods for surface preparation of polymers and composites using low-temperature, atmospheric...

Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field or a gradient of a directionless physical quantity. Scientific challenges in the understanding of plasma jets are exciting and multidisciplinary, invo...

In this work, we have carried out nitridation of epitaxial graphene/SiC(0001) using N2 plasma. The effects of processing conditions on the structure of graphene have been investigated by x-ray photoemission spectroscopy and Raman spectroscopy, and changes in the electronic structures of the nitrogen-doped graphene have been studied using scanning t...

We investigated the effect of high flow rates (> 10−5mol/min) of metalorganic precursors on compositional evolution in indium phosphide antimonide (InP1−xSbx) nanowires grown via chemical vapor deposition in the presence of indium droplets as catalysts on InP(111)B substrates maintained at ∼360°C. The as-grown nanowire morphology, composition, and...

Atmospheric pressure radio frequency plasma activation of composites for adhesive bonding Thomas S. Williams, Hang Yu and Robert F. Hicks University of California at Los Angeles, Department of Chemical and Biomolecular Engineering, Los Angeles, California 90095-1592 The adhesion of bonded composite joints is of great concern to the aerospac...

Silicon native oxide surfaces were cleaned with a radio frequency, atmospheric pressure helium and oxygen plasma and with an RCA standard clean-1. Both processes create a hydrophilic state with water contact angles of <5° and 16.2° ± 1.7°, respectively. During subsequent storage in a chamber purged with boil off from a liquid nitrogen tank, the wat...

We report the growth of group III-V compound InP1-xSbx alloy nanostructures via vapor-liquid-solid process using liquid indium as the catalyst directly on the InP(111)B substrate. Scanning and transmission electron microscopies, electron diffraction, and energy dispersive spectroscopy are used to determine the morphology, crystallinity, and composi...

We report the growth of InP 1- xSb x nanowires, cones, and pillars via the vapor-liquid-solid process using metalorganic precursors and liquid indium as the catalyst. The as-grown nanostructure morphology, crystallinity, and composition were determined using electron microscopy, electron diffraction, and energy dispersive spectroscopy. We obtained...

Indium phosphide/indium arsenide phosphide core–shell nanopillars have been prepared by the vapor–liquid–solid method using liquid indium droplets as the catalyst. The indium droplets were generated in situ in the deposition reactor. The hexagonal nanopillars exhibited hexagonal shaped sidewalls with average width and height of 150 and 250 nm, resp...

A variety of transition-metal films have been grown by organometallic chemical vapor deposition (OMCVD) at low temperatures using hydrocarbon or hydrido-carbonyl metal complexes as precursors. The vapors of the metal complexes are transported with argon as the carrier gas, adding H 2 to the stream shortly before contact with a heated substrate. Hig...

Germanium (100) substrates, 9° off axis towards the [011] direction, were heated in 2.0 Torr tertiarybutylarsine and 97.0 Torr hydrogen for 30 min at 650°C, then transferred to an ultrahigh vacuum system and annealed at several temperatures between 400 and 700°C. The arsenic coverage remained constant at 1.0 monolayer during heating in vacuum to 40...

The effects of temperature of oxygen exposure on metal dispersion were determined for platinum deposited on Al2O3, ZrO2, 12 wt% Y2O3–ZrO2, and MgO. Platinum on zirconia and on magnesia showed higher thermal stability than platinum on alumina.

The atmospheric pressure plasma-enhanced chemical vapor deposition of fluorinated silica glass was demonstrated at a temperature of 120°C. The process was carried out by simultaneously feeding tetramethylcyclotetrasiloxane (TMCTS) and triethoxyfluorosilane (TEOFS) into the afterglow of helium and oxygen plasma. The effect of the flow rate of the fl...

A series of supported platinum and palladium catalysts were tested for heptane oxidation at 75 to 200°C, 20 Torr heptane, 245 Torr oxygen, 795 Torr helium, and conversions below 1%. At these low temperatures, carbon fouls the metal surface. The decline in the turnover frequency with time is accurately fitted with this function: TOFobs = TOFAexp(−kA...

We report on the structural and morphological evolution of indium phosphide nanostructures grown on InP(1 1 1)B via metalorganic chemical vapor deposition using liquid indium as the catalyst. The morphology and crystallinity are examined using scanning and transmission electron microscopies, electron backscattered diffraction, and selected-area ele...

The authors report on the optical properties of GaInP/GaP double-heterostructure (DH) core-shell nanowires (NWs) embedded in polydimethylsiloxane (PDMS) membranes. Self-catalyzed NW structures are grown on Si (111) substrates by initiating with the formation of Ga droplets as a catalyst which is followed by the growth of GaP core and GaInP DH shell...

Silicon (100) surfaces were converted to a hydrophilic state with a water contact angle of <5° by treatment with a radio frequency, atmospheric pressure helium, and oxygen plasma. A 2 in. wide plasma beam, operating at 250 W, 1.0 l/min O ₂ , 30 l/min He, and a source-to-sample distance of 3±0.1 mm , was scanned over the sample at 100±2 m...

The surfaces of high-density polyethylene (HDPE), poly(methyl methacrylate) (PMMA), and polyethersulfone (PES) were treated with a low-temperature, atmospheric pressure oxygen and helium plasma. The polymers were exposed to the downstream afterglow of the plasma, which contained primarily oxygen atoms and metastable oxygen molecules ((1)Delta(g) O(...

The successful integration of III-V materials onto silicon would make it possible to fabricate an array of new electronic and photonic devices with greater functionality and at a lower cost. However, growing compound semiconductors on silicon is extremely challenging due to the polar/non-polar interface and the large lattice mismatch between the ma...

Compound semiconductor nanowire devices are of great interest due to their size-dependent electrical and optical properties and their potential applications in nano-electronics. In this study, we demonstrate the growth of InP/InAs/InP core-shell nanopillars by metalorganic vapor-phase epitaxy (MOVPE). Indium droplets were used to catalyze crystal n...

An atmospheric pressure oxygen and helium plasma was used to treat the surfaces of polyetheretherketone, polyphenylsulfone, polyethersulfone, and polysulfone. These aromatic polymers were exposed to the afterglow of the plasma, which contained oxygen atoms, and to a lesser extent metastable oxygen (1Dg O2) and ozone, for periods of time ranging fro...

A low-temperature, atmospheric pressure oxygen and helium plasma was used to treat the surfaces of polyetheretherketone, polyphenylsulfone, polyethersulfone, and polysulfone. These aromatic polymers were exposed to the afterglow of the plasma, which contained oxygen atoms, and to a lesser extent metastable oxygen (^1deltag O2) and ozone. After less...

Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 2...

The atmospheric pressure plasma-enhanced chemical vapor deposition of diamond-like carbon (DLC) has been investigated. The DLC coatings were grown with a mixture of acetylene, hydrogen and helium that was fed through a linear plasma source. The plasma was driven with radio frequency power at 27.12 MHz. Deposition rates exceeded 0.10 µm/min at subst...

An atmospheric-pressure oxygen and helium plasma was used to treat the surfaces of polyetheretherketone, polyphenylsulfone, polyethersulfone, and polysulfone. Water-contact-angle measurements, mechanical pull tests, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy were used to analyze the change in polymer properties. Plasma trea...

An atmospheric pressure oxygen and helium plasma was used to activate the surface of poly(methyl methacrylate) (PMMA). The plasma physics and chemistry was investigated by numerical modeling. It was shown that as the electron density of the plasma increased from 3 × 10 ¹⁰ to 1 × 10 ¹² cm ⁻³ , the concentration of O atoms and metastable oxygen molec...

Vertical indium phosphide nanowires have been grown epitaxially on silicon (111) by metalorganic vapor-phase epitaxy. Liquid indium droplets were formed in situ and used to catalyze deposition. For growth at 350 degrees C, about 70% of the wires were vertical, while the remaining ones were distributed in the 3 other <111> directions. The vertical f...

The morphological phase diagram is reported for InP nanostructures grown on InP (111)B as a function of temperature and V/III ratio. Indium droplets were used as the catalyst and were generated in situ in the metalorganic vapor-phase epitaxy reactor. Three distinct nanostructures were observed: wires, cones, and pillars. It is proposed that the sha...

Hydrophobic coatings have been produced on glass and acrylic samples by using a low-temperature atmospheric pressure plasma to polymerize liquid fluoroalkylsilane precursors. The fluoroalkylsilane precursor was dissolved in isooctane and spun onto the substrate at 550 rpm. The sample was then exposed to the reactive species generated from a nitroge...

The relationship between crystal quality and the properties of indium phosphide nanowires grown on silicon (111) has been studied by transmission electron microscopy, photoluminescence spectroscopy, and photoelectrochemistry. Wires with no defects and with {111} twin boundaries parallel and perpendicular to the growth direction were obtained by met...

A new process is demonstrated using low-temperature atmospheric pressure plasma to obtain hydrophobic thin films from fluoroalkylsilane precursors on glass and acrylic polymer substrates. An atmospheric pressure plasma is generated at 150 W of RF power using 30.0 L/min of helium and 0.70 L/min nitrogen gases, and is used to polymerize or cure the l...

Nanowire research has gained tremendous momentum due to its potential applications in nano-electronics, photonics, solar cells, and thermoelectrics. Precise control of size, morphology, density, and uniformity is essential for realizing these commercial opportunities. Most indium phosphide nanowire research is prepared by vapor-liquid-solid (VLS) g...

The surfaces of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyphenylene sulfide (PPS) were activated remotely using an atmospheric pressure oxygen and helium plasma. The afterglow of the plasma, containing O atoms, and to a lesser extent metastable oxygen (1Dg O2) and ozone, came into contact with the polymer surface for...

Semiconductor nanowires have potential applications in new and high-performance one-dimensional devices. Epitaxial growth of high-quality semiconductor nanowires on Si surfaces is ideal for utilizing semiconductor nanowires within the frame of mainstream silicon technology. We have achieved epitaxial growth of InP nanowires on Si(111) and Si(100) s...

The surfaces of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN) were treated with an atmospheric-pressure oxygen and helium plasma. Changes in the energy, adhesion, and chemical composition of the surfaces were determined by contact angle measurements, mechanical pull tests, and X-ray photoelectron spectroscopy (XPS). Surfac...

Semiconducting nanowires have recently gained a lot of attention due to their promising applications in a wide variety of areas including nanoscale electronics, optoelectronics, piezoelectronics, thermoelectrics, and sensors. Nanowires are most commonly grown via vapor-liquid-solid (VLS) process in which a liquid alloy catalyzes the preferential di...

This study reports on the efficacy of atmospheric oxygen-argon plasma for bio-decontamination or surface sterilization of infectious agents, such as Bacillus anthracis [Sterne] (Anthrax), MS-2 bacteriophage, and E coli. A 10- second exposure (RF power 77 W, 29.5 mL O2/min, 28 L Ar/min) on the B. a. spores revealed an average post-exposure log reduc...

This study examines the effect of atmospheric pressure plasma treatment on the surface energy and adhesive bond strength of three medical polymers: acetal copolymer (AC), polycarbonate (PC) and polyethylene terephthalate (PET). Surface treatments were applied with a two-inch plasma beam source and reactive oxygen-helium (~1-3 vol% O2) plasma under...

The invention is embodied in a plasma flow device or reactor having a housing that contains conductive electrodes with openings to allow gas to flow through or around them, where one or more of the electrodes are powered by an RF source and one or more are grounded, and a substrate or work piece is placed in the gas flow downstream of the electrode...

The effect of annealing a 75nm-thick layer of indium gallium arsenide nitride (InGaAsN) in 1.0×10−6 Torr of nitrogen trifluoride (NF3) has been studied by photoluminescence spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, and hydrogen adsorption infrared spectroscopy. A red shift of 25 nm in the peak was observed following heating...

The selective area, metalorganic vapor-phase epitaxy of gallium arsenide on silicon substrates was investigated. Low-temperature arsenic passivation of the silicon surface was realized at 650 1C. A two-step growth method was used to deposit the GaAs films with an optimum nucleation temperature of 400 1C. Layers nucleated at 350 1C or below were fou...

This chapter reviews the chemical vapor deposition of platinum, palladium, and nickel. A variety of precursors have been developed for use in this process. Precursors such as Pt(PF3)4, (CH3C5H4)Pt(CH3)3, (C5H5)Pd(ally1), Ni(CO)4, and Ni(CH3C4H5)2 may be used to deposit high-purity metal films at a rapid rate. Direct deposition of metal circuits has...

Surface graft polymerization of 1-vinyl-2-pyrrolidone onto a silicon surface was accomplished by atmospheric pressure (AP) hydrogen plasma surface activation followed by graft polymerization in both N-methyl-2-pyrrolidone (NMP) and in an NMP/water solvent mixture. The formation of initiation sites was controlled by the plasma exposure period, radio...

Adsorption of phosphine on indium phosphide compound semiconductor surfaces is a key process during the chemical vapor deposition of this material. Recent experimental infrared studies of the In-rich InP surfaces exposed to phosphine show a complex vibrational pattern in the P-H stretch region, presumably due to overlapping contributions from sever...

The plasma-enhanced chemical vapor deposition of aluminum-doped zinc oxide has been demonstrated for the first time at 800 Torr and under 250 1C. A film resistivity of 3 Â 10 À2 O cm and a transparency of 95% from 375 to 2500 nm was obtained for deposition at 20-mTorr diethylzinc, 1.0 Torr CO 2 , 799 Torr He, a TMAl/DEZn ratio of 1:100, 41 W=cm 3 R...

The metalorganic chemical vapor deposition of In0.06Ga0.94As1-xNx, with x=0.00 0.02, has been examined using nitrogen trifluoride (NF3) and tertiarybutylarsine. The solid N/V ratio increased linearly with the gas-phase N/V ratio up to a limit of 2.0% nitrogen in the film at a gas N/V=0.35. No further increase in nitrogen content could be achieved a...

The deposition and properties of glass coatings on aluminum was investigated using atmospheric pressure plasma-enhanced chemical vapor deposition. The plasma, generated with radio frequency power at 27.12 MHz, was fed helium, oxygen and two types of silicon precursors, hexamethyldisilazane and tetraethylorthosilicate. After deposition, the coatings...

Phosphine and tertiarybutylphosphine adsorption on the indium-rich InP (001)-(2×4) surface at 25°C have been studied by internal reflection infrared spectroscopy, X-ray photoelectron spectroscopy, and low energy electron diffraction. Both molecules form a dative bond to the empty dangling bonds on the In–P heterodimers and the second-layer In–In di...

The structure of indium phosphide surfaces and interfaces has been investigated during the growth of nanomaterials by metalorganic chemical vapor deposition. In the phosphorus-rich environment of the MOCVD process, the InP (001) surface forms a (2x1) reconstruction that is terminated with a monolayer of phosphorus dimers. Each of these dimers is st...

Ordered and disordered InGaP(001) films were grown by metalorganic vapor-phase epitaxy and studied by low energy electron diffraction, reflectance difference spectroscopy, and X-ray photoemission spectroscopy. Both alloy surfaces were covered with a monolayer of buckled phosphorus dimers, where half of the phosphorus atoms were terminated with hydr...

A capacitively coupled, atmospheric pressure plasma has been developed that produces a high concentration of reactive species at a gas temperature below 300 ° C . The concentration of ground-state oxygen atoms produced by the discharge was measured by NO titration, and found to equal 1.2 vol % , or 1.2±0.4×10¹⁷ cm ^-3 , using 6...

An atmospheric pressure capacitive discharge source has been developed that operates at power densities over 100 W cm −3 . The ground state nitrogen atom concentration was measured at the exit of the source by titration with NO, and it was found to reach a maximum of 3.0 ± 0.8 × 10 17 cm −3 at 6.0 vol% N 2 in argon, 250 • C and 150 W cm −3 . This i...

A handheld atmospheric plasma has been developed to treat polyetheretherketone (PEEK) composites. The instrument produces a plasma beam that covers a circular area 2.5 cm in diameter. The plasma is fed with 30 L/min of helium and 0.45 L/min of oxygen, and is supplied with 80 W of radio frequency power (13.56 MHz). The plasma beam was swept over the...

In this paper, a review is provided of the plasma-enhanced (PE)CVD of thin films using an atmospheric-pressure (AP) capacitive discharge source. This source is unique in that the organometallic precursors are fed downstream of the plasma, where reactions occur exclusively between neutral molecules, radicals, and the substrate surface. As a result,...

Wafer bonding and hydrogen implantation exfoliation techniques have been used to fabricate a thin InP template layer on GaAs with intermediate silicon nitride bonding layers. This template layer was used to directly compare subsequent metal organic vapor phase epitaxial growth of InGaAs/InAlAs quantum-well structures on these wafer-bonded templates...

A chamberless, remote plasma deposition process has been used to coat silicon and plastic substrates with glass at ambient conditions. The films were deposited by introducing an organosilane precursor into the afterglow of an atmospheric plasma fed with helium and 2 vol% oxygen. The precursors examined were hexamethyldisilazane, hexamethyldisiloxan...

The properties of electronegative discharges operating at atmospheric pressure have been investigated. The plasma source consisted of two parallel metal electrodes into which helium was fed with 0.5–8.0 Torr carbon tetrafluoride or sulfur hexafluoride. It was found that the ionization mechanism changed from the α-to the γ -mode at a critical RF pow...

Metalorganic vapor phase epitaxial growth of InGaAs/InAlAs quantum well structures on wafer bonded and exfoliated InP films on GaAs substrates were assessed. The composite substrates were fabricated using silicon nitride intermediate layers and through hydrogen-implant induced exfoliation of an InP layer. The InP layer was subjected to a chemical m...

form only given. A new atmospheric pressure plasma source has been developed that shows exceedingly high processing rates. For example, kapton films have been etched at 5.0 mum/s using an argon and oxygen discharge with 6.0 vol.% O2 and a temperature of 280degC. The plasma source consisted of a small quartz tube that was capacitively coupled to rad...

Specular and diffuse x-ray reflectivity measurements were employed for wafer bonding studies of surface and interfacial reactions in ~800 Å thick SiN films deposited on III–V substrates. CuKα1 radiation was employed for these measurements. The as-deposited films show very low surface roughness and uniform, high density SiN. Reflectivity measurement...

Indium phosphide 001 surfaces were exposed to 0.61-mTorr trimethylantimony in a metalorganic vapor-phase epitaxy reactor. The antimony surface composition increased rapidly with dosage and saturated at 22.0 at. % for temperatures between 450 and 600 ° C. The results indicate that a thin layer of InSb formed on the surface, 6.8 Å thick. Strain from...

The α and γ modes of an atmospheric pressure, radio-frequency plasma have been investigated. The plasma source consisted of two parallel electrodes that were fed with helium and 0.4 vol% nitrogen. The transition from α to γ was accompanied by a 40% drop in voltage, a 12% decrease in current and a surge in power density from 25 to 2083 W cm −3 . Opt...

The physics of an atmospheric pressure, radio frequency plasma has been investigated. The discharge is generated with helium and 0.4 vol.% nitrogen passing between two metal electrodes with a 3.0-mm gap. It was discovered that at a critical power density of 2.1 kW/cm³, the plasma undergoes sheath breakdown and transitions from the α- to...

The effect of an initial saturation coverage of antimony on the growth of indium arsenide quantum dots on gallium arsenide has been studied during metalorganic vapor-phase epitaxy. After depositing one to two bilayers of InAs at 723 K, the samples were quenched, transferred to ultrahigh vacuum, and characterized by scanning tunneling microscopy and...

The physics of helium and argon rf discharges have been investigated in the pressure range from 50 to 760 Torr. The plasma source consists of metal electrodes that are perforated to allow the gas to flow through them. Current and voltage plots were obtained at different purity levels and it was found that trace impurities do not affect the shape of...

Indium phosphide, gallium arsenide phosphide, and aluminum indium phosphide have been deposited by metalorganic vapor-phase epitaxy using tertiarybutylphosphine and tertiarybutylarsine. The effects of growth temperature and V/III ratio on the amount of silicon, sulfur, carbon, and oxygen in InP have been determined. Minimum incorporation was observ...

Optical emission and infrared spectroscopy have been used to study the reactions of nitrogen atoms with silane introduced into the afterglow of an atmospheric-pressure helium–nitrogen plasma. Our experimental observations show that the direct reaction between silane and ground-state nitrogen atoms is slow, with an estimated rate constant no greater...

Amorphous hydrogenated silicon films were grown using an atmospheric pressure helium and hydrogen plasma with silane added downstream of the source. A maximum deposition rate of 120 ± 12 Å min −1 was recorded at a substrate temperature of 450˚C, 6.3 Torr H 2 , 0.3 Torr SiH 4 , 778 Torr He, 32.8 W cm −3 , and an electrode-to-substrate spacing of 6.0...

The etching of uranium oxide films was investigated with a non-thermal, atmospheric pressure plasma fed with a mixture of 2.0 kPa carbon tetrafluoride, 880.0 Pa oxygen and 97.2 kPa helium. Etching rates of up to 4.0 mum/min were recorded at a 200 degreesC sample temperature. X-ray photoemission spectroscopy revealed that the etched surface was high...

Summary form only given. Non-equilibrium atmospheric pressure plasmas are of interest for the surface treatment, cleaning, etching and deposition of materials. We have characterized the properties of a radio-frequency atmospheric pressure plasma fed with helium or argon and up to 2.0 vol% nitrogen. The electrodes consisted of two parallel plates, 0...

Summary form only given. The plasma-enhanced chemical vapor deposition (PECVD) of silicon dioxide films has been examined in a low temperature, atmospheric pressure discharge. A mixture of 2.0 vol% oxygen in helium was utilized in a capacitive discharge operating at 100 W RF power and a neutral gas temperature of ∼100°C. Several silicon precursors...

The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioac...

In this paper, a low temperature, atmospheric pressure plasma source has been examined for the isotropic etching of photoresist, glass and metal film. In addition, the system has been configured for remote plasma enhanced chemical vapour deposition of silicon dioxide, silicon nitride and amorphous hydrogenated silicon.

Gallium phosphide001 surfaces have been prepared by metalorganic vapor-phase epitaxy, and characterized in situ by low-energy electron diffraction, x-ray photoemission spectroscopy, and reflectance difference spectroscopy. Three stable phases were observed: (21), (11), and (2 4) with phosphorus coverages of 1.00, 0.67, and 0.13 ML, respectively. Re...

The surface structure of the indium phosphide (001)-(2×1) reconstruction has been clarified in this work. Infrared spectra collected during atomic deuterium titration of the InP (001)-(2×1) surface reveal a sharp P-H stretching mode at 2308 cm-1. Based on theoretical cluster calculations using density-functional theory, this mode results from a sin...

The kinetics of phosphine adsorption and phosphorus desorption from gallium and indium phosphide (0 0 1) has been determined using reflectance difference spectroscopy to monitor the phosphorus coverage in real time. Assuming a Langmuir adsorption mechanism, phosphine exhibited an initial reactive sticking coefficient at 500 °C of 8.7 ± 1.0 × 10−2,...

The fluorine atom concentration has been measured in the downstream region of a low-temperature, atmospheric-pressure plasma fed with 739.0 Torr helium and 12.6 Torr carbon tetrafluoride (3.1 × 10 17 cm −3). The fluorine atoms were titrated with H 2 molecules, and the HF reaction product was detected by infrared spectroscopy. The radio-frequency ga...

Indium phosphide was deposited on InP(111)A substrates by metalorganic vapor-phase epitaxy. Then, the surface was characterized by scanning tunneling microscopy, low-energy electron diffraction, and x-ray photoelectron spectroscopy. Two reconstructions were observed: the (2×2) and the ((3)×(3))R30° with phosphorus coverages of 0.25 and 1.00±0.05 ML...

We have studied the formation of indium gallium arsenide/indium phosphide heterojunctions during metalorganic vapor-phase epitaxy (MOVPE). The films are characterized using scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and x-ray photoelectron spectroscopy (XPS). Exposing an InP [001] film to 10 mTorr of tertiarybutylar...

The indium phosphide (001) surface provides a unique chemical environment for studying the reactivity of hydrogen toward the electron-deficient group IIIA element, indium. Hydrogen adsorption on the In-rich delta(2 x 4) reconstruction produced a neutral, covalently bound bridging indium hydride. Using vibrational spectroscopy and ab initio cluster...

A model system has been created which allows the surface and bulk contributions to the reflectance difference spectrum to be distinguished. In particular, an indium arsenide film, less than 10 Å thick, has been grown on indium phosphide (001). Reflectance difference spectra of the InAs/InP surfaces were collected and compared to those of InP and In...

The kinetics of tertiarybutylphosphine adsorption and phosphorus desorption from indium phosphide (0 0 1) have been determined using reflectance difference spectroscopy for real-time monitoring of the phosphorus coverage. The precursor adsorption rate depends linearly on the coverage, and the initial sticking coefficient varies from 0.007 to 0.001...

The concentrations of the neutral actiûe species in the afterglow of a nitrogen and helium atmospheric-pressure plasma haûe been determined by optical emission and absorption spectroscopy and by numerical modeling. For operation with 10 Torr N 2 and 750 Torr He, at 15.5 Wcm 3 rf power, 30.4 L/min flow rate, and a neutral temperature of 50°C, the pl...

We have studied the initial stages of heterojunction formation during the metalorganic vapor-phase epitaxy of indium arsenide on indium phosphide. Exposing an InP 001 film to 10 mTorr of tertiarybutylarsine below 500 °C results in the deposition of a thin InAs layer from 1.5 to 5.0 atomic layers thick 2.3–7.5 Å. The surface of this epilayer remains...

The oxidation of anion-and cation-rich indium phosphide 001 has been investigated by exposure to unexcited molecular oxygen. Indium phosphide oxidation is an activated process and strongly structure sensitive. The In-rich (24) surface reacts with oxygen at 300 K and above. Core level x-ray photoemission spectra have revealed that the O 2 dissociati...

Arsenic adsorption and exchange with phosphorus on indium phosphide 001 have been studied by scan-ning tunneling microscopy, low-energy electron diffraction, and x-ray photoelectron spectroscopy. The surface phase diagram as a function of temperature has been obtained. At 285 °C, arsenic adsorbs on the InP (24) surface (P coverage0.25 ML), forming...