JVA Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

SECTION LISTING

Search Issue | RSS Feeds RSS
Previous Issue

Nov 2007

Volume 25, Issue 6, pp. 1489-1603

back to top
RSS Feeds

Enhancement of structural and magnetic properties in sputtered half-metallic Fe3O4 films

Xiao-Li Tang, Huai-Wu Zhang, Hua Su, Zhi-Yong Zhong, and Yu-Lan Jing

J. Vac. Sci. Technol. A 25, 1489 (2007); http://dx.doi.org/10.1116/1.2778689 (4 pages) | Cited 3 times

Online Publication Date: 10 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Polycrystalline Fe3O4 films grown on different thicknesses of Fe underlayers were prepared by dc reactive-magnetron sputtering in an Ar+O2 gas mixture and annealing under an infrared-lamp furnace system. Analyses of structural and magnetic properties revealed that a 15 nm Fe underlayer can be oxidized to Fe3O4 by increasing the oxygen flow rates during initial Fe3O4 layer growth. These analyses also confirmed the stoichiometry and high-crystallographic quality of grown Fe3O4. Adopting this method, Fe3O4 films can be grown without any other elemental buffer layers.
Show PACS
75.50.Dd Nonmetallic ferromagnetic materials
75.70.Ak Magnetic properties of monolayers and thin films
68.55.-a Thin film structure and morphology
81.40.Gh Other heat and thermomechanical treatments

Effect of wall conditions on the self-limiting deposition of metal oxides by pulsed plasma-enhanced chemical vapor deposition

Scott F. Szymanski, Michael T. Seman, and Colin A. Wolden

J. Vac. Sci. Technol. A 25, 1493 (2007); http://dx.doi.org/10.1116/1.2779039 (7 pages) | Cited 6 times

Online Publication Date: 10 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Pulsed plasma-enhanced chemical vapor deposition has been engineered to deliver self-limiting growth (i.e., ∼ Å/pulse) of metal oxides such as Ta2O5 and Al2O3. In this process the reactor walls are alternately exposed to atomic oxygen and metal precursors. The degree of adsorption in the latter step can dramatically influence both deposition rates and film quality. The impact of precursor adsorption on the plasma and gas-phase composition in these systems was quantified using optical emission spectroscopy and quadrupole mass spectrometry, respectively. It is shown that the time scale for a complete adsorption on the chamber walls is much greater than gas-phase residence times. Adsorbed compounds significantly alter the reactor composition, particularly at the initiation of each plasma pulse. As a consequence, careful attention must be paid to reactor design and operation to control deposition rates and maintain film quality.
Show PACS
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.A- Nucleation and growth
52.77.Dq Plasma-based ion implantation and deposition
52.40.Hf Plasma-material interactions; boundary layer effects
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.70.Nc Particle measurements

Electronic band gap of Si/SiO2 quantum wells: Comparison of ab initio calculations and photoluminescence measurements

J.-M. Wagner, K. Seino, F. Bechstedt, A. Dymiati, J. Mayer, R. Rölver, M. Först, B. Berghoff, B. Spangenberg, and H. Kurz

J. Vac. Sci. Technol. A 25, 1500 (2007); http://dx.doi.org/10.1116/1.2779040 (5 pages) | Cited 6 times

Online Publication Date: 10 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the influence of layer thicknesses and interface modifications on the fundamental electronic gap of Si/SiO2 multilayers by a combined ab initio calculation and photoluminescence (PL) analysis. For the band gap calculations different Si/SiO2 interface models are studied. Experimentally investigated multiple quantum wells are prepared by remote plasma-enhanced chemical vapor deposition and rapid thermal annealing. The well-width dependence of the band gap obtained from PL measurements is much weaker than found in previous studies. This sublinear variation is in accordance with simulated electronic band gaps for hydrogen-free Si/SiO2 interfaces. The presence of hydrogen at the interfaces enforces the confinement effect for the band gap. Materials involved: nanocrystalline silicon, amorphous silica, β-cristobalite silica, and Si/SiO2 interface.
Show PACS
78.67.De Quantum wells
78.55.Ap Elemental semiconductors
71.15.-m Methods of electronic structure calculations
61.72.Cc Kinetics of defect formation and annealing

Epitaxial growth of SrO on Si(001): Chemical and thermal stability

M. El Kazzi, G. Delhaye, C. Merckling, E. Bergignat, Y. Robach, G. Grenet, and G. Hollinger

J. Vac. Sci. Technol. A 25, 1505 (2007); http://dx.doi.org/10.1116/1.2784720 (7 pages) | Cited 4 times

Online Publication Date: 20 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Heteroepitaxial SrO films grown on Si(001) are characterized by reflection high energy electron diffraction and x-ray photoelectron spectroscopy. Special emphasis is put on the interface chemical, structural, and thermal stability because SrO films can be used as template layers for growing crystalline high-k oxides on Si(001). Ultrathin SrO layers of good crystalline quality with sharp interface with Si(001) can be grown at low temperature (50 °C) and low partial oxygen pressure (<10−7 Torr). In this case, plastic strain relaxation occurs rapidly at about one-monolayer SrO coverage. At higher temperature (500 °C), both strontium and oxygen react with silicon to form a crystalline silicate with a composition close to Sr2SiO4. This silicate is thermodynamically unstable and, when annealed, transforms into a different silicate close to SrSiO3.
Show PACS
68.55.A- Nucleation and growth
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Temperature programed desorption of C2H4 from pure and graphite-covered Pt(111)

B. Vermang, M. Juel, and S. Raaen

J. Vac. Sci. Technol. A 25, 1512 (2007); http://dx.doi.org/10.1116/1.2784721 (7 pages) | Cited 2 times

Online Publication Date: 20 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ethylene adsorption on Pt(111) at 95 K was studied by temperature programed desorption (TPD), low energy electron diffraction (LEED), and x-ray photoelectron spectroscopy. Ethylene desorbs reversibly at 112 K and irreversibly at 255 and 280 K. It is generally accepted that annealing of ethylene adsorbed on Pt(111) to 300 K results in a dehydrogenation to ethylidyne through an ethylidene intermediate. This was observed by a hydrogen desorption peak at 300 K. Also, hydrogenation of the adsorbed ethylene was observed by a small ethane desorption peak at 300 K. Upon heating to 700 K, the ethylidyne species will further dehydrogenate to carbidic carbon species with hydrogen desorption peaks at 460 and 640 K. If the carbidic species is heated to higher temperatures (up to 1000 K), it will further dehydrogenate and form graphitic islands which will accumulate by Ostwald ripening in larger islands at the step edges of the surface. After annealing the sample to 1000 K, a statistically distributed 8×8 superstructure of these graphite islands is achieved, as interpreted from a ring pattern in the LEED data. The TPD results indicate that ethylene adsorption on Pt(111) results in the formation of graphitic islands upon heating to 1000 K, contrary to previous conjectures of formation of a full graphite monolayer.
Show PACS
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
79.60.Dp Adsorbed layers and thin films
68.43.Mn Adsorption kinetics

Surface interactions of C3 radicals during the deposition of fluorocarbon and hydrocarbon films

Dongping Liu and Ellen R. Fisher

J. Vac. Sci. Technol. A 25, 1519 (2007); http://dx.doi.org/10.1116/1.2784717 (5 pages) | Cited 2 times

Online Publication Date: 21 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The gas-phase density and surface interactions of the carbon trimer C3 have been examined in fluorocarbon and hydrocarbon plasmas. The math‐math fluorescence excitation spectra and relative gas-phase densities of C3 radicals have been collected using laser-induced fluorescence (LIF) spectroscopy. The relative C3 density increases significantly with CH2F2 in the feed, indicating that C3 is primarily produced via decomposing CH2F2 and chemical reactions in the gas phase. In addition, the surface reactivity R of C3 has been measured during fluorocarbon and hydrocarbon film depositions using C3F8/CH2F2 and CH4/CH2F2 13.56 MHz rf plasmas. The C3 radicals were characterized using our LIF-based imaging of radicals interacting with surfaces technique. R values for C3 range from 0.10 to 0.38, depending on plasma conditions, but show no clear dependence on the gas mixture or the plasma conditions used. X-ray photoelectron spectroscopy measurements of the films deposited in these systems provide additional evidence that suggests that C3 carbon clusters may be contributing to the formation of more cross-linked films.
Show PACS
52.77.-j Plasma applications
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
79.60.Bm Clean metal, semiconductor, and insulator surfaces
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

High-flux ion irradiation with energy of ∼ 20 eV affecting phase segregation and low-temperature growth of nc‐TiN/a‐Si3N4 nanocomposite films

Z. G. Li, Y. X. Wu, and S. Miyake

J. Vac. Sci. Technol. A 25, 1524 (2007); http://dx.doi.org/10.1116/1.2784718 (5 pages) | Cited 3 times

Online Publication Date: 21 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ti0.8Si0.2N films were synthesized by an inductively coupled plasma-assisted magnetron sputtering at deposition temperature lower than 200 °C. The effects of the incident ion to Ti+Si flux ratio (0.14 ⩽ Ji/JTi+Si ⩽ 10), with the ion energy constant at ∼ 20 eV, on film growth, microstructure, and morphology were investigated by x-ray diffraction, x-ray photoelectron spectroscopy, and field emission scanning electron microscope. All films have slightly higher than 50 at. % of N content. The film deposited by only magnetron sputtering with Ji/JTi+Si = 0.14 is amorphous with a columnar structure. With the addition of inductively coupled plasma, the as-deposited films become crystalline. The preferred orientation evolves from (111) to (200) with the increase in Ji/JTi+Si. The film grown with Ji/JTi+Si = 10 exhibits a pure (200) preferred orientation with a fine dense-grained globular structure. The lattice constant of this film is about 0.4244 nm, nearly equal to that of monolithic TiN. The binding energy of Si 2p of this film is 101.7 eV, consistent with that of amorphous silicon nitride. The low-temperature growth of a nc‐TiN/a‐Si3N4 nanocomposite structure is believed to be due to the enhancement of kinetic surface migration induced by high-flux low-energy ion irradiation.
Show PACS
61.80.Jh Ion radiation effects
81.05.-t Specific materials: fabrication, treatment, testing, and analysis
68.55.A- Nucleation and growth
64.75.-g Phase equilibria
81.15.Cd Deposition by sputtering

Molecular dynamics simulations of Ar+ bombardment of Si with comparison to experiment

David Humbird, David B. Graves, A. A. E. Stevens, and W. M. M. Kessels

J. Vac. Sci. Technol. A 25, 1529 (2007); http://dx.doi.org/10.1116/1.2787713 (5 pages) | Cited 7 times

Online Publication Date: 26 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors present molecular dynamics (MD) simulations of energetic Ar+ ions (20–200 eV) interacting with initially crystalline silicon, with quantitative comparison to experiment. Ar+ bombardment creates a damaged or amorphous region at the surface, which reaches a steady-state thickness that is a function of the impacting ion energy. Real-time spectroscopic ellipsometry data of the same phenomenon match the MD simulation well, as do analogous SRIM simulations. They define positional order parameters that detect a sharp interface between the amorphous and crystalline regions. They discuss the formation of this interesting feature in the simulation, and show that it provides insight into some assumptions made in the analysis of experimental data obtained by interface-sensitive surface spectroscopy techniques.
Show PACS
61.82.Fk Semiconductors
61.80.Jh Ion radiation effects
68.47.Fg Semiconductor surfaces
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.43.Dq Amorphous semiconductors, metals, and alloys

Effect of nitrogen doping on bonding state of ZnO thin films

Makoto Hirai and Ashok Kumar

J. Vac. Sci. Technol. A 25, 1534 (2007); http://dx.doi.org/10.1116/1.2778687 (5 pages) | Cited 3 times

Online Publication Date: 28 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nitrogen (N) is the most promising p-type dopant for zinc oxide (ZnO) with wurtzite structure. The substitution of N atoms for partial replacement of O atoms in wurtzite structure is predicted to cause the slight change in bonding state. We have synthesized ZnO and N-doped ZnO thin films by utilizing a pulsed laser deposition method. Compared with the ultraviolet-visible spectrum of the ZnO thin film, since the absorption edge of the N-doped ZnO thin film denoted a clear redshift, the band gap shrank for the incorporation of N atoms. The band-gap shrinkage of the N-doped ZnO thin film was considered to be due to the existence of Zn–N bond having smaller ionicity than Zn–O bond. Additionally, from the results of Fourier transform infrared measurements, the absorption peaks of the ZnO and N-doped ZnO thin films emerged at 415 and 408±2 cm−1, respectively, and were attributed to transverse optical phonon of E1 mode. The reduction in phonon frequency of approximately 7 cm−1 can be induced by the complex factors consisting of not only the decrease in reduced mass and interionic distance but also the increase in covalency.
Show PACS
61.72.uj III-V and II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
78.66.Hf II-VI semiconductors
81.15.Fg Pulsed laser ablation deposition
78.30.Fs III-V and II-VI semiconductors
63.20.D- Phonon states and bands, normal modes, and phonon dispersion

Phase configuration, nanostructure evolution, and mechanical properties of unbalanced magnetron-sputtered Ti-Cx-Ny thin films

Y. H. Lu, Y. G. Shen, Z. F. Zhou, and K. Y. Li

J. Vac. Sci. Technol. A 25, 1539 (2007); http://dx.doi.org/10.1116/1.2784719 (8 pages) | Cited 3 times

Online Publication Date: 28 September 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ti-Cx-Ny thin films with different amounts of C incorporated into TiN0.87 were deposited on Si(100) substrates at 500 °C by reactive unbalanced dc magnetron sputtering. Their phase configuration, nanostructure, and mechanical behavior were investigated by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and microindentation measurements. The results indicated that the atomic ratio of (C+N)/Ti played a crucial role in phase configuration, nanostructure evolution, and mechanical behavior. When the ratio was less than one, a nanocrystalline (nc-) Ti(C,N) solid solution was formed by dissolution of C into the TiN lattice. Both microhardness and residual compressive stress values increased with an increase of C content. When the C reached saturation, precipitation of small amounts of sp2 amorphous (a-) phase appeared with more C incorporation. Further increase of C content (up to ∼ 19 at. % C) made the amorphous phase fully wet nanocrystallites, which resulted in the formation of nanocomposite thin films of ∼ 5 nm nc-Ti(C,N) nanocrystallites separated by an ∼ 0.5 nm amorphous phase comprised mainly of sp2 disordered C, graphite, and minor CNx. Thicker amorphous matrices and smaller sized grains followed when C content was further increased. The formation of nanocomposite structure greatly decreased both hardness and residual stress values of thin films. A hardness maximum was believed to be obtained at nc-Ti(C,N) solid solution containing the maximum C amount. Enhancement of the hardness value was attributed to solid solution effect and high residual stress value.
Show PACS
81.15.Cd Deposition by sputtering
81.16.-c Methods of micro- and nanofabrication and processing
68.55.-a Thin film structure and morphology
68.55.A- Nucleation and growth
61.46.-w Structure of nanoscale materials
68.60.Bs Mechanical and acoustical properties

Study of dye molecule orientation and configuration in dye molecule doped polythiophene films

H. Kato, S. Takemura, Y. Watanabe, T. Nara, T. Hayashi, T. Sugiyama, T. Hiramatsu, N. Nanba, O. Nishikawa, and M. Taniguchi

J. Vac. Sci. Technol. A 25, 1547 (2007); http://dx.doi.org/10.1116/1.2784722 (5 pages)

Online Publication Date: 1 October 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dye molecules doped polythiophene (PT) films prepared by electrochemical doping were investigated by Fourier transform infrared spectroscopy (FTIR) reflection absorption spectroscopy (RAS) and transmission in order to investigate whether the presence of an electric field could control the ordering of the dye molecule assembly in the polymer. The present work focuses on organic dye molecules, which contain three benzene rings in plane with a high symmetry such as crystal violet (CV) and brilliant green (BG) as a dopant. In the case of CV doped PT by applying triangle-shaped negative voltage, the orderings of CV molecules were found by FTIR measurements. Since the ring stretching mode due to the componential benzene ring around 1585 cm−1 was observed only in the FTIR transmission spectra while not observed in the spectrum of FTIR RAS spectra, this result shows that CV molecules are doped in the polymer so that the ring plane of CV is inclined to be parallel to the polymer film plane. In the case of CV doped PT samples by field-free casting method, the ring stretching modes were observed in both spectra of FTIR RAS and transmission, indicating that the dopant molecules were randomly oriented.
Show PACS
78.66.Qn Polymers; organic compounds
78.35.+c Brillouin and Rayleigh scattering; other light scattering
79.60.Fr Polymers; organic compounds
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.16.Dn Self-assembly
82.45.Wx Polymers and organic materials in electrochemistry

Effect of growth conditions on the structure and properties of tungsten films prepared using a thermal evaporation process

Chin-Tang Hsieh and Jyh-Ming Ting

J. Vac. Sci. Technol. A 25, 1552 (2007); http://dx.doi.org/10.1116/1.2790913 (5 pages) | Cited 2 times

Online Publication Date: 2 October 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the fabrication and characterization of tungsten films obtained using a thermal evaporation method. Single phase α-tungsten films were obtained at higher substrate temperatures (520–680 °C) than the single phase β-tungsten films (180–220 °C). X-ray spectra show that both the α-tungsten films and the β-tungsten films are polycrystalline having unusual preferred (200) and (321) orientations, respectively. Poor adhesion was observed when the films were deposited on bare silicon substrate. The adhesion is greatly improved by the introduction of a carbon layer between the film and the substrate. The field emission properties of the α-tungsten films and the β-tungsten films were also examined. The α-tungsten films and β-tungsten films exhibit turn-on fields at 1.3 and 2.8 V/μm, respectively. Current densities in the order of 10−1 mA/cm2 were observed. These field emission properties are believed to be better or much better than that of both tungsten nanowires and nanorods. The relation between the field emission properties and the film structures is discussed.
Show PACS
68.55.A- Nucleation and growth
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
78.66.Bz Metals and metallic alloys
78.70.En X-ray emission spectra and fluorescence
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Np Adhesion

Polarized infrared reflectance study of wurtzite GaN thin film: The effects of angle of incidence on the optical phonon modes

S. S. Ng, Z. Hassan, and H. Abu Hassan

J. Vac. Sci. Technol. A 25, 1557 (2007); http://dx.doi.org/10.1116/1.2787696 (5 pages) | Cited 2 times

Online Publication Date: 3 October 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the polarized IR reflectance study of wurtzite GaN thin film grown on 6H‐SiC substrate measured at various angles of incidence, namely, from 15° to 75°. Attention is focused on the effects of incident angles on the Brillouin zone center optical phonon modes of the GaN thin film. The reflection spectra are compared to the calculated spectra generated with a damped single harmonic oscillator model. Good agreement between the measured and calculated spectra has been obtained. Overall, the results revealed that the optical phonon modes of the GaN thin film and 6H‐SiC substrate are independent of the angle of the incidence beam.
Show PACS
78.66.Fd III-V semiconductors
68.55.-a Thin film structure and morphology
63.20.-e Phonons in crystal lattices

Understanding tin plasmas in vacuum: A new approach to tin whisker risk assessment

M. S. Mason and G. Eng

J. Vac. Sci. Technol. A 25, 1562 (2007); http://dx.doi.org/10.1116/1.2796181 (5 pages)

Online Publication Date: 10 October 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This study examines the mechanisms governing sustained tin plasma formation in vacuum. The authors have experimentally demonstrated that sustained tin plasmas can form in vacuum at dc power supply voltages as low as 4 V, and present a qualitative model for the observed voltage and current signatures associated with tin plasma formation. Engineering estimates were developed to help quantify tin whisker risk as a function of power supply voltage. Implications for space applications are also discussed.
Show PACS
52.50.-b Plasma production and heating
68.70.+w Whiskers and dendrites (growth, structure, and nonelectronic properties)

Factors affecting the reproducibility of the accommodation coefficient of the spinning rotor gauge

Ren Fang Chang and Patrick J. Abbott

J. Vac. Sci. Technol. A 25, 1567 (2007); http://dx.doi.org/10.1116/1.2790910 (10 pages) | Cited 1 time

Online Publication Date: 18 October 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The spinning rotor gauge is the most stable device available for measuring pressure between 10−4 and 10−1 Pa. The calibration of these gauges is determined by measuring an effective accommodation coefficient, which is used in conjunction with an equation derived from the kinetic theory of gases to calculate the pressure seen by the rotor gauge. To assess the reproducibility of the spinning rotor gauge (and hence its accommodation coefficient), eight spinning rotor gauges were calibrated numerous times simultaneously with the primary midrange vacuum standard at the National Institute of Standards and Technology over a 15 month period. Events encountered by a rotor during its normal operation were investigated for their effects on the accommodation coefficient of the rotor. The effects of baking as well as “crashing” of the rotors were also investigated. We found that the accommodation coefficient may be dependent on the orientation of the rotor’s suspension as a consequence of anisotropically distributed blemishes on the rotor’s surface. Consequently, the accommodation coefficient will not reproduce well when the rotor is resuspended because the rotational axis is not replicated. Data on the accommodation coefficient obtained from ordinary rotors as well as rotors specifically prepared with a band of scratches to exaggerate the anisotropic nature of the blemishes will be presented.
Show PACS
07.30.Dz Vacuum gauges

Factors influencing charge capacity of vanadium pentoxide thin films during lithium ion intercalation/deintercalation cycles

D. Alamarguy, J. E. Castle, N. Ibris, and A. M. Salvi

J. Vac. Sci. Technol. A 25, 1577 (2007); http://dx.doi.org/10.1116/1.2799961 (10 pages) | Cited 3 times

Online Publication Date: 24 October 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The intercalation of vanadium pentoxide by lithium ions leads to a change in optical properties, a process that is of value in thin-film electrochromic devices. In this study, films of V2O5, deposited on indium tin oxide (ITO) glass coupons by a sol-gel process, were challenged by increasing numbers of charge-discharge cycles ranging from 72 to 589 full cycles. The samples were characterized by x-ray photoelectron spectroscopy (XPS) and then examined in the deintercalated state by time-of-flight secondary ion mass spectroscopy (SIMS). XPS enabled measurement of the thickness and composition of the solid-electrolyte interface and provided evidence of the residual V4+ concentration within the top few nanometers of the surface. The SIMS profile gave direct information on the thickness of the films and on the thickness loss caused by rinsing the samples after the electrochemical exposure. Determination, by SIMS, of the concentration of lithium ions has enabled a correction to be made for the amount of inactive material within the electrochemically active region of the film. The SIMS depth profiles for lithium in the four samples are similar, with a marked buildup of Li at the interface with the ITO. This interphase zone had a thickness of ∼ 27 nm and was electrochemically inactive, enabling a further correction to be made. Thus, by means of the XPS and the SIMS results the chemistry and thickness of the films could be fully characterized. The remaining inconsistency between capacity (between 35% and 100% of the anticipated charge) and number of cycles is ascribed to edge effects arising from the method used for production of the coupons.
Show PACS
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
79.60.Dp Adsorbed layers and thin films
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
82.45.Gj Electrolytes
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.45.Mp Thin layers, films, monolayers, membranes
68.55.-a Thin film structure and morphology
82.80.Rt Time of flight mass spectrometry

High sensitivity permeation measurement system for “ultrabarrier” thin films

Xiao Dong Zhang, Jay S. Lewis, Scott D. Wolter, Charles B. Parker, and Jeffrey T. Glass

J. Vac. Sci. Technol. A 25, 1587 (2007); http://dx.doi.org/10.1116/1.2794075 (7 pages) | Cited 3 times

Online Publication Date: 25 October 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors demonstrate a new technique for high sensitivity gas permeation measurements by integrating mass spectrometry with programed accumulation, detection, and evacuation of permeant. After passing through the film of interest, the gas permeant is captured and accumulated in an isolated ultrahigh vacuum (UHV) volume. The permeant is then allowed to enter an adjacent residual gas analyzer (RGA) and the resulting partial pressure increase is correlated with the steady state permeation rate. Calibrated results are given for helium and argon permeation through polymer films. The measured detection limits of the system are 1.8×10−4 cm3/m2 day for helium and 2.5×10−4 cm3/m2 day for argon. Both values are several orders of magnitude lower than what is available from commercial instruments or similar RGA-based instruments. Potential applications of this technique include measurement of oxygen and water vapor permeation with sensitivities required for assessment of ultrabarrier coatings.
Show PACS
51.20.+d Viscosity, diffusion, and thermal conductivity
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Real-time monitoring of successive sparks in high-density plasma chambers

Michio Sato, Hiroto Ohtake, Koichi Suzuki, and Seiji Samukawa

J. Vac. Sci. Technol. A 25, 1594 (2007); http://dx.doi.org/10.1116/1.2796180 (5 pages) | Cited 2 times

Online Publication Date: 26 October 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Successive sparks in high-density plasma were analyzed using various real-time monitoring systems, such as electromagnetic field sensors and on-wafer sensors. Electron density decreases at the moment the sparking occurs because a large number of electrons flow to the chamber wall and the wafer surface. Due to the potential fluctuation of the plasma, other sparks occur successively during recovery to the stable plasma. The successive sparks sometimes continue for a few milliseconds. Based on these findings, the authors found that electromagnetic field sensors and on-wafer sensors are very effective tools for real-time monitoring of successive sparks.
Show PACS
52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.25.Gj Fluctuation and chaos phenomena
52.70.Ds Electric and magnetic measurements

X-ray photoelectron spectroscopy of rubber compounds: Temperature dependence and cross-link distribution

G. E. Hammer

J. Vac. Sci. Technol. A 25, 1599 (2007); http://dx.doi.org/10.1116/1.2778688 (5 pages)

Online Publication Date: 31 October 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Rubber compounds are complex mixtures of ingredients, including many mobile and volatile species. Exposure to the ultrahigh vacuum environment common to surface analytical instruments can therefore cause significant changes in a rubber surface and produce misleading and even erroneous results. In this work it has been shown that stable, representative x-ray photoelectron spectra could be obtained if the specimen was precooled below a compound-dependent maximum temperature before exposure to the vacuum environment. Maximum temperatures were found to be −50 and −70 °C for two typical tire rubber compounds, a wire adhesion formulation and passenger tire tread, respectively. Effects of specimen preparation were further investigated. High resolution x-ray photoelectron spectra of specimens precooled to −85 °C and analyzed at −140 °C indicated a correlation between the sulfur peak positions and the length of sulfur cross-links in the rubber. Specifically, a linear relationship was found between sulfur 2p binding energy and the percentage of monosulfidic and polysulfide cross-links as determined by standard bulk solvent swelling analysis for three different rubber compounds based on two different polymers.
Show PACS
79.60.Fr Polymers; organic compounds
61.41.+e Polymers, elastomers, and plastics
Close

© 2013 AVS Science & Technology of Materials, Interfaces, and Processing Help | Contact
close