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7 Oct 2002

Volume 81, Issue 15, pp. 2677-2902

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Mechanical properties and interfacial characteristics of carbon-nanotube-reinforced epoxy thin films

Xiaojing Xu, Moe Moe Thwe, Christopher Shearwood, and Kin Liao

Appl. Phys. Lett. 81, 2833 (2002); http://dx.doi.org/10.1063/1.1511532 (3 pages) | Cited 80 times

Online Publication Date: 30 September 2002

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Multiwalled carbon nanotubes (MWNT) reinforced epoxy composite thin films were prepared by a microfabrication process and their elastic modulus was determined using a shaft-loaded blister test and linear and nonlinear elasticity models. Compared to net resin thin films, a 20% increase in elastic modulus was seen when 0.1 wt % MWNTs were added, suggesting MWNT alignment by spin coating. Electron microscopic observations of the fracture surfaces suggested high interfacial shear stress between MWNTs and the epoxy matrix, a result supported by both molecular mechanics simulation and micromechanics calculations. © 2002 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
68.35.Gy Mechanical properties; surface strains
62.25.-g Mechanical properties of nanoscale systems
81.07.De Nanotubes
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.M- Structural failure of materials
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
61.46.-w Structure of nanoscale materials

Watching carbon nanotubes grow

Jean-Marc Bonard, Mirko Croci, Fabien Conus, Thomas Stöckli, and André Chatelain

Appl. Phys. Lett. 81, 2836 (2002); http://dx.doi.org/10.1063/1.1511539 (3 pages) | Cited 13 times

Online Publication Date: 30 September 2002

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The growth of carbon nanotubes by chemical vapor deposition (CVD) is followed and characterized by performing field-emission microscopy directly in a modified CVD reactor, where the hydrocarbon gas is introduced at a partial pressure below 10−2 mbar and a high voltage is applied between the heated substrate and a phosphor screen. This allows us not only to detect a field-emission current that increases with the length of the nanotubes, but also to observe the growth of the individual emitters by following the evolution of their field-emission patterns on the phosphor screen. Nanotubes grow after an activation time of a few s and reach a length of 5–10 μm in typically 10 s. We deduce a growth rate in the range 1–10 μm/s that increases with the gas pressure. © 2002 American Institute of Physics.
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81.07.De Nanotubes
61.46.-w Structure of nanoscale materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.37.Vj Field emission and field-ion microscopy

High internal quantum efficiency, narrow linewidth InGaAs/GaAs/AlGaAs quantum wire light-emitting diodes

H. Weman, L. Sirigu, K. F. Karlsson, K. Leifer, A. Rudra, and E. Kapon

Appl. Phys. Lett. 81, 2839 (2002); http://dx.doi.org/10.1063/1.1511279 (3 pages) | Cited 6 times

Online Publication Date: 30 September 2002

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High internal quantum efficiency (∼60%), narrow linewidth (as narrow as 14 meV) exciton emission at room temperature has been obtained using strained InGaAs V-groove quantum wire (QWR) light-emitting diodes (LEDs). The high efficiency is achieved with the aid of selective carrier injection through self-ordered AlGaAs vertical quantum wells (VQWs), where the VQWs are separated from the InGaAs QWRs by thin GaAs spacer layers in order to reduce nonradiative recombination and inhomogeneous alloy broadening. Evidence for excitonic recombination in these LEDs up to RT is provided by measurements of the emission energy shifts at high magnetic fields. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Atomic force microscope anodic oxidation studied by spectroscopic microscopy

M. Lazzarino, S. Heun, B. Ressel, K. C. Prince, P. Pingue, and C. Ascoli

Appl. Phys. Lett. 81, 2842 (2002); http://dx.doi.org/10.1063/1.1509121 (3 pages) | Cited 15 times

Online Publication Date: 30 September 2002

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Atomic force microscope (AFM) induced local oxidation is a versatile and promising nanofabrication process used successfully to produce quantum devices. Nevertheless, little information is available on the chemical and structural properties of the grown oxide. We address this open issue by a spectromicroscopic study of nanoscopic oxide patterns grown by AFM anodic oxidation on n-type silicon substrate. We show that AFM oxidation produces chemically uniform, stoichiometric SiO2, and that its chemical and structural properties do not depend on the applied voltage. The observed electrostatic shift of the oxide binding energies allows a simple estimation of the electrical properties of the AFM induced oxide. © 2002 American Institute of Physics.
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81.16.Rf Micro- and nanoscale pattern formation
81.16.Pr Micro- and nano-oxidation
68.37.Xy Scanning Auger microscopy, photoelectron microscopy
68.37.Nq Low energy electron microscopy (LEEM)
07.79.Lh Atomic force microscopes
79.60.Dp Adsorbed layers and thin films
73.61.Ng Insulators
68.55.-a Thin film structure and morphology

Frequency modulation response of a liquid-crystal electro-optic device doped with nanoparticles

Yukihide Shiraishi, Naoki Toshima, Kenji Maeda, Hiroaki Yoshikawa, Jun Xu, and Shunsuke Kobayashi

Appl. Phys. Lett. 81, 2845 (2002); http://dx.doi.org/10.1063/1.1511282 (3 pages) | Cited 78 times

Online Publication Date: 30 September 2002

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Palladium nanoparticles covered with liquid-crystal molecules were prepared by UV irradiation of an alcohol solution of palladium(II) acetate in the presence of liquid-crystal molecules. The prepared Pd nanoparticles have an average diameter of 2.5 nm. A twisted nematic (TN) liquid-crystal device (LCD) was fabricated by doping with Pd nanoparticles covered with another kind of nematic liquid-crystal molecules. In this device the sign of the dielectric anisotropy (Δε) of the liquid-crystal molecules, which cover Pd nanoparticles, is opposite to that of nematic liquid-crystal molecules, which work as the host of the device (Δε>0). The TN-LCD cell fabricated in this research exhibits a frequency modulation response to an applied alternative voltage wave form. © 2002 American Institute of Physics.
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42.79.Kr Display devices, liquid-crystal devices
78.20.Jq Electro-optical effects
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
81.07.Bc Nanocrystalline materials

Midinfrared luminescence from InAs quantum dots in unipolar devices

D. Wasserman and S. A. Lyon

Appl. Phys. Lett. 81, 2848 (2002); http://dx.doi.org/10.1063/1.1511537 (3 pages) | Cited 14 times

Online Publication Date: 30 September 2002

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Midinfrared light has been obtained from InAs quantum dots (QDs) in unipolar semiconductor devices with moderate current densities at low temperatures (77 K). The luminescence signals are broad, extending from the 70 meV cutoff of the HgCdTe detector to 200 meV, however they exhibit a peak at about 150 meV and are clearly distinct from thermal radiation. The QDs are contained within a resonant tunneling structure which includes a superlattice (AlGaAs/GaAs) electron energy filter and are grown with all n-type material by molecular-beam epitaxy. Electroluminescence and photoluminescence experiments have been used to examine the transitions responsible for the midinfrared emission. © 2002 American Institute of Physics.
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78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
78.60.Fi Electroluminescence
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.66.Fd III-V semiconductors

Anisotropic pinning enhancement in Nb films with arrays of submicrometric Ni lines

D. Jaque, E. M. González, J. I. Martin, J. V. Anguita, and J. L. Vicent

Appl. Phys. Lett. 81, 2851 (2002); http://dx.doi.org/10.1063/1.1512947 (3 pages) | Cited 10 times

Online Publication Date: 30 September 2002

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Arrays of submicrometric Ni lines have been fabricated in superconducting Nb films by electron beam lithography. In the mixed state, these arrays induce strong anisotropy in the dissipation behavior. The dissipation is reduced several orders of magnitude, in the whole applied magnetic field range, when the vortex motion is perpendicular to the Ni lines (applied current parallel to them) in comparison with dissipation of vortices moving parallel to the lines. In addition, for the samples studied in this work, a change in the slope of the ρ(B) curves is observed when the vortices move perpendicular to the lines and the vortex lattice parameter matches the width of the Ni lines. © 2002 American Institute of Physics.
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74.78.-w Superconducting films and low-dimensional structures
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)

Fabrication of single-hole transistors on hydrogenated diamond surface using atomic force microscope

Minoru Tachiki, Hokuto Seo, Tokishige Banno, Yu Sumikawa, Hitoshi Umezawa, and Hiroshi Kawarada

Appl. Phys. Lett. 81, 2854 (2002); http://dx.doi.org/10.1063/1.1513656 (3 pages) | Cited 19 times

Online Publication Date: 30 September 2002

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Nanofabrication of electron devices based on the stability of hydrogen- and oxygen-terminated diamond surfaces is performed using an atomic force microscope modification technology. A nanotechnology involving the separation of C�H and C�O bonded surfaces has been applied to realize the single-hole transistors. The single-hole transistors operate at liquid-nitrogen temperature (77 K), where the Coulomb oscillation characteristics are clearly observed. © 2002 American Institute of Physics.
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85.35.Gv Single electron devices
81.16.Pr Micro- and nano-oxidation
81.05.U- Carbon/carbon-based materials
68.37.Ps Atomic force microscopy (AFM)
73.23.Hk Coulomb blockade; single-electron tunneling

Local structure and luminescence of nanocrystalline Y2O3:Eu

Zeming Qi, Chaoshu Shi, Weiwei Zhang, Weiping Zhang, and Tiandou Hu

Appl. Phys. Lett. 81, 2857 (2002); http://dx.doi.org/10.1063/1.1513659 (3 pages) | Cited 36 times

Online Publication Date: 30 September 2002

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Nanosized Y2O3:Eu was synthesized by using a solution–combustion method. The samples were characterized by x-ray diffraction, extended x-ray absorption fine structure (EXAFS), and photoluminescence spectroscopy. Our EXAFS result showed that the local environments surrounding both Y and Eu atoms had obviously changed when the particle size was smaller than 10 nm. The coordination number and the bond length of Y (Eu)–O shell increased and the disorder became larger. This change also produced an emission peak and the charge-transfer band showed an unusual redshift as the particle size decreased. The luminescence properties can be explained by use of the EXAFS results. © 2002 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
81.07.Bc Nanocrystalline materials
78.55.Hx Other solid inorganic materials
81.16.Be Chemical synthesis methods
81.05.Cy Elemental semiconductors
78.70.Dm X-ray absorption spectra

Operation of individual integrally gated carbon nanotube field emitter cells

M. A. Guillorn, M. D. Hale, V. I. Merkulov, M. L. Simpson, G. Y. Eres, H. Cui, A. A. Puretzky, and D. B. Geohegan

Appl. Phys. Lett. 81, 2860 (2002); http://dx.doi.org/10.1063/1.1512955 (3 pages) | Cited 14 times

Online Publication Date: 30 September 2002

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In this work, we examine the operation of individual field emitter cells contained in a field emitter array composed of integrally gated multiwalled carbon nanotube (MWNT)-based field emission cathodes. These devices were found to behave in a manner consistent with a multiple emission site model of Fowler–Nordheim field emission. These results show considerable variation in the operational characteristics of cells contained within the same array and indicate that data obtained from arrays of cells are not necessarily indicative of individual cell performance. © 2002 American Institute of Physics.
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85.45.Db Field emitters and arrays, cold electron emitters
79.70.+q Field emission, ionization, evaporation, and desorption
85.35.Kt Nanotube devices

Real-time determination of the segregation strength of indium atoms in InGaAs layers grown by molecular-beam epitaxy

S. Martini, A. A. Quivy, E. C. F. da Silva, and J. R. Leite

Appl. Phys. Lett. 81, 2863 (2002); http://dx.doi.org/10.1063/1.1513182 (3 pages) | Cited 12 times

Online Publication Date: 30 September 2002

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The surface segregation of indium (In) atoms was investigated during the growth of InGaAs layers by reflection high-energy electron diffraction (RHEED). We observed that the decay constant of the RHEED-oscillation amplitude during growth depends on the growth conditions and is related, in a very simple way, to the segregation coefficient of the In atoms in the InGaAs layers. © 2002 American Institute of Physics.
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68.35.Dv Composition, segregation; defects and impurities
68.55.-a Thin film structure and morphology
68.55.A- Nucleation and growth
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Imaging, structural, and chemical analysis of silicon nanowires

R. J. Barsotti, J. E. Fischer, C. H. Lee, J. Mahmood, C. K. W. Adu, and P. C. Eklund

Appl. Phys. Lett. 81, 2866 (2002); http://dx.doi.org/10.1063/1.1512827 (3 pages) | Cited 12 times

Online Publication Date: 30 September 2002

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Laser ablation has been used to grow silicon nanowires with an average silicon crystal core diameter of 6.7 nm±2.9 nm surrounded by an amorphous SiOx sheath of 1–2 nm, the smallest silicon wires reported in the literature. Imaging, chemical, and structural analysis of these wires are reported. Due to the growth temperature and the presence of calcium impurities and trace oxygen, two distinct types of wires are found. They appear to grow by two different processes. One requires a metal catalyst, the other is catalyzed by oxygen. Suggestions for controlled synthesis based on these growth mechanisms are made. © 2002 American Institute of Physics.
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81.07.Bc Nanocrystalline materials
81.15.Fg Pulsed laser ablation deposition
61.46.-w Structure of nanoscale materials
81.16.Hc Catalytic methods
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
81.05.Cy Elemental semiconductors

Nickel antidot arrays on anodic alumina substrates

Z. L. Xiao, Catherine Y. Han, U. Welp, H. H. Wang, V. K. Vlasko-Vlasov, W. K. Kwok, D. J. Miller, J. M. Hiller, R. E. Cook, G. A. Willing, and G. W. Crabtree

Appl. Phys. Lett. 81, 2869 (2002); http://dx.doi.org/10.1063/1.1512993 (3 pages) | Cited 61 times

Online Publication Date: 30 September 2002

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Large-area nickel antidot arrays with a density up to 1010/cm2 have been fabricated by depositing nickel onto anodic aluminum oxide membranes that contain lattices of nanopores. Electron microscopy images show a high degree of order of the antidot arrays. Various sizes and shapes of the antidots were observed with increasing thickness of the deposited nickel. New features appear in the antidot arrays in both magnetization and transport measurements when the external magnetic field is parallel to the current direction, including an enhancement and a nonmonotonous field dependence of the magnetoresistance, larger values of the coercive field and remanence moment, and smaller saturation field. © 2002 American Institute of Physics.
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75.75.-c Magnetic properties of nanostructures
73.63.Kv Quantum dots
75.50.Tt Fine-particle systems; nanocrystalline materials
75.50.Cc Other ferromagnetic metals and alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Scanning Lorentz force microscopy

Atsushi Okuda, Jun Ichihara, and Yutaka Majima

Appl. Phys. Lett. 81, 2872 (2002); http://dx.doi.org/10.1063/1.1512945 (3 pages) | Cited 2 times

Online Publication Date: 30 September 2002

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We describe a technique for imaging magnetic flux density by measuring lateral Lorentz force generated by current through a nonmagnetic tip in a stray magnetic flux density emanating from a sample. We demonstrate its usefulness by showing Lorentz force images of recorded tracks in a magnetic hard disk together with the topographic image. The lateral resolution of the technique is also discussed. © 2002 American Institute of Physics.
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07.79.Pk Magnetic force microscopes

Recording performance of high-density patterned perpendicular magnetic media

M. Albrecht, C. T. Rettner, A. Moser, M. E. Best, and B. D. Terris

Appl. Phys. Lett. 81, 2875 (2002); http://dx.doi.org/10.1063/1.1512946 (3 pages) | Cited 71 times

Online Publication Date: 30 September 2002

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Isolated tracks of magnetic single-domain islands have been fabricated by patterning perpendicular Co70Cr18Pt12 continuous films using focused-ion-beam lithography, reaching areal densities as high as ∼200 Gbit/in2. We demonstrate writing and reading of individual islands using a quasistatic write/read tester. We present results on transition position jitter and signal-to-noise ratio (SNR) for patterned media and compare them with those on equivalent unpatterned strips of the media. We observe that patterning dramatically reduces jitter and improves SNR, which is independent of track width. Moreover, the synchronization requirements needed for writing bits in patterned media was investigated on a single row of islands revealing a significant “write window,” where islands can be written correctly, of about half the island period. © 2002 American Institute of Physics.
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75.50.Ss Magnetic recording materials
75.70.Ak Magnetic properties of monolayers and thin films
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.
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