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1 Jun 2009

Volume 94, Issue 22, Articles (22xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 94, 221101 (2009); http://dx.doi.org/10.1063/1.3143652 (3 pages)

Gangyi Xu, Virginie Moreau, Yannick Chassagneux, Adel Bousseksou, Raffaele Colombelli, G. Patriarche, G. Beaudoin, and I. Sagnes
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Role of microconvection induced by Brownian motion of nanoparticles in the enhanced thermal conductivity of stable nanofluids

P. D. Shima, John Philip, and Baldev Raj

Appl. Phys. Lett. 94, 223101 (2009); http://dx.doi.org/10.1063/1.3147855 (3 pages) | Cited 34 times

Online Publication Date: 1 June 2009

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We investigate the role of microconvection induced by Brownian motion of nanoparticles on thermal conductivity enhancement in stable nanofluids containing nanoparticles of average diameters 2.8–9.5 nm. Nanofluids with a fixed particle loading of 5.5 vol. %, the effective thermal conductivity (k/kf) increases from 1.05 to 1.25 with increasing particle diameter. Upon increasing the aspect ratio of the linear chains in nanofluids, very large enhancement of thermal conductivity is observed. These findings confirm that microconvection is not the key mechanism responsible for thermal conductivity enhancements in nanofluids whereas aggregation has a more prominent role.
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07.10.Cm Micromechanical devices and systems
47.61.Fg Flows in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS)
47.85.Np Fluidics
47.27.T- Turbulent transport processes
05.40.Jc Brownian motion

Mode-locking nanoporous alumina membrane embedded with carbon nanotube saturable absorber

Yuichi Kurashima, Yoshihiko Yokota, Iwao Miyamoto, Hiromichi Kataura, and Youichi Sakakibara

Appl. Phys. Lett. 94, 223102 (2009); http://dx.doi.org/10.1063/1.3147857 (3 pages) | Cited 10 times

Online Publication Date: 1 June 2009

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The saturable absorption effect of semiconducting single-wall carbon nanotubes (SWCNTs) covering the near-infrared region is promising for mode-locking devices of short pulse lasers. However, an issue remains that the heat generated at the SWCNTs would destroy the devices. In this research, we fabricated a nanostructured heat sink in which the SWCNTs are stuffed into specially developed nanopores of heat conductive alumina. Actually, it induced stable mode-locked operation of an Er fiber laser for over 4 months.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Wd Fiber lasers
61.46.Fg Nanotubes
61.43.Gt Powders, porous materials

Optical properties of well-crystallized and size-tuned ZnO quantum dots

Keigo Suzuki, Hiroyuki Kondo, Masashi Inoguchi, Nobuhiko Tanaka, Keisuke Kageyama, and Hiroshi Takagi

Appl. Phys. Lett. 94, 223103 (2009); http://dx.doi.org/10.1063/1.3147874 (3 pages) | Cited 5 times

Online Publication Date: 1 June 2009

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Well-crystallized and size-tuned ZnO quantum dots (QDs) were prepared by pulsed laser ablation and following size classification using a differential mobility analyzer. Photoluminescence (PL) spectra of the ZnO QDs showed predominant ultraviolet (UV) emission. The finely size-tuned ZnO QDs allowed us to precisely evaluate the quantum confinement effect, i.e., the size-driven color-tunable behavior in the UV emission range. The faint green luminescence found in the PL spectra and the low Stokes shifts of several tens meV demonstrated that the present QDs are almost free from defects. These features are quite favorable for use in future optoelectronic devices.
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78.67.Hc Quantum dots
81.05.Dz II-VI semiconductors
81.15.Fg Pulsed laser ablation deposition
68.65.Hb Quantum dots (patterned in quantum wells)
78.55.Et II-VI semiconductors

A scale-bridging method for nanoparticulate polymer nanocomposites and their nondilute concentration effect

Seunghwa Yang and Maenghyo Cho

Appl. Phys. Lett. 94, 223104 (2009); http://dx.doi.org/10.1063/1.3143669 (3 pages) | Cited 9 times

Online Publication Date: 1 June 2009

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Due to the enhanced interaction among constituents and the resultant effect of particle size on the elastic modulus, nanocomposites with volume fractions higher than 12% show critical nondilute concentrations. In order to describe nondilute concentrations and the effect of particle size, a multi-inclusion model was adopted and a method was developed to transfer nanoscale physical information to a continuum-based analytical model. The accuracy and applicability of the present scale-bridging method at dilute and nondilute concentrations were verified by comparing results of the present method with those of molecular dynamics and finite element analysis.
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81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.de Elastic moduli
61.46.-w Structure of nanoscale materials

Magnetic states of zigzag graphene nanoribbons from first principles

Fang Wu, Erjun Kan, Hongjun Xiang, Su-Huai Wei, Myung-Hwan Whangbo, and Jinlong Yang

Appl. Phys. Lett. 94, 223105 (2009); http://dx.doi.org/10.1063/1.3147854 (3 pages) | Cited 13 times

Online Publication Date: 2 June 2009

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The nature of the magnetic states of zigzag graphene nanoribbons (ZGNRs) was explored on the basis of density functional calculations to understand why they are apparently nonmagnetic. Our study shows that the magnetic moments of ZGNRs are destroyed by p-type or n-type carrier doping with ∼ 1013 carriers/cm2 per ribbon, which is close to the amount of unpaired spins that ZGNRs are expected to have. Thus the extrinsic sources of carrier doping should be removed to observe the expected magnetic character of ZGNRs.
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81.05.ub Fullerenes and related materials
61.48.De Structure of carbon nanotubes, boron nanotubes, and other related systems
75.30.Cr Saturation moments and magnetic susceptibilities
73.63.-b Electronic transport in nanoscale materials and structures
72.20.Ee Mobility edges; hopping transport
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

Superhydrophobic amorphous carbon/carbon nanotube nanocomposites

Z. J. Han, B. K. Tay, M. Shakerzadeh, and K. Ostrikov

Appl. Phys. Lett. 94, 223106 (2009); http://dx.doi.org/10.1063/1.3148667 (3 pages) | Cited 20 times

Online Publication Date: 2 June 2009

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Superhydrophobic amorphous carbon/carbon nanotube nanocomposites are fabricated by plasma immersion ion implantation with carbon nanotube forests as a template. The microstructure of the fabricated nanocomposites shows arrays of carbon nanotubes capped with amorphous carbon nanoparticles. Contact angle measurements show that both advancing and receding angles close to 180° can be achieved on the nanocomposites. The fabrication here does not require patterning of carbon nanotubes or deposition of conformal coatings with low surface energy, which are usually involved in conventional approaches for superhydrophobic surfaces. The relationship between the observed superhydrophobicity and the unique microstructure of the nanocomposites is discussed.
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81.07.De Nanotubes
61.48.De Structure of carbon nanotubes, boron nanotubes, and other related systems
61.46.-w Structure of nanoscale materials
68.35.Md Surface thermodynamics, surface energies
68.08.Bc Wetting

Structural and electronic properties of the planar C-skeleton polymers

Jun Nakamura, Nariaki Arimura, Motoi Hirayama, and Akiko Natori

Appl. Phys. Lett. 94, 223107 (2009); http://dx.doi.org/10.1063/1.3148722 (3 pages) | Cited 4 times

Online Publication Date: 2 June 2009

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Atomic arrangements and electronic properties of two-dimensional C-based compounds having the diamondlike skeletons terminated with hydrogen atoms and/or hydroxyl groups, named graphane (poly-C2H2) and planar polymethanol (poly-C2OH2), have been investigated using first-principles calculations within the density functional theory. These planar polymers have direct gaps of 3.32 eV (only with hydrogen terminators) and 1.88 eV (with hydrogen and OH terminators), while crystalline diamond has an indirect band gap. The optical dipole transition between band edges, especially for the planar polymethanol, can be allowed.
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61.41.+e Polymers, elastomers, and plastics
71.20.Rv Polymers and organic compounds
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

The optimal Seebeck coefficient for obtaining the maximum power factor in thermoelectrics

P. Pichanusakorn and P. R. Bandaru

Appl. Phys. Lett. 94, 223108 (2009); http://dx.doi.org/10.1063/1.3147186 (3 pages) | Cited 13 times

Online Publication Date: 3 June 2009

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We propose the existence of an optimal Seebeck coefficient (Sopt) for three-, two-, and one-dimensional thermoelectric materials. This assertion is supported by an exhaustive comparison with experimental data of well characterized bulk thermoelectrics, all of which have shown that the power factor is maximized when Sopt in the range of 130–187 μV/K. Our study serves as a quick guideline for the optimization of thermoelectric materials, and makes the point that efforts should be focused on increasing the electrical conductivity (σ) at the given Sopt.
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72.10.-d Theory of electronic transport; scattering mechanisms
72.15.Jf Thermoelectric and thermomagnetic effects
72.20.Pa Thermoelectric and thermomagnetic effects

Improving lateral resolution of electrostatic force microscopy by multifrequency method under ambient conditions

X. D. Ding, J. An, J. B. Xu, C. Li, and R. Y. Zeng

Appl. Phys. Lett. 94, 223109 (2009); http://dx.doi.org/10.1063/1.3147198 (3 pages) | Cited 3 times

Online Publication Date: 3 June 2009

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A multifrequency scanning probe technique which can enhance the spatial resolution of electrostatic force microscopy (EFM) in amplitude-modulation mode under ambient conditions is demonstrated. The first eigenmode of a cantilever is used for topographic imaging, while the second eigenmode is resonantly excited with a sinusoidal modulation voltage applied to the cantilever to measure electrostatic force in lift mode. Two-dimensional images and spectra of electrostatic force are obtained. The lateral resolution of the multifrequency EFM is demonstrated to be better than 15 nm and a theoretical explanation is postulated.
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07.79.-v Scanning probe microscopes and components
68.37.-d Microscopy of surfaces, interfaces, and thin films
68.35.B- Structure of clean surfaces (and surface reconstruction)

Ultralow-power hydrogen sensing with single palladium nanowires

P. Offermans, H. D. Tong, C. J. M. van Rijn, P. Merken, S. H. Brongersma, and M. Crego-Calama

Appl. Phys. Lett. 94, 223110 (2009); http://dx.doi.org/10.1063/1.3132064 (3 pages) | Cited 24 times

Online Publication Date: 3 June 2009

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Palladium nanowires were fabricated on silicon substrates using conventional microfabrication techniques. Sensors based on such nanowires show a reversible response to hydrogen concentrations as low as 27 ppm with response times varying from 5 s (H2 concentrations >20%) to 30 s (H2 concentrations <100 ppm) at room temperature. The response times can be reduced by increasing the applied bias due to resistive heating. The noise spectrum of the nanowires shows a 1/f behavior, sufficiently low to enables the detection of hydrogen with an ultralow-power consumption. The influence of oxygen on the nanowire response was also investigated.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
81.16.-c Methods of micro- and nanofabrication and processing

Materials design of half-metallic graphene and graphene nanoribbons

Menghao Wu, Xiaojun Wu, Yi Gao, and X. C. Zeng

Appl. Phys. Lett. 94, 223111 (2009); http://dx.doi.org/10.1063/1.3143611 (3 pages) | Cited 25 times

Online Publication Date: 3 June 2009

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Through patterned chemical modification, we show that both graphene sheets and zigzag-edged graphene nanoribbons (ZGNRs) can be converted to half-metals as long as the unmodified carbon strip (or width of ZGNRs) is sufficiently wide. Periodically functionalized graphene can mimic electronic behavior of edge-modified ZGNRs as the edge-modified zigzag carbon chains effectively divide a graphene sheet into a series of identical ZGNRs.
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81.07.Bc Nanocrystalline materials
81.05.U- Carbon/carbon-based materials

Diluted chirality dependence in edge rough graphene nanoribbon field-effect transistors

F. Tseng, D. Unluer, K. Holcomb, M. R. Stan, and A. W. Ghosh

Appl. Phys. Lett. 94, 223112 (2009); http://dx.doi.org/10.1063/1.3147187 (3 pages) | Cited 8 times

Online Publication Date: 4 June 2009

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We investigate the role of various structural nonidealities on the performance of armchair-edge graphene nanoribbon field effect transistors (GNRFETs). Our results show that edge roughness dilutes the chirality dependence often predicted by theory but absent experimentally. Instead, GNRs are classifiable into wide (semimetallic) versus narrow (semiconducting) strips, defining thereby the building blocks for wide-narrow-wide all-graphene devices and interconnects. Small bandgaps limit drain bias at the expense of band-to-band tunneling in GNRFETs. We outline the relation between device performance metrics and nonidealities such as width modulation, width dislocations and surface step, and nonideality parameters such as roughness amplitude and correlation length.
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85.30.Tv Field effect devices

High-resolution surface plasmon coupled resonant filter for monitoring of fluorescence emission from molecular multiplexes

Sai Sathish R, Yordan Kostov, and Govind Rao

Appl. Phys. Lett. 94, 223113 (2009); http://dx.doi.org/10.1063/1.3149828 (3 pages) | Cited 3 times

Online Publication Date: 4 June 2009

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Nanoscale photonic devices made of plasmonic structures can control the reflection, transmission, and polarization properties of the electromagnetic field to achieve high-spectral-resolution of light. Here we experimentally demonstrate the use of a real time plasmonic optical filter for photon sorting of fluorescence emission from nanoenvironments in a multispecies system. This was achieved by utilizing surface plasmon-coupled emission associated with nanometer thick metal films for the fluorescence spectral resolution of monomer, dimer, and higher order aggregates of Rhodamine-6G. We highlight the ability to resolve individual emissions from nanostructures in a complex system in its native state without requiring specialized cryogenic and/or high pressure platforms.
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78.55.-m Photoluminescence, properties and materials
42.79.Ci Filters, zone plates, and polarizers
73.22.Lp Collective excitations

Electrical control of the exciton spin in nitride semiconductor quantum dots

Mathieu Sénès, Delphine Lagarde, Katherine L. Smith, Andrea Balocchi, Stewart E. Hooper, Thierry Amand, Jonathan Heffernan, and Xavier Marie

Appl. Phys. Lett. 94, 223114 (2009); http://dx.doi.org/10.1063/1.3151823 (3 pages) | Cited 2 times

Online Publication Date: 4 June 2009

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We report on the experimental evidence of the manipulation of the exciton spin in InGaN quantum dots through the application of an external electric field up to room temperature. Furthermore, we have found the exciton spin relaxation to be independent of temperature. These findings are highly promising for the potential future use of nitride semiconductor quantum dots in practical spintronic devices.
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71.35.-y Excitons and related phenomena
68.65.Hb Quantum dots (patterned in quantum wells)
72.25.Dc Spin polarized transport in semiconductors
73.21.La Quantum dots

Silver high-aspect-ratio micro- and nanoimprinting for optical applications

Stefano Buzzi, Matteo Galli, Mario Agio, and Jörg F. Löffler

Appl. Phys. Lett. 94, 223115 (2009); http://dx.doi.org/10.1063/1.3142426 (3 pages) | Cited 5 times

Online Publication Date: 4 June 2009

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Metal direct nanoimprinting is a fabrication technique based on plastic deformation of ductile metals such as silver and gold pressed into a structured rigid mold. While this process can be exploited to manufacture metallic micro- and nanoparts by removing the mold after processing, it can also be used as a metallization method for producing two-dimensional metallo-dielectric composites. Dense silver-pillar arrays with diameters down to 140 nm, aspect ratios up to 13, and excellent uniformity over large areas were fabricated. The sample quality was confirmed by near-infrared optical reflectances of Si–Ag photonic crystals, which showed strong collective surface plasmon-polariton resonances.
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81.16.-c Methods of micro- and nanofabrication and processing
42.82.Cr Fabrication techniques; lithography, pattern transfer
78.30.Hv Other nonmetallic inorganics
78.68.+m Optical properties of surfaces
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)

Thermal conductivity of bismuth telluride nanowire array-epoxy composite

Kalapi G. Biswas, Timothy D. Sands, Baratunde A. Cola, and Xianfan Xu

Appl. Phys. Lett. 94, 223116 (2009); http://dx.doi.org/10.1063/1.3143221 (3 pages) | Cited 9 times

Online Publication Date: 4 June 2009

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Electrodeposition of nanowire array in porous anodic alumina (PAA) templates combine the performance benefits offered by crystallographic texture control, lattice thermal conductivity suppression through boundary scattering of phonons, elastic relaxation of misfit strain, and scalablity essential for high efficiency thermoelectric devices. The template material, however, can serve as a thermal shunt thereby reducing the effective thermoelectric performance. Here, we demonstrate a process of minimizing the parasitic thermal conduction by replacing the PAA matrix with SU-8 (κ ∼ 0.2 W/m K). We report a reduction in the performance penalty from 27% for Bi2Te3/PAA to ∼ 5% for Bi2Te3/SU-8 nanocomposite by thermal conductivity measurements using a photoacoustic technique.
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66.70.Lm Other systems such as ionic crystals, molecular crystals, nanotubes, etc.
81.15.Pq Electrodeposition, electroplating
63.22.Gh Nanotubes and nanowires
72.10.Di Scattering by phonons, magnons, and other nonlocalized excitations
81.16.-c Methods of micro- and nanofabrication and processing
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
85.80.Fi Thermoelectric devices

Modulation doping in ZnO nanorods for electrical nanodevice applications

Jinkyoung Yoo, Chul-Ho Lee, Yong-Joo Doh, Hye Seong Jung, and Gyu-Chul Yi

Appl. Phys. Lett. 94, 223117 (2009); http://dx.doi.org/10.1063/1.3148666 (3 pages) | Cited 1 time

Online Publication Date: 4 June 2009

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We introduce a modulation-doping method to control electrical characteristics of ZnO nanorods. Compared with a conventional homogeneous doping method, the modulation-doping method generates localized doping layers along the circumference in ZnO nanorods, useful for many device applications. Here, we investigated electrical, structural, and optical characteristics of Ga-doped ZnO nanorods with the dopant modulation layers. Electrical conductivity of ZnO nanorods was controlled by changing either dopant mole fraction or the number of modulation-doped layers. Furthermore, the modulation-doped nanorod field effect transistors exhibited precisely controlled conductance in the order of magnitude without degradation of electron mobility. The effects of the doping on structural and optical characteristics of the nanorods are also discussed.
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81.05.Dz II-VI semiconductors
61.72.uj III-V and II-VI semiconductors
73.63.Bd Nanocrystalline materials
72.20.Fr Low-field transport and mobility; piezoresistance

Assembly and magnetic properties of nickel nanoparticles on silicon nanowires

S. Ingole, P. Manandhar, J. A. Wright, E. Nazaretski, J. D. Thompson, and S. T. Picraux

Appl. Phys. Lett. 94, 223118 (2009); http://dx.doi.org/10.1063/1.3148860 (3 pages) | Cited 1 time

Online Publication Date: 5 June 2009

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The directed assembly of magnetic Ni nanoparticles at the tips of silicon nanowires is reported. Using electrodeposition Ni shells of thickness from 10 to 200 nm were selectively deposited on Au catalytic seeds at the ends of nanowires. Magnetic characterization confirms a low coercivity ( ≈ 115 Oe) ferromagnetic behavior at 300 K. This approach to multifunctional magnetic-semiconducting nanostructure assembly could be extended to electrodeposition of other materials on the nanowire ends, opening up additional approaches to device integration. Such magnetically functionalized nanowires offer an approach to developing highly localized magnetic probes for high resolution magnetic resonance force microscopy.
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81.07.Bc Nanocrystalline materials
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
81.15.Pq Electrodeposition, electroplating
75.50.Cc Other ferromagnetic metals and alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Enhanced broadband photoresponse of Ge/CdS nanowire radial heterostructures

S. P. Mondal and S. K. Ray

Appl. Phys. Lett. 94, 223119 (2009); http://dx.doi.org/10.1063/1.3149704 (3 pages) | Cited 11 times

Online Publication Date: 5 June 2009

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CdS/Ge nanowire heterojunction has been grown by chemical deposition of CdS on Ge nanowire templates. Transmission electron micrographs show the growth of core-shell Ge/CdS nanowire radial heterostructures. Raman spectra reveal the confinement of phonons in nanocrystalline CdS shell grown on Ge nanowires. A diodelike behavior in I-V characteristics of Ge/CdS heterojunction is observed due to the formation of rectifying junction between CdS shells and Ge nanowire cores. An improved photocurrent spectrum of Ge/CdS heterojunction nanowires with broadband response from visible to near-IR region is demonstrated.
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78.30.-j Infrared and Raman spectra
61.46.Np Structure of nanotubes (hollow nanowires)
81.05.Cy Elemental semiconductors
72.40.+w Photoconduction and photovoltaic effects
81.05.Dz II-VI semiconductors
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

Effect of 16-mercaptohexadecanoic acid modification on liquid transport in a nanoporous carbon

Weiyi Lu, Aijie Han, Taewan Kim, and Yu Qiao

Appl. Phys. Lett. 94, 223120 (2009); http://dx.doi.org/10.1063/1.3149826 (3 pages) | Cited 1 time

Online Publication Date: 5 June 2009

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The inner surfaces of a nanoporous carbon are modified by 16-mercaptohexadecanioic acid. The degree of wettability is electrically controllable: by applying a negative potential difference across the solid-liquid interface, the ion transport pressure in the nanopores can be considerably lowered; while the effect of applying a positive potential difference is negligible. These phenomena can be attributed to the unique surface chain configuration in the confining nanoenvironment.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
61.46.-w Structure of nanoscale materials
47.56.+r Flows through porous media
61.43.Gt Powders, porous materials
68.08.Bc Wetting

A site-controlled quantum dot system offering both high uniformity and spectral purity

L. O. Mereni, V. Dimastrodonato, R. J. Young, and E. Pelucchi

Appl. Phys. Lett. 94, 223121 (2009); http://dx.doi.org/10.1063/1.3147213 (3 pages) | Cited 23 times

Online Publication Date: 5 June 2009

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In this letter we report on the optical properties of site-controlled InGaAs quantum dots with GaAs barriers grown in pyramidal recesses by metalorganic vapor phase epitaxy. The inhomogeneous broadening of excitonic emission from an ensemble of quantum dots is found to be unusually narrow, with a standard deviation of 1.19 meV and the spectral purity of emission lines from individual dots is found to be very high (18–30 μeV), in contrast with other site-controlled dot systems.
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78.67.Hc Quantum dots
71.35.-y Excitons and related phenomena

Nanoenabled microelectromechanical sensor for volatile organic chemical detection

Chiara Zuniga, Matteo Rinaldi, Samuel M. Khamis, A. T. Johnson, and Gianluca Piazza

Appl. Phys. Lett. 94, 223122 (2009); http://dx.doi.org/10.1063/1.3151919 (3 pages) | Cited 8 times

Online Publication Date: 5 June 2009

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A nanoenabled gravimetric chemical sensor prototype based on the large scale integration of single-stranded DNA (ss-DNA) decorated single-walled carbon nanotubes (SWNTs) as nanofunctionalization layer for aluminum nitride contour-mode resonant microelectromechanical (MEM) gravimetric sensors has been demonstrated. The capability of two distinct single strands of DNA bound to SWNTs to enhance differently the adsorption of volatile organic compounds such as dinitroluene (simulant for explosive vapor) and dymethyl-methylphosphonate (simulant for nerve agent sarin) has been verified experimentally. Different levels of sensitivity (17.3 and 28 KHz μm2/fg) due to separate frequencies of operation (287 and 450 MHz) on the same die have also been shown to prove the large dynamic range of sensitivity attainable with the sensor. The adsorption process in the ss-DNA decorated SWNTs does not occur in the bulk of the material, but solely involves the surface, which permits to achieve 50% recovery in less than 29 s.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
82.80.-d Chemical analysis and related physical methods of analysis
07.10.Cm Micromechanical devices and systems
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
87.14.gk DNA
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