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

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

14 Jan 2013

Volume 102, Issue 2, Articles (02xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 102, 023901 (2013); http://dx.doi.org/10.1063/1.4773526 (4 pages)

Yoshihiro Gohda and Shinji Tsuneyuki
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

A first-principles investigation of the optical spectra of oxidized graphene

N. Singh, T. P. Kaloni, and U. Schwingenschlögl

Appl. Phys. Lett. 102, 023101 (2013); http://dx.doi.org/10.1063/1.4781382 (4 pages) | Cited 1 time

Online Publication Date: 14 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electronic and optical properties of mono, di, tri, and tetravacancies in graphene are studied in comparison to each other, using density functional theory. In addition, oxidized monovacancies are considered for different oxygen concentrations. Pristine graphene is found to be more absorptive than any defect configuration at low energy. We demonstrate characteristic differences in the optical spectra of the various defects for energies up to 3 eV. This makes it possible to quantify by optical spectroscopy the ratios of the defect species present in a sample.
Show PACS
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
78.30.Hv Other nonmetallic inorganics
78.40.Ha Other nonmetallic inorganics
78.67.Wj Optical properties of graphene

Tunneling spectroscopy of graphene using planar Pb probes

Yanjing Li and Nadya Mason

Appl. Phys. Lett. 102, 023102 (2013); http://dx.doi.org/10.1063/1.4775600 (4 pages)

Online Publication Date: 14 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We show that evaporating lead (Pb) directly on graphene can create high-yield, high-quality tunnel probes, and we demonstrate high magnetic field/low temperature spectroscopy using these probes. Comparisons of Pb, Al, and Ti/Au probes show that after oxidation a well-formed self-limited tunnel barrier is created only between the Pb and the graphene. Tunneling spectroscopy using the Pb probes manifests energy-dependent features such as scattering resonances and localization behavior and can thus be used to probe the microscopic electronics of graphene.
Show PACS
61.48.Gh Structure of graphene
81.05.ue Graphene
73.40.-c Electronic transport in interface structures
81.65.Mq Oxidation
64.70.fm Thermodynamics studies of evaporation and condensation

A nanoelectromechanical systems optical switch driven by optical gradient force

H. Cai, B. Dong, J. F. Tao, L. Ding, J. M. Tsai, G. Q. Lo, A. Q. Liu, and D. L. Kwong

Appl. Phys. Lett. 102, 023103 (2013); http://dx.doi.org/10.1063/1.4775674 (4 pages)

Online Publication Date: 14 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A nanoelectromechanical systems (NEMS) optical switch driven by optical gradient force is demonstrated. The switch consists of a free-standing ring resonator and two bus waveguides. When the free-standing ring is bended by the optical gradient force, the output transmission signal is tuned from the on-state to the off-state of the switch. The NEMS optical switch shows a switching time of 43.5 ns and a switching contrast of more than 25 dB. With its chip-scale integrability, the optical switch has potential applications in signal processing and high-speed optical communication networks.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Gate voltage induced topological phase transition in hexagonal boron-nitride bilayers

Xuechao Zhai and Guojun Jin

Appl. Phys. Lett. 102, 023104 (2013); http://dx.doi.org/10.1063/1.4775689 (5 pages)

Online Publication Date: 15 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Single or few-layer hexagonal boron nitride sheets usually have very large band gaps, which greatly hinders their applications in electronic circuits. In this letter, we propose a way to significantly reduce the band gap of hexagonal boron-nitride bilayer (BNBL) by applying an interlayer bias voltage. In the presence of the intrinsic and Rashba spin-orbit couplings, we demonstrate whether gated BNBL is topologically nontrivial depends strongly on its stacking type. For AA-stacking BNBL with inversion symmetry, the strong topological insulator phase is obtained, and phase boundaries are analytically given. We also observe a re-entrant phase behavior from a normal insulator to a topological insulator then to a normal insulator, which is switched by the gate voltage. For AB-stacking BNBL, it is always topologically trivial but exhibits an unusual quantum Hall phase with four degenerate low-energy states localized at a single edge. These findings provide potential applications of BNBLs in electronics and spintronics.
Show PACS
64.70.kg Semiconductors
71.20.Nr Semiconductor compounds
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
73.43.Nq Quantum phase transitions

Feedback-controlled electromigration for the fabrication of point contacts

J. M. Campbell and R. G. Knobel

Appl. Phys. Lett. 102, 023105 (2013); http://dx.doi.org/10.1063/1.4775695 (4 pages)

Online Publication Date: 15 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Lithographically fabricated point contacts serve as important examples of mesoscopic conductors, as electrodes for molecular electronics, and as ultra-sensitive transducers for mechanical motion. We have developed a reproducible technique for fabricating metallic point contacts through electromigration. We employ fast analog feedback in a four-wire configuration in combination with slower computer controlled feedback to avoid catastrophic instability. This hybrid system allows electromigration to proceed while dissipating approximately constant power in the wire. We are able to control the final resistance of the point contact precisely below 5 kΩ and to within a factor of three when the target resistance approaches 12 kΩ where only a single conducting channel remains.
Show PACS
66.30.Qa Electromigration
73.40.-c Electronic transport in interface structures

Improved luminescence from CdSe quantum dots with a strain-compensated shell

Y. Lu, Y. Q. Zhang, and X. A. Cao

Appl. Phys. Lett. 102, 023106 (2013); http://dx.doi.org/10.1063/1.4775678 (4 pages)

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Colloidal CdSe quantum dots (QDs) with a strain-compensated ZnS/ZnCdS bilayer shell were synthesized and characterized. The core/shell/shell structure enjoys the benefits of excellent exciton confinement by the ZnS intermediate shell and strain compensation by the ZnCdS outer shell. The resulting CdSe/ZnS/ZnCdS QDs exhibited a 40% higher photoluminescence quantum yield and a more controllable wavelength compared to conventional CdSe/ZnCdS/ZnS core/shell/shell QDs with an intermediate lattice adaptor. CdSe/ZnS/ZnCdS QD light-emitting diodes (LEDs) had a luminance of 556 cd/m2 at 20 mA/cm2, 28% higher than that of CdSe/ZnCdS/ZnS QD-LEDs. The former also had better spectral purity at high injection currents and are thus better suited for full-color displays.
Show PACS
78.67.Hc Quantum dots
82.70.Dd Colloids
85.60.Jb Light-emitting devices
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
71.35.-y Excitons and related phenomena
78.55.Et II-VI semiconductors

Effects of GaAs(Sb) cladding layers on InAs/AlAsSb quantum dots

Meng Sun, Paul J. Simmonds, Ramesh Babu Laghumavarapu, Andrew Lin, Charles J. Reyner, Hsin-Sheng Duan, Baolai Liang, and Diana L. Huffaker

Appl. Phys. Lett. 102, 023107 (2013); http://dx.doi.org/10.1063/1.4776221 (5 pages) | Cited 1 time

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The structural and optical properties of InAs self-assembled quantum dots buried in AlAs0.56Sb0.44 barriers can be controlled using GaAs1−xSbx cladding layers. These cladding layers allow us to manage the amount of Sb immediately underneath and above the InAs quantum dots. The optimal cladding scheme has a GaAs layer beneath the InAs, and a GaAs0.95Sb0.05 layer above. This scheme results in improved dot morphology and significantly increased photoluminescence (PL) intensity. Both power-dependent and time-resolved photoluminescence confirm that the quantum dots have type-II band alignment. Enhanced carrier lifetimes in this quantum dot system show great potential for application in intermediate band solar cells.
Show PACS
78.67.Hc Quantum dots
68.35.bg Semiconductors
78.47.jd Time resolved luminescence
68.65.Hb Quantum dots (patterned in quantum wells)
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.63.Kv Quantum dots

Electronic and optical properties of metal-nanoparticle filled graphene sandwiches

Anna M. Zaniewski, Maria Schriver, J. Gloria Lee, M. F. Crommie, and A. Zettl

Appl. Phys. Lett. 102, 023108 (2013); http://dx.doi.org/10.1063/1.4772542 (4 pages)

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We sandwich gold nanoparticles between graphene sheets and contrast the electronic and optical properties of these hybrid structures to those of single layer graphene with and without gold nanoparticle overlayers, and laminated unfilled double layers. Undecorated graphene has the highest sheet resistance while filled sandwiches have the lowest. The optical extinction spectrum for sandwiches is redshifted and broadened compared to decorated single layer graphene. We also find that the presence of gold nanoparticles in sandwiches shifts the work function relative to unfilled double-layer graphene. The low sheet resistance and favorable optical properties of metal-filled sandwiches make them attractive candidates for optoelectronic applications.
Show PACS
71.20.-b Electron density of states and band structure of crystalline solids
73.30.+y Surface double layers, Schottky barriers, and work functions
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

Reducing thermal transport in electrically conducting polymers: Effects of ordered mixing of polymer chains

Souvik Pal, Ganesh Balasubramanian, and Ishwar K. Puri

Appl. Phys. Lett. 102, 023109 (2013); http://dx.doi.org/10.1063/1.4776676 (4 pages)

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Reducing the phonon thermal conductivity of electrically conducting polymers can facilitate their use as potential thermoelectric materials. Thus, the influence of the coupling between the longitudinal and transverse phonon modes on overall thermal conductivity is explored for binary mixtures of polyaniline (PANI) and polyacetylene (PA) chains by considering various geometric polymer mixture configurations. The molecular simulations reveal that an increase in the interfacial area available for transverse interactions between dissimilar chains enhances atomic interactions that are orthogonal to the heat transfer direction. As transverse collisions between PA and PANI chains are enhanced, the motion of longitudinal phonons is disrupted, impeding thermal transport. This enhances phonon scattering and reduces longitudinal thermal transport. While there is a nonlinear decrease in the phonon thermal conductivity with increasing interfacial contact area, there is a corresponding linear growth in the nonbonded interaction energies between the different polymers.
Show PACS
66.70.Hk Glasses and polymers
61.41.+e Polymers, elastomers, and plastics
72.20.Pa Thermoelectric and thermomagnetic effects
72.80.Le Polymers; organic compounds (including organic semiconductors)
64.75.Ef Mixing

Tunnel-field-effect-transistor based gas-sensor: Introducing gas detection with a quantum-mechanical transducer

Deblina Sarkar, Harald Gossner, Walter Hansch, and Kaustav Banerjee

Appl. Phys. Lett. 102, 023110 (2013); http://dx.doi.org/10.1063/1.4775358 (5 pages) | Cited 2 times

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A gas-sensor based on tunnel-field-effect-transistor (TFET) is proposed that leverages the unique current injection mechanism in the form of quantum-mechanical band-to-band tunneling to achieve substantially improved performance compared to conventional metal-oxide-semiconductor field-effect-transistors (MOSFETs) for detection of gas species under ambient conditions. While nonlocal phonon-assisted tunneling model is used for detailed device simulations, in order to provide better physical insights, analytical formula for sensitivity is derived for both metal as well as organic conducting polymer based sensing elements. Analytical derivations are also presented for capturing the effects of temperature on sensor performance. Combining the developed analytical and numerical models, intricate properties of the sensor such as gate bias dependence of sensitivity, relationship between the required work-function modulation and subthreshold swing, counter-intuitive increase in threshold voltage for MOSFETs and reduction in tunneling probability for TFETs with temperature are explained. It is shown that TFET gas-sensors can not only lead to more than 10 000× increase in sensitivity but also provide design flexibility and immunity against screening of work-function modulation through non-specific gases as well as ensure stable operation under temperature variations.
Show PACS
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.07.Mp Transducers
82.80.-d Chemical analysis and related physical methods of analysis
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
85.30.Tv Field effect devices

Quantitative analysis of annealed scanning probe tips using energy dispersive x-ray spectroscopy

R. J. Cobley, R. A. Brown, C. J. Barnett, T. G. G. Maffeis, and M. W. Penny

Appl. Phys. Lett. 102, 023111 (2013); http://dx.doi.org/10.1063/1.4776705 (4 pages)

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A quantitative method to measure the reduction in oxide species on the surface of electrochemically etched tungsten tips during direct current annealing is developed using energy dispersive x-ray spectroscopy. Oxide species are found to decrease with annealing current, with the trend repeatable over many tips and along the length of the tip apex. A linear resistivity approximation finds significant oxide sublimation occurs at 1714 K, but surface melting and tip broadening at 2215 K. This method can be applied to calibrate any similar annealing stage, and to identify the tradeoff regime between required morphological and chemical properties.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
81.40.Gh Other heat and thermomechanical treatments
FREE

Production of a 100-m-long high-quality graphene transparent conductive film by roll-to-roll chemical vapor deposition and transfer process

Toshiyuki Kobayashi, Masashi Bando, Nozomi Kimura, Keisuke Shimizu, Koji Kadono, Nobuhiko Umezu, Kazuhiko Miyahara, Shinji Hayazaki, Sae Nagai, Yukiko Mizuguchi, Yosuke Murakami, and Daisuke Hobara

Appl. Phys. Lett. 102, 023112 (2013); http://dx.doi.org/10.1063/1.4776707 (4 pages) | Cited 3 times

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A high-quality graphene transparent conductive film was fabricated by roll-to-roll chemical vapor deposition (CVD) synthesis on a suspended copper foil and subsequent transfer. While the high temperature required for the CVD synthesis of high-quality graphene has prevented efficient roll-to-roll production thus far, we used selective Joule heating of the copper foil to achieve this. Low pressure thermal CVD synthesis and a direct roll-to-roll transfer process using photocurable epoxy resin allowed us to fabricate a 100-m-long graphene transparent conductive film with a sheet resistance as low as 150 Ω/sq, which is comparable to that of state-of-the-art CVD-grown graphene films.
Show PACS
81.05.ue Graphene
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.ap Fullerenes
61.48.Gh Structure of graphene
68.65.Pq Graphene films

Surface-plasmon-polariton assisted modification of spontaneous emission of colloidal quantum dots in metal nanostructures

Jayson L. Briscoe, Nadeepa Jayasundara, and Sang-Yeon Cho

Appl. Phys. Lett. 102, 023113 (2013); http://dx.doi.org/10.1063/1.4776736 (4 pages) | Cited 1 time

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We experimentally demonstrate extraordinary optical transmission (EOT) assisted photoluminescence (PL) of CdSe/CdS colloidal quantum dots (QDs). The quantum dots were encapsulated between a metallic nanostructure and a Bragg reflector to enhance the interaction of spontaneously emitted photons with a resonant electromagnetic surface wave. The measured PL spectrum of the fabricated sample exhibits spectral narrowing and a shift in peak wavelength of 22 nm and 7 nm, respectively. Furthermore, we tested the angular dependence of the signal to confirm the existence of EOT. This demonstration is a critical step towards realizing plasmonic colloidal QD based coherent emitters.
Show PACS
73.21.La Quantum dots
73.63.Kv Quantum dots
78.67.Hc Quantum dots
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

The effect of degree of reduction on the electrical properties of functionalized graphene sheets

Christian Punckt, Franziska Muckel, Svenja Wolff, Ilhan A. Aksay, Carlos A. Chavarin, Gerd Bacher, and Wolfgang Mertin

Appl. Phys. Lett. 102, 023114 (2013); http://dx.doi.org/10.1063/1.4775582 (5 pages)

Online Publication Date: 18 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study the effect of carbon to oxygen ratio (C/O) on the electrical resistance of functionalized graphene sheets prepared by thermal exfoliation and reduction of graphite oxide at various temperatures. Using a 2-probe technique in conjunction with Kelvin probe force microscopy, we observe a transition from high-resistance (>400 kΩ/sq) nonlinear current/voltage characteristics at low C/O to low-resistance (<10 kΩ/sq) linear behavior at high C/O, indicating a transition from hopping to diffusive electron transport. Simultaneously, the metal-graphene contacts change from high-resistance Schottky-type behavior to nearly non-invasive metal-metal contact characteristics.
Show PACS
61.48.Gh Structure of graphene
81.05.ue Graphene
81.05.uf Graphite
73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Cg Contact resistance, contact potential
73.61.Wp Fullerenes and related materials

Towards liquid metal ion source chips: Indium liquid metal ion source with glass microcapillaries

M. Tajmar and F. Plesescu

Appl. Phys. Lett. 102, 023115 (2013); http://dx.doi.org/10.1063/1.4781442 (3 pages)

Online Publication Date: 18 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A liquid-metal-ion-source with indium propellant using an uncoated fused quartz glass microcapillary was manufactured and tested. The extremely thin capillary enabled a very low ignition voltage of 1000 V and a high electrical impedance ideal for clustering. However, low bonding forces between indium and glass resulted in a rather short lifetime of little more than 10 min. The use of pure glass as emitter material may enable liquid ion source chips with high current densities in the future.
Show PACS
89.40.Dd Air transporation
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close