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

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

27 Dec 2010

Volume 97, Issue 26, Articles (26xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 97, 263701 (2010); http://dx.doi.org/10.1063/1.3530124 (3 pages)

Shu-Hsien Liao, Kai-Wen Huang, Hong-Chang Yang, Chang-Te Yen, M. J. Chen, Hsin-Hsien Chen, Herng-Er Horng, and Shieh Yueh Yang
Enlarge Image | Read More
Page 3 of 4 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Simultaneous changes of nuclear and magnetic structures across the morphotropic phase boundary in (1−x)BiFeO3−xPbTiO3

Shuvrajyoti Bhattacharjee, Anatoliy Senyshyn, P. S. R. Krishna, H. Fuess, and Dhananjai Pandey

Appl. Phys. Lett. 97, 262506 (2010); http://dx.doi.org/10.1063/1.3533665 (3 pages) | Cited 4 times

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present here the results of a powder neutron diffraction study on the (1−x)BiFeO3–xPbTiO3 (BF-xPT) system, which reveal an abrupt change in magnetic structure from a noncollinear antiferromagnetic one to a collinear G-type antiferromagnetic as the nuclear structure of the ferroelectric phase changes from monoclinic in Cc space group for x ≤ 0.27 to tetragonal in P4mm space group for x ≥ 0.31 across the morphotropic phase boundary (MPB). This reflects the multiferroic character of the MPB in the BF-xPT system.
Show PACS
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
61.05.fm Neutron diffraction
75.50.Ee Antiferromagnetics
75.85.+t Magnetoelectric effects, multiferroics
77.80.B- Phase transitions and Curie point

Embedded clusters and magnetism in Cr-doped AlAs: A first-principles study

Yao Qiu, Yong-Hong Zhao, Yong Liu, Guo-Ping Zhao, and Shao-Quan Wu

Appl. Phys. Lett. 97, 262507 (2010); http://dx.doi.org/10.1063/1.3533799 (3 pages) | Cited 1 time

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Extensive density functional theory investigations have been made on the spatial distribution of Cr atoms and associated magnetism of zinc-blende Cr:AlAs. The calculated results show that embedded Cr clusters, formed on the substitutional Al and interstitial sites, can lead to great changes in the local structure and magnetism of Cr:AlAs, which is very different from that assumed by the usual homogeneous model.
Show PACS
71.20.Nr Semiconductor compounds
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
75.50.Pp Magnetic semiconductors
61.72.jj Interstitials
61.72.uj III-V and II-VI semiconductors

Microwave readout scheme for a Josephson phase qubit

T. Wirth, J. Lisenfeld, A. Lukashenko, and A. V. Ustinov

Appl. Phys. Lett. 97, 262508 (2010); http://dx.doi.org/10.1063/1.3533805 (3 pages) | Cited 2 times

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present experimental results on a microwave scheme for reading out a Josephson phase qubit. A capacitively shunted superconducting quantum interference device (SQUID) is used as a nonlinear resonator which is inductively coupled to the qubit. The flux state of the qubit is detected by measuring the amplitude and phase of a microwave pulse reflected from the SQUID resonator. By this low-dissipative method, the qubit state measurement time is reduced to 25 μs, which is much faster than the conventional readout performed by switching the SQUID to its nonzero dc voltage state. The readout scheme presented here allows for reading out multiple qubits using a single microwave line by employing frequency-division multiplexing.
Show PACS
03.67.Lx Quantum computation architectures and implementations
85.25.Cp Josephson devices
85.25.Dq Superconducting quantum interference devices (SQUIDs)

Modification of magnetic and magnetocaloric properties of Dy–Co–Al bulk metallic glass introduced by hydrogen

H. Fu, M. Zou, and Niraj K. Singh

Appl. Phys. Lett. 97, 262509 (2010); http://dx.doi.org/10.1063/1.3534794 (3 pages) | Cited 2 times

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dy53.8Co17.3Al28.9 bulk metallic glass with a diameter of 3 mm exhibits spin-glass behavior and large coercivity and remanence. Hydrogenation of Dy53.8Co17.3Al28.9 suppresses the magnetic transition temperature and removes coercivity and remanence because of the expansion of average interatomic distance. The advantage of large magnetic entropy changes (17.5 and 9.5 J/kg K for the field changes from 0 to 50, and from 0 to 20 kOe, respectively) without any hysteresis loss makes Dy53.8Co17.3Al28.9 H170.6 alloy a promising magnetic refrigerant.
Show PACS
75.30.Sg Magnetocaloric effect, magnetic cooling
75.50.Lk Spin glasses and other random magnets
75.50.Kj Amorphous and quasicrystalline magnetic materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
back to top
RSS Feeds

Fine tuning epitaxial strain in ferroelectrics: PbxSr1−xTiO3 on DyScO3

G. Rispens, J. A. Heuver, and B. Noheda

Appl. Phys. Lett. 97, 262901 (2010); http://dx.doi.org/10.1063/1.3532103 (3 pages)

Online Publication Date: 29 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Epitaxial strain can be efficiently used to modify the properties of ferroelectric thin films. From the experimental viewpoint, the challenge is to fine-tune the magnitude of the strain. We illustrate here how, by using a suitable combination of composition and substrate, the magnitude of the epitaxial strain can be controlled in a continuous manner. The phase diagram of PbxSr1−xTiO3 films grown epitaxially on (110)-DyScO3 is calculated using a Devonshire–Landau approach. A boundary between in-plane and out-of-plane oriented ferroelectric phases is predicted to take place at x ≈ 0.8. A series of PbxSr1−xTiO3 epitaxial films grown by molecular beam epitaxy shows good agreement with the proposed phase diagram.
Show PACS
77.84.Cg PZT ceramics and other titanates
81.30.Dz Phase diagrams of other materials
77.80.bn Strain and interface effects
77.55.fp Other ferroelectric films

Leakage current behavior in lead-free ferroelectric (K,Na)NbO3-LiTaO3-LiSbO3 thin films

M. Abazari and A. Safari

Appl. Phys. Lett. 97, 262902 (2010); http://dx.doi.org/10.1063/1.3531575 (3 pages) | Cited 2 times

Online Publication Date: 29 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Conduction mechanisms in epitaxial (001)-oriented pure and 1 mol % Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.1,Sb0.06)O3 (KNN-LT-LS) thin films on SrTiO3 substrate were investigated. Temperature dependence of leakage current density was measured as a function of applied electric field in the range of 200–380 K. It was shown that the different transport mechanisms dominate in pure and Mn-doped thin films. In pure (KNN-LT-LS) thin films, Poole-Frenkel emission was found to be responsible for the leakage, while Schottky emission was the dominant mechanism in Mn-doped thin films at higher electric fields. This is a remarkable yet clear indication of effect of 1 mol % Mn on the resistive behavior of such thin films.
Show PACS
77.55.fj Niobate- and tantalate-based films
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Ek Niobates and tantalates
73.50.Fq High-field and nonlinear effects
73.30.+y Surface double layers, Schottky barriers, and work functions

Thermal stability of TiN/HfSiON gate stack structures studied by synchrotron-radiation photoemission spectroscopy

S. Toyoda, H. Kamada, H. Kumigashira, M. Oshima, K. Iwamoto, T. Sukegawa, and Z. Liu

Appl. Phys. Lett. 97, 262903 (2010); http://dx.doi.org/10.1063/1.3532846 (3 pages) | Cited 1 time

Online Publication Date: 29 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the thermal stability of TiN/HfSiON gate stack structures using synchrotron-radiation photoemission spectroscopy. Spectral intensities of the Si-oxide components in Si 2p core-level spectra systematically increase with annealing temperature, which strongly depends on the thickness of the TiN metal gate layer. Changes brought by annealing procedures in depth profiles of atomic concentration indicate segregation of Si-atoms at the TiN surface. Furthermore, chemical-state-resolved depth analyses by angle-resolved photoemission spectroscopy suggest formation of TiSix and HfNy components due to chemical bond breaking in the HfSiON layer during TiN film growth. This can be related to the degradation of thermal stability.
Show PACS
79.60.-i Photoemission and photoelectron spectra
81.40.Gh Other heat and thermomechanical treatments

Effect of domain structure on dielectric nonlinearity in epitaxial BiFeO3 films

J. F. Ihlefeld, C. M. Folkman, S. H. Baek, G. L. Brennecka, M. C. George, J. F. Carroll, III, and C. B. Eom

Appl. Phys. Lett. 97, 262904 (2010); http://dx.doi.org/10.1063/1.3533017 (3 pages) | Cited 6 times

Online Publication Date: 29 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Rayleigh analysis has been used to investigate dielectric nonlinearity in epitaxial (001)-oriented BiFeO3 films with engineered domain structures from single- to four-variant and stripe domain samples with 71° and 109° domain walls. Single-domain variant films display minimal irreversible contributions, whereas the ratio of irreversible to reversible contributions increases by approximately one order of magnitude as the number of variants increases to two- and four-variants, respectively. These measurements indicate that the density of domain walls and degree of domain wall complexity influence the number and strength of domain wall pinning sites.
Show PACS
77.80.Dj Domain structure; hysteresis
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
68.55.-a Thin film structure and morphology

Observation of anomalous phonons in orthorhombic rare-earth manganites

P. Gao, H. Y. Chen, T. A. Tyson, Z. X. Liu, J. M. Bai, L. P. Wang, Y. J. Choi, and S.-W. Cheong

Appl. Phys. Lett. 97, 262905 (2010); http://dx.doi.org/10.1063/1.3533022 (3 pages)

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We observe the appearance of a phonon near the lock-in temperature in orthorhombic REMnO3 (RE denotes rare earth) (RE: Lu and Ho) and anomalous phonon hardening in orthorhombic LuMnO3. The anomalous phonon occurs at the onset of spontaneous polarization. No such changes were found in incommensurate orthorhombic DyMnO3. These observations directly reveal different electric polarization mechanisms in the E-type and incommensurate-type orthorhombic REMnO3.
Show PACS
63.20.Ry Anharmonic lattice modes

Correlation between the nanoscale electrical and morphological properties of crystallized hafnium oxide-based metal oxide semiconductor structures

V. Iglesias, M. Porti, M. Nafría, X. Aymerich, P. Dudek, T. Schroeder, and G. Bersuker

Appl. Phys. Lett. 97, 262906 (2010); http://dx.doi.org/10.1063/1.3533257 (3 pages) | Cited 4 times

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The relationship between electrical and structural characteristics of polycrystalline HfO2 films has been investigated by conductive atomic force microscopy under ultrahigh vacuum conditions. The results demonstrate that highly conductive and breakdown (BD) sites are concentrated mainly at the grain boundaries (GBs). Higher conductivity at the GBs is found to be related to their intrinsic electrical properties, while the positions of the electrical stress-induced BD sites correlate to the local thinning of the dielectric. The results indicate that variations in the local characteristics of the high-k film caused by its crystallization may have a strong impact on the electrical characteristics of high-k dielectric stacks.
Show PACS
77.55.df For silicon electronics
77.22.Jp Dielectric breakdown and space-charge effects
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
64.70.K- Solid-solid transitions
61.72.Mm Grain and twin boundaries
back to top
RSS Feeds

Ion and electron beam nanofabrication of the which-way double-slit experiment in a transmission electron microscope

Stefano Frabboni, Gian Carlo Gazzadi, and Giulio Pozzi

Appl. Phys. Lett. 97, 263101 (2010); http://dx.doi.org/10.1063/1.3529947 (3 pages) | Cited 1 time

Online Publication Date: 28 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have realized a which-way experiment closely resembling the original Feynman’s proposal exploiting focused ion beam milling to prepare two nanoslits and electron beam induced deposition to grow, selectively over one of them, electron transparent layers of low atomic number amorphous material to realize a which-way detector for high energy electrons. By carrying out the experiment in an electron microscope equipped with an energy filter, we show that the inelastic scattering of electron transmitted through amorphous layers of different thicknesses provides the control of the dissipative interaction process responsible for the localization phenomena which cancels out the interference effects.
Show PACS
81.15.Jj Ion and electron beam-assisted deposition; ion plating
81.15.Dj E-beam and hot filament evaporation deposition
81.16.-c Methods of micro- and nanofabrication and processing
79.20.Uv Electron energy loss spectroscopy

Nonradiative energy transfer between vertically coupled indirect and direct bandgap InAs quantum dots

Timur S. Shamirzaev, Demid S. Abramkin, Dmitry V. Dmitriev, and Anton K. Gutakovskii

Appl. Phys. Lett. 97, 263102 (2010); http://dx.doi.org/10.1063/1.3532102 (3 pages)

Online Publication Date: 28 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nonradiative energy transfer from indirect bandgap InAs/AlAs quantum dots (QDs) to direct bandgap InAs/AlGaAs QDs was studied by steady-state and transient photoluminescence. We demonstrate that long excitonic lifetime in donor InAs/AlAs QDs allows one to extend the efficient exciton energy transfer between coupled QDs to distances up to 9 nm.
Show PACS
73.21.La Quantum dots
73.63.Kv Quantum dots
78.55.Cr III-V semiconductors
78.67.Hc Quantum dots

The effect of Ti and ITO adhesion layers on gold split-ring resonators

Claus Jeppesen, Niels Asger Mortensen, and Anders Kristensen

Appl. Phys. Lett. 97, 263103 (2010); http://dx.doi.org/10.1063/1.3532096 (3 pages)

Online Publication Date: 28 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ultrathin adhesion layers serve a well-documented fabrication purpose while its influence on the optical properties of gold nanostructures is often neglected. Gold split-ring resonators are fabricated with two commonly used adhesion layers: titanium and indium tin oxide. When compared to all-gold reference samples, a spectral shift of the ground mode resonance is observed. For the titanium sample the spectral shift is accompanied by a resonance broadening, which is less profound for indium tin oxide. The mutual correlation between the shift and the broadening is shown to be qualitatively consistent with perturbative considerations.
Show PACS
42.79.-e Optical elements, devices, and systems
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.86.+b Optical workshop techniques

Different longitudinal optical—transverse optical mode amplification in tip enhanced Raman spectroscopy of GaAs(001)

Pietro Giuseppe Gucciardi and Jean-Christophe Valmalette

Appl. Phys. Lett. 97, 263104 (2010); http://dx.doi.org/10.1063/1.3532841 (3 pages)

Online Publication Date: 28 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on tip enhanced Raman spectroscopy of GaAs(100) crystals taking advantage of the fields polarization to maximize the near-field contrast. Excitation parallel to either the [100] or the [110] crystallographic axis provide minimum far-field background provided that cross- or parallel-component of the Raman field are detected. Experiments highlight a tip-induced selective enhancement of the one-phonon longitudinal optical mode with respect to the transverse optical mode. We interpret this effect in terms of depolarization of the excitation field and beam deflection which breaks the polarization-based selection rules of the Raman scattering.
Show PACS
63.20.dd Measurements
78.30.Fs III-V and II-VI semiconductors

Work function of single-wall silicon carbide nanotube

Fawei Zheng, Yu Yang, and Ping Zhang

Appl. Phys. Lett. 97, 263105 (2010); http://dx.doi.org/10.1063/1.3532842 (3 pages)

Online Publication Date: 28 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using first-principles calculations, we study the work function of single-wall silicon carbide nanotube (SiCNT). The work function is found to be highly dependent on the tube chirality and diameter. It increases by decreasing the tube diameter. The work function of zigzag SiCNT is always larger than that of armchair SiCNT. We reveal that the difference between the work function of zigzag and armchair SiCNT comes from their different intrinsic electronic structures, for which the singly degenerate energy band above the Fermi level of zigzag SiCNT is specifically responsible. Our finding offers potential usages of SiCNT in field-emission devices.
Show PACS
73.30.+y Surface double layers, Schottky barriers, and work functions
71.15.-m Methods of electronic structure calculations
73.22.-f Electronic structure of nanoscale materials and related systems

Observation of efficient transfer from Mott–Wannier to Frenkel excitons in a hybrid semiconductor quantum dot/polymer composite at room temperature

Sedat Nizamoglu, Xiao Wei Sun, and Hilmi Volkan Demir

Appl. Phys. Lett. 97, 263106 (2010); http://dx.doi.org/10.1063/1.3529450 (3 pages)

Online Publication Date: 29 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Efficient conversion from Mott–Wannier to Frenkel excitons is observed at room temperature. The time-resolved photoluminescence shows that the energy transfer rate and efficiency reach 0.262 ns−1 and 80.9%, respectively. The energy transfer is enabled by strong dipole-dipole coupling in a hybrid inorganic/organic system of CdSe/ZnS core/shell heteronanocrystal and poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene] homopolymer composite, and the measured energy transfer efficiencies are consistent with the analytical model.
Show PACS
73.22.Lp Collective excitations
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.55.-m Photoluminescence, properties and materials
78.47.jd Time resolved luminescence

Thermal conductivity of GaAs nanowires studied by micro-Raman spectroscopy combined with laser heating

Martin Soini, Ilaria Zardo, Emanuele Uccelli, Stefan Funk, Gregor Koblmüller, Anna Fontcuberta i Morral, and Gerhard Abstreiter

Appl. Phys. Lett. 97, 263107 (2010); http://dx.doi.org/10.1063/1.3532848 (3 pages) | Cited 1 time

Online Publication Date: 29 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The thermal properties of freely suspended GaAs nanowires are investigated by applying a method which relies on laser heating and the determination of the local temperature by Raman spectroscopy. In order to determine the values for the thermal conductivity κ, the fraction of the laser power absorbed inside the GaAs nanowire is estimated by numerical simulations. The thermal conductivity of nanowires with homogeneous diameter is found to lie in the range of 8–36 W m−1 K−1. The change of the temperature profile in the presence of a tapering was investigated. Furthermore, we discuss the influence of laser heating in ambient conditions on the value of κ.
Show PACS
66.70.Df Metals, alloys, and semiconductors
78.67.Lt Quantum wires
42.62.-b Laser applications
78.30.Fs III-V and II-VI semiconductors
61.72.Cc Kinetics of defect formation and annealing

Enhanced photorefractivity in a polymer/nanocrystal composite photorefractive device at telecommunication wavelength

Jing Zhu (朱菁), Won Jin Kim, Guang S. He, Jangwon Seo, Ken-Tye Yong, Dongho Lee, Alexander N. Cartwright, Yiping Cui (崔一平), and Paras N. Prasad

Appl. Phys. Lett. 97, 263108 (2010); http://dx.doi.org/10.1063/1.3531650 (3 pages)

Online Publication Date: 29 December 2010

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
Enhanced photorefractive (PR) response in nanocrystal-polymer nanocomposite PR devices at the telecommunication wavelength of 1.3 μm is achieved using facile surface treatment of PbS nanocrystals functionalized with thermally cleavable ligands. The cleavage of the ligands, by heat treatment, results in significant improvement in both photocharge generation and PR response, as demonstrated by photoconductivity and two-beam coupling (TBC) experiments, respectively. The TBC experiment shows that the optical gain coefficient is improved drastically (about 63%) at an applied electric field of 84 V/μm.
Show PACS
85.60.-q Optoelectronic devices
85.30.-z Semiconductor devices

Electron-hole duality during band-to-band tunneling process in graphene-nanoribbon tunnel-field-effect-transistors

Deblina Sarkar, Michael Krall, and Kaustav Banerjee

Appl. Phys. Lett. 97, 263109 (2010); http://dx.doi.org/10.1063/1.3528338 (3 pages) | Cited 6 times

Online Publication Date: 29 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter provides clear insight into the interplay between electron and hole characteristics of carriers within the forbidden gap during the band-to-band tunneling process, taking graphene-nanoribbons as an example. Accurate numerical models are presented and analytical formulas for tunneling probabilities are derived for both source/drain to channel and direct source-drain tunneling based on the Wentzel–Kramers–Brillouin (WKB) method. It is shown that not considering the electron-hole duality can lead to significant errors in numerical calculations, and more importantly, lack of proper understanding of the phenomenon gives rise to seriously misleading conclusions. Furthermore, the regime of validity of the WKB approximation for graphene-nanoribbon tunnel-field-effect-transistors is discussed in light of the electron-hole duality concept.
Show PACS
73.40.Gk Tunneling
73.63.-b Electronic transport in nanoscale materials and structures
72.80.Vp Electronic transport in graphene
85.30.Tv Field effect devices

Comparative study of field enhancement between isolated and coupled metal nanoparticles: An analytical approach

G. Sun and J. B. Khurgin

Appl. Phys. Lett. 97, 263110 (2010); http://dx.doi.org/10.1063/1.3532101 (3 pages) | Cited 3 times

Online Publication Date: 29 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present an analytical model that takes into account the coupling between the surface plasmon modes in complex metal nanostructures. We apply this model to evaluate the field enhancement in the gap of two coupled Au metal spheres embedded in GaN dielectric and compare the result with that obtained by the single sphere. The results show additional improvement can be obtained in the gap depending on the width of the gap. This approach offers a clear physical insight for the enhancement and a straightforward method for optimization.
Show PACS
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Electrical signatures of ferromagnetism in epitaxial FeSi2 nanowires

T. Kim and J. P. Bird

Appl. Phys. Lett. 97, 263111 (2010); http://dx.doi.org/10.1063/1.3533400 (3 pages) | Cited 1 time

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We perform electrical characterization of epitaxial FeSi2 nanowires (NWs) realized by reactive epitaxy. Typical resistance values exceed 100 kΩ, a high value that is attributed to the combined influence of interfacial scattering and process-related damage. Negative magnetoresistance due to weak localization, as well as hysteresis and anisotropic magnetoresistance, are also observed at low temperatures, confirming the ferromagnetic nature of these NWs.
Show PACS
75.47.Np Metals and alloys
73.20.Fz Weak or Anderson localization
75.50.Bb Fe and its alloys
75.70.Ak Magnetic properties of monolayers and thin films
73.61.Le Other inorganic semiconductors

Electrical study of trapped charges in nanoscale Ge islands by Kelvin probe force microscopy for nonvolatile memory applications

Z. Lin, P. Brunkov, F. Bassani, and G. Bremond

Appl. Phys. Lett. 97, 263112 (2010); http://dx.doi.org/10.1063/1.3533259 (3 pages)

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Isolated Germanium nanoisland on top of silicon dioxide (SiO2) layer has been studied by Kelvin probe force microscopy (KPFM) at room temperature. Different surface potentials between Ge island and SiO2 dielectric layer were directly visualized from the KPFM image. The image contrast greatly increased after electron injection by applying a negative bias of −7 V. The dissipation of injected electrons was evaluated by measuring the surface potential variation due to the leakage of these injected charges. The long retention time of local charges in Ge dot is promising for applications in nonvolatile memories.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.63.Bd Nanocrystalline materials

Separation of ultrafast photoexcited electron and hole dynamics in CdSe quantum dots adsorbed onto nanostructured TiO2 films

Qing Shen, Yasumasa Ayuzawa, Kenji Katayama, Tsuguo Sawada, and Taro Toyoda

Appl. Phys. Lett. 97, 263113 (2010); http://dx.doi.org/10.1063/1.3533374 (3 pages)

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The ultrafast photoexcited electron and hole dynamics of CdSe quantum dots (QDs) deposited onto nanostructured TiO2 films were studied using an improved transient grating (TG) technique. By comparing the TG responses measured in air and in a Na2S solution (hole acceptor), we succeeded in separating the dynamic characteristics of photoexcited electrons and holes in the CdSe QDs. We found that charge separation in the CdSe QDs occurred over a very fast time scale from a few hundreds of femtoseconds in the Na2S solution via hole transfer to S2− ions to a few picoseconds in air via hole trapping.
Show PACS
73.63.Kv Quantum dots
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Spin-polarized energy-gap opening in asymmetric bilayer graphene nanoribbons

Gyubong Kim and Seung-Hoon Jhi

Appl. Phys. Lett. 97, 263114 (2010); http://dx.doi.org/10.1063/1.3533643 (3 pages)

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electronic and magnetic properties of bilayer zigzag graphene nanoribbon (bZGNR) are studied using pseudopotential density functional method. The edge atoms in the top and bottom layers of bZGNR make a weak hybridization, which leads to electronic structures different from monolayer ZGNR. For asymmetric bZGNR, where the top and bottom layers have different widths, one edge is pinched by the interlayer bonding and the other sustains antiferromagnetic ordering. A small amount of charge transfer occurs from narrower to wider layer, producing spin-polarized electron and hole pockets. External electric field produces asymmetric energy-gap opening for each spin component, inducing half-metallicity in bZGNR.
Show PACS
73.22.Pr Electronic structure of graphene
75.50.Ee Antiferromagnetics
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
75.50.Tt Fine-particle systems; nanocrystalline materials
75.75.-c Magnetic properties of nanostructures
71.20.Tx Fullerenes and related materials; intercalation compounds

Carbon-based nanomaterials as contacts to graphene nanoribbons

Yijian Ouyang and Jing Guo

Appl. Phys. Lett. 97, 263115 (2010); http://dx.doi.org/10.1063/1.3533803 (3 pages) | Cited 1 time

Online Publication Date: 30 December 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Making good electrical contacts to nanodevice channels is crucial for device performance. Carbon-based nanomaterials are studied and compared to each other as the contact materials for graphene nanoribbons (GNRs) by atomistic quantum transport simulations. A monolayer graphene that has an AB stacking structure on the GNR offers the best electrical contact. Rotation of the graphene layer with regard to the GNR leads to a considerable increase in the contact resistance and contact transfer length. Importance of wave vector matching and interfacial defects is examined for improving electrical contacts to GNRs. This paper could be useful for designing all-carbon-based circuits.
Show PACS
73.63.Rt Nanoscale contacts
73.40.Cg Contact resistance, contact potential
61.48.Gh Structure of graphene
61.46.-w Structure of nanoscale materials
Page 3 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close