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

13 Feb 2012

Volume 100, Issue 7, Articles (07xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 100, 073501 (2012); http://dx.doi.org/10.1063/1.3682479 (3 pages)

S. Tongay, M. Lemaitre, J. Fridmann, A. F. Hebard, B. P. Gila, and B. R. Appleton
Enlarge Image | Read More
Page 1 of 4 Pages Next Page | Jump to Page
back to top
RSS Feeds

Terahertz composite right-left handed transmission-line metamaterial waveguides

Zhijun Liu, Philip W. C. Hon, Amir A. Tavallaee, Tatsuo Itoh, and Benjamin S. Williams

Appl. Phys. Lett. 100, 071101 (2012); http://dx.doi.org/10.1063/1.3684250 (4 pages) | Cited 2 times

Online Publication Date: 13 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report terahertz metamaterial waveguides based on the concept of composite right/left-handed transmission-lines. The waveguides are implemented in a metal-insulator-metal geometry fabricated with spin-coated Benzocyclobutene and contact photolithography. Angle-resolved reflection spectroscopy shows strong resonant absorption features corresponding to both right-handed and left-handed (backward wave) propagating modes within the leaky-wave bandwidth. Tuning of the waveguide dispersion is achieved by varying the effective lumped element series capacitance. The experimental results are in good agreement with full-wave finite element method simulations as well as an intuitive transmission-line circuit model.
Show PACS
42.79.Gn Optical waveguides and couplers

Multiplexing single-beam coherent anti-stokes Raman spectroscopy with heterodyne detection

Alexander Wipfler, Tiago Buckup, and Marcus Motzkus

Appl. Phys. Lett. 100, 071102 (2012); http://dx.doi.org/10.1063/1.3680209 (4 pages) | Cited 2 times

Online Publication Date: 14 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Multiplex detection of single beam coherent anti-Stokes Raman spectra is achieved by phase shaping of a narrow gate probe. The spectrally resolved signal is amplified via a local oscillator derived from the same single beam and is disentangled via double quadrature spectral interferometry. Spectral resolution and spectral range are defined by the width and position of the phase gate, which can be easily set by a femtosecond pulse shaper. Such phase-only multiplexed single beam coherent anti-Stokes Raman spectroscopy is demonstrated for simple molecules and is combined with Raman line reconstruction methods to obtain dispersion free Raman resonances.
Show PACS
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.60.Ly Interferometers

High quality factor two dimensional GaN photonic crystal cavity membranes grown on silicon substrate

N. Vico Triviño, G. Rossbach, U. Dharanipathy, J. Levrat, A. Castiglia, J.-F. Carlin, K. A. Atlasov, R. Butté, R. Houdré, and N. Grandjean

Appl. Phys. Lett. 100, 071103 (2012); http://dx.doi.org/10.1063/1.3684630 (3 pages) | Cited 8 times

Online Publication Date: 14 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the achievement of freestanding GaN photonic crystal L7 nanocavities with embedded InGaN/GaN quantum wells grown by metal organic vapor phase epitaxy on Si (111). GaN was patterned by e-beam lithography, using a SiO2 layer as a hard mask, and usual dry etching techniques. The membrane was released by underetching the Si (111) substrate. Micro-photoluminescence measurements performed at low temperature exhibit a quality factor as high as 5200 at ∼420 nm, a value suitable to expand cavity quantum electrodynamics to the near UV and the visible range and to develop nanophotonic platforms for biofluorescence spectroscopy.
Show PACS
81.16.Nd Micro- and nanolithography
42.70.Qs Photonic bandgap materials
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Understanding ultrafast carrier dynamics in single quasi-one-dimensional Si nanowires

M. A. Seo, S. A. Dayeh, P. C. Upadhya, J. A. Martinez, B. S. Swartzentruber, S. T. Picraux, A. J. Taylor, and R. P. Prasankumar

Appl. Phys. Lett. 100, 071104 (2012); http://dx.doi.org/10.1063/1.3685487 (5 pages) | Cited 9 times

Online Publication Date: 15 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We use femtosecond optical pump-probe spectroscopy to study ultrafast carrier dynamics in single quasi-one-dimensional silicon nanowires. By isolating individual nanowires, we avoid complications resulting from the broad size and alignment distribution in nanowire ensembles, allowing us to directly probe ultrafast carrier dynamics. Spatially-resolved experiments demonstrate the influence of surface-mediated mechanisms on carrier dynamics in a single NW, while polarization-resolved experiments reveal a clear anisotropy in carrier lifetimes measured parallel and perpendicular to the long axis of the NW, due to density-dependent Auger recombination. These results suggest the possibility of tailoring carrier relaxation in a single nanowire for a desired application.
Show PACS
78.47.J- Ultrafast spectroscopy (<1 psec)
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
79.20.Fv Electron impact: Auger emission

Structural dependent ultrafast electron-phonon coupling in multiferroic BiFeO3 films

Zuanming Jin, Yue Xu, Zhengbing Zhang, Gaofang Li, Xian Lin, Guohong Ma, Zhenxiang Cheng, and Xiaolin Wang

Appl. Phys. Lett. 100, 071105 (2012); http://dx.doi.org/10.1063/1.3685496 (4 pages) | Cited 2 times

Online Publication Date: 15 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electronic energy relaxation of polycrystalline BiFeO3 films is studied using ultrafast pump-probe spectroscopy. After photo-excitation with femtosecond laser pulses, the relaxation of hot electrons is identified to decay with two different characteristic times. The fast process is attributed to scattering of electrons with lattice-vibration modes, and the slow one is corresponding to the spin-lattice thermalization. The electron-phonon coupling is characterized by the second moment of the Eliashberg function, λ〈ω2〉. Due to the structural strain and symmetry breaking, the electron-phonon interaction strength of tetragonal BiFeO3 films is larger than that of rhombohedral counterparts.
Show PACS
73.61.Ng Insulators
78.66.Nk Insulators
73.50.Fq High-field and nonlinear effects
63.20.kd Phonon-electron interactions
77.55.Nv Multiferroic/magnetoelectric films
77.80.-e Ferroelectricity and antiferroelectricity

Fiber delivered two-color picosecond source through nonlinear spectral transformation for coherent Raman scattering imaging

Ke Wang and Chris Xu

Appl. Phys. Lett. 100, 071106 (2012); http://dx.doi.org/10.1063/1.3686149 (3 pages)

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate a two-color, fiber-delivered picosecond source for coherent Raman scattering (CRS) imaging through nonlinear spectral transformation. The wavelength tunable picosecond pump is generated by nonlinear spectral compression of a prechirped femtosecond pulse in a fiber wavelength division multiplexer (WDM). The 1064-nm synchronized picosecond Stokes pulse is generated through pulse carving of a continuous wave laser, nonlinear spectral broadening in 100-m standard single-mode fiber, and subsequent dispersive compression with a fiber compressor. The pump and Stokes beams are combined and delivered by the fiber WDM. CRS imaging of mouse skin is performed to demonstrate the practicality of this source.
Show PACS
42.55.Wd Fiber lasers
42.60.Fc Modulation, tuning, and mode locking
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Ultrafast response of tunnel injected quantum dot based semiconductor optical amplifiers in the 1300 nm range

J. Pulka, T. Piwonski, G. Huyet, J. Houlihan, E. Semenova, A. Lematre, K. Merghem, A. Martinez, and A. Ramdane

Appl. Phys. Lett. 100, 071107 (2012); http://dx.doi.org/10.1063/1.3686901 (4 pages) | Cited 1 time

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The ultrafast gain and refractive index dynamics of tunnel injected quantum dot based semiconductor optical amplifiers in the 1300 nm range are investigated using a heterodyne pump probe technique. In the gain regime, ground state wavelengths exhibit full gain recovery in less than 10 ps up to 3 times transparency, attributed to enhanced carrier refilling via the injector layer. The effect of the injector can also been seen in unusual phase dynamics at excited state wavelengths at this injection level.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Four-wave mixing in carbon nanotube-coated optical fiber gratings

Li-Yang Shao, Michael B. Jakubinek, Tingting Sun, Benoit Simard, and Jacques Albert

Appl. Phys. Lett. 100, 071108 (2012); http://dx.doi.org/10.1063/1.3687170 (3 pages)

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The observation of four-wave mixing (FWM) in single-walled carbon nanotubes (SWCNTs) deposited around a tilted fiber Bragg grating (TFBG) has been demonstrated. A thin, floating SWCNT film is manually wrapped around the outer cladding of the fiber and FWM occurs between two core-guided laser signals by TFBG-induced interaction of the core mode and cladding modes. The effective nonlinear coefficient is calculated to be 1.8 × 103 W−1 Km−1. The wavelength of generated idlers is tunable with a range of 7.8 nm.
Show PACS
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.81.Bm Fabrication, cladding, and splicing

Spin Hall effect of reflected light from an air-glass interface around the Brewster’s angle

Ling-Jun Kong (孔令军), Xi-Lin Wang (汪喜林), Si-Min Li, Yongnan Li (李勇男), Jing Chen, Bing Gu (顾兵), and Hui-Tian Wang (王慧田)

Appl. Phys. Lett. 100, 071109 (2012); http://dx.doi.org/10.1063/1.3687186 (3 pages) | Cited 2 times

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed a modified theory of the spin Hall effect of reflected light from a planar interface composed of two dielectric media and obtain the analytical expression valid for any incident angle including the Brewster’s angle. We improved the experimental method and measured the spin-dependent transverse displacement of reflected light from a planar air-glass interface around the Brewster’s angle. The experimental results are in agreement with the theoretical prediction.
Show PACS
72.25.-b Spin polarized transport

Electrically switchable random to photonic band-edge laser emission in chiral nematic liquid crystals

Stephen M. Morris, Damian J. Gardiner, Philip J. W. Hands, Malik M. Qasim, Timothy D. Wilkinson, Ian H. White, and Harry J. Coles

Appl. Phys. Lett. 100, 071110 (2012); http://dx.doi.org/10.1063/1.3684804 (3 pages) | Cited 1 time

Online Publication Date: 17 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using a chiral nematic liquid crystal with a negative dielectric anisotropy, it is possible to switch between band-edge laser emission and random laser emission with an electric field. At low frequencies (<1 kHz), random laser emission is observed as a result of scattering due to electro-hydrodynamic instabilities. However, band-edge laser emission is found to occur at higher frequencies (>5 kHz), where the helix is stabilized due to dielectric coupling. These results demonstrate a method by which the linewidth of the laser source can be readily controlled externally (from 4 nm to 0.5 nm) using electric fields.
Show PACS
42.55.-f Lasers
42.70.Hj Laser materials
42.70.Df Liquid crystals

A statistical exploration of multiple exciton generation in silicon quantum dots and optoelectronic application

W. A. Su and W. Z. Shen

Appl. Phys. Lett. 100, 071111 (2012); http://dx.doi.org/10.1063/1.3687184 (5 pages) | Cited 3 times

Online Publication Date: 17 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have carried out an investigation of multiple exciton generation (MEG) in Si quantum dots (QDs) and its application in optoelectronic devices. A simple yet effective statistical model has been proposed based on Fermi statistical theory and impact ionization mechanism. It is demonstrated that the MEG efficiency depends on both the radius of Si QDs and the energy of incident photons, with the MEG threshold energy in the range of ∼2.2–3.1 Eg depending on the dot radius. While limited improvement has been observed in power conversion efficiency of single stage solar cells, MEG in Si QDs exhibits prospective for application in ultraviolet detectors due to the high internal quantum efficiency under short incident light.
Show PACS
71.35.-y Excitons and related phenomena
73.21.La Quantum dots
88.40.hj Efficiency and performance of solar cells
88.40.jj Silicon solar cells
back to top
RSS Feeds

Photonically enhanced flow boiling in a channel coated with carbon nanotubes

Arun S. Kousalya, Chad N. Hunter, Shawn A. Putnam, Timothy Miller, and Timothy S. Fisher

Appl. Phys. Lett. 100, 071601 (2012); http://dx.doi.org/10.1063/1.3681594 (4 pages) | Cited 4 times

Online Publication Date: 14 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High heat dissipation rates are enabled by multi-phase cooling schemes owing to latent heat uptake. We demonstrate enhanced flow boiling from a carbon nanotube (CNT)-coated copper surface exposed to low-intensity ultraviolet (UV)-visible excitation. Compared to non-illuminated results, the average boiling incipience temperature decreased by 4.6 °C and heat transfer coefficients improved by 41.5% with light exposure. These improved results are attributed to augmented hydrophilicity upon exposure to UV light and possible nanoscale opto-thermal effects, and suggest opportunities for active temperature control of temperature-sensitive devices.
Show PACS
81.65.-b Surface treatments
78.40.-q Absorption and reflection spectra: visible and ultraviolet
65.80.-g Thermal properties of small particles, nanocrystals, nanotubes, and other related systems
61.46.Fg Nanotubes

Using Zintl-Klemm intermetallics in oxide-semiconductor heteroepitaxy

A. A. Demkov, H. Seo, X. Zhang, and J. Ramdani

Appl. Phys. Lett. 100, 071602 (2012); http://dx.doi.org/10.1063/1.3685508 (4 pages) | Cited 3 times

Online Publication Date: 14 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We propose using the Zintl-Klemm (Z-K) bonding to engineer transition layers that provide wetting between ionic oxides and covalent semiconductors to ensure two-dimensional epitaxial growth. Using density functional theory to test this concept, we consider the thermodynamics of wetting at the GaAs/SrTiO3 interface, and identify Sr aluminide SrAl2 as the Z-K wetting layer. We discuss the atomic structure and bonding at the interface, and estimate the conduction band discontinuity to be 0.6 eV, in good agreement with recent experiment.
Show PACS
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
68.35.Md Surface thermodynamics, surface energies
71.20.-b Electron density of states and band structure of crystalline solids
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
68.55.ag Semiconductors
68.08.Bc Wetting

Physical model for the laser induced forward transfer process

Tobias C. Röder and Jürgen R. Köhler

Appl. Phys. Lett. 100, 071603 (2012); http://dx.doi.org/10.1063/1.3685469 (3 pages) | Cited 3 times

Online Publication Date: 15 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper presents a numerical model which describes the underlying physical processes during laser induced forward transfer. The laser induced forward transfer uses a pulsed laser to transfer thin layers from a transparent support to a substrate. The model predicts the threshold energies Eth as well as the blow-off time tblow, thus allowing a profound physical understanding of the transfer process. The good agreement of simulated with measured Eth and tblow of thin nickel layers demonstrates the accuracy of the model. The model shows that gasification of the soda-lime glass support is the main driving force of the transfer process.
Show PACS
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
81.15.Fg Pulsed laser ablation deposition
64.70.F- Liquid-vapor transitions

Altering the sulfur content in the propanethiol plasma polymers using the capacitive-to-inductive mode transition in inductively coupled plasma discharge

Damien Thiry, Nikolay Britun, Stephanos Konstantinidis, Jean-Pierre Dauchot, Laurent Denis, and Rony Snyders

Appl. Phys. Lett. 100, 071604 (2012); http://dx.doi.org/10.1063/1.3686902 (3 pages) | Cited 1 time

Online Publication Date: 15 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of the transition from capacitive (E) to inductive (H) mode on propanethiol plasma polymer films properties was investigated by optical emission as well as by x-ray photoelectron spectroscopy. The E mode is characterized by low deposition rate and by high sulfur content in the films (∼40% vs ∼20% in H mode). After aging, a strong decrease of sulfur to carbon content (from ∼0.75 to 0.13), attributed to desorption of unbounded sulfur-based molecules (e.g., H2S), is detected at low power in E mode. The importance of the E-H transition for altering the film properties is highlighted.
Show PACS
78.66.Qn Polymers; organic compounds
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
68.43.Nr Desorption kinetics
52.77.Dq Plasma-based ion implantation and deposition

Vibrational properties of alkyl monolayers on Si(111) surfaces: Predictions from ab-initio calculations

Yan Li and Giulia Galli

Appl. Phys. Lett. 100, 071605 (2012); http://dx.doi.org/10.1063/1.3685489 (3 pages) | Cited 2 times

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Vibrational properties of Si(111) surfaces terminated by different functional groups have been investigated using density functional theory (DFT). The variations in methyl-related frequencies in different chemical environments, e.g., in methane, methylsilane and ethylsilane, and the methyl- and ethyl-terminated Si(111) surfaces are well predicted by DFT within the local density approximation. In particular, DFT calculations provide useful information on trends and mode assignments in cases where the surface coverage and morphology are not well established experimentally, e.g., in the case of the ethyl-terminated Si(111) surface. Influences of DFT exchange-correlation functionals and anharmonic effects on computed vibrational frequencies are discussed.
Show PACS
63.20.dk First-principles theory
63.20.Ry Anharmonic lattice modes
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
68.35.bg Semiconductors
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

High-k GaAs metal insulator semiconductor capacitors passivated by ex-situ plasma-enhanced atomic layer deposited AlN for Fermi-level unpinning

H. Jussila, P. Mattila, J. Oksanen, A. Perros, J. Riikonen, M. Bosund, A. Varpula, T. Huhtio, H. Lipsanen, and M. Sopanen

Appl. Phys. Lett. 100, 071606 (2012); http://dx.doi.org/10.1063/1.3687199 (4 pages) | Cited 1 time

Online Publication Date: 17 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper examines the utilization of plasma-enhanced atomic layer deposition grown AlN in the fabrication of a high-k insulator layer on GaAs. It is shown that high-k GaAs MIS capacitors with an unpinned Fermi level can be fabricated utilizing a thin ex-situ deposited AlN passivation layer. The illumination and temperature induced changes in the inversion side capacitance, and the maximum band bending of 1.2 eV indicates that the MIS capacitor reaches inversion. Removal of surface oxide is not required in contrast to many common ex-situ approaches.
Show PACS
84.32.Tt Capacitors
back to top
RSS Feeds

Strain relaxation analysis of LaAlO3/SrTiO3 heterostructure using reciprocal lattice mapping

Wei Wei and Alp Sehirlioglu

Appl. Phys. Lett. 100, 071901 (2012); http://dx.doi.org/10.1063/1.3685463 (4 pages)

Online Publication Date: 13 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Strain-relaxation in LaAlO3/SrTiO3 heterostructures was systematically investigated with LaAlO3 film thickness in the range 4.9-84 nm. Heterostructures were characterized using reciprocal lattice mapping (RLM), high resolution rocking curve, and x-ray reflectivity. RLM enables the measurement of lattice constant with accuracy of 10−6 nm. Lattice constant, mismatch, and strain are independently determined in both out-of-plane and in-plane directions. Heterostructures are tetragonally distorted over the entire range of film thickness, even in the film with thickness of 84 nm, in which plastic deformation occurred. This strain-relaxation analysis of LaAlO3/SrTiO3 heterostructure contributes, on the experimental basis, to the knowledge of the strained heterostructure interfaces from thin film growth point of view.
Show PACS
81.40.Lm Deformation, plasticity, and creep
62.20.fq Plasticity and superplasticity
68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties

Depletion of nitrogen‐vacancy color centers in diamond via hydrogen passivation

A. Stacey, T. J. Karle, L. P. McGuinness, B. C. Gibson, K. Ganesan, S. Tomljenovic‐Hanic, A. D. Greentree, A. Hoffman, R. G. Beausoleil, and S. Prawer

Appl. Phys. Lett. 100, 071902 (2012); http://dx.doi.org/10.1063/1.3684612 (4 pages) | Cited 5 times

Online Publication Date: 13 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We show reduction in the emission from nitrogen‐vacancy (NV) centers in single crystal diamond due to exposure to hydrogen plasmas ranging from 700 °C to 1000 °C. Significant fluorescence reduction was observed beneath the exposed surface to 80 μm depth after ∼10 min and did not recover after post‐annealing in vacuum for 7 h at 1100 °C. We attribute the fluorescence reduction to the formation of nitrogen‐vacancy‐hydrogen centers by the plasma‐induced diffusion of hydrogen. These results have important implications for the formation of NV centers for quantum applications, whilst also providing experimental evidence of long range hydrogen diffusion through intrinsic high‐purity diamond.
Show PACS
61.72.jd Vacancies
81.65.-b Surface treatments
66.30.H- Self-diffusion and ionic conduction in nonmetals
81.40.Gh Other heat and thermomechanical treatments
78.55.-m Photoluminescence, properties and materials

Asymmetric coalescence of reactively wetting droplets

C. X. Zheng, W. X. Tang, and D. E. Jesson

Appl. Phys. Lett. 100, 071903 (2012); http://dx.doi.org/10.1063/1.3684616 (3 pages)

Online Publication Date: 13 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Coalescence of droplets during reactive wetting is investigated for the liquid Ga/GaAs(001) system. In situ mirror electron microscopy reveals that coalescence predominantly involves the motion of one reactive droplet relative to the other. This behaviour differs significantly from coalescence in non-reactive systems and is associated with contact line pinning at a ridge/etch pit edge which is identified using atomic force microscopy and selective etching. A simple geometrical model is presented to describe the pinning.
Show PACS
68.08.Bc Wetting
68.03.Cd Surface tension and related phenomena
81.65.Cf Surface cleaning, etching, patterning
68.37.Ps Atomic force microscopy (AFM)

Shear-band arrest and stress overshoots during inhomogeneous flow in a metallic glass

R. Maaß, D. Klaumünzer, G. Villard, P. M. Derlet, and J. F. Löffler

Appl. Phys. Lett. 100, 071904 (2012); http://dx.doi.org/10.1063/1.3684871 (4 pages) | Cited 2 times

Online Publication Date: 13 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
At the transition from a static to a dynamic deformation regime of a shear band in bulk metallic glasses, stress transients in terms of overshoots are observed. We interpret this phenomenon with a repeated shear-melting transition and are able to access a characteristic time for a liquidlike to solidlike transition in the shear band as a function of temperature, enabling us to understand why shear bands arrest during inhomogenous serrated flow in bulk metallic glasses.
Show PACS
62.10.+s Mechanical properties of liquids
64.70.dj Melting of specific substances
64.70.pe Metallic glasses
61.25.Mv Liquid metals and alloys
47.15.St Free shear layers

Temperature dependent phonon Raman scattering of highly a-axis oriented CoFe2O4 inverse spinel ferromagnetic films grown by pulsed laser deposition

Y. Y. Liao (廖原愿), Y. W. Li (李亚巍), Z. G. Hu (胡志高), and J. H. Chu (褚君浩)

Appl. Phys. Lett. 100, 071905 (2012); http://dx.doi.org/10.1063/1.3683520 (4 pages) | Cited 2 times

Online Publication Date: 14 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Lattice vibrations of highly a-axis oriented CoFe2O4 (CFO) films have been investigated by Raman scattering in the temperature range of 80-873 K. The five phonon modes T1g(2), T1g(3), Eg, A1g(1), A1g(2), and their evolutions can be uniquely distinguished. It was found that an electron transfer between Co2+ and Fe3+ cations occurs in octahedral sites at about 173 K. The structure disorder in the CFO films appears with increasing the temperature, which indicates the cation migration between tetrahedral and octahedral sites. The phenomena suggest the structural transformation trend from inverse spinel to normal spinel at the elevated temperatures.
Show PACS
78.30.Hv Other nonmetallic inorganics
75.50.Dd Nonmetallic ferromagnetic materials
81.15.Fg Pulsed laser ablation deposition
68.55.A- Nucleation and growth
75.70.Ak Magnetic properties of monolayers and thin films
63.20.D- Phonon states and bands, normal modes, and phonon dispersion

Sample size effects on the large strain bursts in submicron aluminum pillars

Zhang-Jie Wang, Qing-Jie Li, Zhi-Wei Shan, Ju Li, Jun Sun, and Evan Ma

Appl. Phys. Lett. 100, 071906 (2012); http://dx.doi.org/10.1063/1.3681582 (3 pages) | Cited 5 times

Online Publication Date: 14 February 2012

Full Text: Read Online (HTML) | Download PDF

multimedia

Show Abstract
In situ transmission electron microscope compression testing of submicron Al pillars shows two sample size regimes with contrasting behavior underlying the large strain bursts. For small pillars, the bursts originate from explosive and highly correlated dislocation generation, characterized by very high collapse stresses and nearly dislocation-free post-collapse microstructure. For larger pillars, the bursts result from the reconstruction of jammed dislocation configurations, featuring relative low stress levels and retention of dislocation network after bursts.
Show PACS
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
81.70.Bt Mechanical testing, impact tests, static and dynamic loads
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.F- Deformation and plasticity

Temperature dependence of Raman-active optical phonons in Bi2Se3 and Sb2Te3

Y. Kim, X. Chen, Z. Wang, J. Shi, I. Miotkowski, Y. P. Chen, P. A. Sharma, A. L. Lima Sharma, M. A. Hekmaty, Z. Jiang, and D. Smirnov

Appl. Phys. Lett. 100, 071907 (2012); http://dx.doi.org/10.1063/1.3685465 (3 pages) | Cited 4 times

Online Publication Date: 15 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Inelastic light scattering spectra of Bi2Se3 and Sb2Te3 single crystals have been measured over the temperature range from 5 K to 300 K. The temperature dependence of dominant A1g2 phonons shows similar behavior in both materials. The temperature dependence of the peak position and linewidth is analyzed considering the anharmonic decay of optical phonons and the material thermal expansion. This work suggests that Raman spectroscopy can be used for thermometry in Bi2Se3- and Sb2Te3-based devices in a wide temperature range.
Show PACS
78.30.Hv Other nonmetallic inorganics
65.40.De Thermal expansion; thermomechanical effects
63.20.D- Phonon states and bands, normal modes, and phonon dispersion

Diffusion-controlled formation mechanism of dual-phase structure during Al induced crystallization of SiGe

Tian-Wei Zhang, Fei Ma, Wei-Lin Zhang, Da-Yan Ma, Ke-Wei Xu, and Paul K. Chu

Appl. Phys. Lett. 100, 071908 (2012); http://dx.doi.org/10.1063/1.3685712 (3 pages) | Cited 1 time

Online Publication Date: 15 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Aluminum induced crystallization of amorphous SiGe at low temperature is studied and a dual-phase stacked structure with different compositions emerges when the annealing temperature is higher than a critical value. This behavior is very sensitive to the oxidization state of the interlayer. A model based on energetics is proposed to elucidate this temperature dependent behavior. Thermodynamically, it can be ascribed to the competition between grain-boundary-mediated and interface-mediated crystallization and kinetically, it stems from the different diffusion rates of Si and Ge. The results are useful to the design and fabrication of high-efficiency solar cells.
Show PACS
61.43.Dq Amorphous semiconductors, metals, and alloys
61.72.Mm Grain and twin boundaries
64.70.kg Semiconductors
66.30.-h Diffusion in solids
Page 1 of 4 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close