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

1 Oct 2012

Volume 101, Issue 14, Articles (14xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 101, 141101 (2012); http://dx.doi.org/10.1063/1.4742864 (4 pages)

Po-Hsun Huang, Michael Ian Lapsley, Daniel Ahmed, Yuchao Chen, Lin Wang, and Tony Jun Huang
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Scaling behavior of GaAs and GaMnAs quantum rings grown by droplet epitaxy

E. Placidi, F. Arciprete, A. Balzarotti, and F. Patella

Appl. Phys. Lett. 101, 141901 (2012); http://dx.doi.org/10.1063/1.4756896 (3 pages)

Online Publication Date: 1 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The transition from the liquid phase of Ga droplets to the formation of GaAs and GaMnAs quantum rings has been studied as a function of temperature. We show that different aggregation processes involve the GaAs (GaMnAs) island and the droplet formation. Furthermore, the aspect ratio of the islands exhibits an anomalous scaling law related to a tendency to aggregate in the vertical direction.
Show PACS
68.55.ag Semiconductors
68.55.J- Morphology of films
81.05.Ea III-V semiconductors
81.07.Ta Quantum dots
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
64.70.D- Solid-liquid transitions

Spatial power combination within fan-shaped region using anisotropic zero-index metamaterials

Qiang Cheng, Ben Geng Cai, Wei Xiang Jiang, Hui Feng Ma, and Tie Jun Cui

Appl. Phys. Lett. 101, 141902 (2012); http://dx.doi.org/10.1063/1.4756908 (3 pages)

Online Publication Date: 1 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We show that the radially anisotropic zero-index metamaterials can be used to realize spatial power combination within fan-shaped regions. When the radial component of the permittivity or permeability tensor tends to zero, the coherent omnidirectional radiations will occur when sources are within the fan-shaped metamaterial backed with perfect magnetic conductors (PMCs), which leads to spatial power combination in finite areas. As the included angle of the PMC corner reflector decreases, the powers from internal sources can still be efficiently combined, which has potential applications in radio frequency engineering.
Show PACS
42.70.-a Optical materials
77.22.Ch Permittivity (dielectric function)

Highly promising electrooptic material: Distorted helix ferroelectric liquid crystal with a specific tilt angle

I. Abdulhalim

Appl. Phys. Lett. 101, 141903 (2012); http://dx.doi.org/10.1063/1.4756917 (5 pages)

Online Publication Date: 2 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Short pitch deformable helix ferroelectric liquid crystals are shown to become optically isotropic at certain critical tilt angle with an average dielectric constant (ε1+ε2+ε3)/3. For uniaxial medium, this angle equals θd = cos−1(1/math), and it depends weakly on the local biaxial anisotropy. The degeneracy is removed upon the application of a small electric field and the medium becomes optically biaxial. A high contrast fast electrooptic modulation and display devices can be built using such materials even when aligned in a multi-domain. For tilt angles very near the degeneracy angle, ultrasensitivity of the eigenaxes rotation to the applied field is found.
Show PACS
78.20.Jq Electro-optical effects
78.15.+e Optical properties of fluid materials, supercritical fluids and liquid crystals
61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
77.22.Ch Permittivity (dielectric function)
77.80.Dj Domain structure; hysteresis
77.84.Nh Liquids, emulsions, and suspensions; liquid crystals

Enhanced carrier-carrier interaction in optically pumped hydrogenated nanocrystalline silicon

Thomas W. Roger, Wei He, Igor V. Yurkevich, and Andrey Kaplan

Appl. Phys. Lett. 101, 141904 (2012); http://dx.doi.org/10.1063/1.4755760 (4 pages) | Cited 1 time

Online Publication Date: 2 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A femtosecond pump-probe setup was used to measure the time resolved reflectivity of hydrogenated amorphous silicon containing crystalline silicon nanoparticles at eight different incidence angles. Results fitted with the Drude model found a scattering rate of Γ = 2−1+1.2×1015 s−1 at a corresponding carrier concentration of ∼ 1020 cm−3. The observed scattering rate is attributed to enhanced carrier-carrier interaction in optically pumped nanocrystals.
Show PACS
78.47.J- Ultrafast spectroscopy (<1 psec)
78.47.D- Time resolved spectroscopy (>1 psec)
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
82.30.-b Specific chemical reactions; reaction mechanisms

Nonlinear optical mass sensor with an optomechanical microresonator

Jin-Jin Li and Ka-Di Zhu

Appl. Phys. Lett. 101, 141905 (2012); http://dx.doi.org/10.1063/1.4757004 (4 pages) | Cited 1 time

Online Publication Date: 3 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Mechanical oscillators have been widely used in mass sensing due to the direct relationship of the frequency-shift and mass-change. A conventional method for detecting the mass of deposited sample is to exploit the frequency variation of mechanical resonator in the linear optical regime. In the present letter, we demonstrate a nonlinear optical mass sensor with an optomechanical microresonator which will provide a route towards the use of cavity optomechanical system in biomedical sensors, deposition monitors, chemical reaction monitors and other nonlinear measurement fields. Based on the current experimental conditions, the nonlinear optical mass sensor proposed here can be achieved by experiments.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
84.30.Ng Oscillators, pulse generators, and function generators

Kinetics of interdiffusion in semiconductor ternary quantum dots

Xu Han, Sumeet C. Pandey, and Dimitrios Maroudas

Appl. Phys. Lett. 101, 141906 (2012); http://dx.doi.org/10.1063/1.4757148 (5 pages) | Cited 1 time

Online Publication Date: 3 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We develop a one-dimensional transient model of species transport in ternary quantum dots (QDs) and implement the model for analysis of group-VI species interdiffusion kinetics in ZnSe1−xSx nanocrystals. We use the model results for the interpretation of x-ray photoelectron spectroscopy data for the group-VI species near-surface concentration evolution during thermal annealing of ZnSe1−xSx QDs with a ZnSe/ZnS core/shell initial configuration. The model provides an excellent fitting of the experimental data, which is used to derive transport coefficients and thermal activation barriers for diffusion in the ternary QDs.
Show PACS
66.30.Ny Chemical interdiffusion; diffusion barriers
79.60.Bm Clean metal, semiconductor, and insulator surfaces
82.40.-g Chemical kinetics and reactions: special regimes and techniques
61.72.Cc Kinetics of defect formation and annealing

Nanocluster Si sensitized Er luminescence: Excitation mechanisms and critical factors for population inversion

In Yong Kim, Kyung Joong Kim, and Jung H. Shin

Appl. Phys. Lett. 101, 141907 (2012); http://dx.doi.org/10.1063/1.4757001 (4 pages)

Online Publication Date: 4 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Luminescence from Er3+ ions sensitized by nanocluster Si is investigated using finite-element, Monte-Carlo simulations. We find that we can reproduce and explain many conflicting results that have been reported using only a simple Förster-type interaction. In particular, we show that Er-Er energy migration plays a major role in Er3+ excitation such quantities such as excitation distance and sensitized fraction depend on optically active Er fraction and pumping power. Based on simulation results, we identify optically active fraction as the critical factor and suggest a multi-layered structure as being ideal for achieving population inversion.
Show PACS
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
71.35.-y Excitons and related phenomena
78.55.Ap Elemental semiconductors

Ellipsometry applied to phase transitions and relaxation phenomena in Ni2MnGa ferromagnetic shape memory alloy

A. Dejneka, V. Zablotskii, M. Tyunina, L. Jastrabik, J. I. Pérez-Landazábal, V. Recarte, V. Sánchez-Alarcos, and V. A. Chernenko

Appl. Phys. Lett. 101, 141908 (2012); http://dx.doi.org/10.1063/1.4757393 (5 pages)

Online Publication Date: 4 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The temperature dependences of the refractive index, n(T), calculated from ellipsometric data during the premartensitic and martensite transitions in a Ni2MnGa ferromagnetic shape memory alloy allow to detect all critical temperatures of the sample. The performed measurements reveal the behavior of a surface layer of a few tens nanometers depth due to the light absorption. Optical measurements reveal the earlier onset of premartensitic transition at the sample surface and shows unknown new features like time and temperature dependent effects related to the crystal surface. The underlying mechanisms of the observed temperature changes of the equilibrium n0 may be related to temperature dependent interactions between free electrons and phonons as well as between electrons and defects. A giant isothermal creep (up to 20%) of the refractive index was found for temperatures below T0 = 315 K. Below T0 the creep amplitude grows with the temperature difference T0-T. The creep disappears and the relaxation time becomes zero at temperatures above T0.
Show PACS
81.30.Kf Martensitic transformations
75.75.-c Magnetic properties of nanostructures
62.20.Hg Creep
75.50.Cc Other ferromagnetic metals and alloys
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Infrared absorption coefficients of vertically aligned carbon nanotube films

H. Ye, X. J. Wang, W. Lin, C. P. Wong, and Z. M. Zhang

Appl. Phys. Lett. 101, 141909 (2012); http://dx.doi.org/10.1063/1.4757395 (4 pages)

Online Publication Date: 4 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Vertically aligned carbon nanotube (VACNT) films have promising applications in solar cells, radiometers, and photonic devices. We have fabricated VACNT films with thicknesses of 10, 36, 45, and 120 μm on silicon substrates. The absorption coefficient of each film is obtained from the measured regular transmittance from 1 to 19 μm wavelengths, using a ratio method. The degree of alignment of the VACNT films is estimated by comparison of experiments with an analysis based on the effective medium theory. The effect of thickness on the absorption coefficient of the VACNT films is elucidated according to their morphologies.
Show PACS
78.67.Ch Nanotubes
88.40.J- Types of solar cells
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Growth and characterization of LuAs films and nanostructures

E. M. Krivoy, H. P. Nair, A. M. Crook, S. Rahimi, S. J. Maddox, R. Salas, D. A. Ferrer, V. D. Dasika, D. Akinwande, and S. R. Bank

Appl. Phys. Lett. 101, 141910 (2012); http://dx.doi.org/10.1063/1.4757605 (4 pages) | Cited 1 time

Online Publication Date: 4 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the growth and characterization of nearly lattice-matched LuAs/GaAs heterostructures. Electrical conductivity, optical transmission, and reflectivity measurements of epitaxial LuAs films indicate that LuAs is semimetallic, with a room-temperature resistivity of 90 μΩ cm. Cross-sectional transmission electron microscopy confirms that LuAs nucleates as self-assembled nanoparticles, which can be overgrown with high-quality GaAs. The growth and material properties are very similar to those of the more established ErAs/GaAs system; however, we observe important differences in the magnitude and wavelength of the peak optical transparency, making LuAs superior for certain device applications, particularly for thick epitaxially embedded Ohmic contacts that are transparent in the near-IR telecommunications window around 1.3 μm.
Show PACS
81.16.-c Methods of micro- and nanofabrication and processing
68.55.at Other materials
73.40.Ns Metal-nonmetal contacts
73.61.At Metal and metallic alloys
78.66.Bz Metals and metallic alloys
81.05.Bx Metals, semimetals, and alloys

Electromechanical instabilities of thermoplastics: Theory and in situ observation

Qiming Wang, Xiaofan Niu, Qibing Pei, Michael D. Dickey, and Xuanhe Zhao

Appl. Phys. Lett. 101, 141911 (2012); http://dx.doi.org/10.1063/1.4757867 (4 pages)

Online Publication Date: 5 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thermoplastics under voltages are used in diverse applications ranging from insulating cables to organic capacitors. Electromechanical instabilities have been proposed as a mechanism that causes electrical breakdown of thermoplastics. However, existing experiments cannot provide direct observations of the instability process, and existing theories for the instabilities generally assume thermoplastics are mechanically unconstrained. Here, we report in situ observations of electromechanical instabilities in various thermoplastics. A theory is formulated for electromechanical instabilities of thermoplastics under different mechanical constraints. We find that the instabilities generally occur in thermoplastics when temperature is above their glass transition temperatures and electric field reaches a critical value. The critical electric field for the instabilities scales with square root of yield stress of the thermoplastic and depends on its Young's modulus and hardening property.
Show PACS
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.de Elastic moduli
64.70.pj Polymers

Crystallographic direction dependence of direct current field induced strain and phase transitions in Na0.5Bi0.5TiO3-x%BaTiO3 single crystals near the morphotropic phase boundary

Chengtao Luo, Wenwei Ge, Qinhui Zhang, Jiefang Li, Haosu Luo, and D. Viehland

Appl. Phys. Lett. 101, 141912 (2012); http://dx.doi.org/10.1063/1.4757877 (4 pages) | Cited 1 time

Online Publication Date: 5 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The crystallographic dependence of the DC electric (E) field induced strain and phase transition in Na0.5Bi0.5TiO3-5.6%BaTiO3 (NBT-5.6%BT) single crystals has been investigated. An induced transition between pseudocubic and tetragonal structures was observed under E = 10 kV/cm for fields applied along the 〈001〉 direction, whereas an induced transition between pseudocubic and rhombohedral structures was observed when the E-field was applied along 〈111〉. Our results show near the morphotropic phase boundary that the phase stability of NBT-x%BT is dependent on the crystallographic direction along which E was applied.
Show PACS
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
64.70.K- Solid-solid transitions
61.66.Fn Inorganic compounds

Giant domain wall response of highly twinned ferroelastic materials

W. Schranz, H. Kabelka, A. Sarras, and M. Burock

Appl. Phys. Lett. 101, 141913 (2012); http://dx.doi.org/10.1063/1.4757992 (4 pages)

Online Publication Date: 5 October 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Many ferroelastic crystals display at sufficiently low measurement frequencies a huge elastic softening below Tc which is caused by domain wall motion. Materials range from perovskites to iron based superconductors and shape memory materials. We present a model—based on Landau-Ginzburg theory including long range elastic interaction between needle shaped ferroelastic domains—to describe the observed superelastic softening. The theory predicts that the domain wall contribution to the elastic susceptibility is different for improper and proper ferroelastic materials. A test of the theory against experimental data on SrTiO3, KMnF3, LaAlO3, LaAlO3,La1-xNdxP5O14, and NH4HC2O4·mathH2O yields excellent agreement.
Show PACS
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close