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

25 Aug 2008

Volume 93, Issue 8, Articles (08xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 93, 083901 (2008); http://dx.doi.org/10.1063/1.2973167 (3 pages)

R. J. Martín-Palma, C. G. Pantano, and A. Lakhtakia
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Investigation of the nanomechanical properties in relation to the microstructure of Zn1−xBexTe alloys

S. E. Grillo, H. Glénat, T. Tite, O. Pages, O. Maksimov, and M. C. Tamargo

Appl. Phys. Lett. 93, 081901 (2008); http://dx.doi.org/10.1063/1.2970989 (3 pages) | Cited 2 times

Online Publication Date: 25 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A study by nanoindentation has been performed to investigate the variation of the mechanical properties of Zn1−xBexTe alloys as a function of the beryllium content in the range 0 ≤ x ≤ 0.84. Our data show a very marked increase of hardness (H) and a significant increase of the elastic modulus (E) with Be concentration. These trends are related to an increase in the stiffness of the BeTe bond relative to that of the ZnTe bond. Furthermore, discontinuities are unambiguously revealed in the variations of both H and E at the critical Be content of ∼ 20%. We relate these to Raman studies of the layers’ microstructure and propose an explanation in terms of a percolative behavior.
Show PACS
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.dq Other elastic constants
62.20.de Elastic moduli
78.30.Er Solid metals and alloys

Low-temperature negative thermal expansion of the antiperovskite manganese nitride Mn3CuN codoped with Ge and Si

Rongjin Huang, Laifeng Li, Fangshuo Cai, Xiangdong Xu, and Lihe Qian

Appl. Phys. Lett. 93, 081902 (2008); http://dx.doi.org/10.1063/1.2970998 (3 pages) | Cited 37 times

Online Publication Date: 25 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have synthesized antiperovskite manganese nitrides Mn3(Cu0.6SixGe0.4−x)N, (x = 0–0.2) and investigated their negative thermal expansion (NTE) in the temperature range of 80–300 K. We found that the transition temperature of NTE moves toward lower temperature region and as well the NTE operation-temperature window (ΔT) becomes broader with increasing Si content. Typically, the giant low-temperature NTE coefficient identified in Mn3(Cu0.6Si0.15Ge0.25)N reaches as large as −16×10−6 K−1, and its ΔT reaches as wide as 100 K. The magnetic properties of these compounds were measured and correlated with the broadened NTE operation-temperature window. The present discovery highlights the potential applications of NTE materials in cryogenic engineering.
Show PACS
65.40.De Thermal expansion; thermomechanical effects
75.30.Cr Saturation moments and magnetic susceptibilities
75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
75.80.+q Magnetomechanical effects, magnetostriction

Phase transformations during rapid heating of Al/Ni multilayer foils

Jonathan C. Trenkle, Lucas J. Koerner, Mark W. Tate, Sol M. Gruner, Timothy P. Weihs, and Todd C. Hufnagel

Appl. Phys. Lett. 93, 081903 (2008); http://dx.doi.org/10.1063/1.2975830 (3 pages) | Cited 22 times

Online Publication Date: 25 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have used self-propagating exothermic reactions in Al/Ni multilayers as a means to explore the effect of rapid heating on phase transformations. Using time-resolved synchrotron x-ray microdiffraction with an extremely fast detector, we were able to examine the reaction sequence in detail at heating rates of ∼ 106 K s−1. We observed that the intermediate phases formed during the self-propagating reactions are different from those formed at lower heating rates, even though the final phases are the same. In situ characterization is essential, as other means of studying self-propagating reactions (such as quenching the reaction followed by ex situ analysis) provide different—and potentially misleading—results.
Show PACS
64.70.kd Metals and alloys
81.40.Gh Other heat and thermomechanical treatments
68.65.Ac Multilayers

Characterization of indirect and direct interband transitions of anatase TiO2 by thermoreflectance spectroscopy

Ching-Hwa Ho, Ming-Cheng Tsai, and Ming-Show Wong

Appl. Phys. Lett. 93, 081904 (2008); http://dx.doi.org/10.1063/1.2975846 (3 pages) | Cited 12 times

Online Publication Date: 25 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We characterize three as-deposited anatase TiO2 (a-TiO2) films with different deposition flux angles of 0°, 53°, and 86° tilted to Si 〈001〉 using thermoreflectance (TR) measurement in the temperature range between 30 and 300 K. The TR spectra at low temperature clearly show considerable difference in interband transitions of the tetragonal a-TiO2 with the largely top plane of {001} or the largely side planes of {100} and {010}. The indirect and direct interband transitions of the a-TiO2 are evaluated. The temperature dependences of the interband transition energies of the a-TiO2 are analyzed. The optical-axial anisotropy of the a-TiO2 films is discussed.
Show PACS
78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
68.55.aj Insulators

The determination of Young’s modulus in noble metal nanowires

Z. M. Ao, S. Li, and Q. Jiang

Appl. Phys. Lett. 93, 081905 (2008); http://dx.doi.org/10.1063/1.2976134 (3 pages) | Cited 11 times

Online Publication Date: 25 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The origin of the size and temperature dependent Young’s modulus (Y) in noble metal nanowires with fcc structure was investigated by considering the size effects on surface bond contraction and melting temperature (Tm) variation. The results show that Y decreases with a shrinking disparity between Tm and the material’s application temperature, while the surface bond contraction results in increase in Y with size reduction. Thus, the variation in Y is the consequence of the subtle interplay and competition between these two factors. This finding indicates that Y of nanowires can be controlled by manipulating the size and the application temperature.
Show PACS
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.de Elastic moduli
68.65.La Quantum wires (patterned in quantum wells)
68.35.Gy Mechanical properties; surface strains

Surface roughness effects on the terahertz reflectance of pure explosive materials

M. Ortolani, J. S. Lee, U. Schade, and H.-W. Hübers

Appl. Phys. Lett. 93, 081906 (2008); http://dx.doi.org/10.1063/1.2973403 (3 pages) | Cited 11 times

Online Publication Date: 25 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We studied the effect of surface roughness on terahertz reflectance spectra of explosives at both quasinormal and oblique incidence by Fourier-transform spectroscopy. The optical constants of 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane and 1,3,5 trinitro-1,3,5 triazacyclohexane were determined from the reflectance spectra of pure optically flat pellets and clear spectral signatures were found in the 0.5–8 THz range. In the case of a realistic surface roughness of several tens of microns, the observation of the spectral signatures at quasinormal incidence is hindered by the specular reflectance roll-off at terahertz frequencies. On increasing the angle of incidence, the roll-off occurred at higher frequency and the surface roughness was optically measured. Oblique incidence geometries can benefit the development of terahertz standoff detection devices.
Show PACS
68.35.bm Polymers, organics
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.70.Gq Microwave and radio-frequency interactions
82.33.Vx Reactions in flames, combustion, and explosions

Long-time evolution of the photoluminescence in C- and M-plane GaN/AlN quantum dots upon intense ultraviolet irradiation

O. Brandt, T. Flissikowski, D. M. Schaadt, U. Jahn, A. Trampert, and H. T. Grahn

Appl. Phys. Lett. 93, 081907 (2008); http://dx.doi.org/10.1063/1.2973404 (3 pages) | Cited 3 times

Online Publication Date: 25 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We compare the spontaneous emission of C- and M-plane GaN quantum dots embedded in AlN. C-plane dots are characterized by an intense emission with an exceptionally long decay time up to room temperature. In contrast, M-plane dots exhibit a much weaker emission with a very short decay time. In addition, the emission of the C-plane dots temporally evolves on a timescale of seconds, while the emission of the M-plane dots is stable over time. These findings are correlated with the different growth mode and microstructure of C- and M-plane GaN quantum dots.
Show PACS
78.67.Hc Quantum dots
78.55.-m Photoluminescence, properties and materials

Band-edge emission enhancement by longitudinal stress field in GaN

Duanjun Cai, Junyong Kang, Pierre Gibart, Bernard Beaumont, Takachi Sekiguchi, and Shun Ito

Appl. Phys. Lett. 93, 081908 (2008); http://dx.doi.org/10.1063/1.2973673 (3 pages) | Cited 2 times

Online Publication Date: 25 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Bright ultraviolet luminescence in the wing region of epitaxial-lateral-overgrowth GaN was studied by cathodoluminescence. Analysis of dislocation bending and movement by transmission electron microscopy demonstrates the emergence of another longitudinal stress field, which effectively enhances the band-edge light emission. Ab initio calculations of interband transition probability provide a model showing that introduction of appropriate additional stress component in the longitudinal direction of GaN will improve the efficiency of band-edge emission.
Show PACS
78.66.Fd III-V semiconductors
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
78.60.Hk Cathodoluminescence, ionoluminescence
78.55.Cr III-V semiconductors

Local strain measurement in a strain-engineered complementary metal-oxide-semiconductor device by geometrical phase analysis in the transmission electron microscope

Jayhoon Chung, Guoda Lian, and Lew Rabenberg

Appl. Phys. Lett. 93, 081909 (2008); http://dx.doi.org/10.1063/1.2970050 (3 pages) | Cited 4 times

Online Publication Date: 25 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Local strains in the channel and source/drain (S/D) of an advanced complementary metal-oxide-semiconductor device were measured by the geometric phase analysis applied to high resolution transmission electron microscope images. Two-dimensional strain maps were reconstructed for a 45 nm p-type metal-oxide-semiconductor device which was strain-engineered using a recessed Si0.82Ge0.18 S/D. Lateral strains were uniform across the channel but vertical strains were found to vary considerably in the channel. Measured strains were used to estimate stresses and hole mobility enhancements.
Show PACS
85.30.Tv Field effect devices
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

Resonant coherent Bragg rod analysis of strained epitaxial heterostructures

D. P. Kumah, A. Riposan, C. N. Cionca, N. S. Husseini, R. Clarke, J. Y. Lee, J. M. Millunchick, Y. Yacoby, C. M. Schlepütz, M. Björck, and P. R. Willmott

Appl. Phys. Lett. 93, 081910 (2008); http://dx.doi.org/10.1063/1.2975835 (3 pages) | Cited 6 times

Online Publication Date: 26 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The resonant response of the complex x-ray scattering factor has been used in conjunction with the coherent Bragg rod analysis phase-retrieval algorithm to determine the composition and strain profiles of ultrathin layers of GaAs grown on InGaAs buffers. The buffer layers are nominally latticed matched with the InP substrate and the subsequent GaAs growth is compared at two different temperatures: 480 and 520 °C. We show that electron density maps extracted from Bragg rod scans measured close to the Ga and As K-edges can be used to deconvolute roughness and intermixing. It is found that indium incorporation and roughening lead to a significant reduction of the strain in this system.
Show PACS
68.55.ag Semiconductors
68.55.J- Morphology of films
78.70.Ck X-ray scattering

Effect of adsorption-induced surface stress change on the stiffness of a microcantilever used as a salinity detection sensor

S. Kim and K. D. Kihm

Appl. Phys. Lett. 93, 081911 (2008); http://dx.doi.org/10.1063/1.2976749 (3 pages) | Cited 5 times

Online Publication Date: 27 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A microcantilever surface stress-stiffness relationship has been investigated for three decades. Most of the surface stress induced stiffness change models, however, are limited to apply for vacuum environment, and they did not account for the hydrodynamic loading term that is essential for a microcantilever in a liquid medium. In this letter, we present both analytical and experimental examinations of the effect of adsorption-induced surface stress changes on microcantilever stiffness in a saline solution. It is found that the surface adsorption of sodium ions increases the stiffness of a microcantilever.
Show PACS
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
82.80.-d Chemical analysis and related physical methods of analysis
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.10.Cm Micromechanical devices and systems
68.43.Mn Adsorption kinetics
46.25.-y Static elasticity
Author Select

The high-pressure phase behavior and compressibility of 2,4,6-trinitrotoluene

Lewis L. Stevens, Nenad Velisavljevic, Daniel E. Hooks, and Dana M. Dattelbaum

Appl. Phys. Lett. 93, 081912 (2008); http://dx.doi.org/10.1063/1.2973162 (3 pages)

Online Publication Date: 27 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The phase stability and isothermal compression behavior of 2,4,6-trinitrotoluene (TNT) have been established to 26.5 GPa using angle-dispersive x-ray diffraction. P-V isotherms derived from the high-pressure x-ray spectra displayed a slight density hysteresis around 4.0 GPa and a sharp discontinuity at ∼ 20.0 GPa. The latter transition is ascribed to a monoclinic-to-orthorhombic first-order phase transition in TNT. The conversion of the isothermal P-V data to the shock velocity-particle velocity plane revealed a deviation from linearity at low up, a cusp associated with the phase transition at high up, and general agreement with the wealth of unreacted Hugoniot data on TNT.
Show PACS
62.50.-p High-pressure effects in solids and liquids
64.70.K- Solid-solid transitions
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
78.70.-g Interactions of particles and radiation with matter

Improving selective thermal emission properties of three-dimensional macroporous silicon through porosity tuning

M. Garín, T. Trifonov, A. Rodríguez, R. Alcubilla, F. Marquier, C. Arnold, and J.-J. Greffet

Appl. Phys. Lett. 93, 081913 (2008); http://dx.doi.org/10.1063/1.2976144 (3 pages) | Cited 3 times

Online Publication Date: 27 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a theoretical and experimental study on the effect of progressive porosity increase, through multiple oxidation/oxide removal steps, upon the optical characteristics in three-dimensional macroporous silicon. It is shown that, by increasing porosity, optical features can be pushed toward higher frequencies. Optimum porosities exist where normal or omnidirectional total reflection bandwidths are maximized, doubling the initial values. Results are confirmed experimentally through angle-resolved reflectance and thermal emission measurements.
Show PACS
61.43.Gt Powders, porous materials

Measurement of crack opening stresses and crack closure stress profiles from heat generation in vibrating cracks

Jeremy Renshaw, Stephen D. Holland, and R. Bruce Thompson

Appl. Phys. Lett. 93, 081914 (2008); http://dx.doi.org/10.1063/1.2976310 (3 pages) | Cited 10 times

Online Publication Date: 27 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method is described to measure crack opening stresses and closure stress profiles of a surface-breaking crack. Vibration is used to generate frictional heat by rubbing crack face asperities. Heat is generated at regions of contacting crack asperities under low, but nonzero, closure stress. Increasing force is applied to incrementally open the crack and measure the locations of crack heating as a function of applied load. Surface crack closure stresses are approximated from the heating locations as the load is varied and the crack opening stress is measured from the load required to fully open the crack and terminate heat generation.
Show PACS
68.35.Ja Surface and interface dynamics and vibrations
68.35.Gy Mechanical properties; surface strains
62.20.mt Cracks
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure

Influence of annealing temperature on optical properties of InGaN quantum dot based light emitting diodes

Q. Wang, T. Wang, J. Bai, A. G. Cullis, P. J. Parbrook, and F. Ranalli

Appl. Phys. Lett. 93, 081915 (2008); http://dx.doi.org/10.1063/1.2976324 (3 pages) | Cited 12 times

Online Publication Date: 27 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron-luminescence (EL) and high-resolution transmission electron microscopy (TEM) measurements have been carried out on the InGaN quantum dot (QD) based light emitting diodes (LEDs) annealed at different temperatures for p-type GaN activation. The annealing temperatures are chosen based on the growth temperature for our InGaN QDs as a reference point. A significant improvement with a factor of up to ∼ 3.5 in EL intensity has been achieved when the annealing temperature is increased from 720 to 800 °C. However, the EL intensity dramatically decreases if the annealing temperature further increases to 830 °C. In addition, a clear blueshift in EL emission energy has been observed as a result of increasing annealing temperature. In combination with our TEM study, the change in optical properties of the QD based LEDs due to the thermal annealing can be attributed to the shrinkage of the QDs and then eventual mergence into the wetting layer if the annealing temperature is further increased. The data based on detailed driving-current dependent EL measurements also support the conclusion.
Show PACS
85.60.Jb Light-emitting devices

Enhancement of terahertz electromagnetic wave emission from an undoped GaAs/n-type GaAs epitaxial layer structure

Hideo Takeuchi, Junichi Yanagisawa, Takayuki Hasegawa, and Masaaki Nakayama

Appl. Phys. Lett. 93, 081916 (2008); http://dx.doi.org/10.1063/1.2976436 (3 pages) | Cited 15 times

Online Publication Date: 27 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the emission of the terahertz electromagnetic wave from an undoped GaAs (200 nm)/n-type GaAs (3 μm) epitaxial layer structure (i-GaAs/n-GaAs structure), where the doping concentration of the n-GaAs layer is 3×1018 cm−3. It is found that the first-burst amplitude of terahertz wave of the i-GaAs/n-GaAs sample is remarkably larger than that of a n-GaAs crystal, which means that the i-GaAs layer enhances the terahertz emission intensity. The first-burst amplitude of the i-GaAs/n-GaAs sample, by tuning the pump-beam energy to the higher energy side, exceeds that of an i-InAs crystal that is known as one of the most intense terahertz emitters. We, therefore, conclude that the i-GaAs/n-GaAs structure is useful to obtain intense terahertz emission.
Show PACS
78.66.Fd III-V semiconductors
61.72.uj III-V and II-VI semiconductors

Light reflection from a metal surface with subwavelength cavities

Cheng-ping Huang, Jia-qi Li, Qian-jin Wang, Xiao-gang Yin, and Yong-yuan Zhu

Appl. Phys. Lett. 93, 081917 (2008); http://dx.doi.org/10.1063/1.2976161 (3 pages) | Cited 3 times

Online Publication Date: 28 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The interaction of light with the localized/delocalized system, i.e., a metal surface with rectangular cavities of finite depth, has been studied. Reflection spectrum has been measured in the optical frequencies, and resonant minima have been observed. We have developed an analytical model, which agrees well with the experiment. The localized waveguide resonance and delocalized surface resonance have been identified and discussed. The results may be useful for manipulating the coupling between light and matters.
Show PACS
78.66.Bz Metals and metallic alloys
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.68.+m Optical properties of surfaces

Atomic-scale bonding of bulk metallic glass to crystalline aluminum

K. X. Liu, W. D. Liu, J. T. Wang, H. H. Yan, X. J. Li, Y. J. Huang, X. S. Wei, and J. Shen

Appl. Phys. Lett. 93, 081918 (2008); http://dx.doi.org/10.1063/1.2976667 (3 pages) | Cited 10 times

Online Publication Date: 29 August 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A Ti40Zr25Cu12Ni3Be20 bulk metallic glass (BMG) was welded to a crystalline aluminum by the parallel plate explosive welding method. Experimental evidence and numerical simulation show that atomic-scale bonding between the BMG and the crystalline aluminum can be achieved, and the weldment on the BMG side can retain its amorphous state without any indication of crystallization in the welding process. Nanoindentation tests reveal that the interface of the explosive joints exhibits a significant increase in hardness compared to the matrix on its two sides. The joining of BMG and crystalline materials opens a window to the applications of BMGs in engineering.
Show PACS
81.16.-c Methods of micro- and nanofabrication and processing
81.20.Vj Joining; welding
81.05.Kf Glasses (including metallic glasses)
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close