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11 May 2009

Volume 94, Issue 19, Articles (19xxxx)

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Appl. Phys. Lett. 94, 194101 (2009); http://dx.doi.org/10.1063/1.3130182 (3 pages)

Jeffery Allen, Nathan Kundtz, Daniel A. Roberts, Steven A. Cummer, and David R. Smith
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Catastrophic optical mirror damage in diode lasers monitored during single-pulse operation

Mathias Ziegler, Jens W. Tomm, David Reeber, Thomas Elsaesser, Ute Zeimer, Henning E. Larsen, Paul M. Petersen, and Peter E. Andersen

Appl. Phys. Lett. 94, 191101 (2009); http://dx.doi.org/10.1063/1.3133339 (3 pages) | Cited 13 times

Online Publication Date: 11 May 2009

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Catastrophic optical mirror damage (COMD) is analyzed for 808 nm emitting diode lasers in single-pulse operation in order to separate facet degradation from subsequent degradation processes. During each pulse, nearfield and thermal images are monitored. A temporal resolution better than 7 μs is achieved. The thermal runaway process is unambiguously related to the occurrence of a “thermal flash.” A one-by-one correlation between nearfield, thermal flash, thermal runaway, and structural damage is observed. The single-pulse excitation technique allows for controlling the propagation of the structural damage into the cavity. We propose this technique for the analysis of early stages of COMD.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.87.-d Optical testing techniques
42.79.Bh Lenses, prisms and mirrors

Enhanced quantum efficiency of Ge solar cells by a two-dimensional photonic crystal nanostructured surface

I. Prieto, B. Galiana, P. A. Postigo, C. Algora, L. J. Martínez, and I. Rey-Stolle

Appl. Phys. Lett. 94, 191102 (2009); http://dx.doi.org/10.1063/1.3133348 (3 pages) | Cited 14 times

Online Publication Date: 11 May 2009

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A single-junction germanium solar cell with a photonic crystal nanostructured surface has been developed. The solar cell comprises a Ge p-n junction and an InGaP window layer. The InGaP window layer has been nanopatterned with an extended photonic crystal structure consisting on a triangular lattice of holes with submicronic sizes. Enhancements of the external quantum efficiency of 22% for a wide range of wavelengths and up to a 46% for specific wavelengths have been measured, which implies an increase in photocurrent between 11% and 22%. A clear correlation with the area of photonic crystal patterned has been observed.
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84.60.Jt Photoelectric conversion
42.70.Qs Photonic bandgap materials

Gigantic enhancement in response and reset time of ZnO UV nanosensor by utilizing Schottky contact and surface functionalization

Jun Zhou, Yudong Gu, Youfan Hu, Wenjie Mai, Ping-Hung Yeh, Gang Bao, Ashok K. Sood, Dennis L. Polla, and Zhong Lin Wang

Appl. Phys. Lett. 94, 191103 (2009); http://dx.doi.org/10.1063/1.3133358 (3 pages) | Cited 89 times

Online Publication Date: 11 May 2009

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UV response of ZnO nanowire nanosensor has been studied under ambient condition. By utilizing Schottky contact instead of Ohmic contact in device fabrication, the UV sensitivity of the nanosensor has been improved by four orders of magnitude, and the reset time has been drastically reduced from ∼ 417 to ∼ 0.8 s. By further surface functionalization with function polymers, the reset time has been reduced to ∼ 20 ms even without correcting the electronic response of the measurement system. These results demonstrate an effective approach for building high response and fast reset UV detectors.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
85.60.Gz Photodetectors (including infrared and CCD detectors)
73.30.+y Surface double layers, Schottky barriers, and work functions
07.10.Cm Micromechanical devices and systems

Backside observation of large-scale integrated circuits with multilayered interconnections using laser terahertz emission microscope

Masatsugu Yamashita, Chiko Otani, Kodo Kawase, Toru Matsumoto, Kiyoshi Nikawa, Sunmi Kim, Hironaru Murakami, and Masayoshi Tonouchi

Appl. Phys. Lett. 94, 191104 (2009); http://dx.doi.org/10.1063/1.3133346 (3 pages) | Cited 5 times

Online Publication Date: 13 May 2009

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We have developed a laser terahertz emission microscope utilizing excitation laser pulses at 1.06 μm wavelength for the inspection and localization of electrical failures in large-scale integrated circuits with multilayered interconnection structures. The system enables to measure terahertz emission images from the backside of a large-scale integrated circuits chip with a multilayered interconnection structure that prevents the observation from the front side. By comparing the terahertz emission images, we successfully distinguish a normal circuit from damaged ones with different positions of the interconnection defects without any electrical probing.
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85.40.Qx Microcircuit quality, noise, performance, and failure analysis
85.40.Ls Metallization, contacts, interconnects; device isolation

Reduced divergence angle of photonic crystal vertical-cavity surface-emitting laser

Anjin Liu, Mingxin Xing, Hongwei Qu, Wei Chen, Wenjun Zhou, and Wanhua Zheng

Appl. Phys. Lett. 94, 191105 (2009); http://dx.doi.org/10.1063/1.3136859 (3 pages) | Cited 12 times

Online Publication Date: 14 May 2009

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The reduced divergence angle of the photonic crystal vertical-cavity surface-emitting laser (PC-VCSEL) was investigated in both theory and experiment. The photonic crystal waveguide possessed the weakly guiding waveguide characteristic, which accounted for the reduction of the divergence angle. The three-dimensional finite-difference time-domain method was used to simulate the designed PC-VCSEL, and a calculated divergence angle of 5.2° was obtained. The measured divergence angles of our fabricated PC-VCSEL were between 5.1° and 5.5° over the entire drive current range, consistent with the numerical results. This is the lowest divergence angle of the fabricated PC-VCSEL ever reported.
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42.55.Tv Photonic crystal lasers and coherent effects
42.70.Qs Photonic bandgap materials
42.55.Px Semiconductor lasers; laser diodes
42.79.Gn Optical waveguides and couplers
02.70.Bf Finite-difference methods

Enhancement of light absorption in a quantum well by surface plasmon polariton

J. B. Khurgin and G. Sun

Appl. Phys. Lett. 94, 191106 (2009); http://dx.doi.org/10.1063/1.3137186 (3 pages) | Cited 5 times

Online Publication Date: 14 May 2009

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We investigate analytically the degree to which the absorption of light in a single quantum well can be enhanced in the proximity of a structured metallic surface and show that the wavelength at which the maximum enhancement of about one order of magnitude is attained depends on metal loss and the initial absorption in a quantum well.
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42.25.Bs Wave propagation, transmission and absorption
78.67.De Quantum wells
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Enhanced photoluminescence of heavily n-doped germanium

M. El Kurdi, T. Kociniewski, T.-P. Ngo, J. Boulmer, D. Débarre, P. Boucaud, J. F. Damlencourt, O. Kermarrec, and D. Bensahel

Appl. Phys. Lett. 94, 191107 (2009); http://dx.doi.org/10.1063/1.3138155 (3 pages) | Cited 24 times

Online Publication Date: 14 May 2009

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We show that a significant enhancement of the direct band gap photoluminescence can be achieved at room temperature in bulk Ge and Ge-on-insulator heavily n-doped by gas immersion laser doping. The photoluminescence signal from bulk Ge and Ge-on-insulator increases with the donor concentration. An enhancement factor of 20 as compared to the undoped material is achieved near the 1550 nm wavelength for active dopant concentrations around 5×1019 cm−3. These results are supported by calculations of the Ge spontaneous emission spectrum taking into account the doping effect on the electron distribution in the direct and indirect conduction band valleys.
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78.55.Ap Elemental semiconductors
61.72.sd Impurity concentration

High-reflectivity broadband distributed Bragg reflector lattice matched to ZnTe

W. Pacuski, C. Kruse, S. Figge, and D. Hommel

Appl. Phys. Lett. 94, 191108 (2009); http://dx.doi.org/10.1063/1.3136755 (3 pages) | Cited 7 times

Online Publication Date: 15 May 2009

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We report on the realization of a high quality distributed Bragg reflector with both high and low refractive index layers lattice matched to ZnTe. Our structure is grown by molecular beam epitaxy and is based on binary compounds only. The high refractive index layer is made of ZnTe, while the low index material is made of a short period triple superlattice containing MgSe, MgTe, and ZnTe. The high refractive index step of Δn = 0.5 in the structure results in a broad stop band and the reflectivity coefficient exceeding 99% for only 15 Bragg pairs.
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42.82.-m Integrated optics
42.79.Wc Optical coatings
42.70.-a Optical materials
42.79.Fm Reflectors, beam splitters, and deflectors

Auger recombination rates in nitrides from first principles

Kris T. Delaney, Patrick Rinke, and Chris G. Van de Walle

Appl. Phys. Lett. 94, 191109 (2009); http://dx.doi.org/10.1063/1.3133359 (3 pages) | Cited 70 times

Online Publication Date: 15 May 2009

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We report Auger recombination rates for wurtzite InGaN calculated from first-principles density-functional and many-body-perturbation theory. Two different mechanisms are examined—inter- and intra-band recombination—that affect different parts of the emission spectrum. In the blue to green spectral region and at room temperature the Auger coefficient can be as large as 2×10−30 cm6 s−1; in the infrared it is even larger. Since Auger recombination scales with the cubic power of the free-carrier concentration it becomes an important nonradiative loss mechanism at high current densities. Our results indicate that Auger recombination may be responsible for the loss of quantum efficiency that affects InGaN-based light emitters.
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79.20.Fv Electron impact: Auger emission
71.20.Nr Semiconductor compounds
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
72.80.Ey III-V and II-VI semiconductors
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Sheath and boundary conditions for plasma simulations of a Hall thruster discharge with magnetic lenses

Michael Keidar and Isak I. Beilis

Appl. Phys. Lett. 94, 191501 (2009); http://dx.doi.org/10.1063/1.3132083 (3 pages) | Cited 16 times

Online Publication Date: 11 May 2009

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The effect of magnetic lens configuration on sheath in a Hall thruster discharge channels is considered. A model of the plasma-wall transition is developed in the case of large magnetic field incidence angle with respect to the wall. Peculiarity of such case consists in that the potential drop across the magnetic field is set externally. In this case, standard boundary conditions at the sheath edge for plasma simulations fail and a new formulation for those boundary conditions is proposed. The results obtained demonstrate importance of the effect of the magnetic field incidence angle on the sheath boundary conditions for plasma simulations as well as on the energy balance in the Hall thruster discharge.
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52.75.Di Ion and plasma propulsion
52.40.Kh Plasma sheaths
52.40.Hf Plasma-material interactions; boundary layer effects
52.55.Rk Power exhaust; divertors
52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
52.65.-y Plasma simulation

Development of a dielectric-barrier discharge enhanced microplasma jet

Shinya Kiriu, Hiroyuki Miyazoe, Fumitoshi Takamine, Masaki Sai, Jai Hyuk Choi, Takaaki Tomai, and Kazuo Terashima

Appl. Phys. Lett. 94, 191502 (2009); http://dx.doi.org/10.1063/1.3130183 (3 pages) | Cited 5 times

Online Publication Date: 12 May 2009

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A low-power ultrahigh-frequency-driven inductively coupled microplasma (ICMP) source equipped with dielectric-barrier discharge (DBD) was developed to realize a low-temperature and high-density plasma in fine quartz capillaries with inner diameters of less than 1.0 mm. A stable plasma was generated and its sustainability was independent of the gas flow rate. This plasma jet had a longer plume than that of a thermoelectron-enhanced microplasma jet, and time-resolved characterization suggested interactions between ICMP and DBD jets. By optical emission spectroscopy characterization, the gas temperature and electron density inside a capillary were estimated to be 400–1000 K and 1013–1014 cm−3, respectively.
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52.30.-q Plasma dynamics and flow
52.75.-d Plasma devices

Transport of energetic electrons in a magnetically expanding helicon double layer plasma

Kazunori Takahashi, Christine Charles, Rod Boswell, Wes Cox, and Rikizo Hatakeyama

Appl. Phys. Lett. 94, 191503 (2009); http://dx.doi.org/10.1063/1.3136721 (3 pages) | Cited 12 times

Online Publication Date: 13 May 2009

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Peripheral magnetic field lines extending from the plasma source into the diffusion chamber are found to separate two regions of Maxwellian electron energy probability functions: the central, ion-beam containing region with an electron temperature of 5 eV, and region near the chamber walls with electrons at 3 eV. Along the peripheral field lines a bi-Maxwellian population with a hot tail at 9 eV is shown to both originate from electrons in the source traveling downstream across the double layer and correspond to a local maximum in ion and electron densities.
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52.25.Fi Transport properties
52.25.-b Plasma properties
52.40.Kh Plasma sheaths

Generation of room-temperature atmospheric H2/Ar microplasma jet driven with pulse-modulated ultrahigh frequency and its application to gold nanoparticle preparation

Yoshiki Shimizu, Kenji Kawaguchi, Takeshi Sasaki, and Naoto Koshizaki

Appl. Phys. Lett. 94, 191504 (2009); http://dx.doi.org/10.1063/1.3129168 (3 pages) | Cited 14 times

Online Publication Date: 15 May 2009

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We developed a technique to prepare gold nanoparticles (AuNPs) by wire spraying employing a room-temperature atmospheric H2/Ar microplasma jet driven with pulsing ultrahigh frequency and to subsequently deposit the AuNPs on nonheat-resistant materials such as paper in ambient air without apparent damage. In this technique, the application of a pulse waveform with higher voltage but rather low duty cycle effectively lowered the time-averaged gas temperature and facilitated preparing AuNPs. The size, crystallinity, and optical absorption of the prepared AuNPs were characterized, and the derivation and size evolution mechanisms were simply discussed based on the characterizations.
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81.16.-c Methods of micro- and nanofabrication and processing
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
52.77.Fv High-pressure, high-current plasmas (plasma spray, arc welding, etc.)
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Entropy change and effect of magnetic field on martensitic transformation in a metamagnetic Ni–Co–Mn–In shape memory alloy

S. Kustov, M. L. Corró, J. Pons, and E. Cesari

Appl. Phys. Lett. 94, 191901 (2009); http://dx.doi.org/10.1063/1.3130229 (3 pages) | Cited 30 times

Online Publication Date: 11 May 2009

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We studied the entropy change and the shift of the martensitic transformation temperatures with magnetic field in samples of a polycrystalline Ni–Co–Mn–In alloy having different degrees of long-range atomic order due to different heat treatments. We found, for the samples of the same composition, strong variations of the entropy change with the degree of atomic order, mediated by the difference between the Curie and martensitic transformation temperatures. Calculations of the field-induced shift of the transformation using data of entropy variations show good agreement with experimental results.
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81.30.Kf Martensitic transformations
64.70.K- Solid-solid transitions
81.40.Lm Deformation, plasticity, and creep
62.20.fg Shape-memory effect; yield stress; superelasticity
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)

Deformation mechanisms during large strain deformation of nanocrystalline nickel

N. P. Gurao and Satyam Suwas

Appl. Phys. Lett. 94, 191902 (2009); http://dx.doi.org/10.1063/1.3132085 (3 pages) | Cited 5 times

Online Publication Date: 12 May 2009

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In this letter, a conclusive evidence of the operation of planar slip along with grain boundary mediated mechanisms has been reported during large strain deformation of nanocrystalline nickel. Dislocation annihilation mechanism such as mechanical recovery has been found to play an important role during the course of deformation. The evidences rely on x-ray based techniques, such as dislocation density determination and crystallographic texture measurement as well as microstructural observation by electron microscopy. The characteristic texture evolution in this case is an indication of normal slip mediated plasticity in nanocrystalline nickel.
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62.25.De Low-frequency properties: response coefficients
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
61.72.Mm Grain and twin boundaries
61.72.Lk Linear defects: dislocations, disclinations
81.40.Lm Deformation, plasticity, and creep
62.20.fq Plasticity and superplasticity

Improved semipolar (11math2) GaN quality using asymmetric lateral epitaxy

P. de Mierry, N. Kriouche, M. Nemoz, and G. Nataf

Appl. Phys. Lett. 94, 191903 (2009); http://dx.doi.org/10.1063/1.3134489 (3 pages) | Cited 12 times

Online Publication Date: 13 May 2009

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Semipolar (11math2) GaN films were obtained by epitaxial lateral overgrowth from (11math2) GaN templates patterned with SiO2 stripes 7 μm wide with 3 μm spacing, oriented along the [1math00] GaN in-plane direction. The growth conditions were optimized in order to promote a fast growth rate along the +c [0001] direction. The crystal expands both laterally and vertically until a situation where it overgrows the adjacent crystal, thus stopping the propagation of stacking faults and threading dislocations. The growth anisotropy and filtering of defects is observed by cross-sectional scanning electron microscopy and cathodoluminescence. The lowering of defect density is confirmed by x-ray diffraction measurements. The photoluminescence spectrum of the coalesced epitaxial lateral overgrowth of the (11math2) epilayers exhibits a strong band edge emission and a low emission band at 3.41 eV, assigned to the remaining stacking faults.
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81.05.Ea III-V semiconductors
68.55.ag Semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.Fd III-V semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
78.55.Cr III-V semiconductors

A model of Sn whisker growth by coupled plastic flow and grain boundary diffusion

Eric J. Buchovecky, Ningning Du, and Allan F. Bower

Appl. Phys. Lett. 94, 191904 (2009); http://dx.doi.org/10.1063/1.3136865 (3 pages) | Cited 8 times

Online Publication Date: 13 May 2009

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Finite element simulations are used to calculate the rate of whisker growth due to intermetallic formation in a Sn film with columnar grain structure on a Cu substrate. The simulations account for plastic flow by dislocation motion within the grains, as well as diffusion along grain boundaries. Grains with a slightly lower yield stress than their neighbors are shown to act as sinks for material and are progressively extruded from the film. A simple analytical model is developed to estimate the resulting whisker growth rate, and is shown to be in good agreement with experimental measurements.
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68.70.+w Whiskers and dendrites (growth, structure, and nonelectronic properties)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.40.Lm Deformation, plasticity, and creep
62.20.fq Plasticity and superplasticity
62.20.fg Shape-memory effect; yield stress; superelasticity
66.30.Lw Diffusion of other defects

Coarse-grained description of localized inelastic deformation in amorphous metals

Marios D. Demetriou, William L. Johnson, and Konrad Samwer

Appl. Phys. Lett. 94, 191905 (2009); http://dx.doi.org/10.1063/1.3133942 (3 pages) | Cited 9 times

Online Publication Date: 13 May 2009

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The sequence of shear transformation events that lead to a shear band transition in amorphous metals is described by a spatially random coarse-grained model calibrated to obey the thermodynamic scaling relations that govern flow in a real glass. The model demonstrates that shear banding is a consequence of local shear transformation events that self-organize along planes of maximum resolved shear stress to form extended bands of highly localized deformation. This description suggests that shear band formation is incipient during the early stages of deformation of a randomly inhomogeneous material.
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81.40.Lm Deformation, plasticity, and creep
62.20.fq Plasticity and superplasticity
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.de Elastic moduli

First-principles prediction of mechanical properties of gamma-boron

Chao Jiang, Zhijun Lin, Jianzhong Zhang, and Yusheng Zhao

Appl. Phys. Lett. 94, 191906 (2009); http://dx.doi.org/10.1063/1.3133943 (3 pages) | Cited 12 times

Online Publication Date: 13 May 2009

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The structural and mechanical properties of γ-B28 are investigated using first-principles density functional calculations. The single-crystal elastic constants calculations show that γ-B28 is mechanically stable under ambient conditions. The predicted bulk and shear moduli of γ-B28 are comparable to those of boron suboxide, suggesting that γ-B28 can be a superhard material. We also obtained the ideal tensile strength for γ-B28 through deformation from the elastic regime to structural instability. We find that the breaking of B1–B1 and B1–B2 bonds is responsible for the failure of γ-B28 under 〈100〉 and 〈010〉 tensile deformation, respectively.
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81.40.Lm Deformation, plasticity, and creep
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.de Elastic moduli
62.20.F- Deformation and plasticity
61.50.Ah Theory of crystal structure, crystal symmetry; calculations and modeling
61.66.Bi Elemental solids

Strain-modulated valence band engineering for enhancement of surface emission in polar and nonpolar plane AlN films

D. Y. Fu, R. Zhang, B. G. Wang, Z. Zhang, B. Liu, Z. L. Xie, X. Q. Xiu, H. Lu, Y. D. Zheng, and G. Edwards

Appl. Phys. Lett. 94, 191907 (2009); http://dx.doi.org/10.1063/1.3136431 (3 pages) | Cited 6 times

Online Publication Date: 14 May 2009

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The k⋅p perturbation theory is adopted to calculate the strain-modulated excitonic transition energies and their polarization properties in c- and m-plane AlN. The two topmost valence subbands exchange their band characteristics at the degenerate point where εzz = 0.98% and εxx = εyy = −1.70%. The surface emission efficiency of c-plane AlN films can be dramatically enhanced with εzz>0.98% (εxx = εyy<−1.70%), where the lowest excitonic transition is predominantly z-polarized. Besides, nonpolar plane (m- or a-plane) AlN experiencing anisotropic in-plane strain can be chosen as a candidate for enhancing the surface emission efficiency by proper strain manipulation.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.15.-m Methods of electronic structure calculations
71.20.Nr Semiconductor compounds

Significant second-harmonic generation in two lead-free polar oxides BiInO3 and BiAlO3: A first-principles investigation

Sheng Ju and Tian-Yi Cai

Appl. Phys. Lett. 94, 191908 (2009); http://dx.doi.org/10.1063/1.3136838 (3 pages) | Cited 2 times

Online Publication Date: 14 May 2009

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Density functional theory with the generalized gradient approximation is applied to study the second-harmonic generation (SHG) in two lead-free polar oxides BiInO3 and BiAlO3. Significant SHG susceptibilities, larger than 500 (10−9 esu), are revealed in both of them. The low frequency limit is found to reach 13 (10−9 esu) and 43 (10−9 esu) for BiInO3 and BiAlO3, respectively. In the meantime, the linear optical response shows weak optical anisotropy and the absorption edge is around 3 eV for both of them. All these results are consistent with their unusual polar structure and demonstrate their potential application in nonlinear optoelectronics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.

Gaussian diffusion sphere model to predict mass transfer due to diffusional particle deposition on a flat surface in laminar flow regime

Se-Jin Yook and Kang-Ho Ahn

Appl. Phys. Lett. 94, 191909 (2009); http://dx.doi.org/10.1063/1.3133343 (3 pages) | Cited 11 times

Online Publication Date: 14 May 2009

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Gaussian diffusion sphere model (GDSM) was developed to predict mass transfer in a flow parallel to a flat surface in laminar flow regime. The GDSM is based on the prediction of deposition probability of particles by calculating the volume fraction of a sphere overlapping with the surface, where the distance a particle diffuses for a certain time within the sphere is statistically weighted by a Gaussian distribution with the standard deviation equal to the root-mean-square net displacement by Brownian motion. Mean mass transfer coefficient predicted by the GDSM agreed very well with that calculated by the laminar boundary layer theory.
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47.15.Cb Laminar boundary layers
05.40.Jc Brownian motion
02.50.Ng Distribution theory and Monte Carlo studies

Optical properties of switchable mirrors based on magnesium-calcium alloy thin films

Y. Yamada, S. Bao, K. Tajima, M. Okada, and K. Yoshimura

Appl. Phys. Lett. 94, 191910 (2009); http://dx.doi.org/10.1063/1.3138130 (3 pages) | Cited 5 times

Online Publication Date: 14 May 2009

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Switchable mirrors based on magnesium-calcium alloy thin films were prepared using a direct-current magnetron sputtering method and their gasochromic properties have been investigated. Pd-capped Mg1−zCaz (0.04<z<0.20) films showed excellent switchable mirror properties. The visible transmittance in the transparent state increased with Ca composition, z, and after reaching a maximum of ∼ 46% at z ∼ 0.06, the transmittance decreased gradually with increasing Ca composition. In the transparent state with z<0.08, the optical transmittance spectra of these switchable mirrors were fairly flat in the visible range and their color looked completely neutral. The achromatic properties with high visible transmittance may be because the hydrogenated switchable mirrors are composed of MgH2 and MgCaH3.72 with grayish neutral color appearance.
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42.79.Bh Lenses, prisms and mirrors
78.66.Bz Metals and metallic alloys
78.40.Kc Metals, semimetals, and alloys

From nanoglasses to bulk massive glasses

D. Şopu, K. Albe, Y. Ritter, and H. Gleiter

Appl. Phys. Lett. 94, 191911 (2009); http://dx.doi.org/10.1063/1.3130209 (3 pages) | Cited 5 times

Online Publication Date: 14 May 2009

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Molecular dynamics simulations are presented that provide evidence for the existence of diluted interfaces in nanoglasses, which is a class of material that can be synthesized by consolidating glassy nanoparticles. By comparing simulations of a covalently bonded Ge nanoglass and a metallic CuZr nanoglass, we show that the delocalization of the excess free volume initially located within the interfaces depends on the flow strain of the material. Our results suggest that the density distribution within a nanoglass can be controlled by the initial particle size and the annealing conditions. Therefore, nanoglasses represent an alternative route for controlling the properties of glassy materials.
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61.43.Bn Structural modeling: serial-addition models, computer simulation
81.40.Gh Other heat and thermomechanical treatments
68.35.Ct Interface structure and roughness
61.43.Fs Glasses

Atomic structure of Zr–Cu glassy alloys and detection of deviations from ideal solution behavior with Al addition by x-ray diffraction using synchrotron light in transmission

K. Georgarakis, A. R. Yavari, D. V. Louzguine-Luzgin, J. Antonowicz, M. Stoica, Y. Li, M. Satta, A. LeMoulec, G. Vaughan, and A. Inoue

Appl. Phys. Lett. 94, 191912 (2009); http://dx.doi.org/10.1063/1.3136428 (3 pages) | Cited 19 times

Online Publication Date: 15 May 2009

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The atomic structure of Zr–Cu binary amorphous alloys was studied using real space pair distribution functions derived from x-ray diffraction. The structure can be modeled by an ideal solution approximation because of relatively weak Cu–Zr atomic interactions. Addition of Al to Zr–Cu metallic glasses modifies the atomic structure in the short and medium range order because of the strongly attractive interaction between Al and Zr atoms. These interactions generate strong deviations from the ideal solution behavior.
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61.43.Fs Glasses
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