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9 Mar 2009

Volume 94, Issue 10, Articles (10xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 94, 102502 (2009); http://dx.doi.org/10.1063/1.3093823 (3 pages)

Guozhu Sun, Xueda Wen, Yiwen Wang, Shanhua Cong, Jian Chen, Lin Kang, Weiwei Xu, Yang Yu, Siyuan Han, and Peiheng Wu
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Characterization of archeological human bone tissue by enhanced backscattering of light

M. Leonetti, S. Capuani, M. Peccianti, G. Ruocco, and C. Conti

Appl. Phys. Lett. 94, 101101 (2009); http://dx.doi.org/10.1063/1.3097014 (3 pages) | Cited 2 times

Online Publication Date: 9 March 2009

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Enhanced backscattering of light is used to detect microarchitectural changes in human archeological bones. Measurements on tibia cortical and trabecular tissue demonstrate the high sensitivity of the cone width and enhancement factor to the different morphologies. The approach allows to unveil the presence of periostitic lesions, thus addressing its feasibility for anthropological studies.
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87.64.Cc Scattering of visible, uv, and infrared radiation
87.19.rm Structure

Metal mirror assisting light extraction from patterned AlGaInP light-emitting diodes

Sun-Kyung Kim, Hyun Don Song, Ho-Seok Ee, Hyun Min Choi, Hyun Kyong Cho, Yong-Hee Lee, and Hong-Gyu Park

Appl. Phys. Lett. 94, 101102 (2009); http://dx.doi.org/10.1063/1.3097017 (3 pages) | Cited 8 times

Online Publication Date: 9 March 2009

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We demonstrate light extraction from metal reflector-based AlGaInP photonic crystal (PhC) light-emitting diodes (LEDs). The photons reflected by a high-reflectivity, small-absorption, bottom Ag mirror steadily interact with the PhC, and thus enhanced light extraction is achieved. The square lattice PhC patterns are fabricated on an upper n-doped AlGaInP surface with a depth of 500 nm. An optical power measurement using an integration sphere shows that the extraction efficiency of the PhC LED is ∼ 1.8 times larger than that of the nonpatterned LED. A three-dimensional finite difference time domain simulation is performed to understand the output enhancement extracted by the PhC and the effect of internal absorption.
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85.60.Jb Light-emitting devices
78.66.Fd III-V semiconductors
42.70.Qs Photonic bandgap materials

Practical enhancement of photoluminescence by metal nanoparticles

G. Sun, J. B. Khurgin, and R. A. Soref

Appl. Phys. Lett. 94, 101103 (2009); http://dx.doi.org/10.1063/1.3097025 (3 pages) | Cited 19 times

Online Publication Date: 9 March 2009

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We develop a simple yet rigorous theory of the photoluminescence (PL) enhancement in the vicinity of metal nanoparticles. The enhancement takes place during both optical excitation and emission. The strong dependence on the nanoparticle size enables optimization for maximum PL efficiency. Using the example of InGaN quantum dots (QDs) positioned near Ag nanospheres embedded in GaN, we show that strong enhancement can be obtained only for those QDs, atoms, or molecules that are originally inefficient in absorbing as well as in emitting optical energy. We then discuss practical implications for sensor technology.
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78.55.Cr III-V semiconductors
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)

Electro-optics of polymer-stabilized blue phase liquid crystal displays

Zhibing Ge, Sebastian Gauza, Meizi Jiao, Haiqing Xianyu, and Shin-Tson Wu

Appl. Phys. Lett. 94, 101104 (2009); http://dx.doi.org/10.1063/1.3097355 (3 pages) | Cited 65 times

Online Publication Date: 10 March 2009

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Electro-optics of polymer-stabilized blue phase liquid crystal displays (BP LCDs) is analyzed and validated experimentally. A numerical model for characterizing and optimizing the electro-optical and display properties of BP LCDs in in-plane switching and fringe field switching cells is developed. The simulated voltage-dependent transmittance curves agree well with the measured results. To lower the operating voltage while keeping a high transmittance, both electrode width and gap, and large Kerr constant make important contributions. A wide-view BP LCD using a single biaxial compensation film is simulated.
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42.79.Kr Display devices, liquid-crystal devices
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
42.70.Df Liquid crystals
42.79.Wc Optical coatings
61.30.Vx Polymer liquid crystals

GaN light-emitting diode with monolithically integrated photonic crystals and angled sidewall deflectors for efficient surface emission

Joonhee Lee, Sungmo Ahn, Sihan Kim, Dong-Uk Kim, Heonsu Jeon, Seung-Jae Lee, and Jong Hyeob Baek

Appl. Phys. Lett. 94, 101105 (2009); http://dx.doi.org/10.1063/1.3095495 (3 pages) | Cited 8 times

Online Publication Date: 10 March 2009

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In order to obtain efficient surface emission, we propose and demonstrate a GaN light-emitting diode (LED) structure. A two-dimensional photonic crystal (PC) pattern is integrated to the sapphire substrate before the epigrowth by employing laser holography. In addition, angled sidewall deflectors (ASDs) are formed on the mesa sidewalls. Both the PC and ASDs redirect guided photons into the surface-normal direction. When compared to a conventional LED structure, we could obtain a twofold increase in the total surface emission and the surface-normal emission intensity enhanced by a factor of 2.5.
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85.60.Jb Light-emitting devices
85.60.Bt Optoelectronic device characterization, design, and modeling
81.05.Ea III-V semiconductors

Linear polarization-state generator with high precision in periodically poled lithium niobate

Kun Liu, Jianhong Shi, and Xianfeng Chen

Appl. Phys. Lett. 94, 101106 (2009); http://dx.doi.org/10.1063/1.3097225 (3 pages) | Cited 8 times

Online Publication Date: 10 March 2009

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In this letter, we propose a simple configuration capable of rotating a linear polarization state of light by a certain angle with high precision for a series of wavelengths. This is achieved in a compact one-chip integration of periodically poled lithium niobate (PPLN) by modulating the external electric field. During the experiment, the rotation angle varies between 0° and 100° with high precision of 0.04° and by changing the temperature of the PPLN the operating wavelength shifts with −0.51 nm/°C. The new device may find many applications where high precision control of linear polarization-state light is requested.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.25.Ja Polarization
78.20.Jq Electro-optical effects

Negative A-plates for broadband wide-view liquid crystal displays

Meizi Jiao, Sebastian Gauza, Yan Li, Jin Yan, Shin-Tson Wu, and Tsuyoshi Chiba

Appl. Phys. Lett. 94, 101107 (2009); http://dx.doi.org/10.1063/1.3097247 (3 pages) | Cited 5 times

Online Publication Date: 10 March 2009

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Negative A-plates fabricated by mechanically stretching polystyrene are studied and their physical properties evaluated. A molecular model is developed to explain the underlying physical mechanisms. An example of a broadband wide-view liquid crystal display including a negative A-plate for phase compensation is illustrated.
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85.60.Pg Display systems
42.79.Kr Display devices, liquid-crystal devices
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.20.Fm Birefringence
61.30.Vx Polymer liquid crystals

Hybrid structure laser based on semiconductor nanowires and a silica microfiber knot cavity

Qing Yang (杨青), Xiaoshun Jiang (姜校顺), Xin Guo (郭欣), Yuan Chen (陈圆), and Limin Tong (童利民)

Appl. Phys. Lett. 94, 101108 (2009); http://dx.doi.org/10.1063/1.3093821 (3 pages) | Cited 7 times

Online Publication Date: 12 March 2009

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We demonstrate a hybrid structure laser consisting of a single or multiple zinc oxide (ZnO) nanowires attached to a silica microfiber knot cavity, which is pumped by 355 nm wavelength laser pulses. The laser threshold is lower than 0.2 μJ/pulse. The measured linewidth of the lasing mode is about 0.04 nm. The hybrid structure combines advantages of high gain of semiconductor nanowires and high quality factor of microfiber knot cavities. Additionally, the design offers convenient and efficient approach to both pumping and collection of the semiconductor nanowire lasers.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Wd Fiber lasers
81.07.Vb Quantum wires
78.67.Lt Quantum wires
78.66.Hf II-VI semiconductors

Intermodal four-wave mixing from femtosecond pulse-pumped photonic crystal fiber

H. Tu, Z. Jiang, D. L. Marks, and S. A. Boppart

Appl. Phys. Lett. 94, 101109 (2009); http://dx.doi.org/10.1063/1.3094127 (3 pages) | Cited 3 times

Online Publication Date: 12 March 2009

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Large Stokes-shift ( ∼ 4700 cm−1) four-wave mixing is generated in a deeply normal dispersion regime from a 20 cm commercial large-mode-area photonic crystal fiber pumped by amplified ∼ 800 nm femtosecond pulses. The phase-matching condition is realized through an intermodal scheme involving two pump photons in the fundamental fiber mode and a pair of Stokes/anti-Stokes photons in a higher-order fiber mode. Over 7% conversion efficiency from the pump input to 586 nm anti-Stokes signal has been attained.
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42.70.Qs Photonic bandgap materials
42.81.Wg Other fiber-optical devices
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
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Observations of ultraslow light-based photon logic gates: NAND/OR

B. S. Ham and J. Hahn

Appl. Phys. Lett. 94, 101110 (2009); http://dx.doi.org/10.1063/1.3099039 (3 pages) | Cited 1 time

Online Publication Date: 12 March 2009

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We report observations of photon logic gate operations using ultraslow light phenomena in a rare-earth doped solid medium. Unlike conventional optical logic gates based on semiconductor optical amplifiers, the present photon logic gate utilizes spin coherence, which is completely free from the optical population constraint and gives potential for ultrahigh speed operations. In addition to the possibility of ultralow power operations, the usage of ultraslow light gives a benefit of all-optical buffer memory functions. Thus, the present demonstration has potential applications to cascadable photon logic devices.
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42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
84.30.Sk Pulse and digital circuits
42.25.Kb Coherence

Polarization tunable selective polariton generator

N. Sedoglavich, R. Künnemeyer, and J. C. Sharpe

Appl. Phys. Lett. 94, 101111 (2009); http://dx.doi.org/10.1063/1.3099040 (3 pages)

Online Publication Date: 12 March 2009

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A selective polariton generator (SPG) design, based on surface plasmon antennae principles, is demonstrated to provide a selective light transmission peak. The polarization-sensitive structure selectively generates and transports polaritons of a desired wavelength through a circular subwavelength aperture. By varying the SPG structure around a central nanohole, we are able to control the peak optical transmission wavelengths via the polarization state of the incident photons. We find good agreement between simulations and experimental results.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
42.25.Fx Diffraction and scattering
42.25.Ja Polarization

Formation of x-ray vortex dipoles using a single diffraction pattern and direct phase measurement using interferometry

Yoshiki Kohmura, Kei Sawada, Munetaka Taguchi, Tetsuya Ishikawa, Takuji Ohigashi, and Yoshio Suzuki

Appl. Phys. Lett. 94, 101112 (2009); http://dx.doi.org/10.1063/1.3095828 (3 pages)

Online Publication Date: 12 March 2009

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We have devised a method for generating x-ray vortices by using a diffraction pattern from a simple aperture with illumination wave fronts with spherical curvatures. The interferometry visualized the x-ray vortex dipoles by the direct phase measurement. Our interference technique enabled us to sensitively detect and quantitatively measure various phase dislocations on the x-ray wave fronts, providing useful methodologies for beam diagnostics and materials science.
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07.85.-m X- and γ-ray instruments
07.60.Ly Interferometers
42.15.Dp Wave fronts and ray tracing

Active phase control of a Ag near-field superlens via the index mismatch approach

Kwangchil Lee, Youngjean Jung, Gumin Kang, Haesung Park, and Kyoungsik Kim

Appl. Phys. Lett. 94, 101113 (2009); http://dx.doi.org/10.1063/1.3098980 (3 pages) | Cited 8 times

Online Publication Date: 13 March 2009

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We recognize that the phase control of optical transfer function is profoundly important in realizing nanoimaging beyond the diffraction limit. The difficulty of the optical phase measurement in the near field, required for the conventional adaptive control method, motivates us to achieve active phase control in the superlens imaging system. The visibility and resolving capabilities are significantly enhanced through the index mismatch approach by tuning the wavelength of the incident light.
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42.30.Wb Image reconstruction; tomography
07.05.Dz Control systems
42.30.Lr Modulation and optical transfer functions

Electrical-optical signal mixing and multiplication (2→22 GHz) with a tunnel junction transistor laser

H. W. Then, C. H. Wu, G. Walter, M. Feng, and N. Holonyak, Jr.

Appl. Phys. Lett. 94, 101114 (2009); http://dx.doi.org/10.1063/1.3100294 (3 pages) | Cited 7 times

Online Publication Date: 13 March 2009

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A tunnel junction is incorporated at the collector of a transistor laser to provide an effective method for voltage-controlled modulation via internal (intracavity) Franz–Keldysh photon-assisted tunneling. Electrical-optical signal mixing above threshold is made possible by the nonlinear coupling of the optical field to the base emitter-to-collector carrier transport and the base-to-collector electron tunneling. Microwave signal mixing with a common-emitter tunnel junction transistor laser is demonstrated with a pair of input sinusoidal signals: one (f1 = 2.0 GHz) at the base using current modulation and the other (f2 = 2.1 GHz) at the collector using voltage modulation, producing an optical output with harmonics of up to (4f1+7f2) = 22.7 GHz, despite being limited by amplifier bandwidth.
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85.30.Pq Bipolar transistors
72.20.Ee Mobility edges; hopping transport
84.40.-x Radiowave and microwave (including millimeter wave) technology
42.79.-e Optical elements, devices, and systems
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)

A quantum ring terahertz detector with resonant tunnel barriers

G. Huang, W. Guo, P. Bhattacharya, G. Ariyawansa, and A. G. U. Perera

Appl. Phys. Lett. 94, 101115 (2009); http://dx.doi.org/10.1063/1.3100407 (3 pages) | Cited 7 times

Online Publication Date: 13 March 2009

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The electronic properties of InAs/GaAs quantum rings and the characteristics of resonant tunnel intersubband terahertz detectors with quantum ring active regions have been studied. The electronic states of the quantum rings have been calculated and measured by the capacitance-voltage technique. The detectors exhibit extremely low dark current density values ∼ 5×10−5, 4.7×10−2, and 3.5×10−1 A/cm2 under a −1 V bias at 4.2, 80, and 300 K, respectively. Three prominent response peaks are observed at ∼ 6.5, 10, and 12.5 THz up to T = 120 K. At 80 K, the responsivity of the peaks varies from 0.07 to 0.02 A/W.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
73.21.La Quantum dots
73.40.Gk Tunneling
72.40.+w Photoconduction and photovoltaic effects
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A mode-selective circuit for TE01 gyrotron backward-wave oscillator with wide-tuning range

N. C. Chen, C. F. Yu, C. P. Yuan, and T. H. Chang

Appl. Phys. Lett. 94, 101501 (2009); http://dx.doi.org/10.1063/1.3097236 (3 pages) | Cited 10 times

Online Publication Date: 11 March 2009

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This study proposes a mode-selective circuit to suppress the competing modes in a TE01 gyrotron backward-wave oscillator (gyro-BWO). The circuit, also functioning as an interaction structure, comprises of several transverse slices. It eliminates the restrictions of the mode competitions and allows a longer interaction structure to optimize interacting efficiency. Mode-selective effect will be analyzed. Experimental results indicate that the Ka-band TE01 fundamental harmonic gyro-BWO is capable of continuous tuning from 31.4 to 36.4 GHz with a peak efficiency of 23.7%, corresponding to 100 kW at Ib = 4.5 A and Vb = 93.6 kV.
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84.40.Dc Microwave circuits
84.40.Fe Microwave tubes (e.g., klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.)
84.40.Ik Masers; gyrotrons (cyclotron-resonance masers)

Strong terahertz radiation from air plasmas generated by an aperture-limited Gaussian pump laser beam

Xiao-Yu Peng, Chun Li, Min Chen, Toma Toncian, Ralph Jung, Oswald Willi, Yu-Tong Li, Wei-Min Wang, Shou-Jun Wang, Feng Liu, Alexander Pukhov, Zheng-Ming Sheng, and Jie Zhang

Appl. Phys. Lett. 94, 101502 (2009); http://dx.doi.org/10.1063/1.3098357 (3 pages) | Cited 9 times

Online Publication Date: 12 March 2009

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Terahertz radiation generated by focusing the fundamental laser pulse and its second harmonic into ambient air strongly saturates with increasing pump laser energy. We demonstrate a simple method to control the Gaussian pump laser beam to improve the output of terahertz radiation with an adjustable aperture. With the optimal aperture-limited pump laser beams, the terahertz wave amplitudes can be enhanced by more than eight times depending on the pump laser parameters than those of aperture-free cases.
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52.25.Os Emission, absorption, and scattering of electromagnetic radiation
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.59.-f Intense particle beams and radiation sources

Directional ion emission from thin films under femtosecond laser irradiation

Gareth O. Williams, Sébastian Favre, and Gerard M. O’Connor

Appl. Phys. Lett. 94, 101503 (2009); http://dx.doi.org/10.1063/1.3095851 (3 pages) | Cited 3 times

Online Publication Date: 12 March 2009

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Thin films of nickel have been irradiated using femtosecond laser pulses in vacuum. Subsequent emission of plasma ions is diagnosed using an ion probe. Angular distributions of the emitted ions are presented for a range of target film thicknesses. Data are compared to the Anisimov model of plasma expansion [ S. I. Anisimov, D. Bauerle, and B. S. Luk’yanchuk, Phys. Rev. B 48, 12076 (1993) ]. The tendency of the ions to be ejected at small angles to the normal of the target surface is explained in terms of the initial conditions of the plume. Results are explained in terms of the initial shape and adiabatic index of the plasma.
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52.25.Tx Emission, absorption, and scattering of particles
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
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Colossal photostructural changes in chalcogenide glasses: Athermal photoinduced polymerization in AsxS100−x bulk glasses revealed by near-bandgap Raman scattering

F. Kyriazis and S. N. Yannopoulos

Appl. Phys. Lett. 94, 101901 (2009); http://dx.doi.org/10.1063/1.3095849 (3 pages) | Cited 8 times

Online Publication Date: 9 March 2009

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Near-bandgap Raman scattering was used to induce and study photostructural changes in AsxS100−x bulk glasses (5 ≤ xAs ≤ 40) revealing a new photoinduced polymerization effect. Raman spectra were recorded also in off-resonant conditions allowing for a detailed comparison between the “equilibrium” glass structure and the metastable one induced by illumination. It is shown that in S-rich glasses, structural changes involve the athermal scission of S8 rings and their polymerization to Sn chains. The fraction of bonds involved in this effect is surprisingly high, being one order of magnitude higher than the corresponding fractions reported up to now in photostructural studies in chalcogenide glasses.
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61.43.Fs Glasses
78.35.+c Brillouin and Rayleigh scattering; other light scattering
82.50.-m Photochemistry
82.35.-x Polymers: properties; reactions; polymerization

Phase stability of cubic Mg0.55Zn0.45O thin film studied by continuous thermal annealing method

Z. G. Ju, C. X. Shan, C. L. Yang, J. Y. Zhang, B. Yao, D. X. Zhao, D. Z. Shen, and X. W. Fan

Appl. Phys. Lett. 94, 101902 (2009); http://dx.doi.org/10.1063/1.3097022 (3 pages) | Cited 3 times

Online Publication Date: 9 March 2009

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The phase stability of cubic Mg0.55Zn0.45O thin film grown by metal-organic chemical vapor deposition was studied through continuous thermal annealing. The crystal quality and surface smoothness were greatly improved after a continuous thermal annealing at 750 °C. It is attributed to the reducing of interstitial Zn by thermal annealing. However, phase segregation occurred when the sample was annealed at a higher temperature (850 °C), which is identified from both x-ray diffraction patterns and optical transmission spectra.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.40.Gh Other heat and thermomechanical treatments
78.66.Hf II-VI semiconductors
68.55.ag Semiconductors
64.75.Qr Phase separation and segregation in semiconductors
81.05.Dz II-VI semiconductors

Vibrational modes of Timoshenko beams at small scales

Xian-Fang Li and Bao-Lin Wang

Appl. Phys. Lett. 94, 101903 (2009); http://dx.doi.org/10.1063/1.3094130 (3 pages) | Cited 20 times

Online Publication Date: 10 March 2009

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This letter presents a theoretical treatment of Timoshenko [ S. Timoshenko, Philos. Mag. 41, 744 (1921) ] beams, in which the influences of shear deformation, rotary inertia, and scale coefficient are taken into account. Based on the nonlocal elasticity theory, coupled equations for transverse deflection and rotation of cross section are derived. Free vibration of several typical beams is analyzed. Explicit expressions for modal shapes of vibration are presented. Natural frequencies are evaluated for free vibration of simply supported beams, clamped beams, cantilever beams, and clamped-hinged beams. The effects of the nonlocal parameter on natural frequencies and modal shapes are discussed in detail.
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46.70.De Beams, plates, and shells
46.40.-f Vibrations and mechanical waves
46.25.Cc Theoretical studies
46.35.+z Viscoelasticity, plasticity, viscoplasticity

Edge elastic properties of defect-free single-layer graphene sheets

C. D. Reddy, A. Ramasubramaniam, V. B. Shenoy, and Yong-Wei Zhang

Appl. Phys. Lett. 94, 101904 (2009); http://dx.doi.org/10.1063/1.3094878 (3 pages) | Cited 20 times

Online Publication Date: 10 March 2009

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An energetic model is proposed to describe the edge elastic properties of defect-free single-layer graphene sheets. Simulations with the adaptive intermolecular reactive empirical bond order potential are used to extract the edge stress and edge moduli for different edges structures, namely, zigzag and armchair edges, zigzag and armchair edges terminated with hydrogen, and reconstructed zigzag and armchair edges. It is found that the properties of graphene are sensitively dependent on the edge structures; armchair and zigzag edges with and without hydrogen termination are in compression, while reconstructed edges are in tension.
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81.40.Jj Elasticity and anelasticity, stress-strain relations
62.25.-g Mechanical properties of nanoscale systems
61.46.-w Structure of nanoscale materials
62.20.D- Elasticity

Observation of ultraviolet emission and effect of surface states on the luminescence from tin oxide nanowires

Ayan Kar, Michael A. Stroscio, Mitra Dutta, Jyoti Kumari, and M. Meyyappan

Appl. Phys. Lett. 94, 101905 (2009); http://dx.doi.org/10.1063/1.3097011 (3 pages) | Cited 17 times

Online Publication Date: 10 March 2009

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Ultraviolet (UV) and orange emissions have been observed from vapor-liquid-solid grown SnO2 nanowires. From the luminescence, the donor and acceptor binding energies have been estimated. The dependence of the orange luminescence on the diameters of tin oxide nanowires has been observed and the wavelength of the UV luminescence is found to depend on the laser power. Both the shift in the UV and the intensity of the orange luminescence is found to be dependent on the surface states of the tin oxide nanowires.
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78.55.Hx Other solid inorganic materials
73.21.Hb Quantum wires
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Thermal conductivities and phase transition temperatures of various phase-change materials measured by the 3ω method

W. P. Risk, C. T. Rettner, and S. Raoux

Appl. Phys. Lett. 94, 101906 (2009); http://dx.doi.org/10.1063/1.3097353 (3 pages) | Cited 14 times

Online Publication Date: 11 March 2009

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We have employed the “3ω method” to determine the thermal conductivities of the amorphous and crystalline phases of the technologically important materials Ge2Sb2Te5, nitrogen-doped Ge2Sb2Te5, Ag- and In-doped Sb2Te, and Ge15Sb85. We used the “3ω voltage” as a monitor of thermal conductivity that allowed us to observe the amorphous-to-crystalline phase transition as the material was annealed. For these materials, our results reveal that the thermal conductivity κ is related to the electrical conductivity σ by an empirical relationship of the form κ = σLT+0.175 W/m K, where L is the Lorenz number and T is temperature.
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64.70.K- Solid-solid transitions
73.61.Ng Insulators
66.70.Lm Other systems such as ionic crystals, molecular crystals, nanotubes, etc.

Effect of the miscut direction in (111) 3C-SiC film growth on off-axis (111)Si

A. Severino, M. Camarda, G. Condorelli, L. M. S. Perdicaro, R. Anzalone, M. Mauceri, A. La Magna, and F. La Via

Appl. Phys. Lett. 94, 101907 (2009); http://dx.doi.org/10.1063/1.3085769 (3 pages) | Cited 5 times

Online Publication Date: 11 March 2009

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Two miscut directions of (111) Si substrate on 3C-SiC heteroepitaxial growth have been studied with the resulting 3C-SiC stress and defects as a function of miscut axis direction toward [110] and [112] of (111) Si analyzed. We studied this dependency from an experimental point of view, investigating the structural properties of 3C-SiC, and using a kinetic Monte Carlo method on superlattice to confirm our experimental findings with numerical simulations. Residual stress and stacking fault density were halved by growing on a (111) Si substrate off-cut toward the [110] direction. A different surface morphology was revealed between the two inclinations.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.de Elastic moduli
68.55.ag Semiconductors
68.60.Bs Mechanical and acoustical properties
68.35.bg Semiconductors
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