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15 Nov 2010

Volume 97, Issue 20, Articles (20xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 97, 203101 (2010); http://dx.doi.org/10.1063/1.3495773 (3 pages)

Chi-Cheng Fu, Giulia Ossato, Maureen Long, Michelle A. Digman, Ajay Gopinathan, Luke P. Lee, Enrico Gratton, and Michelle Khine
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Generation of compact radially polarized beam at 850 nm in vertical-cavity surface-emitting laser via plasmonic modulation

Likang Cai, Jing Zhang, Wenli Bai, Qing Wang, Xin Wei, and Guofeng Song

Appl. Phys. Lett. 97, 201101 (2010); http://dx.doi.org/10.1063/1.3518065 (3 pages) | Cited 2 times

Online Publication Date: 15 November 2010

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We propose a convenient approach for generating compact radially polarized laser beam by integrating concentric gold rings on the surface of a vertical-cavity surface-emitting laser. Due to the polarization selection of the surface plasmon polariton mode excited by the gold rings, a radially polarized beam at 850 nm is experimentally demonstrated. The physical mechanisms of the generation are numerically and analytically analyzed by employing finite-difference time-domain method and metal-insulator-metal plasmonic waveguide theory.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.60.Fc Modulation, tuning, and mode locking

Femtosecond laser-ultrasonic investigation of plasmonic fields on the metal/gallium nitride interface

Hung-Pin Chen, Yu-Chieh Wen, Yi-Hsin Chen, Cheng-Hua Tsai, Kuang-Li Lee, Pei-Kuen Wei, Jinn-Kong Sheu, and Chi-Kuang Sun

Appl. Phys. Lett. 97, 201102 (2010); http://dx.doi.org/10.1063/1.3503633 (3 pages) | Cited 1 time

Online Publication Date: 15 November 2010

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By using femtosecond laser-ultrasonic, we demonstrate an approach to study the surface plasmon field optically excited in the interface between metal and a semiconductor thin film. By femtosecond impulsive excitation on gallium–nitride (GaN), different optical probe signals were observed when the impulse-excited nanoacoustic pulse propagated through the metal film and metal nanoslits. By analyzing the shape and temporal response of thus induced acousto-optical signals, our femtosecond laser-ultrasonic study not only reveals the plasmonic field distribution optically excited in the metal/substrate interface but also confirms that the penetration depth of surface plasmon field into the substrate agrees well with a simulation result.
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68.35.Iv Acoustical properties
62.65.+k Acoustical properties of solids
78.66.Bz Metals and metallic alloys
73.22.Lp Collective excitations
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects

Effects of random link removal on the photonic band gaps of honeycomb networks

Marian Florescu, Salvatore Torquato, and Paul J. Steinhardt

Appl. Phys. Lett. 97, 201103 (2010); http://dx.doi.org/10.1063/1.3505322 (3 pages)

Online Publication Date: 16 November 2010

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We explore the effects of random link removal on the photonic band gaps of honeycomb networks. Missing or incomplete links are expected to be common in practical realizations of this class of connected network structures due to unavoidable flaws in the fabrication process. We focus on the collapse of the photonic band gap due to the defects induced by the link removal. We show that the photonic band gap is quite robust against this type of random decimation and survives even when almost 58% of the network links are removed.
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42.70.Qs Photonic bandgap materials
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Intersubband photoluminescence in InAs quantum wells

R. Kaspi, M. L. Tilton, G. C. Dente, R. Barresi, C. Yang, and A. P. Ongstad

Appl. Phys. Lett. 97, 201104 (2010); http://dx.doi.org/10.1063/1.3516041 (3 pages)

Online Publication Date: 17 November 2010

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We conduct a study of photoluminescence in a series of InAs quantum wells with asymmetric barriers that are designed to generate emission from intersubband transitions near 4 μm wavelength. The results show that optical pumping of the barrier layers can be used to transfer carriers into the upper electron state in the InAs wells to produce photoluminescence.
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81.07.St Quantum wells
78.67.De Quantum wells
73.63.Hs Quantum wells
81.05.Ea III-V semiconductors
78.55.Cr III-V semiconductors
72.20.Fr Low-field transport and mobility; piezoresistance

Demonstration of long-range surface plasmon-polariton waveguide sensors with asymmetric double-electrode structures

Yang Hyun Joo, Seok Ho Song, and Robert Magnusson

Appl. Phys. Lett. 97, 201105 (2010); http://dx.doi.org/10.1063/1.3513283 (3 pages) | Cited 2 times

Online Publication Date: 18 November 2010

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We demonstrate a long-range surface plasmon-polaritons (LRSPP) refractive-index sensor using an asymmetric double-electrode LRSPP waveguide configuration. The LRSPP sensor is inherently self-referencing by virtue of two Bragg wavelengths in the transmission spectrum generated by a Bragg grating. The measured sensitivity is about 130 nm/RIU and 27 pm/K, which means a sensing resolution of ∼ 10−6 RIU and a temperature determination with an inaccuracy of 0.04 K under measurement accuracy of the Bragg wavelength of 1 pm. The sensor dimensions of 1.95 mm in total length and submicrometer in fluidic-channel thickness may be desirable for highly integrated sensors based on LRSPP.
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42.82.Et Waveguides, couplers, and arrays
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
42.79.Gn Optical waveguides and couplers
42.79.Dj Gratings
47.85.Np Fluidics

Control of excitons by laterally modulated electrode density

Y. Y. Kuznetsova, A. A. High, and L. V. Butov

Appl. Phys. Lett. 97, 201106 (2010); http://dx.doi.org/10.1063/1.3517444 (3 pages) | Cited 2 times

Online Publication Date: 18 November 2010

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We propose a method for the realization of in-plane potential landscapes for excitons by the lateral modulation of the electrode density and present traps created using this method.
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71.35.-y Excitons and related phenomena
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
82.45.-h Electrochemistry and electrophoresis

Determination of optimum Si excess concentration in Er-doped Si-rich SiO2 for optical amplification at 1.54 μm

Oleksandr Savchyn, Kevin R. Coffey, and Pieter G. Kik

Appl. Phys. Lett. 97, 201107 (2010); http://dx.doi.org/10.1063/1.3518476 (3 pages)

Online Publication Date: 18 November 2010

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The presence of indirect Er3+ excitation in Si-rich SiO2 is demonstrated for Si-excess concentrations in the range of 2.5–37 at. %. The Si excess concentration providing the highest density of sensitized Er3+ ions is demonstrated to be relatively insensitive to the presence of Si nanocrystals and is found to be ∼ 14.5 at. % for samples without Si nanocrystals (annealed at 600 °C) and ∼ 11.5 at. % for samples with Si nanocrystals (annealed at 1100 °C). The observed optimum is attributed to an increase in the density of Si-related sensitizers as the Si concentration is increased, with subsequent deactivation and removal of these sensitizers at high Si concentrations. The optimized Si excess concentration is predicted to generate maximum Er-related gain at 1.54 μm in devices based on Er-doped Si-rich SiO2.
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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)
78.55.Hx Other solid inorganic materials
78.66.Nk Insulators
81.40.Gh Other heat and thermomechanical treatments
81.15.Cd Deposition by sputtering

Pulsed laser deposition of graphite counter electrodes for dye-sensitized solar cells

Krishna P. Acharya, Himal Khatri, Sylvain Marsillac, Bruno Ullrich, Pavel Anzenbacher, and Mikhail Zamkov

Appl. Phys. Lett. 97, 201108 (2010); http://dx.doi.org/10.1063/1.3518481 (3 pages) | Cited 2 times

Online Publication Date: 18 November 2010

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We report on pulsed laser deposition of graphite onto flexible plastic and conductive glass substrates for use as a counter electrode in dye-sensitized solar cells. The efficiency of as-prepared graphite electrodes was tested using CdS-sensitized solar cell architecture resulting in external quantum efficiency comparable to that of conventional platinum counter electrodes. This work highlights the possibility of using pulsed laser deposited graphite as a low-cost alternative to platinum, which could be fabricated both on flexible and rigid substrates.
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81.15.Fg Pulsed laser ablation deposition
81.05.uf Graphite
68.55.-a Thin film structure and morphology
68.60.-p Physical properties of thin films, nonelectronic
82.45.-h Electrochemistry and electrophoresis

Extremely high T0-values ( ∼ 450 K) of long-wavelength ( ∼ 15 μm), low-threshold-current-density quantum-cascade lasers based on the indirect pump scheme

Kazuue Fujita, Masamichi Yamanishi, Tadataka Edamura, Atsushi Sugiyama, and Shinichi Furuta

Appl. Phys. Lett. 97, 201109 (2010); http://dx.doi.org/10.1063/1.3518487 (3 pages) | Cited 5 times

Online Publication Date: 18 November 2010

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The high device performance of a long-wavelength ( ∼ 15 μm), InGaAs/InAlAs, Fabry–Pérot quantum-cascade laser based on the indirect pump scheme is reported. As a result of felicitous designing of the active region and waveguide structure, a low threshold-current-density of ∼ 3.5 kA/cm2, a high maximum output power of ∼ 216 mW, and a high slope efficiency of ∼ 346 mW/A, all at room temperature are obtained. The observed extremely high characteristic temperature of threshold current, T0 ∼ 450 K over wide temperature range, 320–380 K is ascribed to a strong suppression of electron populations in injectors, which are specifically visualized in the indirect pump scheme.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Improved sensitivity of terahertz detection by GaAs photoconductive antennas excited at 1560 nm

T. Kataoka, K. Kajikawa, J. Kitagawa, Y. Kadoya, and Y. Takemura

Appl. Phys. Lett. 97, 201110 (2010); http://dx.doi.org/10.1063/1.3519480 (3 pages)

Online Publication Date: 19 November 2010

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The terahertz detection by photoconductive antennas (PCAs) based on low-temperature grown (LTG) GaAs with 1.5 μm pulse excitation was revisited. We found that the detection efficiency can be improved by a factor of 10 (20 dB) by reducing the excitation spot size and the gap length of the PCA, maintaining the low noise feature of the PCA on LTG GaAs. As a result, the signal-to-noise ratio higher than 50 dB was obtained at a reasonable incident power of 9.5 mW, suggesting that the scheme is promising for the detection of terahertz waves in practical time domain systems.
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84.40.Ba Antennas: theory, components and accessories

Stimulated emission of terahertz radiation by exciton-polariton lasers

K. V. Kavokin, M. A. Kaliteevski, R. A. Abram, A. V. Kavokin, S. Sharkova, and I. A. Shelykh

Appl. Phys. Lett. 97, 201111 (2010); http://dx.doi.org/10.1063/1.3519978 (3 pages)

Online Publication Date: 19 November 2010

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We show that planar semiconductor microcavities in the strong coupling regime can be used as sources of stimulated terahertz radiation. Emitted terahertz photons would have a frequency equal to the splitting of the cavity polariton modes. The optical transition between upper and lower polariton branches is allowed due to mixing of the upper polariton state with one of the excited exciton states and is stimulated in the polariton laser regime.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Sa Microcavity and microdisk lasers
42.60.By Design of specific laser systems
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
71.35.-y Excitons and related phenomena
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Understanding efficiency droop effect in InGaN/GaN multiple-quantum-well blue light-emitting diodes with different degree of carrier localization

Jiaxing Wang, Lai Wang, Wei Zhao, Zhibiao Hao, and Yi Luo

Appl. Phys. Lett. 97, 201112 (2010); http://dx.doi.org/10.1063/1.3520139 (3 pages) | Cited 9 times

Online Publication Date: 19 November 2010

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Two light-emitting diode samples are grown with InGaN and GaN underlying layers beneath the multiple quantum wells (MQWs), respectively. By measuring the carrier lifetime as a function of photon energy, it is found that the MQW with InGaN underlying layer has a higher degree of carrier localization. Comparison between the external quantum efficiency and injection current of these two samples reveals that efficiency droop at small injection current is attributed to the delocalization of carriers, while further droop at a higher injection current is due mostly to the carrier leakage demonstrated through temperature-dependent electroluminescence measurements.
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85.60.Jb Light-emitting devices
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.60.Fi Electroluminescence
78.67.De Quantum wells
73.63.Hs Quantum wells

Magnetically controllable unidirectional electromagnetic waveguiding devices designed with metamaterials

Shiyang Liu, Wanli Lu, Zhifang Lin, and S. T. Chui

Appl. Phys. Lett. 97, 201113 (2010); http://dx.doi.org/10.1063/1.3520141 (3 pages) | Cited 3 times

Online Publication Date: 19 November 2010

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We demonstrate a sharply asymmetric reflection in a geometrically symmetric magnetic metamaterial (MM) system, which originates from the coupling of electromagnetic (EM) wave to magnetic surface plasmon resonance states and the broken time reversal symmetry in MM. Based on this effect, we have designed unidirectional EM waveguide, wave bender, and beam splitter. Our simulations indicate that the designs possess the merits of robustness against strong defect and disorder, controllability with an external magnetic field, in addition to the finite working bandwidth and the high transmission efficiency.
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84.40.Az Waveguides, transmission lines, striplines
42.79.Fm Reflectors, beam splitters, and deflectors
41.20.Jb Electromagnetic wave propagation; radiowave propagation
85.80.-b Thermoelectromagnetic and other devices
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Quenching of NO(A 2Σ+) state in a nonequilibrium air plasma

D. Studer, P. Boubert, and P. Vervisch

Appl. Phys. Lett. 97, 201501 (2010); http://dx.doi.org/10.1063/1.3514250 (3 pages)

Online Publication Date: 17 November 2010

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An unexpectedly high quenching rate (2×109 s−1) of NO(A 2Σ+) state has been measured during laser-induced fluorescence measurements of NO densities carried out using a broadband KrF laser in an inductively coupled nonequilibrium air plasma at moderate pressure (38 hPa) and translational temperatures (2500–3000 K). Many assumptions may be made to explain such a high quenching rate but most fail. The quenching species is identified as being produced during the laser pulse but remains unknown in spite of thorough investigations.
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52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.38.Bv Rayleigh scattering; stimulated Brillouin and Raman scattering
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Density effect on relativistic electron beams in a plasma fiber

C. T. Zhou, X. G. Wang, S. Z. Wu, H. B. Cai, F. Wang, and X. T. He

Appl. Phys. Lett. 97, 201502 (2010); http://dx.doi.org/10.1063/1.3518720 (3 pages) | Cited 2 times

Online Publication Date: 18 November 2010

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Intense short-petawatt-laser driven relativistic electron beams in a hollow high-Z plasma fiber embedded in low-Z plasmas of different densities are studied. When the plasma is of lower density than the hollow fiber, resistive filamentation of the electron beam is observed. It is found that the electron motion and the magnetic field are highly correlated with tens of terahertz oscillation frequency. Depending on the material property around the hollow fiber and the plasma density, the beam electrons can be focused or defocused as it propagates in the plasma. Relativistic electron transport and target heating are also investigated.
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52.50.Gj Plasma heating by particle beams
52.65.Rr Particle-in-cell method
52.38.-r Laser-plasma interactions
52.25.-b Plasma properties

Role of hydrogen in evolution of plasma parameters and dust growth in capacitively coupled dusty plasmas

K. B. Chai, Wonho Choe, C. R. Seon, and C. W. Chung

Appl. Phys. Lett. 97, 201503 (2010); http://dx.doi.org/10.1063/1.3518722 (3 pages) | Cited 1 time

Online Publication Date: 18 November 2010

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The temporal behavior of naturally produced dust parameters (radius and density) and plasma parameters (electron temperature and ion flux) was investigated in radio frequency SiH4/H2/Ar plasmas. As a result, the electron temperature and ion flux were shown to be strongly correlated with the three-step dust growth pattern. In addition, the generation of dust particles was suppressed by mixing more hydrogen gas due to the plasma chemistry, and consequently, the dust growth rate in the molecular accretion growth, which is known to be proportional to the growth rate of thin film deposition, increased.
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52.27.Lw Dusty or complex plasmas; plasma crystals
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
52.80.Pi High-frequency and RF discharges
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Transcription of domain patterns in near-stoichiometric magnesium-doped lithium niobate

Hao Zeng, Yongfa Kong, Tian Tian, Shaolin Chen, Ling Zhang, Tongqing Sun, Romano Rupp, and Jingjun Xu

Appl. Phys. Lett. 97, 201901 (2010); http://dx.doi.org/10.1063/1.3518474 (3 pages)

Online Publication Date: 17 November 2010

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Recently, light-induced domain reversal has been developed to a promising method for domain engineering, but the depth of reversed domain is only of several tens of microns, which greatly limits its practical applications. In this Letter, we fabricated domain patterns on the –z face of 1.0 mol % Mg doped near-stoichiometric lithium niobate with the assistance of a focal 532 nm laser, and then succeeded to transcribe these domain patterns from the –z to the +z face by applying external field without laser illumination. The transcribed domains have much larger depths, can sustain more than 100 times of the transcription cycles without large deformation, and can be erased by one transcription cycle with illumination of 532 nm laser. Finally, a light-induced ferroelectric domain transcription model was proposed.
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77.80.Dj Domain structure; hysteresis
77.84.Ek Niobates and tantalates
61.66.Bi Elemental solids
61.66.Dk Alloys
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Point-defect-mediated dehydrogenation of AlH3

Lars Ismer, Anderson Janotti, and Chris G. Van de Walle

Appl. Phys. Lett. 97, 201902 (2010); http://dx.doi.org/10.1063/1.3518475 (3 pages)

Online Publication Date: 17 November 2010

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Based on hybrid density functional calculations, we propose a microscopic mechanism for the dehydrogenation of AlH3. Our results indicate that mass transport mediated by positively charged hydrogen vacancies (VH+) is likely the rate-limiting mechanism. The calculated activation energy of 1.72 eV is in good agreement with experimental values. The high formation energy and hence low concentration of VH+ explains why AlH3 does not decompose at room temperature, although it is thermodynamically unstable. Issues of maintaining charge neutrality are addressed.
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71.55.Ht Other nonmetals
82.60.Cx Enthalpies of combustion, reaction, and formation
81.05.Hd Other semiconductors
61.66.Fn Inorganic compounds
61.72.jd Vacancies

Effect of nitrogen on the GaAs0.9−xNxSb0.1 dielectric function from the near-infrared to the ultraviolet

N. Ben Sedrine, C. Bouhafs, J. C. Harmand, R. Chtourou, and V. Darakchieva

Appl. Phys. Lett. 97, 201903 (2010); http://dx.doi.org/10.1063/1.3518479 (3 pages)

Online Publication Date: 17 November 2010

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We study the effect of nitrogen on the GaAs0.9−xNxSb0.1 (x = 0.00, 0.65%, 1.06%, 1.45%, and 1.90%) alloy dielectric function by spectroscopic ellipsometry in the energy range from 0.73 to 4.75 eV. The compositional dependences of the critical points energies for the GaAs0.9−xNxSb0.1 are obtained. In addition to the GaAs intrinsic transitions E1, E1+Δ1, and E0′, the nitrogen-induced Γ-point optical transitions E0 and E+, together with a third transition E#, are identified. We find that with increasing the N content, the E0 transition shifts to lower energies while the E+ and E# transitions shift to higher energies. We suggest that the origin of the E0, E+, and E# transitions may be explained by the double band anticrossing (BAC) model, consisting of a conduction BAC model and a valence BAC model.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.40.Fy Semiconductors
71.55.Eq III-V semiconductors
81.05.Ea III-V semiconductors
78.30.Fs III-V and II-VI semiconductors

Major impacts of point defects and impurities on the carrier recombination dynamics in AlN

S. F. Chichibu, T. Onuma, K. Hazu, and A. Uedono

Appl. Phys. Lett. 97, 201904 (2010); http://dx.doi.org/10.1063/1.3517484 (3 pages) | Cited 11 times

Online Publication Date: 17 November 2010

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Impacts of point defects and impurities on the carrier recombination dynamics in AlN are revealed by time-resolved spectroscopy and positron annihilation measurements. Intrinsically short low-temperature excitonic radiative lifetime (τR ∼ 10 ps) was elongated with the increase in Al-vacancy concentration up to 530 ps, irrespective of threading dislocation density. A continuous decrease in τR with temperature rise up to 200 K for heavily doped samples revealed the carrier release from the band-tail formed due to impurities and point defects. Because room-temperature nonradiative lifetime was equally short for all samples, high temperature growth with appropriate defect management is necessary in extracting radiative nature of AlN.
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73.61.Ey III-V semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
61.72.jd Vacancies
78.47.jd Time resolved luminescence

Structure of few-layer epitaxial graphene on 6H-SiC(0001) at atomic resolution

Xiaojun Weng, Joshua A. Robinson, Kathleen Trumbull, Randall Cavalero, Mark A. Fanton, and David Snyder

Appl. Phys. Lett. 97, 201905 (2010); http://dx.doi.org/10.1063/1.3517505 (3 pages) | Cited 3 times

Online Publication Date: 17 November 2010

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Using directly interpretable atomic-resolution cross-sectional scanning transmission electron microscopy, we have investigated the structure of few-layer epitaxial graphene (EG) on 6H-SiC(0001). We show that the buried interface layer possesses a lower average areal density of carbon atoms than graphene, indicating that it is not a graphenelike sheet with the 6math×6mathR30° structure. The EG interlayer spacings are found to be considerably larger than that of the bulk graphite and the surface of the SiC(0001) substrate, often treated as relaxed, is found to be strained. Discontinuity of the graphene layers above the SiC surface steps is observed, in contradiction with the commonly believed continuous coverage.
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68.55.ap Fullerenes
73.61.Cw Elemental semiconductors
81.05.Cy Elemental semiconductors
68.35.Ct Interface structure and roughness
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.47.Fg Semiconductor surfaces

Optically generated adaptive localized structures in confined chiral liquid crystals doped with fullerene

O. Trushkevych, P. Ackerman, W. A. Crossland, and I. I. Smalyukh

Appl. Phys. Lett. 97, 201906 (2010); http://dx.doi.org/10.1063/1.3518477 (3 pages)

Online Publication Date: 18 November 2010

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We report the facile optical creation of switchable localized structures in chiral liquid crystals doped with fullerene. In a cholesteric cell unwound by vertical boundary conditions, the initially dispersed fullerenes are deposited from the bulk to the surface of confining glass plates by low-intensity illumination. This alters the surface boundary conditions and allows for the creation of localized particlelike structures with twist-bound defects (dubbed Torons) that are controlled by electric fields and arranged into patterns of interest for photonic and electro-optic applications.
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61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures
61.30.Jf Defects in liquid crystals
82.70.-y Disperse systems; complex fluids

Impact of surfaces on the optical properties of GaAs nanowires

O. Demichel, M. Heiss, J. Bleuse, H. Mariette, and A. Fontcuberta i Morral

Appl. Phys. Lett. 97, 201907 (2010); http://dx.doi.org/10.1063/1.3519980 (3 pages) | Cited 17 times

Online Publication Date: 19 November 2010

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The effect of surfaces on the optical properties of GaAs nanowires is evidenced by comparing nanowires with or without an AlGaAs capping shell as a function of the diameter. We find that the optical properties of unpassivated nanowires are governed by Fermi-level pinning, whereas, the optical properties of passivated nanowires are mainly governed by surface recombinations. Finally, we measure a surface recombination velocity of 3×103 cm s−1 one order of magnitude lower than values previously reported for {110} GaAs surfaces. These results will serve as guidance for the application of nanowires in solar cell and light emitting devices.
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78.67.Lt Quantum wires
78.55.Cr III-V semiconductors
68.65.La Quantum wires (patterned in quantum wells)
61.46.Km Structure of nanowires and nanorods (long, free or loosely attached, quantum wires and quantum rods, but not gate-isolated embedded quantum wires)
81.65.Rv Passivation
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Direct growth of InAsP/InP quantum well heterostructures on Si using crystalline SrTiO3/Si templates

B. Gobaut, J. Penuelas, J. Cheng, A. Chettaoui, L. Largeau, G. Hollinger, and G. Saint-Girons

Appl. Phys. Lett. 97, 201908 (2010); http://dx.doi.org/10.1063/1.3520143 (3 pages) | Cited 1 time

Online Publication Date: 19 November 2010

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Integrating III-V semiconductors on Si is one of the major challenges of epitaxial growth and presents important applicative interest. We describe here an approach based on the use of crystalline SrTiO3 (STO)/Si templates. The structural and optical properties of InAsP/InP quantum well heterostructures grown directly on Si and on STO/Si templates are compared. Using STO/Si templates strongly improves the structural properties of the III-V heterostructure, and allows observing room-temperature photoluminescence from the quantum well.
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81.05.Ea III-V semiconductors
81.07.St Quantum wells
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.67.De Quantum wells
78.55.Cr III-V semiconductors
68.65.Fg Quantum wells
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Magnetic and electronic switching properties of photochromic diarylethene with two nitronyl nitroxides

L. Zhu, K. L. Yao, and Z. L. Liu

Appl. Phys. Lett. 97, 202101 (2010); http://dx.doi.org/10.1063/1.3515420 (3 pages)

Online Publication Date: 15 November 2010

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Magnetic and electronic switching properties of single photochromic diarylethene with two nitronyl nitroxides sandwiched between two gold surfaces for closed and open configurations were investigated theoretically. Apart from the negative magnetoresistance effect in closed configuration, the negative differential resistance behavior in parallel state is also attained, which are potential for electronic applications. In addition, when using Br and H to substitute F atoms in the peripheral of cyclopentene, the on-off ratios are much smaller than that of the F-ligand one.
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72.25.-b Spin polarized transport
75.76.+j Spin transport effects
72.20.My Galvanomagnetic and other magnetotransport effects
75.47.-m Magnetotransport phenomena; materials for magnetotransport
75.50.Xx Molecular magnets
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