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5 Sep 2011

Volume 99, Issue 10, Articles (10xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 99, 103701 (2011); http://dx.doi.org/10.1063/1.3633066 (3 pages)

Yinan Zhang, David J. S. Birch, and Yu Chen
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Phase retrieval and compression of low-power white-light pulses

D. Wegkamp, D. Brida, S. Bonora, G. Cerullo, J. Stähler, M. Wolf, and S. Wall

Appl. Phys. Lett. 99, 101101 (2011); http://dx.doi.org/10.1063/1.3635396 (3 pages) | Cited 2 times

Online Publication Date: 6 September 2011

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We characterize and compress sub-nJ visible white-light continuum (WLC) pulses generated by self-phase modulation in yttrium aluminium garnet. The spectral phase is retrieved by spectrally resolving the transient reflectivity from an optically excited transition metal oxide. This measured phase is compensated by applying the appropriate distortion to a deformable mirror. By comparing the response of two different materials, we show that the white-light pulses can be compressed to approximately 10 fs duration.
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42.60.Fc Modulation, tuning, and mode locking
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.79.Bh Lenses, prisms and mirrors

A tunable colloidal quantum dot photo field-effect transistor

Subir Ghosh, Sjoerd Hoogland, Vlad Sukhovatkin, Larissa Levina, and Edward H. Sargent

Appl. Phys. Lett. 99, 101102 (2011); http://dx.doi.org/10.1063/1.3636438 (3 pages) | Cited 3 times

Online Publication Date: 6 September 2011

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We fabricate and investigate field-effect transistors in which a light-absorbing photogate modulates the flow of current along the channel. The photogate consists of colloidal quantum dots that efficiently transfer photoelectrons to the channel across a charge-separating (type-II) heterointerface, producing a primary and sustained secondary flow that is terminated via electron back-recombination across the interface. We explore colloidal quantum dot sizes corresponding to bandgaps ranging from 730 to 1475 nm and also investigate various stoichiometries of aluminum-doped ZnO (AZO) channel materials. We investigate the role of trap state energies in both the colloidal quantum dot energy film and the AZO channel.
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85.30.Tv Field effect devices
85.60.Dw Photodiodes; phototransistors; photoresistors

Spatial, spectral, and polarization properties of coupled micropillar cavities

S. Michaelis de Vasconcellos, A. Calvar, A. Dousse, J. Suffczyński, N. Dupuis, A. Lemaître, I. Sagnes, J. Bloch, P. Voisin, and P. Senellart

Appl. Phys. Lett. 99, 101103 (2011); http://dx.doi.org/10.1063/1.3632111 (3 pages) | Cited 8 times

Online Publication Date: 6 September 2011

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We report on an experimental and numerical study of the spatial and spectral properties of the optical modes in coupled pillar microcavities. Highly efficient photon blockade or bright sources of entangled photon pairs can be implemented by coupling a single quantum emitter to coupled cavities. Parameters for optimal coupling with a single quantum emitter are identified. Polarization properties, which are critical for both applications, are finally discussed. We show that an extremely small polarization splitting is obtained for the first modes in a wide range of parameters.
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42.79.Bh Lenses, prisms and mirrors
78.67.Hc Quantum dots
03.67.Mn Entanglement measures, witnesses, and other characterizations
42.50.Pq Cavity quantum electrodynamics; micromasers
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

High-efficiency graded band-gap AlxGa1−xAs/GaAs photocathodes grown by metalorganic chemical vapor deposition

Yijun Zhang, Benkang Chang, Jun Niu, Jing Zhao, Jijun Zou, Feng Shi, and Hongchang Cheng

Appl. Phys. Lett. 99, 101104 (2011); http://dx.doi.org/10.1063/1.3635401 (3 pages)

Online Publication Date: 7 September 2011

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To enhance the quantum efficiency over the wavelength region of interest, a special graded band-gap structure applied to the AlGaAs/GaAs photocathodes is developed, in which the compositional grade in the AlxGa1−xAs layer is associated with the doping grade in the GaAs layer. The experimental results show that this unique structure can be achieved by the metalorganic chemical vapor deposition technique. As a result of the built-in electric fields arising from the graded band-gap structure, the quantum efficiency in the short-wavelength and long-wavelength regions is significantly increased for the transmission-mode and reflection-mode photocathodes, respectively.
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85.60.Ha Photomultipliers; phototubes and photocathodes
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Dynamic size tuning of multidimensional optically bound matter

O. Brzobohatý, V. Karásek, T. Čižmár, and P. Zemánek

Appl. Phys. Lett. 99, 101105 (2011); http://dx.doi.org/10.1063/1.3634007 (3 pages) | Cited 1 time

Online Publication Date: 8 September 2011

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We generate and dynamically control one-, two- and three-dimensional optically bound structures of soft matter in the geometry of counter-propagating incoherent laser beams. We report results for the Bessel, Gaussian, and Laguerre-Gaussian laser modes and particularly focus on the influence of the lateral dimensions of the beam profile on the resulting self-arranged optically bound structures. Employing the transfer of the orbital angular momentum of light in the Laguerre-Gaussian beams, we show that optically bound structures can conserve their spatial arrangements even while orbiting along the beam circumference.
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42.50.Wk Mechanical effects of light on material media, microstructures and particles
42.50.Dv Quantum state engineering and measurements
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
33.80.Wz Other multiphoton processes

Metal organic vapor-phase epitaxy of InAs/InGaAsP quantum dots for laser applications at 1.5 μm

E. S. Semenova, I. V. Kulkova, S. Kadkhodazadeh, M. Schubert, and K. Yvind

Appl. Phys. Lett. 99, 101106 (2011); http://dx.doi.org/10.1063/1.3634029 (3 pages) | Cited 2 times

Online Publication Date: 8 September 2011

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The epitaxial growth of InAs/InGaAsP/InP quantum dots (QDs) for emission around 1.5 μm by depositing a thin layer of GaAs on top of the QDs is presented in this letter. The infuence of various growth parameters on the properties of the QDs, in particular, size, shape, chemical composition, and emission wavelength are investigated. Continuous wave lasing in ridge waveguide QD laser structures in the 1.5 μm wavelength range is demonstrated.
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81.07.Ta Quantum dots
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
78.67.Hc Quantum dots

Dilute nitride InGaAsN/GaAs V-groove quantum wires emitting at 1.3 μm wavelength at room temperature

R. Carron, D. Fekete, P. Gallo, B. Dwir, A. Rudra, M. Felici, B. Bartova, M. Cantoni, and E. Kapon

Appl. Phys. Lett. 99, 101107 (2011); http://dx.doi.org/10.1063/1.3610950 (3 pages) | Cited 6 times

Online Publication Date: 9 September 2011

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Site-controlled InGaAsN quantum wires (QWRs) emitting at 1.3 μm at room temperature were grown on V-grooved GaAs substrates by modulated-flux metallorganic vapor phase epitaxy. The nonplanar substrate template is shown to enhance the nitrogen uptake, evidenced by a redshift in photoluminescence wavelength twice larger for the QWRs than for the adjacent quantum well regions. The mechanism of this increase in nitrogen incorporation efficiency, achieved without degradation in optical properties, is explained by the extended gradient of In content at the step-rich QWR interfaces.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.82.Cr Fabrication techniques; lithography, pattern transfer
78.55.Cr III-V semiconductors
78.67.Lt Quantum wires
81.07.Vb Quantum wires
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Excitonic parameters of GaN studied by time-of-flight spectroscopy

T. V. Shubina, A. A. Toropov, G. Pozina, J. P. Bergman, M. M. Glazov, N. A. Gippius, P. Disseix, J. Leymarie, B. Gil, and B. Monemar

Appl. Phys. Lett. 99, 101108 (2011); http://dx.doi.org/10.1063/1.3625431 (3 pages) | Cited 1 time

Online Publication Date: 9 September 2011

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We refine excitonic parameters of bulk GaN by means of time-of-flight spectroscopy of light pulses propagating through crystals. The influence of elastic photon scattering is excluded by using the multiple reflections of the pulses from crystal boundaries. The shapes of these reflexes in the time-energy plane depict the variation of the group velocity induced by excitonic resonances. Modeling of the shapes, as well as optical spectra, shows that a homogeneous width of the order of 10 μeV characterizes the exciton-polariton resonances within the crystal. The oscillator strength of A and B exciton-polaritons is determined as 0.0022 and 0.0016, respectively.
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82.80.Rt Time of flight mass spectrometry
78.55.Cr III-V semiconductors

Highly selective standoff detection and imaging of trace chemicals in a complex background using single-beam coherent anti-Stokes Raman scattering

Marshall T. Bremer, Paul J. Wrzesinski, Nathan Butcher, Vadim V. Lozovoy, and Marcos Dantus

Appl. Phys. Lett. 99, 101109 (2011); http://dx.doi.org/10.1063/1.3636436 (3 pages) | Cited 15 times

Online Publication Date: 9 September 2011

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A non-destructive and highly selective method of standoff detection is presented and quantitatively evaluated. The method is found to be orders of magnitude more sensitive than previous coherent spectroscopy methods, identifying concentrations as low as 2 μg/cm2 of an explosive simulant mixed in a polymer matrix. The approach uses a single amplified femtosecond laser to generate high-resolution multiplex coherent anti-Stokes Raman scattering (CARS) spectra encompassing the fingerprint region (400−2500 cm−1) at standoff distance. Additionally, a standoff imaging modality is introduced, visually demonstrating similar sensitivity and high selectivity, providing promising results toward highly selective trace detection of explosives or warfare agents.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
42.65.Dr Stimulated Raman scattering; CARS
42.65.Es Stimulated Brillouin and Rayleigh scattering

Deep-ultraviolet light-emitting device realized via a hole-multiplication process

H. Zhu, C. X. Shan, B. H. Li, Z. Z. Zhang, B. Yao, and D. Z. Shen

Appl. Phys. Lett. 99, 101110 (2011); http://dx.doi.org/10.1063/1.3637575 (3 pages) | Cited 4 times

Online Publication Date: 9 September 2011

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By proper controlling the carrier generation and multiplication processes, an Au/MgO/Mg0.52Zn0.48O/MgxZn1−xO/n-ZnO structure has been designed and fabricated. In this structure, holes are multiplied via an impact ionization process in the MgO layer and injected into the Mg0.52Zn0.48O layer, and electrons are injected into the Mg0.52Zn0.48O layer from the n-ZnO layer through a composition-gradient MgxZn1−xO bridging layer. With the injection of electrons and holes, a deep ultraviolet emission at around 276 nm, coming from the Mg0.52Zn0.48O active layer, has been observed. The results reported in this letter may provide a promising route to high performance deep ultraviolet light-emitting devices.
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85.60.Jb Light-emitting devices
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Tuning the wavelength drift between resonance light absorption and scattering of plasmonic nanoparticle

Jian Zhu, Jian-jun Li, and Jun-wu Zhao

Appl. Phys. Lett. 99, 101901 (2011); http://dx.doi.org/10.1063/1.3636403 (3 pages) | Cited 5 times

Online Publication Date: 6 September 2011

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Local surface plasmon resonance in a metallic nanoparticle can induce intense light absorption and scattering simultaneously. However, the light absorption does not always have the same resonance wavelength with the scattering. Both the red and blue drifts of the scattering peak from the absorption peak are observed in the dielectric coated gold nanosphere, gold nanoshell, and nanorod. The wavelength drift between the absorption and scattering has been optimized by changing the particle shape and structure. This tunable wavelength drift can be used in selecting the resonance absorption or scattering for optical applications by altering the incident wavelength.
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78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.68.+m Optical properties of surfaces

Compositional effects on the electronic structure of ZnSe1−xSx ternary quantum dots

Sumeet C. Pandey, T. J. Mountziaris, and Dimitrios Maroudas

Appl. Phys. Lett. 99, 101902 (2011); http://dx.doi.org/10.1063/1.3633354 (3 pages) | Cited 4 times

Online Publication Date: 6 September 2011

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We report first-principles density functional theory calculations of the electronic structure of ZnSe1−xSx ternary quantum dots (TQDs) and the impact of composition and compositional distribution on the electron density distribution, electronic density of states, and band gap. We find that the band gaps for ZnSe/ZnS core/shell TQDs are nearly independent of the number of S atoms in the shell, whereas the presence of S in the core of alloyed TQDs modifies the electronic energy levels significantly. Our results imply that distribution of S atoms can be used to achieve quantum confinement in different regions of the TQDs.
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73.21.La Quantum dots
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
71.20.Nr Semiconductor compounds

Absence of Casimir regime in two-dimensional nanoribbon phonon conduction

Zhao Wang and Natalio Mingo

Appl. Phys. Lett. 99, 101903 (2011); http://dx.doi.org/10.1063/1.3635394 (3 pages) | Cited 8 times

Online Publication Date: 7 September 2011

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In stark contrast with three-dimensional (3D) nanostructures, we show that boundary scattering in two-dimensional (2D) nanoribbons alone does not lead to a finite phonon mean free path. If combined with an intrinsic scattering mechanism, 2D boundary scattering does reduce the overall mean free path; however, the latter does not scale proportionally to the ribbon width, unlike the well known Casimir regime occurring in 3D nanowires. We show that boundary scattering can be accounted for by a simple Mathiessen-type approach for many different 3D nanowire cross sectional shapes; however, this is not possible in the 2D nanoribbon case, where a complete solution of the Boltzmann transport equation is required. These facts have strong implications for the thermal conductivity of suspended nanostructures.
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63.22.Gh Nanotubes and nanowires
81.07.Gf Nanowires

Amorphous interface layer in thin graphite films grown on the carbon face of SiC

R. Colby, M. L. Bolen, M. A. Capano, and E. A. Stach

Appl. Phys. Lett. 99, 101904 (2011); http://dx.doi.org/10.1063/1.3635786 (3 pages) | Cited 4 times

Online Publication Date: 7 September 2011

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Cross-sectional transmission electron microscopy (TEM) is used to characterize an amorphous layer observed at the interface in graphite and graphene films grown via thermal decomposition of C-face 4H-SiC. The amorphous layer does not cover the entire interface, but uniform contiguous regions span microns of cross-sectional interface. Scanning transmission electron microscopy (STEM) images and electron energy loss spectroscopy (EELS) demonstrate that the amorphous layer is a carbon-rich composition of Si/C. The amorphous layer is clearly observed in samples grown at 1600 °C for a range of growth pressures in argon, but not at 1500 °C, suggesting a temperature-dependent formation mechanism.
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68.55.ap Fullerenes
81.05.ub Fullerenes and related materials
79.20.Uv Electron energy loss spectroscopy
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
61.48.-c Structure of fullerenes and related hollow and planar molecular structures

Measurement of electric field across individual wurtzite GaN quantum dots using electron holography

Lin Zhou, David J. Smith, Martha R. McCartney, Tao Xu, and Theodore D. Moustakas

Appl. Phys. Lett. 99, 101905 (2011); http://dx.doi.org/10.1063/1.3636109 (3 pages) | Cited 2 times

Online Publication Date: 7 September 2011

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Electrostatic potential profiles across wurtzite AlN/GaN quantum dot (QD) superlattices grown by molecular beam epitaxy have been measured using off-axis electron holography. The profiles for individual GaN QDs show large phase shifts which can be understood in terms of spontaneous polarization and piezoelectric fields and the accumulation of positive and negative charge at the GaN/AlN interfaces. An electric field with magnitude of ∼7.8 ± 2 MV/cm was measured across the center of a GaN QD, in reasonable agreement with reported simulations.
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06.30.Ka Basic electromagnetic quantities
42.40.My Applications
77.65.-j Piezoelectricity and electromechanical effects
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)

Broadband slow-wave systems of subwavelength thickness excited by a metal wire

Yong Jin Zhou and Tie Jun Cui

Appl. Phys. Lett. 99, 101906 (2011); http://dx.doi.org/10.1063/1.3634024 (3 pages) | Cited 3 times

Online Publication Date: 7 September 2011

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We propose a broadband slow-wave system based on metallic graded grating structures of subwavelength thickness. A metal wire is used to excite the slow waves propagating along the gratings. The analysis and full-wave simulations show that the electromagnetic waves could be stopped at designed positions under different frequencies. Experiments are conducted in the microwave frequencies to verify the proposed system. The measured results show very good agreements to the full-wave simulations. We have further modeled a broadband slow-wave system of subwavelength thickness in the terahertz (THz) frequencies to demonstrate its validity.
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42.79.Dj Gratings
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.15.Eq Optical system design

Magnetic resonance on core-shell nanowires with notches

Lina Xu, Zhi-Jian Zhang, and Bong Jae Lee

Appl. Phys. Lett. 99, 101907 (2011); http://dx.doi.org/10.1063/1.3637042 (3 pages) | Cited 1 time

Online Publication Date: 7 September 2011

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In this paper, a two-dimensional core-shell nanowire made of a dielectric core and metallic cladding is proposed for exciting the magnetic resonance on an isolated nanostructure. The key idea is to remove a small portion of the metallic cladding on the nanowire so that the incident magnetic field can be localized in the dielectric core. It is also found that the core-shell nanowire can support the localized surface plasmon, whose resonance frequency mainly depends on the thickness of the metallic cladding. The finite-difference time-domain method is employed to calculate the scattering cross-section of the proposed structure and the near-field distribution of the magnetic field at resonance conditions. The results obtained from this study will advance our fundamental understanding of the light-matter interaction at nanometer scales and facilitate the development of multi-dimensional metamaterials for subwavelength imaging.
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81.07.Gf Nanowires
75.30.Cr Saturation moments and magnetic susceptibilities
75.50.Tt Fine-particle systems; nanocrystalline materials
77.22.Ch Permittivity (dielectric function)
02.70.Bf Finite-difference methods
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Selectively solvated triblock copolymer networks under biaxial strain

Arjun S. Krishnan, John H. van Zanten, Sönke Seifert, Byeongdu Lee, and Richard J. Spontak

Appl. Phys. Lett. 99, 101908 (2011); http://dx.doi.org/10.1063/1.3635780 (3 pages) | Cited 3 times

Online Publication Date: 9 September 2011

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Triblock copolymers swollen with a midblock-selective solvent provide a test platform by which to interrogate the properties of highly elastic physical gel networks. Here, such networks are biaxially strained and studied by synchrotron small-angle x-ray scattering. Analysis of the form factor reveals that initially spherical micellar cores deform to ellipsoids when strained. The Percus-Yevick hard-sphere model describes the structure factor of micelles exhibiting liquid-like order prior to deformation but requires an attractive potential to match the structure factor under strain. The magnitude of this potential increases with increasing strain, indicating a change in coronal overlap as the network is stretched.
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82.70.Gg Gels and sols
61.25.hk Polymer melts and blends
62.10.+s Mechanical properties of liquids
78.70.Ck X-ray scattering
81.40.Cd Solid solution hardening, precipitation hardening, and dispersion hardening; aging
82.70.Dd Colloids

Charge propagation dynamics at trapping centers that induce the luminescence of rare-earth dopants in wide-gap materials

Masashi Ishii, Susumu Harako, Xinwei Zhao, Shuji Komuro, and Bruce Hamilton

Appl. Phys. Lett. 99, 101909 (2011); http://dx.doi.org/10.1063/1.3636393 (3 pages) | Cited 3 times

Online Publication Date: 9 September 2011

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For rare-earth doped semiconductors, charge propagation from semiconductors to rare-earths is essential for excitation of optically active dopants. However, the qualitative model that has been widely accepted to describe this process is based upon indirect evidence; in this model, it is believed that trapping and subsequent recombination of the charges at some rare-earth-related defect excite the dopants. In this work, we observe the sequential process directly, and quantify the trapped charge density and relaxation frequency using a photoelectric measurement technique for samarium-doped titanium dioxide with intense visible luminescence under ultraviolet light.
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78.55.Hx Other solid inorganic materials
61.72.jn Color centers
72.40.+w Photoconduction and photovoltaic effects
72.80.Jc Other crystalline inorganic semiconductors
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Thermoelectric figure of merit as a function of carrier propagation angle in semiconducting superlattices

Shuo Liu and E. W. Carlson

Appl. Phys. Lett. 99, 102101 (2011); http://dx.doi.org/10.1063/1.3633112 (3 pages)

Online Publication Date: 7 September 2011

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Superlattices have been a fruitful approach for enhancing the figure of merit, ZT, of thermoelectric materials. Generally, superlattice transport is measured either parallel or perpendicular to the superlattice planes. We show here that the figure of merit is a function of carrier propagation angle in the superlattice and that ZT generically exhibits a maximum at an oblique angle, near θ ≈ π/6.
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73.63.-b Electronic transport in nanoscale materials and structures
72.20.Pa Thermoelectric and thermomagnetic effects

Graphene/GaN Schottky diodes: Stability at elevated temperatures

S. Tongay, M. Lemaitre, T. Schumann, K. Berke, B. R. Appleton, B. Gila, and A. F. Hebard

Appl. Phys. Lett. 99, 102102 (2011); http://dx.doi.org/10.1063/1.3628315 (3 pages) | Cited 10 times

Online Publication Date: 7 September 2011

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Rectification and thermal stability of diodes formed at graphene/GaN interfaces have been investigated using Raman Spectroscopy and temperature-dependent current-voltage measurements. The Schottky barriers formed between GaN and mechanically transferred graphene display rectification that is preserved up to 550 K with the diodes eventually becoming non-rectifying above 650 K. Upon cooling, the diodes show excellent recovery with improved rectification. We attribute these effects to the thermal stability of graphene, which acts like an impenetrable barrier to the diffusion of contaminants across the interface, and to changes in the interface band alignment associated with thermally induced dedoping of graphene.
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85.30.Kk Junction diodes

Suppression in the negative bias illumination instability of Zn-Sn-O transistor using oxygen plasma treatment

Shinhyuk Yang, Kwang Hwan Ji, Un Ki Kim, Cheol Seong Hwang, Sang-Hee Ko Park, Chi-Sun Hwang, Jin Jang, and Jae Kyeong Jeong

Appl. Phys. Lett. 99, 102103 (2011); http://dx.doi.org/10.1063/1.3634053 (3 pages) | Cited 5 times

Online Publication Date: 7 September 2011

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This study examined the effect of oxygen plasma treatment on light-enhanced bias instability in Zn-Sn-O (ZTO) thin film transistors (TFTs). The treated ZTO TFT exhibited only a threshold voltage (Vth) shift of −2.05 V under negative bias illumination stress (NBIS) conditions, whereas the pristine device suffered from a negative Vth shift of 3.76 V under identical conditions. X-ray photoelectron spectroscopic analysis revealed that the oxygen vacancy defect density was diminished via the oxygen plasma treatment. This suggests the Vth degradation under NBIS is due to photo-transition of oxygen vacancy defects.
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85.30.Tv Field effect devices
52.77.-j Plasma applications
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Do we really need high thermoelectric figures of merit? A critical appraisal to the power conversion efficiency of thermoelectric materials

Dario Narducci

Appl. Phys. Lett. 99, 102104 (2011); http://dx.doi.org/10.1063/1.3634018 (3 pages) | Cited 8 times

Online Publication Date: 8 September 2011

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This paper will show that, while ZT is an appropriate performance index when optimizing the heat conversion rate, it may mislead research in view of applications aiming at large electric power production. This is of special relevance when related to the surge of research in the area of low-dimensionality semiconductors where ZT is increased by lowering the thermal conductivity κ. It will be shown that, when operating between sources at fixed temperature, the highest power output can be obtained by increasing κ, not decreasing it, the larger electric power output economically enabling thermoelectric generators for massive electric power production.
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72.20.Pa Thermoelectric and thermomagnetic effects
84.60.Rb Thermoelectric, electrogasdynamic and other direct energy conversion
66.70.Df Metals, alloys, and semiconductors

Properties of the SiO2- and SiNx-capped GaAs(100) surfaces of GaInAsN/GaAs quantum-well heterostructures studied by photoelectron spectroscopy and photoluminescence

J. Dahl, V. Polojärvi, J. Salmi, P. Laukkanen, and M. Guina

Appl. Phys. Lett. 99, 102105 (2011); http://dx.doi.org/10.1063/1.3634046 (3 pages) | Cited 2 times

Online Publication Date: 8 September 2011

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SiO2 and SiNx layers are routinely deposited onto III-V(100) surfaces at different device processing steps. We elucidate these insulator-interface properties with photoemission and photoluminescence (PL) of SiO2- and SiNx-capped GaAs(100) surfaces of GaInAsN/GaAs quantum wells (QWs). Post-growth annealing led to an increase of the QW-PL intensity, of which origin can be clearly linked to the SiO2 and SiNx interfaces. Concomitantly, Ga2O–related photoemission increased, indicating useful formation of Ga2O at both insulator interfaces. Furthermore, higher Ga-oxidation-state emission, identified with Ga diffused into SiO2 and SiNx, correlates with the blue-shift of the QW-PL wavelength. Also, interfacial As-As related photoemission was identified.
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78.67.De Quantum wells
78.55.Cr III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
52.77.-j Plasma applications

PN junction rectification in electrolyte gated Mg-doped InN

E. Alarcón-Lladó, M. A. Mayer, B. W. Boudouris, R. A. Segalman, N. Miller, T. Yamaguchi, K. Wang, Y. Nanishi, E. E. Haller, and J. W. Ager

Appl. Phys. Lett. 99, 102106 (2011); http://dx.doi.org/10.1063/1.3634049 (3 pages) | Cited 3 times

Online Publication Date: 8 September 2011

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PN junction rectification is demonstrated in indium nitride. The junction is formed between the n-type surface accumulation layer and the Mg-doped, p-type bulk in a top-contacted thin film structure. The parasitic shorting path between the top contacts is controlled by gating with an electrolyte. For positive gate voltages, electrons accumulate at the surface and the current flows preferentially through n type regions, and linear current-voltage (I-V) behavior is observed. However, for negative gate voltages, surface electrons are depleted and current flows through the p-type bulk. This creates an n-p-n structure and a characteristic non-linear I-V curve is observed.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Ei Rectification
78.66.Fd III-V semiconductors
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