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19 Sep 2011

Volume 99, Issue 12, Articles (12xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 99, 121101 (2011); http://dx.doi.org/10.1063/1.3617472 (3 pages)

M. Davanço, M. T. Rakher, W. Wegscheider, D. Schuh, A. Badolato, and K. Srinivasan
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Efficient quantum dot single photon extraction into an optical fiber using a nanophotonic directional coupler

M. Davanço, M. T. Rakher, W. Wegscheider, D. Schuh, A. Badolato, and K. Srinivasan

Appl. Phys. Lett. 99, 121101 (2011); http://dx.doi.org/10.1063/1.3617472 (3 pages) | Cited 9 times

Online Publication Date: 19 September 2011

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We demonstrate a spectrally broadband and efficient technique for collecting emission from a single InAs quantum dot directly into a standard single mode optical fiber. In this approach, an optical fiber taper waveguide is placed in contact with a suspended GaAs nanophotonic waveguide with embedded quantum dots, forming a broadband directional coupler with standard optical fiber input and output. Efficient photoluminescence collection over a wavelength range of tens of nanometers is demonstrated, and a maximum collection efficiency of 6% (corresponding single photon rate of 3.0 MHz) into a single mode optical fiber is estimated for a single quantum dot exciton.
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42.81.Qb Fiber waveguides, couplers, and arrays

Extreme optical nonlinearities in chalcogenide glass fibers embedded with metallic and semiconductor nanowires

Bora Ung and Maksim Skorobogatiy

Appl. Phys. Lett. 99, 121102 (2011); http://dx.doi.org/10.1063/1.3641423 (3 pages) | Cited 1 time

Online Publication Date: 19 September 2011

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A nanostructured chalcogenide-metal optical fiber is proposed. This hybrid nanofiber is embedded with a periodic array of triangular-shaped deep-subwavelength metallic (or semiconductor) nanowires set up in a bowtie configuration. Calculations show that the proposed nanostructured fiber supports a guided collective plasmonic mode enabling both subwavelength field confinement and extreme nonlinear light-matter interactions. A scheme is also proposed whereby the large linear absorption losses are compensated via nonlinear optical gain when semiconducting single-wall carbon nanotubes are used in place of metal.
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42.81.-i Fiber optics
42.70.Ce Glasses, quartz
42.65.-k Nonlinear optics

A micropillar for cavity optomechanics

A. G. Kuhn, M. Bahriz, O. Ducloux, C. Chartier, O. Le Traon, T. Briant, P.-F. Cohadon, A. Heidmann, C. Michel, L. Pinard, and R. Flaminio

Appl. Phys. Lett. 99, 121103 (2011); http://dx.doi.org/10.1063/1.3641871 (3 pages) | Cited 3 times

Online Publication Date: 19 September 2011

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We have designed a micromechanical resonator suitable for cavity optomechanics. We have used a micropillar geometry to obtain a high-frequency mechanical resonance with a low effective mass and a very high quality factor. We have coated a 60-μm diameter low-loss dielectric mirror on top of the pillar and are planning to use this micromirror as part of a high-finesse Fabry-Perot cavity to laser cool the resonator down to its quantum ground state and to monitor its quantum position fluctuations by quantum-limited optical interferometry.
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42.79.Bh Lenses, prisms and mirrors
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
42.15.Eq Optical system design
42.50.-p Quantum optics
07.60.Ly Interferometers

Ultra bright AlGaInP light emitting diodes with pyramidally patterned GaP spreading layer

Zhiyuan Zuo, Ruijun Wang, Duo Liu, Qian Yu, Zhaobin Feng, and Xiangang Xu

Appl. Phys. Lett. 99, 121104 (2011); http://dx.doi.org/10.1063/1.3641906 (3 pages) | Cited 2 times

Online Publication Date: 19 September 2011

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A mild photo-assisted chemical method is developed to fabricate pyramidally patterned GaP:Mg spreading layer to improve the light extraction efficiency of 625 nm AlGaInP red light emitting diodes. The pyramid patterns fabricated by using hydrofluoric acid and H2O2 mixed solution in combination with 532 nm laser radiation, are experimentally confirmed to be very efficient for light extraction. Angle resolved electroluminescent tests reveal that the patterned chips show an average 66.2% enhancement of the light emission intensity over the original chips. The output power measured on encapsulated samples exhibits an enhancement of 41.3%.
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85.60.Jb Light-emitting devices
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Spatially resolved measurement of high doses in microbeam radiation therapy using samarium doped fluorophosphate glasses

Go Okada, Brian Morrell, Cyril Koughia, Andy Edgar, Chris Varoy, George Belev, Tomasz Wysokinski, Dean Chapman, and Safa Kasap

Appl. Phys. Lett. 99, 121105 (2011); http://dx.doi.org/10.1063/1.3633102 (3 pages) | Cited 6 times

Online Publication Date: 20 September 2011

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The measurement of spatially resolved high doses in microbeam radiation therapy has always been a challenging task, where a combination of high dose response and high spatial resolution (microns) is required for synchrotron radiation peaked around 50 keV. The x-ray induced Sm3+ → Sm2+ valence conversion in Sm3+ doped fluorophosphates glasses has been tested for use in x-ray dosimetry for microbeam radiation therapy. The conversion efficiency depends almost linearly on the dose of irradiation up to ∼5 Gy and saturates at doses exceeding ∼80 Gy. The conversion shows strong correlation with x-ray induced absorbance of the glass which is related to the formation of phosphorus-oxygen hole centers. When irradiated through a microslit collimator, a good spatial resolution and high “peak-to-valley” contrast have been observed by means of confocal photoluminescence microscopy.
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87.53.Kn Conformal radiation treatment
87.50.wj Dosimetry/exposure assessment
87.59.B- Radiography

Emission and absorption cross-sections of an Er:GaN waveguide prepared with metal organic chemical vapor deposition

Q. Wang, R. Dahal, I.-W. Feng, J. Y. Lin, H. X. Jiang, and R. Hui

Appl. Phys. Lett. 99, 121106 (2011); http://dx.doi.org/10.1063/1.3636418 (3 pages) | Cited 2 times

Online Publication Date: 20 September 2011

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We repost the characterization of emission and absorption cross-sections in an erbium-doped GaN waveguide prepared by metal organic chemical vapor deposition. The emission cross-section was obtained with the Füchtbauer–Ladenburg equation based on the measured spontaneous emission and the radiative carrier lifetime. The absorption cross-section was derived from the emission cross-section through their relation provided from the McCumber’s theory. The conversion efficiency from a 1480 nm pump to 1537 nm emission was measured, which reasonably agreed with the calculation based on the emission and absorption cross-sections.
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42.79.Gn Optical waveguides and couplers
78.30.Fs III-V and II-VI semiconductors
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Mechanical exfoliation of graphene for the passive mode-locking of fiber lasers

Amos Martinez, Kazuyuki Fuse, and Shinji Yamashita

Appl. Phys. Lett. 99, 121107 (2011); http://dx.doi.org/10.1063/1.3641419 (3 pages) | Cited 22 times

Online Publication Date: 20 September 2011

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Graphene exhibits wavelength-independent, saturable optical absorption with fast response time, and large modulation depth. Thus, it is an attractive material for the saturable absorption of fiber lasers. In this paper, we report a simple method for the in-situ monitoring of the deposition of few-layers graphene in an optical fiber end by mechanical exfoliation. Saturable absorbers with different number of graphene layers (from 4 layers of graphene to few 10 s of layers) are prepared and low threshold, self-starting passive mode-locked operation of a fiber laser with sub-picosecond pulse duration is demonstrated.
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42.55.Wd Fiber lasers
42.60.Fc Modulation, tuning, and mode locking
42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption

Precise, real-time, single-shot carrier-envelope phase measurement in the multi-cycle regime

M. Möller, A. M. Sayler, T. Rathje, M. Chini, Zenghu Chang, and G. G. Paulus

Appl. Phys. Lett. 99, 121108 (2011); http://dx.doi.org/10.1063/1.3641472 (3 pages) | Cited 2 times

Online Publication Date: 20 September 2011

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Polarization gating is used to extend a real-time, single-shot, carrier-envelope phase (CEP) measurement, based on high-energy above-threshold ionization in xenon, to the multi-cycle regime. The single-shot CEP precisions achieved are better than 175 and 350 mrad for pulse durations up to 10 fs and 12.5 fs, respectively, while only 130 μJ of pulse energy are required. This opens the door to study and control of CEP-dependent phenomena in ultra-intense laser-matter interaction using optical parametric chirped pulse amplifier based tera- and petawatt class lasers.
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52.38.-r Laser-plasma interactions
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)

2 W high efficiency PbS mid-infrared surface emitting laser

A. Ishida, Y. Sugiyama, Y. Isaji, K. Kodama, Y. Takano, H. Sakata, M. Rahim, A. Khiar, M. Fill, F. Felder, and H. Zogg

Appl. Phys. Lett. 99, 121109 (2011); http://dx.doi.org/10.1063/1.3634054 (3 pages) | Cited 2 times

Online Publication Date: 20 September 2011

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High efficiency laser operation with output power exceeding 2 W was obtained for vertical external-cavity PbS based IV-VI compound surface emitting quantum-well structures. The laser showed external quantum efficiency as high as 16%. Generally, mid-infrared III-V or II-VI semiconductor laser operation utilizing interband electron transitions are restricted by Auger recombination and free carrier absorption. Auger recombination is much lower in the IV-VI semiconductors, and the free-carrier absorption is significantly reduced by an optically pumped laser structure including multi-step optical excitation layers.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Near-infrared luminescent and antireflective in SiO2/YVO4:Yb3+ bilayer films for c-Si solar cells

Yingjie Peng, Jie Liu, Kun Zhang, Hui Luo, Jihong Li, Bo Xu, Lixian Han, Xiaojuan Li, and Xibin Yu

Appl. Phys. Lett. 99, 121110 (2011); http://dx.doi.org/10.1063/1.3630003 (3 pages) | Cited 3 times

Online Publication Date: 21 September 2011

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We demonstrate a facile approach for the architecture of a multifunctional bilayer thin films which show both antireflection and near-infrared (NIR) luminescence. NIR luminescence YVO4:Yb3+ transparent film and nanoporous SiO2 film were successively built on slide glass. Intense NIR emission around 900–1100 nm has been obtained, which is assigned to the electronic transition 2F7/2→2F5/2 of Yb3+, meanwhile, the maximum transmittance reached as high as ∼95%, whereas that of the glass substrate is ∼91%. It is the sought candidate material for c-Si solar cell by downconversion of UV light to NIR photons and increasing photon transmission.
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42.79.Wc Optical coatings
78.55.Hx Other solid inorganic materials
78.66.Nk Insulators
88.40.H- Solar cells (photovoltaics)
88.40.jj Silicon solar cells
42.70.-a Optical materials

High-precision frequency measurements in the THz spectral region using an unstabilized femtosecond laser

Heiko Füser, Rolf Judaschke, and Mark Bieler

Appl. Phys. Lett. 99, 121111 (2011); http://dx.doi.org/10.1063/1.3640234 (3 pages)

Online Publication Date: 21 September 2011

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We perform high-precision frequency measurements in the THz frequency range using an unstabilized femtosecond laser. A simple and flexible algorithm is used to correct the beating signal resulting from the THz source and one comb line of the rectified optical comb for fluctuations of the laser repetition rate. Using this technique, we demonstrate an accuracy of our measurement device as high as (9 ± 3) · 10−14 for the measurement of a 100 GHz source. This is two orders of magnitude better than previous precision measurements in this frequency range employing femtosecond lasers.
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42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
06.30.Ft Time and frequency
07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Dark current filtering in unipolar barrier infrared detectors

G. R. Savich, J. R. Pedrazzani, D. E. Sidor, S. Maimon, and G. W. Wicks

Appl. Phys. Lett. 99, 121112 (2011); http://dx.doi.org/10.1063/1.3643515 (3 pages) | Cited 3 times

Online Publication Date: 22 September 2011

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Control of dark current mechanisms is essential to improving the performance of infrared photodetectors and many other electronic devices. Unipolar barriers can readily be applied to practically and efficiently filter out multiple dark current components exhibited by infrared photodetectors. Via careful placement of unipolar barriers in a standard photodetector architecture, effective suppression of dark currents due to surface leakage, direct band-to-band tunneling, trap-assisted tunneling, and Shockley-Read-Hall generation is demonstrated. We present unipolar barrier photodiodes exhibiting six orders of magnitude improvement in RoA and near Auger-limited device performance.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
72.40.+w Photoconduction and photovoltaic effects

Continuous-wave operation above room temperature of GaSb-based laser diodes grown on Si

J. R. Reboul, L. Cerutti, J. B. Rodriguez, P. Grech, and E. Tournié

Appl. Phys. Lett. 99, 121113 (2011); http://dx.doi.org/10.1063/1.3644983 (3 pages) | Cited 2 times

Online Publication Date: 23 September 2011

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We have investigated specifically designed GaSb-based laser diodes epitaxially grown on a Si substrate. We demonstrate continuous-wave operation of these laser diodes emitting near 2 μm up to 35 °C with several mW/facet output powers, limited by our experimental setup. Our results open the way to direct monolithic III-V/Si integration.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
68.55.A- Nucleation and growth
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Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

Q. Th. Algwari and D. O'Connell

Appl. Phys. Lett. 99, 121501 (2011); http://dx.doi.org/10.1063/1.3628455 (3 pages) | Cited 13 times

Online Publication Date: 19 September 2011

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The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.
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52.50.-b Plasma production and heating
52.75.-d Plasma devices
52.25.Fi Transport properties

Experimental study of the hydrodynamic expansion following a nanosecond repetitively pulsed discharge in air

Da A. Xu, Deanna A. Lacoste, Diane L. Rusterholtz, Paul-Quentin Elias, Gabi D. Stancu, and Christophe O. Laux

Appl. Phys. Lett. 99, 121502 (2011); http://dx.doi.org/10.1063/1.3641413 (3 pages) | Cited 1 time

Online Publication Date: 21 September 2011

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We report on an experimental study of the hydrodynamic expansion following a nanosecond repetitively pulsed (NRP) discharge in atmospheric pressure air preheated up to 1000 K. Single-shot schlieren images starting from 50 ns after the discharge were recorded to show the shock-wave propagation and the expansion of the heated gas channel. The temporal evolution of the gas temperature behind the shock-front is estimated from the measured shock-wave velocity by using the Rankine-Hugoniot relationships. The results show that a gas temperature increase of up to 1100 K can be observed 50 ns after the nanosecond pulse.
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47.40.Nm Shock wave interactions and shock effects
47.60.Dx Flows in ducts and channels
47.80.Jk Flow visualization and imaging

Microwave breakdown of low pressure N2 gas in microgaps

T. J. Klein, Christopher J. Ploch, Cameron J. Recknagel, and S. K. Remillard

Appl. Phys. Lett. 99, 121503 (2011); http://dx.doi.org/10.1063/1.3641900 (3 pages)

Online Publication Date: 21 September 2011

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The pressure dependence of the breakdown of nitrogen gas by a microwave field in microgaps down to 13 μm has been measured. Fits to a phenomenological function suggest that microwave breakdown in small gaps requires a higher collision frequency, νc. If the effective electric field on an electron in a microgap is interpreted as Eeff = Eomath and then as the gap size is reduced, we find that the collision frequency needed to produce a minimum breakdown electric field shifts from νc = ω for large gaps to νc = 2ω for small gaps.
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52.80.Pi High-frequency and RF discharges

Fast ion acceleration from thin foils irradiated by ultra-high intensity, ultra-high contrast laser pulses

R. Prasad, A. A. Andreev, S. Ter-Avetisyan, D. Doria, K. E. Quinn, L. Romagnani, C. M. Brenner, D. C. Carroll, N. P. Dover, D. Neely, P. S. Foster, P. Gallegos, J. S. Green, P. McKenna, Z. Najmudin, et al.

Appl. Phys. Lett. 99, 121504 (2011); http://dx.doi.org/10.1063/1.3643133 (3 pages) | Cited 4 times

Online Publication Date: 22 September 2011

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Ion acceleration resulting from the interaction of ultra-high intensity (2 × 1020 W/cm2) and ultra-high contrast (∼1010) laser pulses with 0.05–10 μm thick Al foils at normal (0°) and 35° laser incidence is investigated. When decreasing the target thickness from 10 μm down to 0.05 μm, the accelerated ions become less divergent and the ion flux increases, particularly at normal (0°) laser incidence on the target. A laser energy conversion into protons of ∼6.5% is estimated at 35° laser incidence. Experimental results are in reasonable agreement with theoretical estimates and can be a benchmark for further theoretical and computational work.
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52.38.Kd Laser-plasma acceleration of electrons and ions

Quasi-optical theory of relativistic submillimeter surface-wave oscillators

N. S. Ginzburg, A. M. Malkin, A. S. Sergeev, and V. Yu. Zaslavsky

Appl. Phys. Lett. 99, 121505 (2011); http://dx.doi.org/10.1063/1.3641868 (3 pages) | Cited 8 times

Online Publication Date: 22 September 2011

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Within the framework of a quasi-optical approach, the nonlinear theory of relativistic surface-wave oscillators is developed. By presenting the radiation field as a sum of two counter-propagating wave-beams which are coupled on a shallow corrugated surface, we describe formation of an evanescent slow wave. Taking into account the excitation of a slow wave by a sheet electron beam, we simulate linear and nonlinear stages of interaction that allows us to define the threshold conditions, the electron efficiency, and the output coupling. It is shown that the considered type of an oscillator can be used for generation of powerful sub-THz radiation.
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84.40.Fe Microwave tubes (e.g., klystrons, magnetrons, traveling-wave, backward-wave tubes, etc.)
84.30.Ng Oscillators, pulse generators, and function generators

Spin effects on the instability and propagation modes of electrostatic plasma waves in quantum plasmas

Dae-Han Ki and Young-Dae Jung

Appl. Phys. Lett. 99, 121506 (2011); http://dx.doi.org/10.1063/1.3643519 (3 pages) | Cited 1 time

Online Publication Date: 23 September 2011

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The effects of the electron spin interaction on the pure instability and propagation modes of the quantum electrostatic waves are investigated in cold quantum electron plasmas. It is found that the influence of the electron spin interaction increases the group velocity of the propagation mode of the quantum electrostatic wave. In addition, it is shown that the electron spin interaction enhances the growth rate of the instability mode of the quantum electrostatic wave. It is also found that the effects of the electron spin interaction would be more important in the domain of small Fermi wave numbers.
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52.35.Fp Electrostatic waves and oscillations (e.g., ion-acoustic waves)
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)
52.27.Aj Single-component, electron-positive-ion plasmas
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In-situ investigation of spontaneous and plasma-enhanced oxidation of AlN film surfaces

Shigeng Song and Frank Placido

Appl. Phys. Lett. 99, 121901 (2011); http://dx.doi.org/10.1063/1.3640219 (3 pages)

Online Publication Date: 19 September 2011

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The oxidation of sputtered AlN thin films on silicon substrates is investigated in-situ by high precision, single-wavelength optical monitoring of reflectance for low pressures of oxygen and room temperature conditions. Modelling of spontaneous surface oxidation and plasma enhanced oxidation shows that at the start of oxidation, the amount of available reactants dominates the reaction rate. The Mott potential for plasma enhanced oxidation is found to be much higher than that for spontaneous oxidation, providing explanation of why the oxygen plasma can enhance oxidation of AlN.
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81.65.Mq Oxidation
52.77.-j Plasma applications
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.Hf II-VI semiconductors

Molecular motions in glass-rubber transition region in polyisobutylene investigated by two-dimensional correlation dielectric relaxation spectroscopy

Xiaoan Wang, G. S. Huang, J. R. Wu, Y. J. Nie, X. J. He, and K. W. Xiang

Appl. Phys. Lett. 99, 121902 (2011); http://dx.doi.org/10.1063/1.3640479 (3 pages) | Cited 4 times

Online Publication Date: 19 September 2011

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In this letter, we report the first study of the molecular relaxation dynamics in the glass-rubber transition region in polyisobutylene by 2D correlation dielectric relaxation spectroscopy (2DC-DRS). With the help of the high resolution and high sensitivity of 2DC-DRS, it is also the first time to observe and locate the positions of the Rouse modes and sub-Rouse modes in type-B polymers in the dielectric spectrum. 2DC-DRS was also applied to compare the temperature dependences of different molecular motions. Moreover, 2DC-DRS has been demonstrated as a powerful tool for studying the molecular motions with different time/length scales.
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64.70.pj Polymers
77.22.Gm Dielectric loss and relaxation

Femtosecond laser-induced nanostructure formation in Sb2Te3

Yuwei Li, Vladimir A. Stoica, Lynn Endicott, Guoyu Wang, Huarui Sun, Kevin P. Pipe, Ctirad Uher, and Roy Clarke

Appl. Phys. Lett. 99, 121903 (2011); http://dx.doi.org/10.1063/1.3634014 (3 pages)

Online Publication Date: 19 September 2011

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We report femtosecond laser-induced nanotracks in highly absorbing Sb2Te3. Groups of nanotracks are observed with widths ∼50 nm and periodicity ∼130 nm, their area of coverage extending with the increase of laser fluence. We demonstrate that under a narrow range of laser fluences and laser irradiation times, long highly aligned nanotracks can be formed in Sb2Te3. The results suggest a promising avenue for laser nanostructuring of chalcogenide thermoelectrics, with implications for high efficiency thermoelectric energy conversion.
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81.07.Bc Nanocrystalline materials
42.62.-b Laser applications
73.50.Lw Thermoelectric effects
68.55.ag Semiconductors

Thermal stability of epitaxial Mn5Ge3 and carbon-doped Mn5Ge3 films

Aurélie Spiesser, Vinh Le Thanh, Sylvain Bertaina, and Lisa A. Michez

Appl. Phys. Lett. 99, 121904 (2011); http://dx.doi.org/10.1063/1.3638472 (3 pages) | Cited 5 times

Online Publication Date: 19 September 2011

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The thermal stability of epitaxial Mn5Ge3 and carbon-doped Mn5Ge3 films was investigated by combining structural and magnetic characterizations. It is shown that ferromagnetic Mn5Ge3 films transform into antiferromagnetic Mn11Ge8 upon post-annealing at 650 °C whereas carbon-doped Mn5Ge3 conserves its ferromagnetism up to 850 °C. The magnetic properties of Mn5Ge3 (Curie temperature, magnetization at saturation, and magnetic moment per Mn atom) are found to undergo a reversible transition upon carbon doping and its extraction during thermal annealing. The stability of carbon-doped Mn5Ge3 films will be discussed in terms of carbon filling of interstitial sites of Mn5Ge3, which prevents Ge diffusion from the substrate.
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75.70.Ak Magnetic properties of monolayers and thin films
68.60.Dv Thermal stability; thermal effects
75.30.Cr Saturation moments and magnetic susceptibilities
75.50.Cc Other ferromagnetic metals and alloys
75.50.Ee Antiferromagnetics
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Influence of localized electric field on the bandedge emission of hybrid Au-GaN/InGaN quantum wells

Karol G. Gryczynski, Padma Rekha Vemuri, Ian Watson, and Arup Neogi

Appl. Phys. Lett. 99, 121905 (2011); http://dx.doi.org/10.1063/1.3640492 (3 pages) | Cited 1 time

Online Publication Date: 20 September 2011

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The modification in the bandgap of single GaN/InGaN quantum wells in the presence of a gold thin film with surface plasmon polariton energy off-resonant and resonant to the photoluminesnce emission energy is studied. The quantum well emission energy can be either blue shifted or red-shifted depending on the localized electric field induced by the metal thin film. A theory of electrostatic image charge induced alteration of the confinement potential is presented to explain the observed experimental shifts.
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73.21.Fg Quantum wells
78.55.Cr III-V semiconductors
78.67.De Quantum wells
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Demonstration of enhanced optical polarization for improved deep ultraviolet light extraction in coherently grown semipolar Al0.83Ga0.17N/AlN on ZnO substrates

Kohei Ueno, Atsushi Kobayashi, Jitsuo Ohta, Masaharu Oshima, and Hiroshi Fujioka

Appl. Phys. Lett. 99, 121906 (2011); http://dx.doi.org/10.1063/1.3641876 (3 pages)

Online Publication Date: 20 September 2011

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We have grown a semipolar Al0.83Ga0.17N/AlN heterostructure on ZnO (1math02) substrates and investigated the optical polarization characteristics of the near-band-edge (NBE) emission of Al0.83Ga0.17N experimentally and theoretically. Reciprocal space mapping measurements revealed that AlN is fully relaxed with respect to ZnO, and Al0.83Ga0.17N grows coherently in both of the in-plane orthogonal directions on AlN. The NBE emissions of coherently grown Al0.83Ga0.17N (1math02) at 5.4 eV were clearly polarized with E||X2. The polarization ratio of the surface emission was as high as −0.66 at room temperature. This phenomenon is consistent with a large crystal splitting energy, which was clarified by theoretical investigations based on the k · p method.
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81.15.Fg Pulsed laser ablation deposition
81.16.Mk Laser-assisted deposition
68.55.A- Nucleation and growth
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
71.15.-m Methods of electronic structure calculations
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