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12 Sep 2011

Volume 99, Issue 11, Articles (11xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 99, 113501 (2011); http://dx.doi.org/10.1063/1.3634072 (3 pages)

Asif Islam Khan, Debanjan Bhowmik, Pu Yu, Sung Joo Kim, Xiaoqing Pan, Ramamoorthy Ramesh, and Sayeef Salahuddin
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Radiation patterns from coupled photonic crystal nanocavities

M. Brunstein, T. J. Karle, I. Sagnes, F. Raineri, J. Bloch, Y. Halioua, G. Beaudoin, L. Le Gratiet, J. A. Levenson, and A. M. Yacomotti

Appl. Phys. Lett. 99, 111101 (2011); http://dx.doi.org/10.1063/1.3633106 (3 pages) | Cited 7 times

Online Publication Date: 12 September 2011

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We report on far field measurements on two coupled photonic crystal nanocavities. The distinct features of the antisymmetric modes (minima of intensity at zero-emission angles) allow us to demonstrate a π-phase difference between the cavity fields, a clear signature of evanescent coupling. Good agreement between experimental results and simulated radiation patterns has been found.
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42.70.Qs Photonic bandgap materials
07.60.-j Optical instruments and equipment

A hot-carrier solar cell with optical energy selective contacts

D. J. Farrell, Y. Takeda, K. Nishikawa, T. Nagashima, T. Motohiro, and N. J. Ekins-Daukes

Appl. Phys. Lett. 99, 111102 (2011); http://dx.doi.org/10.1063/1.3636401 (3 pages) | Cited 2 times

Online Publication Date: 12 September 2011

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The hot-carrier solar cell (HC-SC) is an ambitious approach to solar energy conversion which in principle can achieve high efficiency (84%) from a single bandgap semiconductor. Here we propose a method of utilising hot-carriers within a photovoltaic device in which energy is extracted optically from a hot-carrier distribution rather than through the usual approach of electrical conduction. Depending on the optical extraction rate, the concept proposed here may attain an upper efficiency approaching that of the conventional HC-SC.
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88.40.H- Solar cells (photovoltaics)
72.20.Ht High-field and nonlinear effects

Light-induced spontaneous pattern formation in nematic liquid crystal cells

István Jánossy, Katalin Fodor-Csorba, Anikó Vajda, and Laura O. Palomares

Appl. Phys. Lett. 99, 111103 (2011); http://dx.doi.org/10.1063/1.3635785 (3 pages) | Cited 1 time

Online Publication Date: 13 September 2011

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Optically induced instabilities were observed in nematic liquid crystals sandwiched between a photosensitive layer and a reference plate. The instabilities occurred when the light entered the cell from the reference plate and its polarization was parallel to the director alignment at the entrance face. Two kinds of patterns were detected, a static and a dynamic one. The underlying mechanism of pattern formation is the coupling between the director orientation on the photosensitive plate and the polarization direction of the light on that plate.
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78.15.+e Optical properties of fluid materials, supercritical fluids and liquid crystals
42.65.Sf Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics
42.70.Df Liquid crystals
61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures

Distance-dependence of the coupling between split-ring resonators and single-quantum-well gain

N. Meinzer, M. König, M. Ruther, S. Linden, G. Khitrova, H. M. Gibbs, K. Busch, and M. Wegener

Appl. Phys. Lett. 99, 111104 (2011); http://dx.doi.org/10.1063/1.3633353 (3 pages) | Cited 3 times

Online Publication Date: 13 September 2011

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We present low-temperature femtosecond pump-probe experiments on arrays of silver split-ring resonators coupled to single quantum wells, in which we vary the geometrical separation between the two components to study the variation of coupling with distance. Its strength is found to decrease exponentially with increasing separation with a 1/e length on the order of 8 nm. We further link our experimental results to numerical calculations of the near fields which show the same distance-dependence as the coupling strength in the experiment. Together, this confirms the assumption of a near-field-assisted coupling mechanism.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Direct generation of 20 W peak power picosecond optical pulses from an external-cavity mode-locked GaInN laser diode incorporating a flared waveguide

Tomoyuki Oki, Rintaro Koda, Shunsuke Kono, Takao Miyajima, Hideki Watanabe, Masaru Kuramoto, Masao Ikeda, and Hiroyuki Yokoyama

Appl. Phys. Lett. 99, 111105 (2011); http://dx.doi.org/10.1063/1.3640499 (3 pages) | Cited 2 times

Online Publication Date: 13 September 2011

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We directly generated 1.6-ps optical pulses with a peak power of 20 W at a repetition of 1 GHz using a blue-violet GaInN mode-locked laser diode incorporating a flared waveguide operating in single transverse mode. The flared waveguide enabled optical pulses to be generated with peak powers of over six times higher than those produced using a straight waveguide while preserving the pulse duration.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.60.Fc Modulation, tuning, and mode locking
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.79.Gn Optical waveguides and couplers
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Ultra-low threshold polariton lasing in photonic crystal cavities

Stefano Azzini, Dario Gerace, Matteo Galli, Isabelle Sagnes, Rémy Braive, Aristide Lemaître, Jacqueline Bloch, and D. Bajoni

Appl. Phys. Lett. 99, 111106 (2011); http://dx.doi.org/10.1063/1.3638469 (3 pages) | Cited 9 times

Online Publication Date: 13 September 2011

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The authors show clear experimental evidence of lasing of exciton polaritons confined in L3 photonic crystal cavities. The samples are based on an InP membrane in air containing five InAsP quantum wells. Polariton lasing is observed with thresholds as low as 120 nW, below the Mott transition, while conventional photon lasing is observed for a pumping power one to three orders of magnitude higher.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Tv Photonic crystal lasers and coherent effects
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.70.Qs Photonic bandgap materials
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Angular resolved scattering by a nano-textured ZnO/silicon interface

M. Schulte, K. Bittkau, K. Jäger, M. Ermes, M. Zeman, and B. E. Pieters

Appl. Phys. Lett. 99, 111107 (2011); http://dx.doi.org/10.1063/1.3640238 (3 pages) | Cited 8 times

Online Publication Date: 14 September 2011

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Textured interfaces in thin-film silicon solar cells improve the efficiency by light scattering. A technique to get experimental access to the angular intensity distribution (AID) at textured interfaces of the transparent conductive oxide (TCO) and silicon is introduced. Measurements are performed on a sample with polished microcrystalline silicon layer deposited onto a rough TCO layer. The AID determined from the experiment is used to validate the AID obtained by a rigorous solution of Maxwell’s equations. Furthermore, the applicability of other theoretical approaches based on scalar scattering theory and ray tracing is discussed with respect to the solution of Maxwell’s equations.
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88.40.jj Silicon solar cells
88.40.hj Efficiency and performance of solar cells

Superconducting single photon detectors integrated with single flux quantum readout circuits in a cryocooler

Shigehito Miki, Hirotaka Terai, Taro Yamashita, Kazumasa Makise, Mikio Fujiwara, Masahide Sasaki, and Zhen Wang

Appl. Phys. Lett. 99, 111108 (2011); http://dx.doi.org/10.1063/1.3640503 (3 pages) | Cited 5 times

Online Publication Date: 14 September 2011

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We report the operation of superconducting single photon detectors (SSPDs) with integrated readout electronics based on a single-flux-quantum (SFQ) circuit. The SSPDs were connected to a SFQ readout circuit without bias tee in a cryocooler system, and detection efficiencies (DEs) were measured to verify their correct operation. The DE curves matched well with those measured by conventional readout electronics, and the maximum bias current for normal operation was increased. In addition, we confirmed that the SFQ circuit correctly merged the input signals from two SSPDs. SSPDs with a SFQ readout circuit demonstrated a favorable timing jitter of 50 ps.
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85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices
84.30.-r Electronic circuits
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

Enhanced electrostatic discharge properties of nitride-based light-emitting diodes with inserting Si-delta-doped layers

Zhiyuan Zheng, Zimin Chen, Yulun Xian, Bingfeng Fan, Shanjin Huang, Weiqing Jia, Zhisheng Wu, Gang Wang, and Hao Jiang

Appl. Phys. Lett. 99, 111109 (2011); http://dx.doi.org/10.1063/1.3637599 (3 pages) | Cited 2 times

Online Publication Date: 14 September 2011

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We report significantly improved electrostatic discharge (ESD) properties of InGaN/GaN-based light-emitting diodes (LEDs) with inserting Si-delta-doped layers between multiple quantum wells and n-cladding layer. The ESD endurance voltage increased from −1200 V to −4000 V with the insertion of delta-doped layers. The mechanism of the enhanced ESD properties was then investigated. According to capacitance-voltage results, the factor of capacitance modulation was ruled out. However, infrared microscopy image proved better current spreading in the LEDs with delta-doped layers. In addition, current-voltage, photoluminescence, and atomic force microscope measurements demonstrated substantial quality improvements. These two reasons were considered as the dominant mechanisms of the enhanced ESD properties.
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85.60.Jb Light-emitting devices

Polariton laser based on a ZnO photonic crystal slab

D. D. Solnyshkov, T. Weiss, G. Malpuech, and N. A. Gippius

Appl. Phys. Lett. 99, 111110 (2011); http://dx.doi.org/10.1063/1.3639272 (3 pages) | Cited 2 times

Online Publication Date: 15 September 2011

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We propose a scheme of a ZnO room-temperature polariton laser based on a photonic crystal slab. We predict a very low threshold density for optical pumping: 5 × 1016 cm−3. We have studied the threshold dependence on the parameters of the system, such as detuning. The main advantage of photonic-crystal-based polariton laser is expected to be the simplicity of production.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Fc Modulation, tuning, and mode locking
42.70.Qs Photonic bandgap materials

Controlled tuning of whispering gallery modes of GaN/InGaN microdisk cavities

Igor Aharonovich, Nan Niu, Fabian Rol, Kasey J. Russell, Alexander Woolf, Haitham A. R. El-Ella, Menno J. Kappers, Rachel A Oliver, and Evelyn L. Hu

Appl. Phys. Lett. 99, 111111 (2011); http://dx.doi.org/10.1063/1.3640211 (3 pages) | Cited 1 time

Online Publication Date: 15 September 2011

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Controlled tuning of the whispering gallery modes of GaN/InGaN microdisk cavities is demonstrated. The whispering gallery mode (WGM) tuning is achieved at room temperature by immersing the microdisks in water and irradiating with ultraviolet laser. The tuning rate can be controlled by varying the laser excitation power, with a nanometer precision accessible at low excitation power (approximately several μW). The selective oxidation mechanism is proposed to explain the results and supported by theoretical analysis. The tuning of WGMs in GaN/InGaN microdisk cavities may have important implications in cavity quantum electrodynamics and the development of efficient light emitting devices.
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42.62.-b Laser applications

Stability of Al/Ti/Au contacts to N-polar n-GaN of GaN based vertical light emitting diode on silicon substrate

Junlin Liu, Feifei Feng, Yinhua Zhou, Jianli Zhang, and Fengyi Jiang

Appl. Phys. Lett. 99, 111112 (2011); http://dx.doi.org/10.1063/1.3640229 (3 pages) | Cited 2 times

Online Publication Date: 15 September 2011

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The electrical characteristics of Al/Ti/Au contact to N-polar n-GaN on Si substrate are investigated. It was found that a pre-treatment to the surface with Ar plasma could significantly enhance the stability of Al/Ti/Au contact. Forward voltage of the pre-treated sample was stabilized at about 3.23 V upon 1000 h aging under 900 mA and room temperature. In contrast, forward voltage of the untreated sample increased from 3.52 V to 4 V after 24 h aging. Those differences between the Ar plasma treated sample and untreated sample were attributed to the increase of the VN concentrate near surface of n-GaN by the Ar plasma treatment.
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85.60.Jb Light-emitting devices

Tuning of a cavity in a silicon photonic crystal by thermal expansion of an elastomeric infill

A. Koray Erdamar, M. M. van Leest, S. J. Picken, and J. Caro

Appl. Phys. Lett. 99, 111113 (2011); http://dx.doi.org/10.1063/1.3640235 (3 pages) | Cited 1 time

Online Publication Date: 16 September 2011

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We use an elastomer as infill material for a photonic crystal. As a result of the thermal-expansion-induced strongly negative thermal optical coefficient, this material is highly suitable for thermal tuning of the transmission of a cavity. This is demonstrated by global infilling of a hole-type silicon photonic crystal slab and global thermal tuning. In the temperature range 20-60 °C the cavity peak shows a pronounced elastomer-induced blue shift of 2.7 nm, which amply overcompensates the red shift arising from the thermo-optic property of the silicon. These results qualify the elastomer for tuning by local optical heating.
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78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
78.20.N- Thermo-optic effects
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
42.70.Qs Photonic bandgap materials

Improvement of surface-enhanced Raman scattering performance for broad band gap semiconductor nanomaterial (TiO2): Strategy of metal doping

Libin Yang, Xin Jiang, and Ming Yang

Appl. Phys. Lett. 99, 111114 (2011); http://dx.doi.org/10.1063/1.3638467 (3 pages) | Cited 1 time

Online Publication Date: 16 September 2011

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The strategy of metal doping was performed to improve surface-enhanced Raman scattering (SERS) performance for semiconductor TiO2 and deeply understand the contributing/controlling factors of semiconductor (TiO2)-to-molecule charge transfer (CT) mechanism contributed to SERS. The amount and intrinsic nature of doping ions have a great influence on SERS enhancement. An appropriate doping amount of Fe3+, Co2+, and Ni2+ is 0.5%, 1%, 3% mol., respectively, which can enormously improve SERS properties of TiO2 substrate. The considerable SERS enhancement is attributed to doped metal ions, which can embed abundant doping level in TiO2 band gap contributing to semiconductor (TiO2)-to-molecule CT and SERS effect.
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78.30.Hv Other nonmetallic inorganics
61.72.U- Doping and impurity implantation
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Computational study of cold atmospheric nanosecond pulsed helium plasma jet in air

Doug Breden, Kenji Miki, and Laxminarayan L. Raja

Appl. Phys. Lett. 99, 111501 (2011); http://dx.doi.org/10.1063/1.3636433 (3 pages) | Cited 18 times

Online Publication Date: 12 September 2011

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A luminous plasma jet is produced when helium gas issuing into atmospheric pressure ambient air is excited by high voltage nanosecond pulsing of a dielectric covered electrode. A detailed computational modeling study of such a discharge is presented. The dynamics of streamer propagation, its dependence on the diffusional mixing layer between helium and air species, and the role of photoionization are discussed.
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52.75.-d Plasma devices
52.80.-s Electric discharges

Development of a cold atmospheric pressure microplasma jet for freeform cell printing

Halim Ayan, Eda D. Yildirim, Daphne D. Pappas, and Wei Sun

Appl. Phys. Lett. 99, 111502 (2011); http://dx.doi.org/10.1063/1.3638062 (3 pages) | Cited 1 time

Online Publication Date: 12 September 2011

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An atmospheric pressure non-thermal microplasma jet (Ø 50 μm) was developed for localized functionalization of various substrates, including polymers, to allow maskless freeform cell printing. The applied microplasma jet power ranged from 0.1 to 0.2 W without causing any damage to the polyethylene substrate. The surface characterization results demonstrate that the microplasma treatment locally changes the surface roughness and the concentration of oxygen-containing functional groups on the polyethylene surface. The biological characterization confirms that the osteoblast cells attach and survive on the plasma activated line while untreated surfaces show almost no attachment and viability.
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52.77.-j Plasma applications
81.65.-b Surface treatments

Electric propulsion using an alternating positive/negative corona discharge configuration composed of wire emitters and wire collector arrays in air

Chul Kim, Kwang-Chul Noh, Sang-Yoon Kim, and Jungho Hwang

Appl. Phys. Lett. 99, 111503 (2011); http://dx.doi.org/10.1063/1.3636409 (3 pages) | Cited 2 times

Online Publication Date: 14 September 2011

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We present a study on a corona discharge configuration exclusively composed of thin wires that provides maximal thrust performance and a compact unit staging method. The ion and air flow behaviors were experimentally and numerically investigated. The basic characteristics derived from the experiments are reported for three discharge configurations (positive, negative, and positive/negative alternation). The proposed alternating positive/negative configuration enhanced the thrust (5.4 N/m2 of maximum thrust to air flow area ratio) through the ability to achieve compact staging, compared to a previous study. In addition, two useful equations as criteria in the evaluation of the thrust performance were derived.
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52.80.Hc Glow; corona
89.40.-a Transportation
52.75.Di Ion and plasma propulsion
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Influence of the silicon carbide surface morphology on the epitaxial graphene formation

M. H. Oliveira, Jr., T. Schumann, M. Ramsteiner, J. M. J. Lopes, and H. Riechert

Appl. Phys. Lett. 99, 111901 (2011); http://dx.doi.org/10.1063/1.3638058 (3 pages) | Cited 5 times

Online Publication Date: 12 September 2011

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Graphene grown on SiC(0001) by Si depletion has a stepped surface with terraces and step heights up to 10 times larger than those observed in the original SiC surface. This is due to an additional step bunching that usually occurs during graphene formation. In this work, we show that such process can be suppressed by controlling the initial step structure of the SiC surface. In this case, the graphene monolayer is formed on the SiC without modification of the original surface morphology. We observe that the absence of step bunching during growth has no influence on the graphene structural quality.
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81.05.ue Graphene
68.35.bg Semiconductors
68.55.ap Fullerenes
61.48.Gh Structure of graphene
68.65.Pq Graphene films

First-principles studies on the dominant acceptor and the activation mechanism of phosphorus-doped ZnO

Ping Li, Sheng-Hua Deng, and Jing Huang

Appl. Phys. Lett. 99, 111902 (2011); http://dx.doi.org/10.1063/1.3638460 (3 pages) | Cited 5 times

Online Publication Date: 12 September 2011

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Based on first-principles calculations, we suggest that the PZn-2VZn complex is the dominant acceptor in phosphorus-doped ZnO with a calculated transition level of 150 meV. We suggest that the out-diffusion of zinc interstitials will indirectly favor the formation of the PZn-2VZn complex. According to this mechanism, an upper limit of annealing temperature of about 860 °C is obtained, which is high enough to activate the doped ZnO from n- to p-type. This mechanism applies to the other group-V dopants. The above results are in agreement with the experimental reports.
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71.55.Gs II-VI semiconductors
61.72.jj Interstitials
66.30.J- Diffusion of impurities
61.72.Cc Kinetics of defect formation and annealing

Cd diffusion and thermal stability of CdZnO/ZnO heterostructures

A. Yu. Azarov, T. C. Zhang, B. G. Svensson, and A. Yu. Kuznetsov

Appl. Phys. Lett. 99, 111903 (2011); http://dx.doi.org/10.1063/1.3639129 (3 pages) | Cited 5 times

Online Publication Date: 13 September 2011

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Structural properties and thermal stability of CdZnO/ZnO heterostructures grown on sapphire substrate by metal-organic vapor phase epitaxy (MOVPE) have been studied. Zn/Cd interdiffusion and Cd evaporation appear as key factors limiting the thermal stability of CdZnO/ZnO heterostructures. Cd diffusion in MOVPE ZnO is found to start already at 600 °C with an activation energy of ∼2.2 eV and yields a saturation in the Cd concentration at 0.1-1 at. %. The actual Cd content remaining in the samples upon annealing is determined by a competition between Cd evaporation via the surface and diffusion/segregation in the bulk.
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66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Dv Composition, segregation; defects and impurities
68.35.Fx Diffusion; interface formation
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization

Bidirectional bending splitter of designer surface plasmons

Yong Jin Zhou, Quan Jiang, and Tie Jun Cui

Appl. Phys. Lett. 99, 111904 (2011); http://dx.doi.org/10.1063/1.3639277 (3 pages) | Cited 5 times

Online Publication Date: 13 September 2011

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We propose and experimentally verify a bidirectional bending splitter of designer surface plasmons which is composed of two metallic gratings of trapezoid grooves. A metal wire is used to excite the designer surface plasmons propagating along the gratings. A full-wave numerical method has been used to simulate the performance of the bending splitter. The experimental verifications in the microwave frequencies have excellent agreements to the simulations. It is demonstrated that the splitter can not only split the electromagnetic waves at different frequencies, but also guide the electromagnetic waves effectively for large-angle bending.
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42.79.Fm Reflectors, beam splitters, and deflectors
42.79.Dj Gratings

Calculating the specific contact resistance from the nanostructure at the interface of silver thick film contacts on n-type silicon

Stefan Kontermann, Ralf Preu, and Gerhard Willeke

Appl. Phys. Lett. 99, 111905 (2011); http://dx.doi.org/10.1063/1.3635383 (3 pages) | Cited 1 time

Online Publication Date: 14 September 2011

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Nanoscale silver crystals located on the silicon surface at the interface of silver thick film contacts carry the current across the contacts. By quantifying the interface area between the silver crystals and the silicon from scanning electron microscopy images of the silicon surface beneath the contact, we calculate the macroscopic specific contact resistance for contacts of different quality. We find good agreement with experimental contact resistance measurements. The presented results enable the prediction of the macroscopic specific contact resistance from the nanostructure found at the contact interface.
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73.40.Cg Contact resistance, contact potential
73.63.Rt Nanoscale contacts
81.07.Lk Nanocontacts
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
73.40.Ns Metal-nonmetal contacts

Defect migration and recombination in nanoindentation of silica glass

Ken-ichi Nomura, Yi-Chun Chen, Rajiv K. Kalia, Aiichiro Nakano, and Priya Vashishta

Appl. Phys. Lett. 99, 111906 (2011); http://dx.doi.org/10.1063/1.3637052 (3 pages) | Cited 2 times

Online Publication Date: 14 September 2011

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Deformation, plasticity, and flow in silica-based glasses have been studied for decades, and yet important questions remain about the atomistic mechanisms underlying these processes. Our molecular dynamics simulations of nanoindentation indicate that these mechanical processes have a unified underlying atomistic mechanism. The simulations reveal that indentation nucleates under-coordinated silicon and oxygen defects, which migrate by switching bonds in string-like processes. We also observe defect annihilation in the plastic region underneath and the pileup region around the indenter. These defects have also been observed in simulations of nanovoid coalescence under hydrostatic tension and in nanovoid deformation and breakup in shearing silica glass.
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81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness
62.20.fq Plasticity and superplasticity
61.72.Qq Microscopic defects (voids, inclusions, etc.)
81.40.Lm Deformation, plasticity, and creep

Tetrahedral chalcopyrite quantum dots for solar-cell applications

Juho Ojajärvi, Esa Räsänen, Sascha Sadewasser, Sebastian Lehmann, Philipp Wagner, and Martha Ch. Lux-Steiner

Appl. Phys. Lett. 99, 111907 (2011); http://dx.doi.org/10.1063/1.3640225 (3 pages)

Online Publication Date: 15 September 2011

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Chalcopyrite structures are candidates for efficient intermediate-band solar cells in thin-film technology. Here, we examine a material combination of CuInSe2 dots embedded in CuGaS2 matrix and show that epitaxial growth leads to distinctive tetrahedral nanostructures. Our model calculations provide us with the optimal nanodot size to reach the maximum efficiency—in principle up to 61%. The optimal quantum dot satisfies the known physical constraints, and it is in excellent qualitative agreement with our grown samples.
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88.40.jn Thin film Cu-based I-III-VI2 solar cells
73.21.La Quantum dots
78.67.Hc Quantum dots

The role of plasmons and interband transitions in the color of AuAl2, AuIn2, and AuGa2

V. J. Keast, K. Birt, C. T. Koch, S. Supansomboon, and M. B. Cortie

Appl. Phys. Lett. 99, 111908 (2011); http://dx.doi.org/10.1063/1.3638061 (3 pages) | Cited 3 times

Online Publication Date: 15 September 2011

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First principles calculations of the optical properties of the intermetallic compounds AuAl2, AuIn2, and AuGa2 have been performed. Analysis of the dielectric functions showed that AuAl2 is unique because a bulk plasmon is seen in the optical region and contributes to the purple color of this material. An experimental electron energy-loss spectrum showed excellent agreement with the theoretical prediction and confirmed the presence of the bulk plasmon.
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71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
79.20.Uv Electron energy loss spectroscopy
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