APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter UniPHY Group iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

31 Aug 2009

Volume 95, Issue 9, Articles (09xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 95, 091901 (2009); http://dx.doi.org/10.1063/1.3212896 (3 pages)

Noy Bassik, George M. Stern, and David H. Gracias
Enlarge Image | Read More
Page 1 of 4 Pages Next Page | Jump to Page
back to top
RSS Feeds

Photonic bandgap engineering with inverse opal multistacks of different refractive index contrasts

Dae-Kue Hwang, Heeso Noh, Hui Cao, and Robert P. H. Chang

Appl. Phys. Lett. 95, 091101 (2009); http://dx.doi.org/10.1063/1.3216582 (3 pages) | Cited 5 times

Online Publication Date: 31 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have self-assembled photonic crystal with a multistack structure using same size of spheres but from materials with different refractive indices. Al2O3, ZnO, and TiO2 are infiltrated into opal templates by atomic layer deposition. Stacking multiple inverse opal structures with different refractive index contrasts broadens the reflection bands dramatically. Numerical simulations with plane wave expansion method show good agreement with experimental results.
Show PACS
42.70.Qs Photonic bandgap materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
81.16.Dn Self-assembly
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.66.-w Optical properties of specific thin films

Slow light in narrow paraffin-coated vapor cells

M. Klein, M. Hohensee, A. Nemiroski, Y. Xiao, D. F. Phillips, and R. L. Walsworth

Appl. Phys. Lett. 95, 091102 (2009); http://dx.doi.org/10.1063/1.3207825 (3 pages) | Cited 2 times

Online Publication Date: 2 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Alkali vapor cells with antirelaxation coated walls can have long atomic coherence times. However, using such coated cells in the hyperfine configuration for electromagnetically induced transparency (EIT) requires longitudinal atomic motion to be confined to less than the hyperfine wavelength. We employed a narrow (1 mm) coated cell geometry to study hyperfine EIT and slow and stored light in warm 87Rb vapor, with results comparable to those in buffer gas cells and showing the promise of such cells for several applications.
Show PACS
42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption
42.79.Wc Optical coatings

Practical fast gate rate InGaAs/InP single-photon avalanche photodiodes

Jun Zhang, Rob Thew, Claudio Barreiro, and Hugo Zbinden

Appl. Phys. Lett. 95, 091103 (2009); http://dx.doi.org/10.1063/1.3223576 (3 pages) | Cited 16 times

Online Publication Date: 3 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a practical and easy-to-implement method for high-speed near infrared single-photon detection based on InGaAs/InP single-photon avalanche photodiodes (SPADs), combining aspects of both sine gating and self-differencing techniques. At a gating frequency of 921 MHz and temperature of −30 °C we achieve a detection efficiency of 9.3%, a dark count probability of 2.8×10−6 ns−1, while the afterpulse probability is 1.6×10−4 ns−1, with a 10 ns “count-off time” setting. In principle, the maximum count rate of the SPAD can approach 100 MHz, which can significantly improve the performance for diverse applications.
Show PACS
85.60.Dw Photodiodes; phototransistors; photoresistors

Extremely high efficient coupling between long range surface plasmon polariton and dielectric waveguide mode

Fang Liu, Ruiyuan Wan, Yunxiang Li, Yidong Huang, Yoshikatsu Miura, Dai Ohnishi, and Jiangde Peng

Appl. Phys. Lett. 95, 091104 (2009); http://dx.doi.org/10.1063/1.3212145 (3 pages) | Cited 3 times

Online Publication Date: 3 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
To connect the surface plasmon polariton (SPP) based devices with the conventional dielectric devices is a significant issue for the further development of SPP and related applications. In this paper, extremely high efficient coupling (>99%) between long range SPP (LRSPP) waveguide mode and TM mode of dielectric waveguide has been demonstrated from a hybrid coupler, which composed of an Au (LRSPP) waveguide and a SiN (dielectric) waveguide. Based on this hybrid coupler, a polarization splitter with pure TM mode output from one arm and TE mode output from the other arm with high TE/TM extinction ratio has been realized.
Show PACS
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
84.40.Az Waveguides, transmission lines, striplines

Surface-plasmon distributed-feedback quantum cascade lasers operating pulsed, room temperature

A. Bousseksou, Y. Chassagneux, J. R. Coudevylle, R. Colombelli, C. Sirtori, G. Patriarche, G. Beaudoin, and I. Sagnes

Appl. Phys. Lett. 95, 091105 (2009); http://dx.doi.org/10.1063/1.3202765 (3 pages) | Cited 1 time

Online Publication Date: 3 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report distributed-feedback surface-plasmon quantum cascade lasers operating at λ ≈ 7.6 μm. The distributed feedback is obtained by the sole patterning of the top metal contact on a surface plasmon waveguide. Single mode operation with more than 30 dB side mode suppression ratio is obtained in pulsed mode and at room temperature. A careful experimental study confirms that by varying the grating duty cycle, one can reduce the waveguide losses with respect to standard, unpatterned surface-plasmon devices. This allows one to reduce the laser threshold current of more than a factor of 2 in the 200–300 K temperature range. This approach may lead to a fabrication technology for midinfrared distributed-feedback lasers based on a very simple processing.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.79.Gn Optical waveguides and couplers
42.60.By Design of specific laser systems

High efficiency reflective liquid crystal polarization gratings

R. K. Komanduri and M. J. Escuti

Appl. Phys. Lett. 95, 091106 (2009); http://dx.doi.org/10.1063/1.3197011 (3 pages) | Cited 7 times

Online Publication Date: 3 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We experimentally demonstrate a reflective-mode liquid crystal polarization grating with high reflectance, small grating period, and subms switching times. This switchable optical element can diffract ∼ 100% into a single order, have highly polarization-sensitive first orders, and have a polarization-insensitive zero order. Here we introduce an absorbing layer that overcomes the reflection of the (ultraviolet) holographic beams, which otherwise prevents high quality fabrication. At a grating period of 2.1 μm, we report 98% diffraction efficiency, 90% reflectance, ∼ 600:1 contrast-ratio, and ∼ 3000:1 polarization contrast. These elements can therefore be configured as polarization-independent modulators or switchable polarizing beam splitters, for use in telecommunications, displays, spatial-light modulators, and polarimetry.
Show PACS
42.79.Dj Gratings
61.30.-v Liquid crystals
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Fm Reflectors, beam splitters, and deflectors
42.40.Eq Holographic optical elements; holographic gratings
42.79.Hp Optical processors, correlators, and modulators
42.82.Cr Fabrication techniques; lithography, pattern transfer

Contribution of water droplets to charge release by laser filaments in air

Stefano Henin, Yannick Petit, Denis Kiselev, Jérôme Kasparian, and Jean-Pierre Wolf

Appl. Phys. Lett. 95, 091107 (2009); http://dx.doi.org/10.1063/1.3220066 (3 pages) | Cited 3 times

Online Publication Date: 4 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We measured the electric charge release from single water microdroplets illuminated by ultrashort laser filaments in air. This charge is up to 600 times larger than from a comparable filament volume in air. In contrast, for atmospheric droplet concentrations and sizes, the volume-averaged overall droplet contribution to the charge is small as compared with that of the filaments along its whole propagation path.
Show PACS
92.60.Jq Water in the atmosphere
47.55.D- Drops and bubbles

Laser dynamic forming of functional materials laminated composites on patterned three-dimensional surfaces with applications on flexible microelectromechanical systems

Cunjiang Yu, Huang Gao, Hongyu Yu, Hanqing Jiang, and Gary J. Cheng

Appl. Phys. Lett. 95, 091108 (2009); http://dx.doi.org/10.1063/1.3222863 (3 pages) | Cited 8 times

Online Publication Date: 4 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Laser dynamic forming (LDF) is a three-dimensional (3D) forming technique, which utilizes laser to induce shock wave and shape the target thin films onto micro/nanoscale 3D surfaces. This technique has been used to form metals on 3D surfaces. This letter extends LDF to functional and brittle materials sandwiched by elastomeric polymers on patterned 3D surface. The elastomeric polymers absorb the shock energy and minimize the degradation of the functional materials. The patterned 3D surfaces control the plasticity in the structure and therefore retain the function of the structure. The performance was evaluated and mechanisms were studied.
Show PACS
42.62.-b Laser applications
81.10.Fq Growth from melts; zone melting and refining
61.41.+e Polymers, elastomers, and plastics
62.50.Ef Shock wave effects in solids and liquids
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
62.20.mj Brittleness

Selective excitation of laser modes in an organic photonic dot microcavity

M. Langner, M. Sudzius, H. Fröb, V. G. Lyssenko, and K. Leo

Appl. Phys. Lett. 95, 091109 (2009); http://dx.doi.org/10.1063/1.3222981 (3 pages) | Cited 2 times

Online Publication Date: 4 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We experimentally investigate variable laser mode excitation in an organic photonic dot microcavity by shifting the excitation beam position. The sample comprises two highly reflective dielectric mirrors (R>99.9%) and a square-shaped organic dye mesa of a DCM doped (2 wt %) Alq3-matrix. Its wavelength-size ( ≈ 5×5 μm2) transforms the cavity mode dispersion to a set of discrete states, each with a different intensity distribution of the electromagnetic field in space. Numerical simulations, including absorption and gain, confirm the experimentally observed relation between mode distribution and progression on the excitation condition.
Show PACS
42.55.Sa Microcavity and microdisk lasers
42.60.By Design of specific laser systems
42.79.Bh Lenses, prisms and mirrors
42.55.Px Semiconductor lasers; laser diodes

High-temperature continuous-wave operation of low power consumption single-mode distributed-feedback quantum-cascade lasers at λ ∼ 5.2 μm

Feng Xie, Catherine G. Caneau, Herve P. LeBlanc, Nick J. Visovsky, Sean Coleman, Lawrence C. Hughes, and Chung-en Zah

Appl. Phys. Lett. 95, 091110 (2009); http://dx.doi.org/10.1063/1.3216074 (3 pages) | Cited 11 times

Online Publication Date: 4 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Continuous-wave operation of a distributed-feedback quantum-cascade laser in a packaged module is demonstrated up to a heat sink temperature of 80 °C with an output power of greater than 10 mW and a power consumption of less than 3.8 W. Single longitudinal mode emission near 5.24 μm is observed over a temperature range from 10 to 80 °C with a side mode suppression ratio greater than 20 dB limited by the instrumentation. A single spatial mode is determined with far-field pattern measurement. The above performance is achieved using a buried heterostructure and a small cavity of 7.6 μm×1.5 mm.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Capacitance switching in SiO2 thin film embedded with Ge nanocrystals caused by ultraviolet illumination

M. Yang, T. P. Chen, L. Ding, Y. Liu, F. R. Zhu, and S. Fung

Appl. Phys. Lett. 95, 091111 (2009); http://dx.doi.org/10.1063/1.3224191 (3 pages)

Online Publication Date: 4 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A structure of indium tin oxide/SiO2 embedded with Ge nanocrystal (nc-Ge)/p-Si substrate was fabricated. The capacitance of the structure can be switched to a high-capacitance or low-capacitance state by an ultraviolet (UV) illumination. The increase (or decrease) in the capacitance is accompanied with the decrease (or increase) in the oxide resistance. The capacitance switching is explained in terms of the UV illumination-induced charging and discharging in the nc-Ge.
Show PACS
72.40.+w Photoconduction and photovoltaic effects
73.50.Pz Photoconduction and photovoltaic effects
77.55.-g Dielectric thin films
73.63.Bd Nanocrystalline materials
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
back to top
RSS Feeds

Wakefield driven by Gaussian (1,0) mode laser pulse and laser-plasma electron acceleration

H. O. Che, Q. Kong, Q. Q. Mao, P. X. Wang, Y. K. Ho, and S. Kawata

Appl. Phys. Lett. 95, 091501 (2009); http://dx.doi.org/10.1063/1.3187221 (3 pages) | Cited 1 time

Online Publication Date: 2 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An ultraintense Gaussian (1,0) mode pulsed laser applied to laser-plasma electron acceleration is investigated based on 2.5-dimensional particle-in-cell simulation (PIC). It has been found that Gaussian (1,0) mode laser pulse may blow out plasma electrons and form two symmetrical electron cavities with an electron wall between them. This electron wall separates two twisting bunches of transverse injected electrons and lets each of them be accelerated in one cavity, respectively. At the front of the wall, a bunch of reflux electrons with a magnetic field contributes to the electron self-bunching effect. This mechanism may generate two symmetrical, high-density, and monoenergetic electron beams with small transverse emittances.
Show PACS
29.20.Ej Linear accelerators
52.38.Kd Laser-plasma acceleration of electrons and ions
52.38.Dx Laser light absorption in plasmas (collisional, parametric, etc.)
52.65.Rr Particle-in-cell method
41.75.Fr Electron and positron beams
29.27.Eg Beam handling; beam transport
29.27.Ac Beam injection and extraction
52.25.-b Plasma properties
back to top
RSS Feeds
FREE

Microassembly based on hands free origami with bidirectional curvature

Noy Bassik, George M. Stern, and David H. Gracias

Appl. Phys. Lett. 95, 091901 (2009); http://dx.doi.org/10.1063/1.3212896 (3 pages) | Cited 12 times

Online Publication Date: 31 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Microassembly based on origami, the Japanese art of paper folding, presents an attractive methodology for constructing complex three-dimensional (3D) devices and advanced materials. A variety of functional structures have been created using patterned metallic, semiconducting, and polymeric thin films, but have been limited to those that curve in a single direction. We report a design framework that can be used to achieve spontaneous bidirectional folds with any desired angle, and we demonstrate theoretical and experimental realizations of complex 3D structures with +90°, −90°, +180°, and −180° folds. The strategy is parallel, versatile, and compatible with conventional microfabrication.
Show PACS
07.10.Cm Micromechanical devices and systems

Self-organization of polymer nanoneedles into large-area ordered flowerlike arrays

Dong Wu, Qi-Dai Chen, Bin-Bin Xu, Jian Jiao, Ying Xu, Hong Xia, and Hong-Bo Sun

Appl. Phys. Lett. 95, 091902 (2009); http://dx.doi.org/10.1063/1.3213394 (3 pages) | Cited 11 times

Online Publication Date: 31 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Combination of top-down and bottom-up process is crucial for fabricating ordered complex micronanostructures. Here we report a simple, rapid, and versatile approach to demonstrate this useful concept, which involves the joint use of multibeam interference patterning and capillary force self-organization. Regular hydrophobic arrays of four-peddle nanoflowers consisting of bent needles with 300 nm tip diameters are readily produced. A “domino model” based on the balance of the capillary and support forces were proposed to interpret realization of large-area homogeneity of the array. The technology, promising for preparing more complex and functional structures, may find broad utilization in nano and biological researches.
Show PACS
81.16.Rf Micro- and nanoscale pattern formation
61.41.+e Polymers, elastomers, and plastics

A comprehensive study of the phase diagram of KxNa1−xNbO3

D. W. Baker, P. A. Thomas, N. Zhang, and A. M. Glazer

Appl. Phys. Lett. 95, 091903 (2009); http://dx.doi.org/10.1063/1.3212861 (3 pages) | Cited 9 times

Online Publication Date: 31 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The phase diagram of lead-free piezoelectric KxNa1−xNbO3 has been studied, with particular focus on the proposed morphotropic phase boundaries, by powder and single crystal x-ray diffraction. The tilt system and cation displacement has been mapped out as a function of temperature and composition, highlighting changes in the oxygen octahedra at x = 0.2 and x = 0.4 at room temperature. The orthorhombic to monoclinic boundary at x = 0.5 has been investigated, with a subtle change in the structure observed. The conclusion is that KxNa1−xNbO3 does not display a morphotropic phase boundary comparable with that in lead zirconate titanate, and that the most significant structural change as a function of composition occurs at x = 0.2 because of the change of the tilt system.
Show PACS
81.30.Dz Phase diagrams of other materials
77.65.-j Piezoelectricity and electromechanical effects
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials

Characterization of the quality of ZnO thin films using reflective second harmonic generation

Yi-Jen Huang, Kuang-Yao Lo, Chung-Wei Liu, Chun-Chu Liu, and Sheng-Yuan Chu

Appl. Phys. Lett. 95, 091904 (2009); http://dx.doi.org/10.1063/1.3216848 (3 pages) | Cited 1 time

Online Publication Date: 31 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A polar mirror symmetrical contribution originated from the arrangement of grain boundaries existing in the ZnO film is detected by reflective second harmonic generation pattern. The ordering of ZnO grain boundary is dependent on the kinetic energy of deposited atoms and affects the quality of ZnO films. The net direction of the grain boundary in ZnO film trends toward the [math10] direction of Si(111) to reach the minimum grain energy for better quality ZnO film. The polar structure of the mirrorlike boundaries under the optically macroscopic viewpoint presents a correlation with film quality.
Show PACS
68.55.ag Semiconductors
81.15.Cd Deposition by sputtering
81.05.Dz II-VI semiconductors
78.66.Hf II-VI semiconductors
61.72.Mm Grain and twin boundaries
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Direct measurement of thermal conductivity of aluminum nanowires

N. Stojanovic, J. M. Berg, D. H. S. Maithripala, and M. Holtz

Appl. Phys. Lett. 95, 091905 (2009); http://dx.doi.org/10.1063/1.3216035 (3 pages) | Cited 3 times

Online Publication Date: 1 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A nanofabricated electrothermal test structure is reported for directly measuring the thermal conductivity of aluminum nanowires near room temperature. Interdigitated nanowires perturb an otherwise symmetric heater-sensor structure analogous to an electrical bridge circuit. Nanowires studied are 100 nm thick with 75, 100, and 150 nm widths. Finite element simulation accounts for complex device geometry. Thermal conductivity and electrical resistivity vary significantly with nanowire dimensions. Electron transport equation models which adequately describe the resistivity data consistently underestimate the thermal conductivity. Incorporating a phonon contribution of ∼ 21 W/m K to the total thermal conductivity is found to accurately describe the measured values.
Show PACS
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys
63.22.Gh Nanotubes and nanowires
81.16.-c Methods of micro- and nanofabrication and processing
81.07.-b Nanoscale materials and structures: fabrication and characterization

Optical anisotropy readout in solid-state porphyrins for the detection of volatile compounds

G. Bussetti, S. Cirilli, A. Violante, P. Chiaradia, C. Goletti, L. Tortora, R. Paolesse, E. Martinelli, A. D’Amico, C. Di Natale, G. Giancane, and L. Valli

Appl. Phys. Lett. 95, 091906 (2009); http://dx.doi.org/10.1063/1.3202400 (3 pages) | Cited 4 times

Online Publication Date: 1 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The controlled adsorption of molecules of volatile compounds on Langmuir–Schäfer films of tetraphenylporphyrins produces a modification of the film optical anisotropy, as revealed by reflectance anisotropy spectroscopy (RAS). These experiments allow a better understanding of the molecular package occurring in the film as well as of its alteration upon the interaction with volatile compounds, helping in the comprehension of the mechanisms responsible for the binding of molecules. The results recommend RAS as a potential transducer technique for chemical sensing.
Show PACS
42.70.Jk Polymers and organics
78.66.Qn Polymers; organic compounds
42.79.Wc Optical coatings
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Depth-profiling of elastic inhomogeneities in transparent nanoporous low-k materials by picosecond ultrasonic interferometry

C. Mechri, P. Ruello, J. M. Breteau, M. R. Baklanov, P. Verdonck, and V. Gusev

Appl. Phys. Lett. 95, 091907 (2009); http://dx.doi.org/10.1063/1.3220063 (3 pages) | Cited 9 times

Online Publication Date: 2 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We achieve depth-profiling of the elasticity of a thin transparent film of a nanoporous low-k material using picosecond acoustic interferometry. The variation in the material properties with depth is extracted from time-resolved femtosecond optical reflectivity measurements. More than 40% of the variation in the longitudinal elastic modulus between the front and the back surfaces of an 800 nm thick nanoporous layer is mapped with a 40 nm spatial resolution. We attribute this variation to the spatially inhomogeneous UV curing of the film during fabrication.
Show PACS
68.60.Bs Mechanical and acoustical properties
78.66.-w Optical properties of specific thin films
81.40.Jj Elasticity and anelasticity, stress-strain relations
77.55.-g Dielectric thin films
61.43.Gt Powders, porous materials
78.47.D- Time resolved spectroscopy (>1 psec)

Effect of microcontent of oil in water under confined condition

Liran Ma, Jianbin Luo, Chenhui Zhang, Shuhai Liu, and Tao Zhu

Appl. Phys. Lett. 95, 091908 (2009); http://dx.doi.org/10.1063/1.3222913 (3 pages) | Cited 3 times

Online Publication Date: 2 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The lubricant film thickness between two contacting surfaces is important for the evaluation of lubrication effectiveness. According to the elastohydrodynamic lubrication theory, the film thickness of pure water is usually on the order of a few nanometers. It was found, however, that microcontent of oil contamination can cause a lubricant film more than 100 nm, much thicker than the predicted. The effect of micro-oil content in water between a smooth plate and a highly polished steel ball was investigated. The film forming characteristic of such films was presented. The film formation mechanism and influencing factors were discussed.
Show PACS
68.15.+e Liquid thin films
68.08.Bc Wetting
81.40.Pq Friction, lubrication, and wear
62.10.+s Mechanical properties of liquids

Reversing the temperature dependence of the sensitized Er3+ luminescence intensity

F. Lenz, A. Hryciw, R. DeCorby, and A. Meldrum

Appl. Phys. Lett. 95, 091909 (2009); http://dx.doi.org/10.1063/1.3220060 (3 pages) | Cited 4 times

Online Publication Date: 3 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The temperature-induced quenching of the Er3+ luminescence is a significant problem in silicon-based materials systems ultimately designed for room-temperature applications. Here, we show that amorphous silicon-rich oxide, moderately annealed in order to avoid growth of Si nanocrystals, exhibits a reversed temperature dependence in which the integrated Er3+ luminescence increases in intensity upon heating from 77 up to 300 K. This behavior is attributed to a unique spectrum of interacting defects that efficiently sensitize the Er3+ levels, even in the absence of nanocrystals. The effect could have ramifications in fiber-optic emitters or amplifiers to be operated at noncryogenic temperatures.
Show PACS
78.55.Hx Other solid inorganic materials
81.40.Gh Other heat and thermomechanical treatments
42.55.Wd Fiber lasers

Dynamics of carrier recombination and localization in AlGaN quantum wells studied by time-resolved transmission spectroscopy

V. Liuolia, S. Marcinkevičius, A. Pinos, R. Gaska, and M. S. Shur

Appl. Phys. Lett. 95, 091910 (2009); http://dx.doi.org/10.1063/1.3222972 (3 pages) | Cited 4 times

Online Publication Date: 3 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Time-resolved transmission and photoluminescence measurements were performed on Al0.35Ga0.65N/Al0.49Ga0.51N quantum well structures with different well widths. Comparison of transmission and luminescence data shows that dynamics of electrons and holes excited into extended quantum well states are governed by nonradiative recombination. For excita-tion into potential minima formed by band gap fluctuations, localization of electrons was observed. Excitation energy dependence of the pump-probe transient shape allows estimating locali-zation potential, which is about 80 meV independently of the well width, and is prob-ably caused by fluctuations of AlN molar fraction.
Show PACS
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.63.Hs Quantum wells
71.20.Nr Semiconductor compounds
78.67.De Quantum wells
73.21.Fg Quantum wells
78.47.jd Time resolved luminescence
78.47.D- Time resolved spectroscopy (>1 psec)
78.55.Cr III-V semiconductors

Interdiffusion and crystallization in HfO2/Al2O3 superlattices

C. Adelmann, J. Kesters, K. Opsomer, C. Detavernier, J. A. Kittl, and S. Van Elshocht

Appl. Phys. Lett. 95, 091911 (2009); http://dx.doi.org/10.1063/1.3223616 (3 pages) | Cited 4 times

Online Publication Date: 3 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The interplay of interdiffusion and crystallization in HfO2/Al2O3 superlattices during spike annealing at 1050 °C was studied using x-ray reflectivity and x-ray diffraction. A transition in thermal stability was found as a function of HfO2 thickness between 2.3 and 3.2 nm. This transition is due to a crossover of HfO2 crystallization and amorphous HfO2/Al2O3 interdiffusion kinetics. For thin HfO2, amorphous HfO2 and Al2O3 interdiffuse and subsequently crystallize as HfAlOx into a cubic-HfO2-like phase. For thicker HfO2, HfO2 layers crystallize individually into the monoclinic phase. As a consequence, interdiffusion between HfO2 and Al2O3 is suppressed because of the immiscibility of Al2O3 in monoclinic HfO2.
Show PACS
66.30.Ny Chemical interdiffusion; diffusion barriers
68.65.Cd Superlattices
81.40.Gh Other heat and thermomechanical treatments
64.75.Bc Solubility
64.70.K- Solid-solid transitions
68.55.-a Thin film structure and morphology

Diameter dependence of modulus in zinc oxide nanowires and the effect of loading mode: In situ experiments and universal core-shell approach

Mo-Rigen He, Y. Shi, W. Zhou, J. W. Chen, Y. J. Yan, and J. Zhu

Appl. Phys. Lett. 95, 091912 (2009); http://dx.doi.org/10.1063/1.3205102 (3 pages) | Cited 8 times

Online Publication Date: 4 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Uniaxial tensile measurements have been performed on [0001]-oriented zinc oxide nanowires (NWs) with diameters ranging from 18 to 204 nm using a homemade in situ mechanical testing system. Diameter dependence of tensile modulus (TM) is further compared with that of bending modulus (BM, shown earlier). With diameters of NWs decreasing in an intermediate range (about 30–120 nm), TM increases slower than BM, while it gets close to the latter with diameters decreasing below 30 nm; for rather large diameters, they both tend to the bulk modulus. A core-shell model is developed based on diameter-dependent and radial-distributed elastic stiffening in NWs and well explains our experimental results.
Show PACS
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.40.Lm Deformation, plasticity, and creep
62.25.-g Mechanical properties of nanoscale systems
62.20.de Elastic moduli
81.40.Jj Elasticity and anelasticity, stress-strain relations
81.70.Bt Mechanical testing, impact tests, static and dynamic loads

Room-temperature green upconversion luminescence in LaMgAl11O19:Mn2+, Yb3+ upon infrared excitation

R. Martín-Rodríguez, R. Valiente, and M. Bettinelli

Appl. Phys. Lett. 95, 091913 (2009); http://dx.doi.org/10.1063/1.3220059 (3 pages) | Cited 6 times

Online Publication Date: 4 September 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a spectroscopic study of the green upconversion luminescence of Mn2+ upon near infrared Yb3+ excitation in LaMgAl11O19 codoped with manganese and ytterbium. Excitation at 975 nm with a diode laser resonant with the 2F7/2→2F5/2 Yb3+ transition induces a broad emission band centered at 514 nm and assigned to the 4T1→6A1 transition of tetrahedral Mn2+. The upconversion luminescence can be seen by the naked eye up to 500 K. This finding is a promising step in order to use the Mn2+–Yb3+ system as a potential candidate for display phosphors by upconversion.
Show PACS
78.55.Hx Other solid inorganic materials
61.72.up Other materials
Page 1 of 4 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Your Recent History Recent History Help

Recently Viewed

  1. Measurement of the Peltier coefficient of semiconductors by lock-in thermography
  2. Chemical and electronic surface structure of 20%-efficient Cu(In,Ga)Se2 thin film solar cell absorbers
  3. Bendable high-frequency microwave switches formed with single-crystal silicon nanomembranes on plastic substrates
  4. Nanosecond switching in GeTe phase change memory cells
  5. Optical black hole: Broadband omnidirectional light absorber
Go to AIP Home
Copyright © American Institute of Physics
close