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

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

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

15 Dec 2003

Volume 83, Issue 24, pp. 4897-5097

Issue Cover Spotlight Figure

Appl. Phys. Lett. 83, 4912 (2003); http://dx.doi.org/10.1063/1.1633331 (3 pages)

Bharat R. Acharya, Tom Krupenkin, Siddharth Ramachandran, Z. Wang, C. C. Huang, and John A. Rogers
Enlarge Image | Read More
Page 1 of 3 Pages Next Page | Jump to Page
back to top
RSS Feeds

Photothermal detection of local thermal effects during selective nanophotothermolysis

Vladimir P. Zharov, Valentin Galitovsky, and Mark Viegas

Appl. Phys. Lett. 83, 4897 (2003); http://dx.doi.org/10.1063/1.1632546 (3 pages) | Cited 76 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Photothermal (PT) technique was applied to the detection of laser-induced local thermal effects around absorbing nanoparticles into cells. The experiments demonstrated the capability of this technique for studying the threshold and the dynamic of thermal events around even a single particle in a broad temperature range, including monitoring of microbubble dynamic. PT technique shows promise for optimizing cancer-cell killing by incorporation of gold nanoparticles into the cells (selective “nanophotothermolysis”), as verified by electron microscopy and conventional viability tests. © 2003 American Institute of Physics.
Show PACS
87.85.Qr Nanotechnologies-design
87.85.Rs Nanotechnologies-applications
87.19.Pp Biothermics and thermal processes in biology
87.50.W- Optical/infrared radiation effects
87.17.-d Cell processes
42.62.Be Biological and medical applications
87.19.X- Diseases

Nonperturbing observation of optical near field

S. K. Sekatskii, G. Dietler, B. N. Mironov, V. O. Kompanets, Yu. A. Matveets, S. V. Chekalin, and V. S. Letokhov

Appl. Phys. Lett. 83, 4900 (2003); http://dx.doi.org/10.1063/1.1630860 (3 pages) | Cited 3 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The spatial distribution of light intensity in the near field is studied by observing the photoelectron projection images of a subwavelength nanoaperture. The imaging electrons are obtained as a result of a two-photon external photoelectric effect induced in the aperture formed at the end of an optical fiber by femtosecond pulses of the second-harmonic radiation (410 nm) of a Ti:sapphire laser. The light-field distribution in the aperture is not distorted by any near-by object (such as a medium containing fluorescent molecules), which allows nonperturbing measurement of such a distribution. © 2003 American Institute of Physics.
Show PACS
07.79.Fc Near-field scanning optical microscopes
42.30.Va Image forming and processing
07.60.Vg Fiber-optic instruments
42.81.Wg Other fiber-optical devices
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Luminescence and visible upconversion in nanocrystalline ZrO2:Er3+

E. De la Rosa-Cruz, L. A. Díaz-Torres, R. A. Rodríguez-Rojas, M. A. Meneses-Nava, O. Barbosa-García, and P. Salas

Appl. Phys. Lett. 83, 4903 (2003); http://dx.doi.org/10.1063/1.1632020 (3 pages) | Cited 51 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The structural and luminescence properties of erbium doped zirconium oxide prepared by the sol-gel processes were analyzed. The annealed powders presented a concentration dependent crystallite sizes and crystalline phase, ranging from 28 to 46 nm and from 40 to 96% for the monoclinic phase, respectively. Green (545 nm) and red (680 nm) emissions bands were observed with 489 and 962 nm excitation. Experimental results showed that the emission bands can be tuned by controlling the Er3+ concentration and that the red band is almost quenched with 489 nm whereas it is enhanced with 962 nm excitation. The nature of this behavior is discussed taking into account the nonradiative energy transfer and cross-relaxation process. © 2003 American Institute of Physics.
Show PACS
78.55.Hx Other solid inorganic materials
81.40.Gh Other heat and thermomechanical treatments
61.72.Cc Kinetics of defect formation and annealing
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
61.46.-w Structure of nanoscale materials

Internal quantum efficiency of highly-efficient InxGa1−xN-based near-ultraviolet light-emitting diodes

Satoshi Watanabe, Norihide Yamada, Masakazu Nagashima, Yusuke Ueki, Chiharu Sasaki, Yoichi Yamada, Tsunemasa Taguchi, Kazuyuki Tadatomo, Hiroaki Okagawa, and Hiromitsu Kudo

Appl. Phys. Lett. 83, 4906 (2003); http://dx.doi.org/10.1063/1.1633672 (3 pages) | Cited 61 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The internal quantum efficiency (IQE) of highly-efficient near-UV light-emitting diodes, which shows an external quantum efficiency of 43% at 406 nm, has been measured by excitation power and temperature-dependent photoluminescence (PL). Assuming peak PL quantum efficiency at 8 K is 100%, peak IQE at 300 K was measured to be as high as 63%. At the injected carrier density, which corresponds to 20 mA current injection, IQE and light extraction efficiency were estimated to be about 54% and 80%, respectively. © 2003 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices

Sculpting of three-dimensional nano-optical structures in silicon

Prakash Koonath, Koichiro Kishima, Tejaswi Indukuri, and Bahram Jalali

Appl. Phys. Lett. 83, 4909 (2003); http://dx.doi.org/10.1063/1.1634384 (3 pages) | Cited 6 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Separation by IMplantation of OXygen (SIMOX) based process has been developed to sculpt three-dimensionally integrated nano-optical waveguiding structures in silicon. An approach, based on the implantation of oxygen ions into a silicon substrate, patterned with thermal oxide, has been adopted to synthesize low loss buried rib waveguides in a single implantation step of thickness 286 nm and widths varying from 2 μm to 12 μm. These waveguides show propagation losses in the range of 3–4 dB/cm. The capability of the process to sculpt three-dimensional (3-D) structures has also been demonstrated by defining rib waveguides on the top silicon layer. © 2003 American Institute of Physics.
Show PACS
42.82.Et Waveguides, couplers, and arrays
42.65.Wi Nonlinear waveguides
61.72.uf Ge and Si
81.05.Cy Elemental semiconductors
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
42.86.+b Optical workshop techniques

Tunable optical fiber devices based on broadband long-period gratings and pumped microfluidics

Bharat R. Acharya, Tom Krupenkin, Siddharth Ramachandran, Z. Wang, C. C. Huang, and John A. Rogers

Appl. Phys. Lett. 83, 4912 (2003); http://dx.doi.org/10.1063/1.1633331 (3 pages) | Cited 21 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter describes classes of tunable microfluidic fiber (μFF) devices that use specially designed long-period gratings in which the phase matching condition is satisfied over a wide spectral range. Dynamic tuning is achieved by electrowetting-based pumping of microfluidic plugs back and forth over the gratings. As specific examples, we demonstrate dynamically tunable broadband attenuators and filters with adjustable profiles by using fluids with different refractive indices. These devices have attractive features that include in-fiber design and polarization-independent behavior together with low-power, nonmechanical, fully reversible, and latchable tuning. © 2003 American Institute of Physics.
Show PACS
42.81.Wg Other fiber-optical devices
42.65.-k Nonlinear optics
42.79.Dj Gratings
back to top
RSS Feeds

Caterpillar structures in single-wire Z-pinch experiments

M. D. Johnston, Y. Y. Lau, R. M. Gilgenbach, T. S. Strickler, M. C. Jones, M. E. Cuneo, and T. A. Mehlhorn

Appl. Phys. Lett. 83, 4915 (2003); http://dx.doi.org/10.1063/1.1632535 (3 pages) | Cited 3 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A series of experiments have been performed on single-wire Z pinches (1–2 kA, 20 kV, pulse length 500 ns; Al, Ag, W, or Cu wire of diameter 7.5–50 μm, length 2.5 cm). Excimer laser absorption photographs show expansion of metallic plasmas on a time scale of order 100 ns. The edge of this plasma plume begins to develop structures resembling a caterpillar only after the current pulse reaches its peak value. The growth of these caterpillar structures is shown to be consistent with the Rayleigh–Taylor instability of the decelerating plasma plume front at the later stage of the current pulse. © 2003 American Institute of Physics.
Show PACS
52.59.Qy Wire array Z-pinches
52.59.Px Hard X-ray sources
52.35.Py Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.58.Lq Z-pinches, plasma focus, and other pinch devices
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

Absolute densities of N and excited N2 in a N2 plasma

Sumit Agarwal, Bram Hoex, M. C. M. van de Sanden, Dimitrios Maroudas, and Eray S. Aydil

Appl. Phys. Lett. 83, 4918 (2003); http://dx.doi.org/10.1063/1.1630843 (3 pages) | Cited 33 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Atomic N and excited N2 (N2∗) play important roles in plasma-assisted synthesis of nitride materials, such as GaN. Absolute densities of N and N2∗ were measured at the substrate plane in an inductively coupled N2 plasma in the pressure range of 10 to 200 mTorr using modulated-beam line-of-sight threshold ionization mass spectrometry. The density of N increased with increasing pressure from 2.9×1018 to 1.8×1019 m−3, while the density of N2∗ was in the range of 9.7×1017 to 2.4×1018 m−3, with a maximum at 50 mTorr. Based on the appearance potential of N2∗ at ∼12 eV, we identify this excited molecule as long-lived N2 (A3Σu+) metastable. © 2003 American Institute of Physics.
Show PACS
52.77.Dq Plasma-based ion implantation and deposition
52.25.-b Plasma properties
52.70.Nc Particle measurements
81.15.Jj Ion and electron beam-assisted deposition; ion plating
81.05.Ea III-V semiconductors
back to top
RSS Feeds

Forcibly driven coherent soft phonons in GeTe with intense THz-rate pump fields

Muneaki Hase, Masahiro Kitajima, Shin-ichi Nakashima, and Kohji Mizoguchi

Appl. Phys. Lett. 83, 4921 (2003); http://dx.doi.org/10.1063/1.1633016 (3 pages) | Cited 14 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We propose an experimental technique to generate large amplitude coherent phonons with irradiation of THz-rate pump pulses and to study the dynamics of phase transition in GeTe ferroelectrics. When a single pump pulse irradiates the sample at various pump power densities, the frequency of the soft phonon decreases sublinearly and saturates at higher pump powers. By contrast, when the THz-rate pump pulse sequence irradiates the sample at matched time intervals to forcibly drive oscillation, a large redshift of the phonon frequency is observed without any saturation effects. After excitation with a four pump pulse sequence, the coherent soft phonon becomes strongly damped and leads to a near critical damping condition. This condition indicates that the lattice is driven to a precursor state of the phase transition. © 2003 American Institute of Physics.
Show PACS
63.70.+h Statistical mechanics of lattice vibrations and displacive phase transitions
77.80.B- Phase transitions and Curie point
64.70.K- Solid-solid transitions
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.

Electronically active layers and interfaces in polycrystalline devices: Cross-section mapping of CdS/CdTe solar cells

Iris Visoly-Fisher, Sidney R. Cohen, David Cahen, and Christos S. Ferekides

Appl. Phys. Lett. 83, 4924 (2003); http://dx.doi.org/10.1063/1.1632532 (3 pages) | Cited 13 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electronic mapping of cross sections of a polycrystalline device, the n-CdS/p-CdTe solar cell, show that the photovoltaic and metallurgical junctions coincide to within experimental resolution (50 nm), which rules out both type conversion of CdS and buried homojunctions. Compositional analysis of the CdS supports this. Mapping was done using scanning capacitance, complemented by scanning Kelvin probe microscopy. Our results explain why a high-resistance transparent conducting oxide layer is needed as contact to the CdS for successful device operation. They define limits on inputs for modeling performance of these devices. © 2003 American Institute of Physics.
Show PACS
84.60.Jt Photoelectric conversion
68.35.Ct Interface structure and roughness
85.30.De Semiconductor-device characterization, design, and modeling
81.05.Dz II-VI semiconductors

Island chain formation during liquid phase epitaxy of SiGe on silicon

M. Hanke, H. Raidt, R. Köhler, and H. Wawra

Appl. Phys. Lett. 83, 4927 (2003); http://dx.doi.org/10.1063/1.1633028 (3 pages) | Cited 14 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the evolution of lateral ordering of SiGe nanoscale islands on Si(001), which have been grown by means of liquid phase epitaxy in the Stranski-Krastanow mode. Applying post-growth atomic force microscopy on different sample areas covered by different island densities, we could trace ex-situ the development of extended island chains along the 〈100〉-directions. The linear alignment happens by further nucleation of islands at the end of an already existing formation. Those direct observations will be discussed in terms of finite element strain energy calculations around various island configurations. © 2003 American Institute of Physics.
Show PACS
68.55.A- Nucleation and growth
81.16.Dn Self-assembly
61.46.-w Structure of nanoscale materials
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.37.Ps Atomic force microscopy (AFM)
68.47.Fg Semiconductor surfaces

Room-temperature ultraviolet light-emitting zinc oxide micropatterns prepared by low-temperature electrodeposition and photoresist

Masanobu Izaki, Seiji Watase, and Hisaya Takahashi

Appl. Phys. Lett. 83, 4930 (2003); http://dx.doi.org/10.1063/1.1633677 (3 pages) | Cited 18 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High-quality (0001)-oriented zinc oxide (ZnO) micropatterns, 5-μm-wide microlines and 5-μm-diam microdot arrays, have been prepared on (111) Au-coated (100) Si wafer substrates by electrodeposition at 333 K in zinc nitrate aqueous solution and industrially employed positive type photoresist techniques. The ZnO micropatterns emitted ultraviolet light at photon energy of 3.25 eV due to recombination of bound excitons and visible light at 2.37 and 2.80 eV at room temperature. © 2003 American Institute of Physics.
Show PACS
78.66.Hf II-VI semiconductors
78.55.Et II-VI semiconductors
71.35.Cc Intrinsic properties of excitons; optical absorption spectra

Laterally patterned band structure in micromachined semiconductors

T. H. Stievater, W. S. Rabinovich, J. B. Boos, D. S. Katzer, and M. L. Biermann

Appl. Phys. Lett. 83, 4933 (2003); http://dx.doi.org/10.1063/1.1633671 (3 pages) | Cited 3 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate that micromachining lattice-matched InGaAs quantum wells grown on (001) InP with strained barriers produces precise laterally patterned modifications to the semiconductor band structure. The light-hole and heavy-hole excitonic transitions are mixed and differentially shifted by the micromachining, inducing a surface-normal optical anisotropy characterized by a peak birefringence of Δn = 0.028. The measured optical properties agree with calculations based on finite-element models of the strain combined with an eight-band k⋅p model that includes deformation potentials. This technique may find applications in fields such as surface-normal polarization modulators, quasi-phase matching, and optically-acitve piezoelectric materials.
Show PACS
73.21.Fg Quantum wells
78.67.De Quantum wells
68.65.Fg Quantum wells
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.35.Lk Collective effects (Bose effects, phase space filling, and excitonic phase transitions)
71.15.-m Methods of electronic structure calculations

Launching and decoupling surface plasmons via micro-gratings

Eloise Devaux, Thomas W. Ebbesen, Jean-Claude Weeber, and Alain Dereux

Appl. Phys. Lett. 83, 4936 (2003); http://dx.doi.org/10.1063/1.1634379 (3 pages) | Cited 63 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Controlling separately the launching of surface plasmons and their recovery as freely propagating light is essential for the development of surface plasmon photonic circuits. With this target in mind, we have studied in the near-field the launching of surface plasmons in a well-defined direction by micro-arrays of subwavelength holes milled in a thick metal film. We show that surface plasmons can then be converted back to freely propagating light by means of another appropriately designed array. These results not only provide insight into the efficient decoupling of surface plasmons but also into their role in the enhanced transmission mechanism. © 2003 American Institute of Physics.
Show PACS
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
42.70.Qs Photonic bandgap materials
42.79.Dj Gratings

Green emission from c-axis oriented AlN nanorods doped with Tb

Q. L. Liu, T. Tanaka, J. Q. Hu, F. F. Xu, and T. Sekiguchi

Appl. Phys. Lett. 83, 4939 (2003); http://dx.doi.org/10.1063/1.1634696 (3 pages) | Cited 11 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Green emission has been obtained from c-axis oriented aluminum nitride (AlN) nanorods doped with terbium (Tb) on silicon (111). The nanorods were prepared by reactive radio-frequency magnetron sputtering in argon and nitrogen atmosphere using a target of Al and TbN mixtures, and characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The sharp characteristic emission lines observed in the photoluminescence and cathodoluminescence (CL) spectra at room temperature correspond to the Tb3+ intra-4fn shell transitions. The monochromatic (wavelength = 554 nm) CL images with the high spatial resolution directly show the green emission from the well-aligned nanorods. © 2003 American Institute of Physics.
Show PACS
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
81.07.Bc Nanocrystalline materials
78.55.Cr III-V semiconductors
61.46.-w Structure of nanoscale materials
78.66.Fd III-V semiconductors
81.15.Cd Deposition by sputtering
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
78.60.Hk Cathodoluminescence, ionoluminescence

Ge1−xSnx alloys pseudomorphically grown on Ge(001)

H. Pérez Ladrón de Guevara, A. G. Rodríguez, H. Navarro-Contreras, and M. A. Vidal

Appl. Phys. Lett. 83, 4942 (2003); http://dx.doi.org/10.1063/1.1634374 (3 pages) | Cited 12 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ge1−xSnx alloys were grown on Ge(001) substrates in a conventional rf sputtering system. We determined the in-plane and in-growth lattice parameters, as well as the alloy bulk lattice parameter of the alloys for different Sn concentrations by high resolution x-ray diffraction. The Sn concentration was determined assuming Vegard’s law for the alloy lattice parameter. At low concentrations, we observed that Ge1−xSnx layers have pseudomorphic characteristics for layer thickness from 320 to 680 nm. These characteristics of Ge1−xSnx layers agree with the People and Bean critical thickness model. This structural study opens the possibility of growing dislocation-free Ge1−xSnx alloys below the critical thickness. © 2003 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
81.15.Cd Deposition by sputtering
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.50.Lt Crystal binding; cohesive energy
61.66.Dk Alloys
61.72.Lk Linear defects: dislocations, disclinations

Concentration efficiency of doping in phosphors: Investigation of the copper- and aluminum-doped zinc sulfide

Lai Qi, Burtrand I. Lee, Xuejun Gu, Mica Grujicic, William D. Samuels, and Gregory J. Exarhos

Appl. Phys. Lett. 83, 4945 (2003); http://dx.doi.org/10.1063/1.1633335 (3 pages) | Cited 4 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We studied the effect of dopant concentration in ZnS:Cu, Al phosphor. Photoluminescent (PL) intensity of the chemically etched phosphor particles increased up to 140%, which proved the existence of a dopant concentration gradient. Calculation revealed the quantitative relationship between the dopant concentration and the luminescent intensity by relating the concentration gradient to the PL intensity. The result showed that the most efficient concentration is 100 ppm copper and the concentration quenching starts at 152 ppm. © 2003 American Institute of Physics.
Show PACS
61.72.S- Impurities in crystals
78.55.Et II-VI semiconductors
71.55.Gs II-VI semiconductors
61.72.uj III-V and II-VI semiconductors

Compositional changes on GaN surfaces under low-energy ion bombardment studied by synchrotron-based spectroscopies

Prakash N. K. Deenapanray, M. Petravić, K.-J. Kim, B. Kim, and G. Li

Appl. Phys. Lett. 83, 4948 (2003); http://dx.doi.org/10.1063/1.1626792 (3 pages) | Cited 8 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated compositional changes on GaN surfaces under Ar-ion bombardment using synchrotron-based high-resolution x-ray photoemission (PES) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The low-energy ion bombardment of GaN produces a Ga-rich surface layer which transforms into a metallic Ga layer at higher bombarding energies. At the same time, the photoemission spectra around N 1s core levels reveal the presence of both uncoordinated nitrogen and nitrogen interstitials, which we have analyzed in more details by x-ray absorption measurements at N K edge. We have demonstrated that PES and NEXAFS provide a powerful combination for studying the compositional changes on GaN surfaces. A mechanism for the relocation and loss of nitrogen during ion bombardment in agreement with some recent experimental and theoretical studies of defect formation in GaN has been proposed. © 2003 American Institute of Physics.
Show PACS
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
68.47.Fg Semiconductor surfaces
68.35.Dv Composition, segregation; defects and impurities
79.60.Bm Clean metal, semiconductor, and insulator surfaces
73.20.At Surface states, band structure, electron density of states
78.70.Dm X-ray absorption spectra

Improving optical properties of 1.55 μm GaInNAs/GaAs multiple quantum wells with Ga(In)NAs barrier and space layer

H. Y. Liu, M. Hopkinson, P. Navaretti, M. Gutierrez, J. S. Ng, and J. P. R. David

Appl. Phys. Lett. 83, 4951 (2003); http://dx.doi.org/10.1063/1.1632027 (3 pages) | Cited 30 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present the 1.55 μm GaInNAs/GaAs multiple quantum well (QW) heterostructures with a GaNAs or a GaInNAs barrier and space layer (BSL). The stronger improvement of photoluminescence efficiency has been observed with increasing N concentration in a GaNAs BSL, instead of increasing N composition in GaInNAs QWs, to achieve room-temperature emission above 1.5 μm for GaInNAs/GaNAs multiple QW structure, when the nitrogen concentration in GaInNAs QW is as high as 3%. A further enhancement of photoluminescence intensity and a remarkable reduction of emission linewidth of GaInNAs multiple QWs have been demonstrated by using a GaInNAs quaternary BSL. These effects of a GaInNAs BSL could be understood in terms of the improvement of structural properties of GaInNAs QWs, resulting from the reduction of the strain at QW/BSL interface. These results present a variable approach to further developing GaAs-based light sources in the telecommunication-wavelength range near 1.55 μm. © 2003 American Institute of Physics.
Show PACS
78.67.De Quantum wells
78.55.Cr III-V semiconductors
68.65.Fg Quantum wells

Structure of Nd-doped glasses measured by isotopic substitution in neutron diffraction

C. J. Benmore, J. K. R. Weber, J. E. Siewenie, and K. J. Hiera

Appl. Phys. Lett. 83, 4954 (2003); http://dx.doi.org/10.1063/1.1634690 (3 pages) | Cited 3 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The structural environment of Nd ions in glasses can have a significant effect on their performance in optical devices. Isotopic substitution in neutron diffraction has been used to probe the structure of Nd2O3 doped SiO2 and La2O3+Y2O3+Al2O3 glasses. In the silicate glass, Nd is found to be ∼sixfold coordinated by oxygen atoms at a distance of 2.28(2) Å with additional Nd–O/Si correlations at 3.55(3), 4.78(3), 5.89(3) Å, and higher distances. In the rare-earth aluminate glass a peak at 2.49(2) Å and a shoulder at ∼3 Å indicate the presence of 8 or higher coordinate Nd polyhedra by comparison with bond valence theory. © 2003 American Institute of Physics.
Show PACS
61.43.Fs Glasses
42.70.Ce Glasses, quartz

Core structure and properties of partial dislocations in silicon carbide p-i-n diodes

S. Ha, M. Benamara, M. Skowronski, and H. Lendenmann

Appl. Phys. Lett. 83, 4957 (2003); http://dx.doi.org/10.1063/1.1633969 (3 pages) | Cited 28 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electroluminescence, mobility, and core nature of partial dislocations bounding stacking faults in 4H silicon carbide p-i-n diodes were investigated using optical emission microscopy and transmission electron microscopy (TEM). The stacking faults developed and expanded in the blocking layer during high current forward biasing. Their bounding partial dislocations showed two distinct characteristics. Bright luminescent segments were mobile while dark invisible ones were stationary during biasing. TEM analysis of their Burgers vectors indicated that the mobile segments were silicon-core 30° partial dislocations while the immobile segments were carbon-core 30° ones. © 2003 American Institute of Physics.
Show PACS
85.30.Kk Junction diodes
78.60.Fi Electroluminescence
61.72.Nn Stacking faults and other planar or extended defects
68.35.Dv Composition, segregation; defects and impurities

Unconventional polarization characteristic of rapid photoinduced material motion in liquid crystalline azobenzene polymer films

Nobuyuki Zettsu, Takashi Fukuda, Hiro Matsuda, and Takahiro Seki

Appl. Phys. Lett. 83, 4960 (2003); http://dx.doi.org/10.1063/1.1629800 (3 pages) | Cited 16 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We carried out double-beam interference experiments using an argon ion laser with controlled polarization in order to cause the formation of photoinduced surface relief in liquid crystalline azobenzene polymer films. The irradiation was undertaken on a film in the cis-rich state obtained by a pre-exposure to ultraviolet light. In this procedure, the efficiency of the photoinduced mass transfer was high, more than 1000 times greater than hitherto reported for amorphous azobenzene polymers. This approach revealed the unusual nature of the migration process. Rapid mass migration is promoted by intensity holographic recording, independent of the polarization of the light used for the irradiation. This insensitivity with respect to the polarization of the light led us to the conclusion that rapid mass migration starting from a cis-rich azobenzene polymer is predominately driven by phototriggered elemental processes such as local dewetting, self-organizing motion, and translation diffusion. © 2003 American Institute of Physics.
Show PACS
77.84.Nh Liquids, emulsions, and suspensions; liquid crystals
61.30.Vx Polymer liquid crystals
61.25.H- Macromolecular and polymers solutions; polymer melts

Hydrostatic pressure dependence of the fundamental bandgap of InN and In-rich group III nitride alloys

S. X. Li, J. Wu, E. E. Haller, W. Walukiewicz, W. Shan, Hai Lu, and William J. Schaff

Appl. Phys. Lett. 83, 4963 (2003); http://dx.doi.org/10.1063/1.1633681 (3 pages) | Cited 32 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report studies of the hydrostatic pressure dependence of the fundamental bandgap of InN, In-rich In1−xGaxN (0<x<0.5) and In1−xAlxN (x = 0.25) alloys. The bandgap shift with pressure was measured by optical absorption experiments with samples mounted in diamond anvil cells. The pressure coefficient is found to be 3.0±0.1 meV/kbar for InN. A comparison between our results and previously reported theoretical calculations is presented and discussed. Together with previous experimental results, our data suggest that the pressure coefficients of group III nitride alloys have only a weak dependence on the alloy composition. The photoluminescence signals appear to yield significantly smaller pressure coefficients than the bandgap from absorption measurements. This is due to emission associated with highly localized states. Based on these results, the absolute deformation potentials of the conduction and valence band edges are estimated. © 2003 American Institute of Physics.
Show PACS
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.55.Cr III-V semiconductors
62.50.-p High-pressure effects in solids and liquids
71.20.Nr Semiconductor compounds

Positronium time-of-flight measurements of porous low-k films

R. S. Yu, T. Ohdaira, R. Suzuki, K. Ito, K. Hirata, K. Sato, Y. Kobayashi, and Jun Xu

Appl. Phys. Lett. 83, 4966 (2003); http://dx.doi.org/10.1063/1.1634380 (3 pages) | Cited 14 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate that positronium (Ps) time-of-flight (TOF) spectroscopy provides a powerful technique for probing the structure of porous low-dielectric constant (low-k) films. The emission of ortho-positronium (o-Ps) from the surface of a series of nano-porous silsesquioxane films was studied with a newly developed TOF spectrometer. Clear Ps emission peaks were observed from the two high porosity films (F38 and KI31), indicating their higher open porosity in comparison with other films. We also observed that the energy of o-Ps emission from F38 is much higher than that from KI31. It was concluded that the open pores in the former film are less tortuous, and o-Ps loses significantly less energy emerging from its surface than from that of latter film. © 2003 American Institute of Physics.
Show PACS
07.81.+a Electron and ion spectrometers
77.55.-g Dielectric thin films
77.84.Jd Polymers; organic compounds
77.22.Ch Permittivity (dielectric function)
61.46.-w Structure of nanoscale materials

Model for isothermal crystallization kinetics with metastable phase formation

B. Laine, G. Trapaga, E. Prokhorov, E. Morales-Sánchez, and J. González-Hernández

Appl. Phys. Lett. 83, 4969 (2003); http://dx.doi.org/10.1063/1.1633962 (3 pages) | Cited 4 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter we propose a simple computer stochastic model to represent and gain some insight into the kinetics of transformation in materials with metastable phase formation. This model explains deviations from the well-known Johnson–Mehl–Avrami–Kolmogorov kinetics theory and predicts the three slopes in Avrami’s plot. The model predictions were compared with experimental results obtained from thin-film samples of Ge2Sb2Te5 during isothermal phase transformations. The model includes the two-stage transformation and is capable to reproduce the experimental transformation curves. © 2003 American Institute of Physics.
Show PACS
64.60.My Metastable phases
64.70.K- Solid-solid transitions
Page 1 of 3 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close