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

6 Feb 2006

Volume 88, Issue 6, Articles (06xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 88, 063509 (2006); http://dx.doi.org/10.1063/1.2171834 (3 pages)

M. Feng, N. Holonyak, R. Chan, A. James, and G. Walter
Enlarge Image | Read More
Page 2 of 5 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Laser-induced shockwave propagation from ablation in a cavity

Xianzhong Zeng, Xianglei Mao, Samuel S. Mao, Sy-Bor Wen, Ralph Greif, and Richard E. Russo

Appl. Phys. Lett. 88, 061502 (2006); http://dx.doi.org/10.1063/1.2172738 (3 pages) | Cited 20 times

Online Publication Date: 10 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The propagation of laser-induced shockwaves from ablation inside of cavities was determined from time-resolved shadowgraph images. The temperature and electron number density of the laser-induced plasma was determined from spectroscopic measurements. These properties were compared to those for laser ablation on the flat surface under the same energy and background gas condition. A theoretical model was proposed to determine the amount of energy and vaporized mass stored in the vapor plume based on these measurements.
Show PACS
52.38.Mf Laser ablation
52.38.Dx Laser light absorption in plasmas (collisional, parametric, etc.)
52.35.Tc Shock waves and discontinuities
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
back to top
RSS Feeds

Plasmon-enhanced molecular fluorescence from an organic film in a tunnel junction

Hongwen Liu, Yutaka Ie, Tatsuo Yoshinobu, Yoshio Aso, Hiroshi Iwasaki, and Ryusuke Nishitani

Appl. Phys. Lett. 88, 061901 (2006); http://dx.doi.org/10.1063/1.2171795 (3 pages) | Cited 21 times

Online Publication Date: 6 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Scanning tunneling microscope (STM)-excited molecular fluorescence from H2TBP porphyrin (H2TBPP) thin films on Au (111), Ag, highly oriented pyrolytic graphite (HOPG), and indium tin oxide (ITO) surfaces has been investigated in air. Molecular fluorescence was observed from the H2TBPP films on Au and Ag, but it was extremely weak or undetectable from films on HOPG and ITO. The maximum intensity of molecular fluorescence from H2TBPP/Ag is at least 100 times stronger than that from H2TBPP/HOPG. Strong enhancement of molecular excitation by substrate surface plasmons is suggested for the STM-excited molecular fluorescence from H2TBPP only on the noble metal substrates.
Show PACS
78.55.Kz Solid organic materials
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)

First-principles study of the anisotropic thermal expansion of wurtzite ZnS

S. Q. Wang

Appl. Phys. Lett. 88, 061902 (2006); http://dx.doi.org/10.1063/1.2172145 (3 pages) | Cited 13 times

Online Publication Date: 6 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, a first-principles study of the anisotropic thermal expansion of wurtzite ZnS in the framework of the density-functional theory and the density-functional perturbation theory is reported. The compound in zinc blende structure is also studied for comparison. The curves of the linear and volume thermal expansion coefficients to temperature are presented. The volume thermal expansion coefficient of zinc blende ZnS changes from smaller to larger than that of wurtzite ZnS as temperature increases. The theoretical cross point is at 867 K. The recent experimental observation of phase controlled synthesis of ZnS nanomaterials is explained from the viewpoint of Gibbs free energy.
Show PACS
65.40.De Thermal expansion; thermomechanical effects
61.66.Fn Inorganic compounds
65.40.G- Other thermodynamical quantities

Determining thermal diffuse scattering of vanadium with x-ray transmission scattering

Yang Ding, Paul Chow, Ho-Kwang Mao, Yang Ren, and Charles T. Prewitt

Appl. Phys. Lett. 88, 061903 (2006); http://dx.doi.org/10.1063/1.2170142 (3 pages) | Cited 1 time

Online Publication Date: 6 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this work, we have proposed a fitting model to evaluate thermal diffuse scattering in the case of high energy incident x ray with Laue transmission scattering, applicable in future studies on samples at high pressure in a diamond anvil cell. We show that the fitting model including a Voigt function and a lattice contribution can account for the measured data. Phonon dispersion curves extracted in this way are consistent with data collected previously by other methods.
Show PACS
78.70.Ck X-ray scattering
63.20.D- Phonon states and bands, normal modes, and phonon dispersion

Crack-free GaN/AlN distributed Bragg reflectors incorporated with GaN/AlN superlattices grown by metalorganic chemical vapor deposition

G. S. Huang, T. C. Lu, H. H. Yao, H. C. Kuo, S. C. Wang, Chih-Wei Lin, and Li Chang

Appl. Phys. Lett. 88, 061904 (2006); http://dx.doi.org/10.1063/1.2172007 (3 pages) | Cited 29 times

Online Publication Date: 7 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A crack-free GaN/AlN distributed Bragg reflector (DBR) incorporated with GaN/AlN superlattice (SL) layers was grown on a c-plane sapphire substrate by metalorganic chemical vapor deposition. Three sets of half-wave layers consisting of 5.5 periods of GaN/AlN SL layers and GaN layer were inserted in every five pairs of the 20 pair GaN/AlN DBR structure to suppress the crack generation. The grown GaN/AlN DBRs with SL insertion layers showed no observable cracks in the structure and achieved high peak reflectivity of 97% at 399 nm with a stop band width of 14 nm. Based on the x-ray analysis, the reduction in the in-plane tensile stress in the DBR structure with insertion of SL layers could be responsible for the suppression of crack formation and achievement of high reflectivity.
Show PACS
81.05.Ea III-V semiconductors
68.65.Cd Superlattices
68.60.Bs Mechanical and acoustical properties
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Deformation twinning mechanisms in nanocrystalline Ni

Xiao-Lei Wu and En (Evan) Ma

Appl. Phys. Lett. 88, 061905 (2006); http://dx.doi.org/10.1063/1.2172404 (3 pages) | Cited 20 times

Online Publication Date: 7 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Extensive transmission electron microscopy examinations confirm that twinning does occur upon large plastic deformation in nanocrystalline Ni, for which no sign of deformation twinning was found in previous tensile tests. Compelling evidence has been obtained for several twinning mechanisms that operate in nanocrystalline grains, with the grain boundary emission of partial dislocations determined as the most proficient.
Show PACS
61.72.Mm Grain and twin boundaries
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
61.46.Hk Nanocrystals
68.37.Lp Transmission electron microscopy (TEM)
81.70.Bt Mechanical testing, impact tests, static and dynamic loads

Energy transfer between Pr3+ and Mn2+ in SrB4O7:Pr,Mn

Yonghu Chen, Chaoshu Shi, Wuzhao Yan, Zeming Qi, and Yibing Fu

Appl. Phys. Lett. 88, 061906 (2006); http://dx.doi.org/10.1063/1.2172731 (3 pages) | Cited 20 times

Online Publication Date: 7 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The luminescence of Pr3+ or Mn2+ singly doped, as well as Pr3+ and Mn2+ codoped, SrB4O7 powder microcrystalline samples were investigated using synchrotron radiation. The photon cascade emission originating from the math level was observed in the SrB4O7:Pr3+ (0.1 mol %) sample upon 206 nm excitation. There are desirable spectral overlaps in the region of 330–430 nm between the emission spectra of the SrB4O7:Pr3+ sample and the excitation spectra of the SrB4O7:Mn2+ sample monitoring the Mn2+ luminescence at 640 nm. These spectral overlaps are in favor of the energy transfer from Pr3+ to Mn2+, converting the first step photon from Pr3+:math in the unpractical ultraviolet or near-ultraviolet regions into the red Mn2+ emission. A comparison of the emission spectra of the SrB4O7:Pr3+, Mn2+ sample with that of the SrB4O7:Pr3+ sample revealed the existence and the efficiency of the proposed energy transfer between Pr3+ and Mn2+, suggesting an promising vacuum ultraviolet phosphor based on Pr3+ and Mn2+ combination with visible quantum efficiency greater than unit.
Show PACS
78.55.Hx Other solid inorganic materials
78.40.Ha Other nonmetallic inorganics

Phase separation and dilution in implanted MnxGe1−x alloys

L. Ottaviano, M. Passacantando, S. Picozzi, A. Continenza, R. Gunnella, A. Verna, G. Bihlmayer, G. Impellizzeri, and F. Priolo

Appl. Phys. Lett. 88, 061907 (2006); http://dx.doi.org/10.1063/1.2171485 (3 pages) | Cited 43 times

Online Publication Date: 7 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The structural and electronic properties of MnxGe1−x alloys (x ⩽ 0.15) fabricated by ion implantation are investigated by means of x-ray diffraction and synchrotron radiation photoemission spectroscopy. The diffraction patterns point to the presence of ferromagnetic Mn5Ge3 nanoparticles; however, valence band spectra, interpreted by means of accurate ab initio calculations including Hubbard-like correlations, show clear fingerprints of an effective substitutional Mn dilution in the Ge semiconducting host.
Show PACS
75.50.Pp Magnetic semiconductors
61.72.up Other materials
79.60.Bm Clean metal, semiconductor, and insulator surfaces
75.50.Cc Other ferromagnetic metals and alloys
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
73.22.-f Electronic structure of nanoscale materials and related systems

Improved quality (11math0) a-plane GaN with sidewall lateral epitaxial overgrowth

Bilge M. Imer, Feng Wu, Steven P. DenBaars, and James S. Speck

Appl. Phys. Lett. 88, 061908 (2006); http://dx.doi.org/10.1063/1.2172159 (3 pages) | Cited 62 times

Online Publication Date: 7 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate a technique to reduce the extended defect densities in a-plane GaN deposited on r-plane sapphire. The SiO2 lateral epitaxial overgrowth mask consisted of 〈1math00〉GaN stripes. Both the mask and GaN were etched through the mask openings and the lateral growth was initiated from the etched c-plane GaN sidewalls, and the material was grown over the mask regions until a smooth coalesced film was achieved. Threading dislocation densities in the range of 106–107 cm−2 were realized throughout the film surface. The on-axis and off-axis full width at half maximum value and surface roughness were 0.082°, 0.114°, and 0.622 nm, respectively.
Show PACS
81.05.Ea III-V semiconductors
68.47.Fg Semiconductor surfaces
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.A- Nucleation and growth
61.72.Nn Stacking faults and other planar or extended defects
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Electrical charge trapping at defects on the Si(111)7×7 surface

C.-S. Jiang, H. R. Moutinho, M. J. Romero, M. M. Al-Jassim, and L. L. Kazmerski

Appl. Phys. Lett. 88, 061909 (2006); http://dx.doi.org/10.1063/1.2172229 (3 pages) | Cited 7 times

Online Publication Date: 7 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on a direct measurement of electron trapping at defects on the Si(111)7×7 surface, by combining Kelvin probe force microscopy (KPFM) and scanning tunneling microscopy (STM) measurements. One-dimensional defects of atomic steps and two-dimensional defects of disordered domains were found on the surface. STM reveals that the disordered domain is located in the intersection area between three 7×7 domains. KPFM measurement shows that electrons are trapped at both the atomic steps and the disordered domains, and this electron trapping gives rise to a larger local work function on the defect region than on the defect-free 7×7 regions.
Show PACS
68.47.Fg Semiconductor surfaces
73.25.+i Surface conductivity and carrier phenomena
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.72.-y Defects and impurities in crystals; microstructure

Wetting and crystallization at grain boundaries: Origin of aluminum-induced crystallization of amorphous silicon

J. Y. Wang, D. He, Y. H. Zhao, and E. J. Mittemeijer

Appl. Phys. Lett. 88, 061910 (2006); http://dx.doi.org/10.1063/1.2172707 (3 pages) | Cited 23 times

Online Publication Date: 9 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It has been shown experimentally that the grain boundaries in aluminium in contact with amorphous silicon are the necessary agents for initiation of the crystallization of silicon upon annealing temperatures as low as 438 K. Thermodynamic analysis has shown (i) that Si can “wet” the Al grain boundaries due to the favorable Si/Al interface energy as compared to the Al grain-boundary energy and (ii) that Si at the Al grain boundaries can maintain its amorphous state up to a thickness of about 1.0 nm. Beyond that thickness crystalline Si develops at the Al grain boundaries.
Show PACS
05.70.Np Interface and surface thermodynamics
68.35.Rh Phase transitions and critical phenomena
61.72.Cc Kinetics of defect formation and annealing
61.05.cp X-ray diffraction
81.70.Jb Chemical composition analysis, chemical depth and dopant profiling
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Optical properties of nanocrystalline FeSi2 and the effects of hydrogenation

K. Takarabe, H. Doi, Y. Mori, K. Fukui, Y. Shim, N. Yamamoto, T. Yoshitake, and K. Nagayama

Appl. Phys. Lett. 88, 061911 (2006); http://dx.doi.org/10.1063/1.2172711 (3 pages) | Cited 9 times

Online Publication Date: 9 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Various optical measurements confirm that optical absorption in uniform thin films made from nanocrystalline iron disilicide (nc-FeSi2) with a 3–5 nm radius is larger by about 10% than that of single crystalline β-FeSi2. It is also found that the hydrogenation of nc-FeSi2 changes strongly its optical characteristic energies. The nanocrystalline state appears characteristically in the imaginary part of dielectric constants of β-FeSi2 around 2–3 eV.
Show PACS
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.66.Nk Insulators
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
61.46.Hk Nanocrystals
77.22.Ch Permittivity (dielectric function)

In situ observations of crack propagation mechanisms along interfaces between confined polymer layers and glass

W. P. Vellinga, R. Timmerman, R. van Tijum, and J. Th. M. De Hosson

Appl. Phys. Lett. 88, 061912 (2006); http://dx.doi.org/10.1063/1.2172713 (3 pages) | Cited 4 times

Online Publication Date: 9 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper concentrates on microscopic observations of the propagation of cracks along polymer-glass interfaces and crack propagation mechanisms. The experimental set-up consists of an asymmetric double cantilever beam in an optical microscope. Image processing techniques used to isolate the crack fronts are presented. The fronts propagate inhomogeneously in space and time, i.e., in bursts that spread laterally along the front over a certain distance. It is interesting to note that two different cases are detected; one in which crack propagation is dominated by initiation of instabilities on the front, and another one in which it is dominated by propagation of existing instabilities.
Show PACS
62.20.M- Structural failure of materials
46.50.+a Fracture mechanics, fatigue and cracks
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure

Melting and optical properties of ZnO nanorods

Xin Su, Zhengjun Zhang, and Minmin Zhu

Appl. Phys. Lett. 88, 061913 (2006); http://dx.doi.org/10.1063/1.2172716 (3 pages) | Cited 29 times

Online Publication Date: 9 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We observed that, by heating in air, the ZnO nanorods could start to melt at a temperature of ∼ 750 °C, which is greatly reduced comparing with that of the bulk form. Prolonged annealing at this temperature resulted in partial melting of individual nanorods and the coalescence of the nanorods with their neighbors, leading to a great change in their optical properties, i.e., a new photoluminescence peak emerged at ∼ 468 nm. Further analysis indicated that the new photoluminescence is closely related to the melting and the coalescence of the ZnO nanorods which probably induced some defects by thermal annealing at this temperature.
Show PACS
64.70.D- Solid-liquid transitions
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.55.Et II-VI semiconductors
61.72.Cc Kinetics of defect formation and annealing

Lattice vibrations in hexagonal Ga1−xMnxN epitaxial films on c-plane sapphire substrates by infrared reflectance spectra

Z. G. Hu, M. Strassburg, A. Weerasekara, N. Dietz, A. G. U. Perera, M. H. Kane, A. Asghar, and I. T. Ferguson

Appl. Phys. Lett. 88, 061914 (2006); http://dx.doi.org/10.1063/1.2172718 (3 pages) | Cited 10 times

Online Publication Date: 9 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The lattice vibrations of undoped hexagonal Ga1−xMnxN (x from 0.0% to 1.5%) epitaxial films grown on c-plane sapphire substrates by metalorganic chemical vapor deposition have been investigated using infrared reflectance spectra in the frequency region of 200–2000 cm−1 (5–50 μm) at room temperature. The experimental reflectance spectra were analyzed using the Lorentz oscillator model for infrared-active phonon observed. The E1(LO) phonon frequency slightly decreases with increasing Mn composition. However, the E1(TO) phonon frequency linearly increases with the Mn composition, which can be well expressed by (558.7+350x) cm−1 and the broadening values are found to be larger than that of the GaN film. It indicates that Mn incorporation decreases the peak values (from the E1 phonon) of the infrared dielectric functions due to the local variation in the lattice constants and to the destruction of the crystal translational symmetry.
Show PACS
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
81.70.Fy Nondestructive testing: optical methods

Direct imaging of phase separation in ZnCdO layers

F. Bertram, S. Giemsch, D. Forster, J. Christen, R. Kling, C. Kirchner, and A. Waag

Appl. Phys. Lett. 88, 061915 (2006); http://dx.doi.org/10.1063/1.2172146 (3 pages) | Cited 18 times

Online Publication Date: 9 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A direct correlation of structural and optical properties of MOCVD-grown ZnCdO-layers with a systematic variation of Cd-content has been achieved on a microscopic scale using highly spatially and spectrally resolved cathodoluminescence. The ZnCdO layer luminescence measured in cathodoluminescence wavelength images reveals strong lateral fluctuations directly visualizing local band gap fluctuation as a consequence of different local Cd incorporation. We give direct evidence for a chemical phase separation into Cd-rich and Cd-poor nanodomains in ZnCdO.
Show PACS
78.60.Hk Cathodoluminescence, ionoluminescence
78.66.Hf II-VI semiconductors
81.05.Dz II-VI semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Change in photoluminescence spectra of Eu-doped GaN powders due to the aggregation of nanosized grains into micrometer-sized conglomerations

R. Kudrawiec, M. Nyk, A. Podhorodecki, J. Misiewicz, W. Strek, and M. Wołcyrz

Appl. Phys. Lett. 88, 061916 (2006); http://dx.doi.org/10.1063/1.2168016 (3 pages) | Cited 15 times

Online Publication Date: 10 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, we report a phenomenon of the aggregation of nanocrystalline grains of GaN:Eu into micrometer-sized conglomerates having optical properties different from those of the initial GaN:Eu grains. The nanocrystalline GaN:Eu powders exhibit no emission related to the GaN band gap and a very broad yellow/red PL band associated with recombination in the GaN host matrix via surface states, in addition to the strong Eu3+-related emission, i.e., the math→math transitions with J = 1, 2, 3, and 4. For the microcrystalline powders, the yellow/red photoluminescence (PL) band disappears and a strong PL band related to the GaN band gap arises. In addition, the Eu3+-related transitions start to split into individual lines typical of Eu-doped bulk-like GaN crystals. These differences in PL spectra have been correlated with the surface/volume ratio of the GaN grains. It has been concluded that, for very small grains (<50 nm), surface states determine the optical properties of GaN:Eu powders. Postgrowth processing, which is able to change the size of the GaN grains, seems to be very useful in order to improve and to control the optical properties of GaN:Eu powders.
Show PACS
78.55.Cr III-V semiconductors
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.20.At Surface states, band structure, electron density of states

Deforming nanocrystalline nickel at ultrahigh strain rates

Y. M. Wang, E. M. Bringa, J. M. McNaney, M. Victoria, A. Caro, A. M. Hodge, R. Smith, B. Torralva, B. A. Remington, C. A. Schuh, H. Jamarkani, and M. A. Meyers

Appl. Phys. Lett. 88, 061917 (2006); http://dx.doi.org/10.1063/1.2173257 (3 pages) | Cited 23 times

Online Publication Date: 10 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The deformation mechanism of nanocrystalline Ni (with grain sizes in the range of 30–100 nm) at ultrahigh strain rates (>107 s−1) was investigated. A laser-driven compression process was applied to achieve high pressures (20–70 GPa) on nanosecond timescales and thus induce high-strain-rate deformation in the nanocrystalline Ni. Postmortem transmission electron microscopy examinations revealed that the nanocrystalline structures survive the shock deformation, and that dislocation activity is a prevalent deformation mechanism for the grain sizes studied. No deformation twinning was observed even at stresses more than twice the threshold for twin formation in micron-sized polycrystals. These results agree qualitatively with molecular dynamics simulations and suggest that twinning is a difficult event in nanocrystalline Ni under shock-loading conditions.
Show PACS
62.50.-p High-pressure effects in solids and liquids
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Mm Grain and twin boundaries
61.72.Lk Linear defects: dislocations, disclinations

Interaction of an elastic wave with a circular crack in a fluid-saturated porous medium

Robert J. Galvin and Boris Gurevich

Appl. Phys. Lett. 88, 061918 (2006); http://dx.doi.org/10.1063/1.2165178 (3 pages) | Cited 6 times

Online Publication Date: 10 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We consider interaction of a normally incident time-harmonic longitudinal plane wave with a circular crack imbedded in a porous medium governed by Biot’s equations of dynamic poroelasticity. The problem is formulated in cylindrical coordinates as a system of dual integral equations for the Hankel transform of the wave field, which is then reduced to a single Fredholm integral equation of the second kind. The solution of this equation yields elastic wave dispersion and attenuation in a medium containing a random distribution of aligned cracks. These dissipation effects are caused by wave induced fluid flow between pores and cracks.
Show PACS
62.30.+d Mechanical and elastic waves; vibrations
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.M- Structural failure of materials
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity

Multifunctional characteristics of BaNb0.3Ti0.7O3/Si p-n junctions

Yanhong Huang, Kun Zhao, Huibin Lu, Kui-juan Jin, Meng He, Zhenghao Chen, Yueliang Zhou, and Guozhen Yang

Appl. Phys. Lett. 88, 061919 (2006); http://dx.doi.org/10.1063/1.2172290 (3 pages) | Cited 13 times

Online Publication Date: 10 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
BaNb0.3Ti0.7O3/Si p-n junction combining the functional properties of oxide and Si electronics was fabricated by laser molecular-beam epitaxy, and the multifunctional properties of rectification, ferroelectricity and photoelectricity were experimentally studied. The good rectifying I-V characteristics, nanosecond ultrafast photoelectric effect, and ferroelectric property due to the interface enhancement were observed experimentally. The mechanisms of ferroelectric behavior and photoelectric process are discussed briefly.
Show PACS
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
73.40.Ei Rectification
72.40.+w Photoconduction and photovoltaic effects
back to top
RSS Feeds

Propagation of stacking faults from surface damage in SiC PiN diodes

Z. Zhang, S. I. Maximenko, A. Shrivastava, P. Sadagopan, Y. Gao, and T. S. Sudarshan

Appl. Phys. Lett. 88, 062101 (2006); http://dx.doi.org/10.1063/1.2172015 (3 pages) | Cited 3 times

Online Publication Date: 6 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The propagation of stacking faults (SF) in SiC PiN diodes under forward bias was studied by the electron beam induced current mode of scanning electron microscopy. The primary SF nucleation sites were confirmed to be pre-existing basal plane dislocations (BPD). Damage to the diode surface can also cause SF propagation in the device. Hence, in addition to the elimination of BPDs in the active layer of the diode, avoidance of surface damage by paying careful attention to device processing and testing is also important for fabricating stable SiC PiN diodes.
Show PACS
61.72.−y
61.72.Nn Stacking faults and other planar or extended defects
61.72.Lk Linear defects: dislocations, disclinations
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Studies of charge carrier trapping and recombination processes in Si/SiO2/MgO structures using second-harmonic generation

Y. V. White, X. Lu, R. Pasternak, N. H. Tolk, A. Chatterjee, R. D. Schrimpf, D. M. Fleetwood, A. Ueda, and R. Mu

Appl. Phys. Lett. 88, 062102 (2006); http://dx.doi.org/10.1063/1.2172008 (3 pages) | Cited 5 times

Online Publication Date: 6 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Effects of MgO deposition on Si/SiO2 system and charge carrier trapping and recombination in Si/SiO2/MgO structures are studied using second-harmonic generation (SHG). An ultrafast 800 nm laser was used both for multi-photon induced electron injection through the SiO2 into a potential well in the MgO, and for monitoring the time-dependent SHG signal, which is sensitive to the electric field at the Si/SiO2 interface. Our results indicate that the MgO deposition introduces new trap states, and electrons trapped in the MgO transport more readily through the SiO2 than those in traps on the surface of SiO2. We attribute this to differences in trap energy levels and/or differences in process damage-induced defect densities in the SiO2.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Exciton localization in AlGaN alloys

N. Nepal, J. Li, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang

Appl. Phys. Lett. 88, 062103 (2006); http://dx.doi.org/10.1063/1.2172728 (3 pages) | Cited 24 times

Online Publication Date: 6 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Deep ultraviolet (UV) photoluminescence emission spectroscopy has been employed to study the exciton localization effect in AlGaN alloys. The temperature dependence of the exciton emission peak energy in AlxGa1−xN alloys (0 ⩽ x ⩽ 1) was measured from 10 to 800 K and fitted by the Varshni equation. Deviations of the measured data from the Varshni equation at low temperatures directly provide the exciton localization energies, ELoc. It was found that ELoc increases with x for x ⩽ 0.7, and decreases with x for x ≥ 0.8. Our experimental results revealed that for AlGaN alloys, ELoc obtained by the above method has simple linear relations with the localized exciton thermal activation energy and the emission linewidth, thereby established three parallel methods for directly measuring the exciton localization energies in AlGaN alloys. The consequence of strong carrier and exciton localization in AlGaN alloys on the applications of nitride deep UV optoelectronic devices is also discussed.
Show PACS
78.66.Fd III-V semiconductors
71.35.-y Excitons and related phenomena
78.55.Cr III-V semiconductors
78.40.Fy Semiconductors
73.61.Ey III-V semiconductors

Investigation of a polythiophene interface using photoemission spectroscopy in combination with electrospray thin-film deposition

A. J. Cascio, J. E. Lyon, M. M. Beerbom, R. Schlaf, Y. Zhu, and S. A. Jenekhe

Appl. Phys. Lett. 88, 062104 (2006); http://dx.doi.org/10.1063/1.2172069 (3 pages) | Cited 24 times

Online Publication Date: 9 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The conjugated polymer poly(3-hexylthiophene) (P3HT) was deposited in several steps onto a highly oriented pyrolytic graphite (HOPG) substrate directly from solution in high vacuum, using an electrospray thin-film deposition system. The deposition system was attached to a photoemission spectroscopy setup via in situ sample transfer, allowing characterization in between deposition steps with x-ray and ultraviolet photoemission spectroscopy. The resultant series of spectra enabled the determination of the ionization energy, work function, and highest occupied molecular orbital binding energy of the P3HT overlayer, while giving detailed insight into the orbital alignment and dipole formation at the P3HT/HOPG contact.
Show PACS
78.66.Qn Polymers; organic compounds
81.15.Pq Electrodeposition, electroplating
68.37.Xy Scanning Auger microscopy, photoelectron microscopy
79.60.Bm Clean metal, semiconductor, and insulator surfaces
68.55.-a Thin film structure and morphology
73.30.+y Surface double layers, Schottky barriers, and work functions

Electrical spin injection from ZnMnSe into InGaAs quantum wells and quantum dots

W. Löffler, D. Tröndle, J. Fallert, H. Kalt, D. Litvinov, D. Gerthsen, J. Lupaca-Schomber, T. Passow, B. Daniel, J. Kvietkova, M. Grün, C. Klingshirn, and M. Hetterich

Appl. Phys. Lett. 88, 062105 (2006); http://dx.doi.org/10.1063/1.2172221 (3 pages) | Cited 26 times

Online Publication Date: 9 February 2006

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on efficient injection of electron spins into InGaAs-based nanostructures. The spin light-emitting diodes incorporate an InGaAs quantum well or quantum dots, respectively, as well as a semimagnetic ZnMnSe spin-aligner layer. We show a circular polarization degree of up to 35% for the electroluminescence from InGaAs quantum wells and up to 21% for InGaAs quantum dots. We can clearly attribute the polarization of the emitted photons to the spin alignment in the semimagnetic layer by comparison to results from reference devices (where the ZnMnSe is replaced by ZnSe) and from all-optical measurements.
Show PACS
73.63.Kv Quantum dots
73.63.Hs Quantum wells
72.25.Dc Spin polarized transport in semiconductors
78.67.Hc Quantum dots
78.67.De Quantum wells
75.50.Pp Magnetic semiconductors
Page 2 of 5 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close