jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

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

21 Jan 2013

Volume 113, Issue 3, Articles (03xxxx)

Issue Cover Spotlight Figure

J. Appl. Phys. 113, 031101 (2013); http://dx.doi.org/10.1063/1.4763353 (21 pages)

S. Mirabella, D. De Salvador, E. Napolitani, E. Bruno, and F. Priolo
Enlarge Image | Read More
Page 1 of 4 Pages Next Page | Jump to Page
back to top
RSS Feeds
Author Select

Mechanisms of boron diffusion in silicon and germanium

S. Mirabella, D. De Salvador, E. Napolitani, E. Bruno, and F. Priolo

J. Appl. Phys. 113, 031101 (2013); http://dx.doi.org/10.1063/1.4763353 (21 pages) | Cited 1 time

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
B migration in Si and Ge matrices raised a vast attention because of its influence on the production of confined, highly p-doped regions, as required by the miniaturization trend. In this scenario, the diffusion of B atoms can take place under severe conditions, often concomitant, such as very large concentration gradients, non-equilibrium point defect density, amorphous-crystalline transition, extrinsic doping level, co-doping, B clusters formation and dissolution, ultra-short high-temperature annealing. In this paper, we review a large amount of experimental work and present our current understanding of the B diffusion mechanism, disentangling concomitant effects and describing the underlying physics. Whatever the matrix, B migration in amorphous (α-) or crystalline (c-) Si, or c-Ge is revealed to be an indirect process, activated by point defects of the hosting medium. In α-Si in the 450-650 °C range, B diffusivity is 5 orders of magnitude higher than in c-Si, with a transient longer than the typical amorphous relaxation time. A quick B precipitation is also evidenced for concentrations larger than 2 × 1020 B/cm3. B migration in α-Si occurs with the creation of a metastable mobile B, jumping between adjacent sites, stimulated by dangling bonds of α-Si whose density is enhanced by B itself (larger B density causes higher B diffusivity). Similar activation energies for migration of B atoms (3.0 eV) and of dangling bonds (2.6 eV) have been extracted. In c-Si, B diffusion is largely affected by the Fermi level position, occurring through the interaction between the negatively charged substitutional B and a self-interstitial (I) in the neutral or doubly positively charged state, if under intrinsic or extrinsic (p-type doping) conditions, respectively. After charge exchanges, the migrating, uncharged BI pair is formed. Under high n-type doping conditions, B diffusion occurs also through the negatively charged BI pair, even if the migration is depressed by Coulomb pairing with n-type dopants. The interplay between B clustering and migration is also modeled, since B diffusion is greatly affected by precipitation. Small (below 1 nm) and relatively large (5-10 nm in size) BI clusters have been identified with different energy barriers for thermal dissolution (3.6 or 4.8 eV, respectively). In c-Ge, B motion is by far less evident than in c-Si, even if the migration mechanism is revealed to be similarly assisted by Is. If Is density is increased well above the equilibrium (as during ion irradiation), B diffusion occurs up to quite large extents and also at relatively low temperatures, disclosing the underlying mechanism. The lower B diffusivity and the larger activation barrier (4.65 eV, rather than 3.45 eV in c-Si) can be explained by the intrinsic shortage of Is in Ge and by their large formation energy. B diffusion can be strongly enhanced with a proper point defect engineering, as achieved with embedded GeO2 nanoclusters, causing at 650 °C a large Is supersaturation. These aspects of B diffusion are presented and discussed, modeling the key role of point defects in the two different matrices.
Show PACS
66.30.-h Diffusion in solids
61.72.uf Ge and Si
61.72.J- Point defects and defect clusters
64.75.Bc Solubility
71.55.Cn Elemental semiconductors
back to top
RSS Feeds
back to top Lasers, Optics, and Optoelectronics

Photopolymerizable organically modified holographic glass with enhanced thickness for spectral filters

A. V. Velasco, M. L. Calvo, and P. Cheben

J. Appl. Phys. 113, 033101 (2013); http://dx.doi.org/10.1063/1.4775787 (5 pages)

Online Publication Date: 15 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A novel formulation and synthesis method to overcome the thickness limitations in samples of photopolymerizable glasses with high refractive index species is presented. The reported method allows the recording of volume holographic diffraction gratings in samples of ∼500 μm thickness with a high optical quality and low scattering. Holographic grating recording is performed in a single coherent light exposure step, resulting in volume gratings of high optical quality. A holographic notch filter implemented in a 500 μm thick photopolymerizable glass with a spectral bandwidth below 0.3 nm and an excellent filter extinction ratio of <−27 dB is also demonstrated.
Show PACS
42.40.Eq Holographic optical elements; holographic gratings
42.40.Pa Volume holograms
42.40.Ht Hologram recording and readout methods
42.79.Ci Filters, zone plates, and polarizers
42.70.Ce Glasses, quartz

Surface enhanced fluorescence and Raman scattering by gold nanoparticle dimers and trimers

Zhenglong Zhang, Pengfei Yang, Hongxing Xu, and Hairong Zheng

J. Appl. Phys. 113, 033102 (2013); http://dx.doi.org/10.1063/1.4776227 (5 pages)

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dimers and trimers of gold nanoparticles were synthesized using wet chemistry method for surface enhanced fluorescence and Raman scattering. The dimers and trimers provide hot spots for enhancing the fluorescence and Raman signals, and significantly obvious enhancement is obtained from Raman signals in solution. Using finite element method, we calculate the enhancement of fluorescence and Raman signals in the experimental system. Both experimental and theoretical results show that the dimers and trimers solution can be used in micro-quantitative detection from fluorescence and Raman signals.
Show PACS
81.07.Bc Nanocrystalline materials
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
78.30.Er Solid metals and alloys

Mid-infrared-pumped, electrically driven terahertz quantum laser: Enhanced pumping efficiency and prevention of electric-field domains

X. Lü, M. Wienold, L. Schrottke, K. Biermann, and H. T. Grahn

J. Appl. Phys. 113, 033103 (2013); http://dx.doi.org/10.1063/1.4776762 (6 pages)

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated GaAs/(Al,Ga)As structures for mid-infrared-pumped, electrically driven terahertz quantum lasers (TQLs) based on the concept of Waldmueller et al. [Phys. Rev. Lett. 99, 117401 (2007)]. We developed a design with the gain maximum appearing at a relatively low field strength of 6.5 kV/cm. The present TQL design avoids pumping-induced current instabilities, which prevented a previous design from operating at the required field strength as discussed by Giehler et al. [J. Appl. Phys. 110, 103104 (2011)]. We applied photocurrent (PC) spectroscopy to examine the pumping process. The measured PC spectra are found to be in agreement with simulated spectra in the vicinity of the desired operating field strength. We demonstrate that electric-field domain formation can be suppressed using a continuous-wave CO2 laser as the pump.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
78.45.+h Stimulated emission
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Investigation of large Stark shifts in InGaN/GaN multiple quantum wells

Guibao Xu, Guan Sun, Yujie J. Ding, Hongping Zhao, Guangyu Liu, Jing Zhang, and Nelson Tansu

J. Appl. Phys. 113, 033104 (2013); http://dx.doi.org/10.1063/1.4775605 (5 pages)

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Photoluminescence (PL) spectra of InGaN/GaN multiple quantum wells excited by ultrafast laser pulses are investigated over broad ranges of excitation levels and temperatures. The PL peak energy undergoes blue, red, zero, and blue shifts with increasing the excitation fluence density. Such a peculiar behavior can be explained based on competing processes of screening of the built-in electric field by the photogenerated carriers, band-gap renormalization, and band-filling effect. We have also measured and analyzed the dependence of the PL energy and linewidth on the temperature. Due to the interplay between the band-gap renormalization and band-filling effect, the PL energy shifts to the highest value, whereas the PL linewidth reaches the minimum value at ≈60 K.
Show PACS
68.65.Fg Quantum wells
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
75.40.-s Critical-point effects, specific heats, short-range order
78.55.Cr III-V semiconductors
81.07.St Quantum wells

Leaky and bound modes in terahertz metasurfaces made of transmission-line metamaterials

Philip W. C. Hon, Zhijun Liu, Tatsuo Itoh, and Benjamin S. Williams

J. Appl. Phys. 113, 033105 (2013); http://dx.doi.org/10.1063/1.4776761 (10 pages)

Online Publication Date: 18 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Prism coupling and reflection spectroscopy are used to characterize bound modes within composite right/left handed terahertz metamaterial waveguides. The cavity antenna model is used to understand the polarization dependence of the radiative coupling to TM00 and TM01 waveguide modes. Furthermore, the cavity model along with transmission-line theory is used to derive a surface impedance model for a waveguide array metasurface. Qualitative agreement with the experiment is observed, including a mode splitting for p-polarized surface waves at the light line and the existence of s-polarized magnetic spoof surface plasmons.
Show PACS
84.40.-x Radiowave and microwave (including millimeter wave) technology
84.40.Az Waveguides, transmission lines, striplines
84.40.Ba Antennas: theory, components and accessories
41.20.Jb Electromagnetic wave propagation; radiowave propagation
back to top Plasmas and Electrical Discharges
FREE

Electron current extraction from radio frequency excited micro-dielectric barrier discharges

Jun-Chieh Wang, Napoleon Leoni, Henryk Birecki, Omer Gila, and Mark J. Kushner

J. Appl. Phys. 113, 033301 (2013); http://dx.doi.org/10.1063/1.4775723 (14 pages)

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Micro dielectric barrier discharges (mDBDs) consist of micro-plasma devices (10–100 μm diameter) in which the electrodes are fully or partially covered by dielectrics, and often operate at atmospheric pressure driven with radio frequency (rf) waveforms. In certain applications, it may be desirable to extract electron current out of the mDBD plasma, which necessitates a third electrode. As a result, the physical structure of the m-DBD and the electron emitting properties of its materials are important to its operation. In this paper, results from a two-dimensional computer simulation of current extraction from mDBDs sustained in atmospheric pressure N2 will be discussed. The mDBDs are sandwich structures with an opening of tens-of-microns excited with rf voltage waveforms of up to 25 MHz. Following avalanche by electron impact ionization in the mDBD cavity, the plasma can be expelled from the cavity towards the extraction electrode during the part of the rf cycle when the extraction electrode appears anodic. The electron current extraction can be enhanced by biasing this electrode. The charge collection can be controlled by choice of rf frequency, rf driving voltage, and permittivity of the dielectric barrier.
Show PACS
52.25.Fi Transport properties
52.25.Mq Dielectric properties
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.65.-y Plasma simulation
52.75.-d Plasma devices
52.80.Pi High-frequency and RF discharges

Criteria of radio-frequency ring-shaped hollow cathode discharge using H2 and Ar gases for plasma processing

Yasunori Ohtsu and Yujiro Kawasaki

J. Appl. Phys. 113, 033302 (2013); http://dx.doi.org/10.1063/1.4776220 (5 pages)

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In order to achieve high-density capacitively coupled plasma, a radio-frequency (RF) ring-shaped hollow cathode discharge has been developed as a candidate for processing plasma sources. The plasma density in the hollow cathode discharge reaches a high magnitude of 1010–1011 cm−3. The RF ring-shaped hollow cathode discharge depends on the pressure and mass of the working gas. Criteria required for producing a RF ring-shaped hollow cathode discharge have been investigated for various gas pressures using H2 and Ar gases for high-density plasma production. The results reveal that the criteria for the occurrence of the hollow cathode effect are that the trench width should be approximately equal to the sum of the electron-neutral mean free paths and twice the sheath thickness of the RF powered electrode.
Show PACS
52.80.Hc Glow; corona
52.80.Pi High-frequency and RF discharges
52.25.Fi Transport properties
52.40.Kh Plasma sheaths
52.50.Dg Plasma sources

Optical emission characteristics of surface nanosecond pulsed dielectric barrier discharge plasma

Yun Wu, Yinghong Li, Min Jia, Huimin Song, and Hua Liang

J. Appl. Phys. 113, 033303 (2013); http://dx.doi.org/10.1063/1.4776721 (6 pages) | Cited 1 time

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
This paper reports an experimental study of the optical emission characteristics of the surface dielectric barrier discharge plasma excited by nanosecond pulsed voltage. N2(C3Пu) rotational and vibrational temperatures are almost the same with upper electrode powered with positive polarity and lower electrode grounded or upper electrode grounded and lower electrode powered with positive polarity. While the electron temperature is 12% higher with upper electrode powered with positive polarity and lower electrode grounded. When the frequency is below 2000 Hz, there is almost no influence of applied voltage amplitude and frequency on N2(C3Пu) rotational, vibrational temperature and electron temperature. As the pressure decreases from 760 Torr to 5 Torr, N2(C3Пu) rotational temperature remains almost unchanged, while its vibrational temperature decreases initially and then increases. The discharge mode changes from a filamentary type to a glow type around 80 Torr. In the filamentary mode, the electron temperature remains almost unchanged. In the glow mode, the electron temperature increases while the pressure decreases.
Show PACS
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.80.Hc Glow; corona

Impact of hydrogen radical-injection plasma on fabrication of microcrystalline silicon thin film for solar cells

Yusuke Abe, Sho Kawashima, Atsushi Fukushima, Ya Lu, Keigo Takeda, Hiroki Kondo, Kenji Ishikawa, Makoto Sekine, and Masaru Hori

J. Appl. Phys. 113, 033304 (2013); http://dx.doi.org/10.1063/1.4778608 (6 pages)

Online Publication Date: 18 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A plasma-enhanced chemical deposition system with hydrogen radical-injection (RI) is proposed for the fabrication of hydrogenated microcrystalline silicon (μc-Si:H) thin films. The plasma parameters and resultant growth characteristics obtained with the RI-capacitively coupled plasma (RI-CCP) system excited with 60 MHz power were compared with those obtained using a conventional CCP (C-CCP) system. The absolute density of hydrogen (H) radicals was measured by vacuum ultraviolet laser absorption spectroscopy (VUVLAS) to evaluate the effect of RI for controlling the H radical density. A higher density of H radicals was achieved with RI-CCP than with C-CCP by H RI. The crystallinity factor, preferential orientation, defect density, microstructure, and post-deposition oxidation of Si thin films deposited using C-CCP and RI-CCP were investigated. Crystallinity factor of 0.6 was realized with high deposition rate of about 2 nm/s even under a low plasma density using RI-CCP. The defect density of μc-Si:H thin films prepared using RI-CCP was lower than that in thin films prepared using C-CCP. In addition, post-deposition oxidation of the films with RI-CCP was lower than that with C-CCP. The high performance of RI-CCP for the fabrication of μc-Si:H thin films for solar cell devices is also demonstrated.
Show PACS
88.40.jj Silicon solar cells
52.77.Dq Plasma-based ion implantation and deposition
back to top Structural, Mechanical, Thermodynamic, and Optical Properties of Condensed Matter

N-type conductivity and properties of carbon-doped InN(0001) films grown by molecular beam epitaxy

M. Himmerlich, A. Knübel, R. Aidam, L. Kirste, A. Eisenhardt, S. Krischok, J. Pezoldt, P. Schley, E. Sakalauskas, R. Goldhahn, R. Félix, J. M. Mánuel, F. M. Morales, D. Carvalho, T. Ben, et al.

J. Appl. Phys. 113, 033501 (2013); http://dx.doi.org/10.1063/1.4775736 (10 pages)

Online Publication Date: 15 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this work, we have analyzed the effect of intentional carbon doping on molecular beam epitaxy grown In-polar InN epilayers using carbon bromide (CBr4) as dopant source. Hall effect measurements, high resolution X-ray diffraction, atomic force microscopy, transmission electron microscopy, secondary ion mass spectrometry, spectroscopic ellipsometry, as well as X-ray photoelectron spectroscopy were employed to characterize the influence of different dopant concentrations on the electrical, optical, crystallographic, morphological, and electronic properties of InN. It was found that the electron concentration increases linearly with the incorporation of carbon pointing towards the effect of n-type doping and that incorporated C impurities reduce the electron mobility within the InN films. This correlation is further reflected in associated properties such as the onset of optical absorption, the plasmon frequency, the effective electron mass and the position of the bulk and surface Fermi level. Furthermore, it is found that the dislocation densities are independent of carbon incorporation, ruling them out as origin for the increased n-type conductivity and reduced carrier mobility in these epilayers.
Show PACS
73.61.Ey III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
68.55.ag Semiconductors
71.20.Nr Semiconductor compounds

N incorporation in GaInNSb alloys and lattice matching to GaSb

M. J. Ashwin, D. Walker, P. A. Thomas, T. S. Jones, and T. D. Veal

J. Appl. Phys. 113, 033502 (2013); http://dx.doi.org/10.1063/1.4775745 (5 pages)

Online Publication Date: 15 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The incorporation of N into MBE grown GaNSb and GaInNSb is investigated. Measurements of the N fraction in GaNSb show the familiar linear dependence on inverse growth rate, followed by a departure from this at low growth rates; a similar behaviour is observed for GaInNSb. Unexpectedly, the point at which there is a departure from this linear behaviour is found to be extended to lower growth rates by the addition of small amounts of In. These results are compared to a kinetic theory-based model from which it is postulated that the change in behaviour can be attributed to an In-induced change in the characteristic surface residence lifetime of the N atoms. In addition, a method is demonstrated for growing GaInNSb lattice-matched to GaSb(001) for compositions with band gaps covering the 2–5 μm region.
Show PACS
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.ag Semiconductors

Photoinduced scalar and vectorial optical phenomena in nano-dimensional glassy chalcogenide films and their liquid crystal photoalignment

M. Klebanov, V. Lyubin, M. Gelbaor Kirzhner, and I. Abdulhalim

J. Appl. Phys. 113, 033503 (2013); http://dx.doi.org/10.1063/1.4775801 (6 pages)

Online Publication Date: 15 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Photoinduced (PI) scalar and vectorial optical phenomena in chalcogenide glassy films' early studies were performed on films thicker than 0.5–l μm. Recent finding of nano-dimensional (ND) As2S3 films possibility to act as a photoalignment layer for nematic liquid crystals (LCs) made careful investigation of PI anisotropy and other PI phenomena in nano-dimensional (<100 nm thick) chalcogenide films of different composition. Results of such investigation are considered in this paper. The scalar and vectorial PI phenomena having many similar characteristics are shown to exist in all studied (ND) As-containing chalcogenide glassy films both stoichiometric and non-stoichiometric. The ND Ge-containing chalcogenide glassy films are shown to have very different optical characteristics. We demonstrated that ND chalcogenide glassy films of different compositions are able to act as photoalignment layers for nematic LCs under irradiation with linearly polarized light.
Show PACS
78.66.Jg Amorphous semiconductors; glasses

Radiation effects and tolerance mechanism in β-eucryptite

Badri Narayanan, Ivar E. Reimanis, Hanchen Huang, and Cristian V. Ciobanu

J. Appl. Phys. 113, 033504 (2013); http://dx.doi.org/10.1063/1.4775838 (10 pages)

Online Publication Date: 15 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Previous studies on Li-silicates have shown that these materials are resistant to radiation damage even in extreme physical and chemical environments, and are thus promising solid-state breeder materials in fusion reactors. Here, we focus on β-eucryptite as a member of Li-Al silicate class of ceramics with potential for nuclear applications, and study the atomic-scale processes induced by radiation. Using molecular dynamics simulations based on a reactive force field, we have found that upon radiation dosage of 0.21 displacements-per-atom or less, the structure largely retains its long-range order while exhibiting (a) disordering of the Li atoms, (b) distortion of the Si and Al tetrahedra defined as the change in their oxygen-coordination number, and (c) tilting of the Si and Al tetrahedra with respect to one another. We find that Si tetrahedra that distort to SiO3 during exposure to radiation recover significantly upon thermal relaxation, and provide the mechanism for this recovery. This mechanism consists in the tilting of AlO5 polyhedra formed upon exposure so as to satisfy the oxygen-coordination of distorted Si tetrahedra. Doubling the dosage results in a significant increase of the concentration of Si-Al antisite defects, which renders the tolerance mechanism inefficient and leads to amorphization.
Show PACS
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
61.72.J- Point defects and defect clusters
61.80.Az Theory and models of radiation effects
61.82.Ms Insulators

Substrate orientation dependence on the solid phase epitaxial growth rate of Ge

B. L. Darby, B. R. Yates, I. Martin-Bragado, J. L. Gomez-Selles, R. G. Elliman, and K. S. Jones

J. Appl. Phys. 113, 033505 (2013); http://dx.doi.org/10.1063/1.4776718 (5 pages)

Online Publication Date: 15 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The solid phase epitaxial growth process has been studied at 330 °C by transmission electron microscopy for Ge wafers polished at 10°–15° increments from the [001] to [011] orientations. The velocity showed a strong dependence on substrate orientation with the [001] direction displaying a velocity 16 times greater than the [111] direction. A lattice kinetic Monte Carlo model was used to simulate solid phase epitaxial growth (SPEG) rates at different orientations, and simulations compared well with experimental results. Cross sectional transmission electron microscopy and plan view transmission electron microscopy revealed stacking fault and twin defect formation in the [111] orientation where all other orientations showed only hairpin dislocations. The twin defects formed from Ge SPEG were comparatively less dense than what has previously been reported for Si, which gave rise to higher normalized velocities and a constant [111] SPEG velocity for Ge.
Show PACS
81.15.Np Solid phase epitaxy; growth from solid phases
68.55.ag Semiconductors
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.Nn Stacking faults and other planar or extended defects

Temperature dependent carrier dynamics in telecommunication band InAs quantum dots and dashes grown on InP substrates

Nahid A. Jahan, Claus Hermannstädter, Jae-Hoon Huh, Hirotaka Sasakura, Thomas J. Rotter, Pankaj Ahirwar, Ganesh Balakrishnan, Kouichi Akahane, Masahide Sasaki, Hidekazu Kumano, and Ikuo Suemune

J. Appl. Phys. 113, 033506 (2013); http://dx.doi.org/10.1063/1.4775768 (11 pages)

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
InAs quantum dots (QDs) grown on InP substrates can be used as light emitters in the telecommunication bands. In this paper, we present optical characterization of high-density circular quantum dots (QDots) grown on InP(311)B substrates and elongated dots (QDashes) grown on InP(001) substrates. We study the charge carrier transfer and luminescence thermal quenching mechanisms of the QDots and QDashes by investigating the temperature dependence of their time-integrated and time-resolved photoluminescence properties. This results in two different contributions of the thermal activation energies. The larger activation energies are attributed to the carrier escape to the barrier layer and the wetting layer (WL) from QDots and QDashes, respectively. The smaller activation energies are found to be originated from inter-dot/dash carrier transfer via coupled excited states. The variation of the average oscillator strength associated with the carrier re-distribution is discussed. The relation of the two activation energies is also quantitatively studied with the measurements of excited-state and ground-state energy separations. Finally, we show an approach to isolate individual quantum dots or dashes in a suitable nanostructure.
Show PACS
78.66.Fd III-V semiconductors
81.40.Gh Other heat and thermomechanical treatments
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.55.Cr III-V semiconductors

Radial x-ray diffraction of tungsten tetraboride to 86 GPa under nonhydrostatic compression

Lun Xiong, Jing Liu, Ligang Bai, Yanchun Li, Chuanlong Lin, Duanwei He, Fang Peng, and Jung-Fu Lin

J. Appl. Phys. 113, 033507 (2013); http://dx.doi.org/10.1063/1.4775482 (5 pages)

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Investigations of the equation of state of tungsten tetraboride (WB4) have been performed under nonhydrostatic compression to 85.8 GPa using radial x-ray diffraction techniques in a diamond anvil cell at room temperature. The hexagonal structure of WB4 is found to be stable up to the highest pressure of 85.8 GPa. The radial x-ray diffraction data yield a bulk modulus K0 = 319(5) GPa with K0′ = 4.1(0.2) at ψ = 54.7°. With a fixed K0′ of 4, the derived K0 is 323(1) GPa. The bulk modulus obtained from fits of diffraction data at ψ = 0° and 90° is 196(6) GPa and 507(13) GPa, respectively. The values gradually increased from ψ = 0° to 90°, showing the compressibility of the sample strongly depends on the stress environment. In addition, the compressibility of the unit cell axes (a- and c-axes) of WB4 demonstrates an almost isotropic nature with pressure increasing.
Show PACS
81.40.Lm Deformation, plasticity, and creep
62.20.de Elastic moduli
62.20.F- Deformation and plasticity
62.50.-p High-pressure effects in solids and liquids
64.30.Jk Equations of state of nonmetals
81.40.Jj Elasticity and anelasticity, stress-strain relations

Effects of quasicrystal formation on the crystallization of (Ti36.1Zr33.2Ni5.8Be24.9)100−xCux (x = 5, 7, 9, 11, 13, 15, 17) metallic glasses

P. F. Sha, Z. W. Zhu, M. Q. Tang, H. M. Fu, Z. K. Li, H. Li, A. M. Wang, H. W. Zhang, H. F. Zhang, and Z. Q. Hu

J. Appl. Phys. 113, 033508 (2013); http://dx.doi.org/10.1063/1.4775836 (7 pages)

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The crystallization behaviors of the (Ti36.1Zr33.2Ni5.8Be24.9)100−xCux (x = 5, 7, 9, 11, 13, 15, 17; at. %) metallic glasses are investigated under both the continuous heating and isothermal conditions by the differential scanning calorimetry. Quasicrystals are found in the crystallization products under both conditions by X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The evolution of the primary crystallization products of these alloys is discussed in detail. The effects of the increasing distortion energy of the icosahedral short-range order with the increasing Cu content in the(Ti36.1Zr33.2Ni5.8Be24.9)100−xCux (x = 5, 7, 9, 11, 13, 15, 17) alloys are found to be responsible for the evolution of the crystallization products. The isothermal crystallization kinetics deviates from the Johnson-Mehl-Avrami-Kolmogoroff (JMAK) model. A modified JMAK model with an impingement parameter is found to be suitable for the isothermal crystallization kinetics of the current alloys. The effects of quasicrystal formation on the crystallization kinetics are disscussed in detail. And it is found that the isothermal crystallization kinetics are influenced by both of the “soft impingement” effect and the formation of the quasicrystals.
Show PACS
64.70.dg Crystallization of specific substances
64.70.P- Glass transitions of specific systems
64.70.pe Metallic glasses
61.43.Fs Glasses
81.40.Gh Other heat and thermomechanical treatments

Pressure effect on ZnO nanoparticles prepared via laser ablation in water

S. A. Kulinich, Takahiro Kondo, Yoshiki Shimizu, and Tsuyohito Ito

J. Appl. Phys. 113, 033509 (2013); http://dx.doi.org/10.1063/1.4775733 (5 pages)

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
ZnO nanoparticles were prepared via laser ablation of metallic Zn in neat deionized water at pressures up to ∼31 MPa and at constant ablation time, fluence, and wavelength. The high-pressure products were compared with those prepared at 1 atm, and the effect of water pressure on the product size and photoluminescent properties was studied. The results indicate that the use of pressure permits to control the particle size, the position of their exciton emission peak, and the intensity of their visible emission. While smaller and more homogeneous in size ZnO particles were produced at elevated pressures, their UV emission peak blue-shifted and green emission was enhanced. At pressures ∼22 MPa, a discontinuity in the improvement of the product green emission was observed, which should be related to the appearance of supercritical water in the ablated zone.
Show PACS
81.07.Bc Nanocrystalline materials
62.50.-p High-pressure effects in solids and liquids
78.40.Fy Semiconductors
78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
81.05.Dz II-VI semiconductors

Hybrid density functional study of electronic and optical properties of phase change memory material: Ge2Sb2Te5

T. Kaewmaraya, M. Ramzan, H. Löfås, and Rajeev Ahuja

J. Appl. Phys. 113, 033510 (2013); http://dx.doi.org/10.1063/1.4775715 (5 pages)

Online Publication Date: 16 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this article, we use hybrid density functional (HSE06) to study the crystal and electronic structures and optical properties of well known phase change memory material Ge2Sb2Te5. We calculate the structural parameters, band gaps, and dielectric functions of three stable structures of this material. We also analyze the electron charge distribution using the Bader's theory of charge analysis. We find that hybrid density functional slightly overestimates the value of “c” parameter. However, overall, our results calculated with the use of hybrid density functional (HSE06) are very close to available experimental values than calculated with the use of Perdew Burke-Ernzerhof functional. Specifically, the electronic band gap values of this material calculated with HSE06 are in good agreement with the available experimental data in the literature. Furthermore, we perform the charge analysis and find that naive ionic model fails to explain the charge distribution between the constituent atoms, showing the complex nature of this compound.
Show PACS
71.23.Cq Amorphous semiconductors, metallic glasses, glasses
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
61.43.Fs Glasses

Pressure-induced series of phase transitions in sodium azide

Hongyang Zhu, Fuxiang Zhang, Cheng Ji, Dongbin Hou, Jianzhe Wu, Trevor Hannon, and Yangzhang Ma

J. Appl. Phys. 113, 033511 (2013); http://dx.doi.org/10.1063/1.4776235 (4 pages) | Cited 1 time

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The phase analysis of sodium azide (NaN3) has been investigated by in situ synchrotron X-ray diffraction measurements in a diamond anvil cell up to 52.0 GPa at room temperature. Three pressure-induced phase transitions were observed. The phase transition pressures were determined to be 0.3, 17.3, and 28.7 GPa verified by three different pressure transmitting media. The first high pressure phase, α-NaN3 (0.3 ∼ 17.3 GPa), was identified to be monoclinic with a C2/m space group. The β-NaN3 to α-NaN3 transition is a second-order phase transition, accompanied by the shearing of the Na-layers and the tilting of the azide chains. The second high pressure phase, γ-NaN3 (18.4 ∼ 28.7 GPa), has a lower symmetry than the α-NaN3. A further phase transition of γ-NaN3 to δ-NaN3 at 28.7 GPa was observed.
Show PACS
62.50.-p High-pressure effects in solids and liquids
64.70.K- Solid-solid transitions
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder

Surface plasmon enhanced photoluminescence and Raman scattering of ultra thin ZnO-Au hybrid nanoparticles

K. Saravanan, B. K. Panigrahi, R. Krishnan, and K. G. M. Nair

J. Appl. Phys. 113, 033512 (2013); http://dx.doi.org/10.1063/1.4776654 (5 pages)

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report substantially enhanced photoluminescence (PL) and Raman signal from ZnO nanoparticles (NPs) deposited on Si with Au NPs. The resonant excitation of surface plasmon of Au NPs is responsible for the enhanced PL intensity and Raman signal from the ZnO-Au hybrid NPs. Low temperature PL measurements exhibit 14 fold enhancements in the PL intensity of ZnO-Au sample in comparison with ZnO/Si sample. It is found that, at low temperature, the donor bound exciton (DX) has dominant contribution in the PL emission of ZnO-Au hybrid NPs. At high temperature, the free exciton (FX) has dominant contribution in PL emission of these NPs. The thermal activation energies of DX and FX are found to be 5 meV and 50 meV, respectively. The defect related visible PL emission of ZnO is completely suppressed in the ZnO-Au hybrid NPs.
Show PACS
81.07.-b Nanoscale materials and structures: fabrication and characterization
73.22.Lp Collective excitations
78.30.-j Infrared and Raman spectra
78.40.-q Absorption and reflection spectra: visible and ultraviolet
78.55.-m Photoluminescence, properties and materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

Localized Si enrichment in coherent self-assembled Ge islands grown by molecular beam epitaxy on (001)Si single crystal

M. Valvo, C. Bongiorno, F. Giannazzo, and A. Terrasi

J. Appl. Phys. 113, 033513 (2013); http://dx.doi.org/10.1063/1.4775772 (17 pages)

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Transmission electron microscopy (TEM), atomic force microscopy, and Rutherford backscattering spectrometry (RBS) have been used to investigate the morphology, structure, and composition of self-assembled Ge islands grown on Si (001) substrates by molecular beam epitaxy (MBE) at different temperatures. Increasing the temperature from 550 °C to 700 °C causes progressive size and shape uniformity, accompanied by enhanced Si-Ge intermixing within the islands and their wetting layer. Elemental maps obtained by energy filtered-TEM (EF-TEM) clearly show pronounced Si concentration not only in correspondence of island base perimeters, but also along their curved surface boundaries. This phenomenon is strengthened by an increase of the growth temperature, being practically negligible at 550 °C, while very remarkable already at 650 °C. The resulting island shape is affected, since this localized Si enrichment not only provides strain relief near their highly stressed base perimeters but it also influences the cluster surface energy by effective alloying, so as to form Si-enriched SiGe interfaces. Further increase to 700 °C causes a shape transition where more homogenous Si-Ge concentration profiles are observed. The crucial role played by local “flattened” alloyed clusters, similar to truncated pyramids with larger bases and enhanced Si enrichment at coherently stressed interfaces, has been further clarified by EF-TEM analysis of a multi-layered Ge/Si structure containing stacked Ge islands grown at 650 °C. Sharp accumulation of Si has been here observed not only in proximity of the uncapped island surface in the topmost layer but also at the buried Ge/Si interfaces and even in the core of such capped Ge islands.
Show PACS
68.55.ag Semiconductors
68.35.Ct Interface structure and roughness
68.35.Dv Composition, segregation; defects and impurities
81.05.Cy Elemental semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.bg Semiconductors

Surface effects on the optical and photocatalytic properties of graphene-like ZnO:Eu3+ nanosheets

Lili Yang, Zhe Wang, Zhiqiang Zhang, Yunfei Sun, Ming Gao, Jinghai Yang, and Yongsheng Yan

J. Appl. Phys. 113, 033514 (2013); http://dx.doi.org/10.1063/1.4776225 (8 pages)

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The graphene-like ZnO:Eu3+ (ZEO) nanosheets with different Eu3+ doping concentrations are synthesized successfully by a simple hydrothermal method. We utilize the native surface effect in the ZEO nanosheets for the first time to certify the resonant energy transfer mechanism from the ZnO host to the Eu3+ ions by means of the power-dependent photoluminescence technique. Meanwhile, to further explore the functional applications of the graphene-like ZEO, we also characterize their photocatalytic activity on the Rhodamine B dye and reveal that both the higher specific surface area and Eu3+ doping lead to the higher degradation efficiency of ZEO nanosheets.
Show PACS
78.55.Et II-VI semiconductors
81.16.-c Methods of micro- and nanofabrication and processing
82.50.Hp Processes caused by visible and UV light
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
61.72.U- Doping and impurity implantation
61.46.-w Structure of nanoscale materials

Theoretical study of the indium incorporation into III-V compounds revisited: The role of indium segregation and desorption

R. R. Pelá, L. K. Teles, M. Marques, and S. Martini

J. Appl. Phys. 113, 033515 (2013); http://dx.doi.org/10.1063/1.4776741 (8 pages)

Online Publication Date: 17 January 2013

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Indium based III-V compounds are very important technological materials. However, the indium incorporation depends on several phenomena, among them, the influence of indium segregation has been the most studied. In this paper, we show that to predict accurately the energy levels of In based III-V quantum structures, besides the indium segregation, the indium desorption must also be considered. In order to verify this assumption, we consider InGaAs/GaAs quantum wells as a benchmark case, and simulate 48 different quantum wells comparing with photoluminescence results.
Show PACS
78.55.Cr III-V semiconductors
78.67.De Quantum wells
81.05.Ea III-V semiconductors
68.43.Nr Desorption kinetics
Page 1 of 4 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close