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

21 Jan 2002

Volume 80, Issue 3, pp. 341-531

Return to All Sections
back to top
RSS Feeds

Lateral redistribution of excitons in CdSe/ZnSe quantum dots

M. Strassburg, M. Dworzak, H. Born, R. Heitz, A. Hoffmann, M. Bartels, K. Lischka, D. Schikora, and J. Christen

Appl. Phys. Lett. 80, 473 (2002); http://dx.doi.org/10.1063/1.1432743 (3 pages) | Cited 36 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Lateral redistribution processes of excitons localized in CdSe/ZnSe quantum dot structures are investigated by time-integrated and time-resolved spectroscopy. The photoluminescence properties are governed by lateral energy transfer within a dense ensemble of quantum dots. The quantum dots differ in size and Cd concentration and provide a complex potential landscape with localization sites for excitons. At low temperatures, lateral transfer by tunneling leads to a redshift with increasing delay after pulsed excitation. The mobility edge was determined to 2.561 eV. Above 100 K, thermally activated escape and recapture of excitons cause a strong redshift of the PL maximum in the first 500 ps. © 2002 American Institute of Physics.
Show PACS
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
73.21.La Quantum dots
78.67.Hc Quantum dots
78.55.Et II-VI semiconductors
78.47.-p Spectroscopy of solid state dynamics

Effects of spatial separation on the growth of vertically aligned carbon nanofibers produced by plasma-enhanced chemical vapor deposition

Vladimir I. Merkulov, Anatoli V. Melechko, Michael A. Guillorn, Douglas H. Lowndes, and Michael L. Simpson

Appl. Phys. Lett. 80, 476 (2002); http://dx.doi.org/10.1063/1.1433905 (3 pages) | Cited 22 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Vertically aligned carbon nanofibers (VACNFs) with vastly different spacing were grown by catalytically controlled dc glow discharge chemical vapor deposition. Both densely packed VACNFs and essentially isolated VACNFs were studied using scanning electron microscopy and x-ray energy dispersive spectroscopy. The morphology and chemical composition of isolated VACNFs were found to have a strong dependence upon the growth conditions, in particular on the C2H2/NH3 gas mixture used. This is attributed to the sidewalls of isolated VACNFs being exposed to reactive species during growth. In contrast, the sidewalls of densely packed VACNFs were shielded by the neighboring VACNFs, so that their growth occurred mainly in the vertical direction, by diffusion of carbon through the catalyst nanoparticle and subsequent precipitation at the nanofiber/nanoparticle interface. These striking differences in the growth process result in the formation of flattened carbon nanostructures (carbon nanotriangles) and also are quite important for the realization of VACNF-based devices. © 2002 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
81.07.Bc Nanocrystalline materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

β-Ga2O3 nanowires synthesized from milled GaN powders

B. C. Kim, K. T. Sun, K. S. Park, K. J. Im, T. Noh, M. Y. Sung, S. Kim, S. Nahm, Y. N. Choi, and S. S. Park

Appl. Phys. Lett. 80, 479 (2002); http://dx.doi.org/10.1063/1.1435073 (3 pages) | Cited 36 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
White-colored materials synthesized by a thermal annealing of milled GaN powders at 930 °C in a nitrogen atmosphere were identified to be monoclinic β-Ga2O3 nanowires by x-ray diffraction and scanning electron microscopy. High-resolution transmission electron microscopy revealed that these nanowires are single nanocrystals, and energy dispersive x-ray indicated that these nanomaterials are free of any metals. In addition, bundles of these crystalline nanowires in the rectangular-pole shape are a few centimeters in length.© 2002 American Institute of Physics.
Show PACS
81.07.Bc Nanocrystalline materials
61.46.-w Structure of nanoscale materials
81.40.Gh Other heat and thermomechanical treatments
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

Laser manipulation and fixation of single gold nanoparticles in solution at room temperature

Syoji Ito, Hiroyuki Yoshikawa, and Hiroshi Masuhara

Appl. Phys. Lett. 80, 482 (2002); http://dx.doi.org/10.1063/1.1432753 (3 pages) | Cited 37 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method to fix single gold nanoparticles on glass substrate was demonstrated in solution at room temperature by utilizing focused intense laser beams. A single gold nanoparticle of 80 nm was optically trapped and manipulated to a surface of a glass substrate, and then fixed on it by irradiation with ultraviolet (UV) laser light. Suitable laser fluence range for the fixation was determined to be 32–60 mJ/cm2, above which the individual nanoparticles were fragmented to several smaller fragments of 10 to 40 nm. The fixation mechanism is discussed in view of pulsed-laser-induced transient temperature elevation. © 2002 American Institute of Physics.
Show PACS
81.16.Ta Atom manipulation
61.46.-w Structure of nanoscale materials
37.10.Vz Mechanical effects of light on atoms, molecules, and ions

InGaN self-assembled quantum dots grown by metalorganic chemical-vapor deposition with indium as the antisurfactant

J. Zhang, M. Hao, P. Li, and S. J. Chua

Appl. Phys. Lett. 80, 485 (2002); http://dx.doi.org/10.1063/1.1433163 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nanometer-scale InGaN self-assembled quantum dots have been formed in an InGaN single-quantum-well structure on a (0001) sapphire substrate with In as the antisurfactant using low-pressure metalorganic chemical-vapor deposition. High-resolution transmission electron microscopy reveals that the average dimensions of InGaN nanometer-scale structures are as small as 4 nm wide and 1.5 nm high. Strong photoluminescence emission of the InGaN quantum dots was observed at room temperature with an emission peak of about 2.56 eV (485 nm) and a full width at half maximum of about 150 meV (30 nm). The choice of In as the antisurfactant also avoids the incorporation of foreign atoms in the active layers. © 2002 American Institute of Physics.
Show PACS
81.07.Ta Quantum dots
81.15.Kk Vapor phase epitaxy; growth from vapor phase
78.55.Cr III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.65.Hb Quantum dots (patterned in quantum wells)
78.67.Hc Quantum dots
87.64.Ee Electron microscopy

Raman scattering and x-ray absorption studies of Ge–Si nanocrystallization

A. Kolobov, H. Oyanagi, N. Usami, S. Tokumitsu, T. Hattori, S. Yamasaki, K. Tanaka, S. Ohtake, and Y. Shiraki

Appl. Phys. Lett. 80, 488 (2002); http://dx.doi.org/10.1063/1.1435076 (3 pages) | Cited 19 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied the local structure of GeSi nanocrystals embedded in SiO2 prepared by co-sputtering of Ge, Si, and SiO2 targets onto a Si(100) substrate. From Raman scattering, we conclude that the formation of the isotropic crystalline Ge phase starts at about 800 °C followed by the formation of a GeSi phase at higher temperatures. The formed nanocrystals, whose size depends on the annealing temperature, are randomly oriented. The local structure of the nanocrystals has been studied by x-ray absorption fine structure spectroscopy. They are found to consist of a relaxed Ge core with a typical diameter of ∼4 nm and the Ge–Ge bond length of 2.45 Å and of a GeSi outer shell, the Ge–Si bond length being 2.39 Å. The average composition of the grown nanocrystals is estimated to be Ge0.75Si0.25. © 2002 American Institute of Physics.
Show PACS
78.30.Hv Other nonmetallic inorganics
78.66.Li Other semiconductors
78.70.Dm X-ray absorption spectra
68.55.-a Thin film structure and morphology
61.46.-w Structure of nanoscale materials
61.72.Cc Kinetics of defect formation and annealing

Bright visible photoluminescence from silica nanotube flakes prepared by the sol–gel template method

Ming Zhang, Eugenia Ciocan, Y. Bando, K. Wada, L. L. Cheng, and P. Pirouz

Appl. Phys. Lett. 80, 491 (2002); http://dx.doi.org/10.1063/1.1434309 (3 pages) | Cited 68 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report macroscopic synthesis of silica nanotubes by the sol–gel template method. A large number of silica nanotubes with small diameters (30–50 nm) were produced and were shaped into flakes successfully. Strong photoluminescence (PL) was observed in both as-grown and annealed nanotube flakes. The PL spectra have maxima at 2.55 and 2.30 eV for the as-grown and annealed samples, respectively; the PL intensity of annealed nanotubes is much higher than that of as-grown nanotubes. The strong emission may be due to the Si–OH complex located on both the inner and outer surfaces of the nanotubes. The nanotube flakes we prepared may have potential applications in future integrated optical devices. © 2002 American Institute of Physics.
Show PACS
78.67.Ch Nanotubes
78.55.Hx Other solid inorganic materials
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
81.07.De Nanotubes
61.46.-w Structure of nanoscale materials

Single InP/GaInP quantum dots studied by scanning tunneling microscopy and scanning tunneling microscopy induced luminescence

U. Håkanson, M. K.-J. Johansson, J. Persson, J. Johansson, M.-E. Pistol, L. Montelius, and L. Samuelson

Appl. Phys. Lett. 80, 494 (2002); http://dx.doi.org/10.1063/1.1435796 (3 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied the optical and structural properties of single, self-assembled InP quantum dots (QDs) overgrown with nominally 5 nm of GaInP, using an ultrahigh-vacuum scanning tunneling microscope (STM) operating at low temperatures. The STM is combined with an optical detection system, which allows us to detect the emission from individual quantum dots with high spatial resolution. We find that the InP QDs act as nucleation points for the GaInP overgrowth, where the strain induced by the overlayer give rise to a QD emission around 1.46 eV. © 2002 American Institute of Physics.
Show PACS
78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
68.65.Hb Quantum dots (patterned in quantum wells)
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)

Two-dimensional periodic alignment of self-assembled Ge islands on patterned Si(001) surfaces

Takeshi Kitajima, Bing Liu, and Stephen R. Leone

Appl. Phys. Lett. 80, 497 (2002); http://dx.doi.org/10.1063/1.1434307 (3 pages) | Cited 38 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Two-dimensional alignment of Ge islands is obtained by molecular beam epitaxy of Ge on lithographically patterned Si(001) surfaces composed of periodic arrays of square Si mesas. When the period of the Si mesa arrays is reduced to 140 nm, a “one island on one mesa” relationship is achieved. The Ge islands have an average base width of 85 nm and take on the shape of a truncated pyramid with four {114} facets and a (001) top. The patterning also serves to improve the island size uniformity. The dependencies of the island morphology on the sizes of the Si mesas and Ge coverages are examined to clarify the mechanism of preferential nucleation of Ge islands on the tops of Si mesas. © 2002 American Institute of Physics.
Show PACS
81.16.Dn Self-assembly
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
81.05.Cy Elemental semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.65.Hb Quantum dots (patterned in quantum wells)

Boron carbide nanolumps on carbon nanotubes

J. Y. Lao, W. Z. Li, J. G. Wen, and Z. F. Ren

Appl. Phys. Lett. 80, 500 (2002); http://dx.doi.org/10.1063/1.1435062 (3 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Boron carbide nanolumps are formed on the surface of multiwall carbon nanotubes by a solid-state reaction between boron and carbon nanotubes. The reaction is localized so that the integrity of the structure of carbon nanotubes is maintained. Inner layers of multiwall carbon nanotubes are also bonded to boron carbide nanolumps. These multiwall carbon nanotubes with boron carbide nanolumps are expected to be the ideal reinforcing fillers for high-performance composites because of the favorable morphology. © 2002 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
81.07.Bc Nanocrystalline materials
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
81.07.De Nanotubes
68.35.B- Structure of clean surfaces (and surface reconstruction)

Quantum description of the resistor–capacitor circuit and Brownian motion

W. H. Richardson

Appl. Phys. Lett. 80, 503 (2002); http://dx.doi.org/10.1063/1.1432761 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An equation for the reduced density matrix which describes a capacitor, that is coupled to a resistor, is derived using the total Hamiltonian, and without resorting to any artificial model. A Master equation is also obtained for the dissipative medium. The theory erases the notion of the reservoir. It is shown that the dynamical interaction with the medium is not completely determined by the resistance (or the corresponding fluctuation–dissipation relation). Unexpectedly, through the charge density–density correlation, the longitudinal dielectric function is shown to play a critical role. © 2002 American Institute of Physics.
Show PACS
05.40.Jc Brownian motion
03.65.Sq Semiclassical theories and applications
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)
84.32.Tt Capacitors

Universal field-emission model for carbon nanotubes on a metal tip

D. Y. Zhong, G. Y. Zhang, S. Liu, T. Sakurai, and E. G. Wang

Appl. Phys. Lett. 80, 506 (2002); http://dx.doi.org/10.1063/1.1430507 (3 pages) | Cited 53 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron-field-emission properties have been investigated systematically for carbon nanotubes (CNTs) fabricated on a metal tip. With a vacuum gap of 0.7 mm, the threshold field is as low as 0.7 V/μm and the current density approaches 10 mA/cm2 at an electronic field of 1.0 V/μm. The emission current is quite stable with very low fluctuation. The emission behavior is in excellent agreement with Fowler–Nordheim theory and no current saturation is found even with an emission current reaching 1 A/cm2. A universal relationship 1/β = d2/d+1/β0 between the field amplification factor β and the vacuum gap d is developed within a two-region field-emission model. This relationship provides the basis for a microscopic understanding of CNT emitters and is applicable to other systems as well. © 2002 American Institute of Physics.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close