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

1 Aug 2005

Volume 87, Issue 5, Articles (05xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 87, 054101 (2005); http://dx.doi.org/10.1063/1.2006209 (3 pages)

Xiuqin Chen, S. Yang, M Hasegawa, K. Kawabe, and S. Motojima
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

PbS quantum dot electroabsorption modulation across the extended communications band 1200–1700 nm

Ethan J. D. Klem, Larissa Levina, and Edward H. Sargent

Appl. Phys. Lett. 87, 053101 (2005); http://dx.doi.org/10.1063/1.2001737 (3 pages) | Cited 10 times

Online Publication Date: 25 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report electric field-induced modulation of absorption in PbS nanocrystal quantum dots across the spectral region 600–2000 nm, encompassing the entire telecommunications band. The maxima in the electroabsorption spectra correspond with the positions of the first excitonic peak, confirming the predominance of excitonic broadening as the basis for the observed effect. We estimate the change in dipole moment to be on the order of 20 D in 7 nm diameter PbS nanocrystals compared to previously-reported ∼ 100 D in CdSe.
Show PACS
78.67.Hc Quantum dots
78.20.Jq Electro-optical effects
71.35.-y Excitons and related phenomena
61.46.-w Structure of nanoscale materials
42.79.Hp Optical processors, correlators, and modulators

Well-defined excited states of self-assembled InAs/InAlGaAs quantum dots on InP (001)

Jin Soo Kim, Jin Hong Lee, Sung Ui Hong, Ho-Sang Kwack, Byung Seok Choi, and Dae Kon Oh

Appl. Phys. Lett. 87, 053102 (2005); http://dx.doi.org/10.1063/1.2005385 (3 pages) | Cited 6 times

Online Publication Date: 25 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Self-assembled InAs/InAlGaAs quantum dots (QDs) in an InAlGaAs matrix on InP (001) substrates were grown by the alternate growth method (AGQD), where an InAs layer with a thickness of 1 monolayer (ML) and an InAlGaAs layer with a thickness of 1 ML were alternately deposited. Cross-sectional transmission electron microscopy images indicated that the aspect ratio (height/width) for the AGQDs was ∼ 0.25, which was higher than ∼ 0.10 of conventionally grown InAs QDs. The photoluminescence (PL) peak position for the ground states of the AGQDs was 1.485 μm with a linewidth broadening of 42 meV at room temperature, while the PL linewidth for the conventionally grown QDs was 85 meV. And the peaks for the excited-state transitions were also clearly observed from the excitation-power dependent PL. This is the first observation on the well-defined excited-state transitions from the InP-based InAs QDs, even though there were several reports on the features of the excited states.
Show PACS
81.05.Ea III-V semiconductors
81.07.Ta Quantum dots
73.21.La Quantum dots
68.65.Hb Quantum dots (patterned in quantum wells)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Cr III-V semiconductors
78.67.Hc Quantum dots
68.37.Lp Transmission electron microscopy (TEM)

ZnO symmetric nanosheets integrated with nanowalls

Ruey-Chi Wang, Chuan-Pu Liu, Jow-Lay Huang, and Shu-Jen Chen

Appl. Phys. Lett. 87, 053103 (2005); http://dx.doi.org/10.1063/1.2005386 (3 pages) | Cited 33 times

Online Publication Date: 25 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Diverse ZnO integrated nanostructures, constructed by epitaxial nanowalls and symmetric single-crystalline nanosheets, were successfully synthesized via a strain-assisted self-catalyzed process at a low temperature of 500 °C. The nanostructures started with the growth of ZnO nanowires, nucleated on a rugged ZnO single-crystalline film via a strain-assisted self-catalyzed growth mechanism. The nanowalls were then formed by the interconnection of the nanowires. Finally, the nanosheets were grown from the edges of the nanowalls. The growth mechanisms were supported by direct experimental evidence. Room-temperature cathodoluminance spectra show a relatively strong and sharp ultraviolet emission as well as a weak and broad green emission. The integrated nanostructure may be applied to develop self-inclusive nanoelectronics.
Show PACS
81.05.Dz II-VI semiconductors
81.07.Bc Nanocrystalline materials
81.16.Hc Catalytic methods
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
78.40.Fy Semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

Mechanism of nanoparticle agglomeration during the combustion synthesis

Igor S. Altman, Igor E. Agranovski, and Mansoo Choi

Appl. Phys. Lett. 87, 053104 (2005); http://dx.doi.org/10.1063/1.2005387 (3 pages) | Cited 10 times

Online Publication Date: 25 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The mechanism of agglomeration of nanoparticles generated during combustion synthesis is discussed. This is based on the analysis of the transmission electron microscope images of probes collected at different heights. Although direct temperature measurements were not available, the qualitative temperature dependence of the particle formation streamlines is taken into account. It is demonstrated that agglomeration of the MgO nanoparticles, which are formed during a Mg particle combustion, occurs as the result of bonding the mature nanoparticles by the supercritical clusters existing in the system. Accumulation of these supercritical clusters in the flame has been revealed and their nature has been explained in our recent paper [ I.S. Altman, I.E. Agranovski, and M. Choi, Phys. Rev E 70, 062603 (2004) ]. Also, some inspection of the previously published experimental data on the nanoparticle generation shows that the similar supercritical clusters may exist in another flame reactor generating titania nanopaprticles. If this is the case, the cluster-based process of nanoparticle bonding we suggest can be considered to be general.
Show PACS
82.33.Vx Reactions in flames, combustion, and explosions
61.46.-w Structure of nanoscale materials
68.37.Lp Transmission electron microscopy (TEM)

Nanocrystals of cerium and europium trifluorides generated by coaxial Taylor cone electrospray of aqueous solutions at room temperature

I. Aguirre de Cárcer, P. Herrero, A. R. Landa-Cánovas, and B. Sobolev

Appl. Phys. Lett. 87, 053105 (2005); http://dx.doi.org/10.1063/1.1999840 (3 pages) | Cited 5 times

Online Publication Date: 26 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Cerium and europium trifluoride nanocrystals have been obtained in a Taylor’s double-cone electrospray by chemical reactions of precipitation from two miscible aqueous solutions of rare earth (RE = Ce,Eu) nitrates and HF. The products of the chemical reactions CeF3 and EuF3 have a very low solubility precipitating as nanocrystals of controllable size and composition. The change of the starting concentration, from 0.13 M Ce(NO3)3 to 0.01 M Eu(NO3)3, seems to have influence on the morphology of the nanoparticles, producing well crystallized EuF3 nanocrystals for the dilute solution and mosaic-like multidomain CeF3 nanocrystals for the more concentrated solution. This procedure can be used for the production of a great variety of inorganic compounds. The low-solubility requirement of the products of chemical reactions is the only key and it assures a high rate of insoluble crystals formation.
Show PACS
81.07.Bc Nanocrystalline 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)
81.30.Mh Solid-phase precipitation
61.46.-w Structure of nanoscale materials
61.50.-f Structure of bulk crystals
64.75.-g Phase equilibria

Self-assembled supported Co nanocrystals: The adhesion energy of face-centered-cubic Co on SrTiO3(001)-(2×2)

Fabien Silly and Martin R. Castell

Appl. Phys. Lett. 87, 053106 (2005); http://dx.doi.org/10.1063/1.2005390 (3 pages) | Cited 12 times

Online Publication Date: 27 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the structure and morphology of self-assembled cobalt nanocrystals supported on a SrTiO3(001)-(2×2) substrate using scanning tunneling microscopy. Nanocrystals with a truncated pyramid shape were imaged, allowing crystallographic identification of the cluster facets. These nanocrystals result from the epitaxial growth of fcc Co on SrTiO3(001). The dimension of the nanocrystal facets at equilibrium and an energy minimization calculation result in γadh = (3.96±0.37)J/m2 for the adhesion energy of face-centered-cubic Co/SrTiO3(001)-(2×2).
Show PACS
81.07.Bc Nanocrystalline materials
81.16.Dn Self-assembly
68.35.Np Adhesion
61.46.-w Structure of nanoscale materials
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)

Nanostaircases: An atomic shadowing instability during epitaxial CrN(001) layer growth

J. R. Frederick and D. Gall

Appl. Phys. Lett. 87, 053107 (2005); http://dx.doi.org/10.1063/1.2005369 (3 pages) | Cited 5 times

Online Publication Date: 27 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Epitaxial CrN(001) layers, 57 and 230 nm thick, were grown on MgO(001) at 700 °C by ultrahigh-vacuum magnetron sputter deposition in pure N2 discharges. An oblique deposition angle α = 80° was utilized to purposely increase the effect of atomic shadowing on surface morphological and microstructural evolution. The layers are single crystals with a surface morphology that is characterized by dendritic ridge patterns extending along orthogonal 〈110〉 directions superposed by square-shaped supermounds with 〈100〉 edges. The ridge patterns are due to a two-dimensional growth instability related to a gradient in the adatom density while the supermounds form due to atomic shadowing. The supermounds protrude out of the surface and capture a larger deposition flux than the surrounding layer. This leads to both vertical and lateral growth and the formation of inverted pyramids that are epitaxially embedded in a single crystalline matrix. The inverted pyramids are terminated by 1–3-nm-wide tilted voids that form nanostaircases due to kinetic faceting along orthogonal {100} planes.
Show PACS
68.55.-a Thin film structure and morphology
81.15.Cd Deposition by sputtering
61.72.Qq Microscopic defects (voids, inclusions, etc.)
81.07.Bc Nanocrystalline materials
61.46.-w Structure of nanoscale materials

Characteristics of HfO2 thin films grown by plasma atomic layer deposition

Jinwoo Kim, Seokhoon Kim, Hyeongtag Jeon, M.-H. Cho, K.-B. Chung, and Choelhwyi Bae

Appl. Phys. Lett. 87, 053108 (2005); http://dx.doi.org/10.1063/1.2005370 (3 pages) | Cited 25 times

Online Publication Date: 28 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The characteristics of HfO2 films grown on Si substrates using a tetrakis-diethyl-amino-hafnium precursor by the remote plasma atomic layer deposition (RPALD) and direct plasma ALD (DPALD) methods were investigated by physical and electrical measurement techniques. The as-deposited HfO2 layer from RPALD exhibits an amorphous structure, while the HfO2 layer from DPALD exhibits a clearly visible polycrystalline structure. Medium energy ion scattering measurement results indicate that the interfacial layer consists of the interfacial SiO2−x and silicate layers. These results suggested that the stoichiometric change in the depth direction could be related to the energetic reactant in a state of plasma used in the plasma ALD process, resulting in damage to the Si surface and interactions between Hf and SiO2−x. The as-deposited HfO2 films using RPALD have the better interfacial layer characteristics than those using DPALD. A metal-oxide-semiconductor capacitor fabricated using the RPALD method exhibits electrical characteristics such as equivalent oxide thickness (EOT) of 1.8 nm with an effective fixed oxide charge density (Qf,eff) of ∼ 4.2×1011 q/cm2 and that for DPALD has a EOT (2.0 nm), and Qf,eff( ∼ −1.2×1013 q/cm2).
Show PACS
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.55.-g Dielectric thin films
81.15.Jj Ion and electron beam-assisted deposition; ion plating
81.15.Kk Vapor phase epitaxy; growth from vapor phase
52.77.Dq Plasma-based ion implantation and deposition
68.55.-a Thin film structure and morphology
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
84.32.Tt Capacitors
61.66.Bi Elemental solids
61.66.Dk Alloys

Suppression of the photoluminescence quenching effect in self-assembled InAs/GaAs quantum dots

N. V. Baidus, A. Chahboun, M. J. M. Gomes, M. I. Vasilevskiy, P. B. Demina, E. A. Uskova, and B. N. Zvonkov

Appl. Phys. Lett. 87, 053109 (2005); http://dx.doi.org/10.1063/1.2006978 (3 pages) | Cited 4 times

Online Publication Date: 28 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report results that witness the possibility of controlling the temperature (T) dependence of the photoluminescence (PL) from self-assembled InAs/GaAs quantum dots (QDs) overgrown by an InxGa1−xAs layer forming a quantum well. A growth treatment using tetrachloromethane eliminates the quenching of the PL intensity at room temperature. A reduction in the concentration of defects in the GaAs matrix and the corresponding increase of the radiative lifetime of the photocarriers are invoked to explain this effect. A simple model analyzing the behavior of the quasi-Fermi level in the QD heterostructure confirms our explanation.
Show PACS
81.07.Ta Quantum dots
81.05.Ea III-V semiconductors
78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Giant field enhancement at carbon nanotube tips induced by multistage effect

J. Y. Huang, K. Kempa, S. H. Jo, S. Chen, and Z. F. Ren

Appl. Phys. Lett. 87, 053110 (2005); http://dx.doi.org/10.1063/1.2008363 (3 pages) | Cited 43 times

Online Publication Date: 29 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Recently, we have reported an extremely strong field emission from carbon nanotubes grown on carbon cloth, with the field-enhancement factor of up to 18 800. In this paper, we study the origins of this effect, by investigating field emission from individual carbon nanotubes, in a transmission electron microscope equipped with a piezo manipulator. Microscopic analysis reveals a multistage structure of some of the nanotubes, characterized by an order of magnitude smaller nanotubes branching off the tips of bigger nanotubes (or carbon fibers). The multistage structure causes a macroscopic enhancement of the electric field, which can match that of a single macroscopically long nanotube with length equal to the combined length of all stages, and the tip radius equal to that of the thinnest nanotube in the structure. This not only explains the observed giant field enhancement, but also provides important clues for the design of nanotube emitters for electronic applications.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
61.46.-w Structure of nanoscale materials
68.37.Lp Transmission electron microscopy (TEM)

Mechanical elasticity of single and double clamped silicon nanobeams fabricated by the vapor-liquid-solid method

A. San Paulo, J. Bokor, R. T. Howe, R. He, P. Yang, D. Gao, C. Carraro, and R. Maboudian

Appl. Phys. Lett. 87, 053111 (2005); http://dx.doi.org/10.1063/1.2008364 (3 pages) | Cited 51 times

Online Publication Date: 29 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Atomic force microscopy has been used to characterize the mechanical elasticity of Si nanowires synthesized by the vapor-liquid-solid method. The nanowires are horizontally grown between the two facing Si(111) sidewalls of microtrenches prefabricated on a Si(110) substrate, resulting in suspended single and double clamped nanowire-in-trench structures. The deflection of the nanowires is induced and measured by the controlled application of normal forces with the microscope tip. The observed reversibility of the nanowire deflections and the agreement between the measured deflection profiles and the theoretical behavior of single and double clamped elastic beams demonstrate the overall beamlike mechanical behavior and the mechanical rigidity of the clamping ends of the nanowire-in-trench structures. These results demonstrate the potential of the nanowire-in-trench fabrication approach for the integration of VLS grown nanostructures into functional nanomechanical devices.
Show PACS
81.07.Vb Quantum wires
68.65.La Quantum wires (patterned in quantum wells)
61.46.-w Structure of nanoscale materials
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity
81.05.Cy Elemental semiconductors

Sample-profile estimate for fast atomic force microscopy

Srinivasa Salapaka, Tathagata De, and Abu Sebastian

Appl. Phys. Lett. 87, 053112 (2005); http://dx.doi.org/10.1063/1.2006213 (3 pages) | Cited 11 times

Online Publication Date: 29 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, a design scheme that achieves an optimal tip-sample force regulation with an ideal topography image reconstruction is presented. It addresses the problem of obtaining accurate sample profiles when scanning at high bandwidth while maintaining a constant cantilever-tip sample force in atomic force microscopes. In this design scheme, the objective of maintaining a constant tip-sample force while scanning at high bandwidth does not impose limitations on the reconstruction of the sample topography. It is shown that the proposed scheme provides a faithful replica of the sample at all relevant scanning speeds limited only by the inaccuracy in the model for the atomic force microscope. This provides an improvement over existing designs where the sample profile reconstruction is typically bandwidth limited. Comparison with the existing methods of using the control signal as the image is provided. The experimental results corroborate the theoretical development.
Show PACS
07.79.Lh Atomic force microscopes
42.30.Wb Image reconstruction; tomography
42.30.Lr Modulation and optical transfer functions

Electron-hole asymmetry and two-state lasing in quantum dot lasers

E. A. Viktorov, Paul Mandel, Yann Tanguy, John Houlihan, and Guillaume Huyet

Appl. Phys. Lett. 87, 053113 (2005); http://dx.doi.org/10.1063/1.1995947 (3 pages) | Cited 26 times

Online Publication Date: 29 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study the decrease of the ground-state output with increasing current in two-state quantum dot lasing. We show that the asymmetry in the thermal population redistribution breaks the symmetric dynamical evolution of the electron-hole pairs. This fully explains the transition from two-state to single-state lasing observed experimentally. The model also reproduces the temperature dependence of the two-state lasing.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
78.20.N- Thermo-optic effects
78.20.nb Photothermal effects

Imaging and spectroscopy of individual CdSe nanocrystals on atomically resolved surfaces

R. Bernard, G. Comtet, G. Dujardin, V. Huc, and A. J. Mayne

Appl. Phys. Lett. 87, 053114 (2005); http://dx.doi.org/10.1063/1.2008378 (3 pages) | Cited 12 times

Online Publication Date: 29 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Imaging and spectroscopy of individual CdSe nanocrystals have been performed with the scanning tunneling microscope (STM) on atomically resolved hydrogenated Si(100) surfaces. The CdSe nanocrystals have been deposited under vacuum onto the surface by using the pulse valve method. Two different types of CdSe nanocrystals, capped either with trioctylphosphine oxide ligands or with cadmium stearate ligands, have been studied to optimize their anchoring to the surface. The I(V) spectroscopy shows a characteristic resonant excitation spectrum through the unoccupied levels of the nanocrystals with no significant charging effect. This suggests that the nanocrystals are weakly coupled to the surface, thus requiring a stronger coupling with the STM tip to achieve a measurable tunnel current. These results demonstrate the importance of depositing nanocrystals on clean and atomically well-defined surfaces for reliable measurement of their properties.
Show PACS
81.05.Dz II-VI semiconductors
81.07.Bc Nanocrystalline materials
73.63.Bd Nanocrystalline materials
61.46.-w Structure of nanoscale materials
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)

Three-dimensional modeling of nanoscale Seebeck measurements by scanning thermoelectric microscopy

Zhixi Bian, Ali Shakouri, Li Shi, Ho-Ki Lyeo, and C. K. Shih

Appl. Phys. Lett. 87, 053115 (2005); http://dx.doi.org/10.1063/1.2008381 (3 pages) | Cited 7 times

Online Publication Date: 29 July 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A three-dimensional electrothermal model has been developed to investigate the spatial resolution of the scanning thermoelectric microscopy (SThEM). We found that if the electrical resistivity of the sample changes abruptly, the SThEM will measure a voltage close to the local thermoelectric voltage where electrical resistivity is relatively low, rather than a simple weighted average of the thermoelectric voltage distribution based on the temperature profile. This is due to the presence of internal currents in the sample. The spatial resolution of the Seebeck profiling is limited by the finite value of the phonon mean free path of the sample and the tip size of the microscopy. With a tip size around 1 nm, the scanning thermoelectric microscopy can achieve a spatial resolution of the physical limit defined by the statistical nature of the charge carrier and phonon behavior in a very small region.
Show PACS
07.79.Cz Scanning tunneling microscopes
72.20.Pa Thermoelectric and thermomagnetic effects
63.20.-e Phonons in crystal lattices
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close