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 Nov 2004

Volume 85, Issue 18, pp. 3959-4247

Issue Cover Spotlight Figure

Appl. Phys. Lett. 85, 4142 (2004); http://dx.doi.org/10.1063/1.1811774 (3 pages)

Hong Jin Fan, Roland Scholz, Florian M. Kolb, and Margit Zacharias
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Dopant profiling in vertical ultrathin channels of double-gate metal–oxide–semiconductor field-effect transistors by using scanning nonlinear dielectric microscopy

Meishoku Masahara, Shinichi Hosokawa, Takashi Matsukawa, Kazuhiko Endo, Yuuichi Naitou, Hisao Tanoue, and Eiichi Suzuki

Appl. Phys. Lett. 85, 4139 (2004); http://dx.doi.org/10.1063/1.1812571 (3 pages) | Cited 8 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nanometer-scale dopant profiling in the vertical ultrathin channels (UTCs) of double-gate metal–oxide–semiconductor field-effect transistors has been performed by using scanning nonlinear dielectric microscopy. UTCs 18–58 nm thick and 175 nm high were formed on a bulk silicon substrate by orientation-dependent wet etching. An n+∕p junction was fabricated on the top of the UTC by angled ion implantation. By beveling the UTC with an ultragentle angle, the vertical size of the UTC was amplified by a factor of 86. Using the beveled samples, the channel thickness dependence of the dopant depth profile in the UTC was quantitatively investigated. It was found that a significant dopant loss occurs when the channel thickness is reduced to 18 nm.
Show PACS
85.30.Tv Field effect devices
61.72.S- Impurities in crystals
61.72.up Other materials
81.65.Cf Surface cleaning, etching, patterning

Two-dimensional dendritic ZnO nanowires from oxidation of Zn microcrystals

Hong Jin Fan, Roland Scholz, Florian M. Kolb, and Margit Zacharias

Appl. Phys. Lett. 85, 4142 (2004); http://dx.doi.org/10.1063/1.1811774 (3 pages) | Cited 56 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spontaneous formation of ZnO dendritic nanowires has been achieved on the faceted surfaces of polyhedral Zn microcrystals by oxidizing the latter at 600 °C. Electron microscopy investigations reveal that all the dendritic branches are elongated in 〈11–20〉 directions within the ±(0001) primary planes, forming two-dimensional web-like structure. Homoepitaxial interconnections are observed at the branch-to-arm and branch-to-branch regions, and the whole dendrites are wurtzite single crystals. The growth process of the dendritic nanowires is discussed, which is proposed to be a combination of “self-catalytic liquid–solid” and vapor–solid process.
Show PACS
81.07.Bc Nanocrystalline materials
81.16.Pr Micro- and nano-oxidation
81.65.Mq Oxidation
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
61.46.-w Structure of nanoscale materials
78.55.Et II-VI semiconductors
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

Photon lifetime dependence of modulation efficiency and K factor in 1.3 μm self-assembled InAs∕GaAs quantum-dot lasers: Impact of capture time and maximum modal gain on modulation bandwidth

Mitsuru Ishida, Nobuaki Hatori, Tomoyuki Akiyama, Koji Otsubo, Yoshiaki Nakata, Hiroji Ebe, Mitsuru Sugawara, and Yasuhiko Arakawa

Appl. Phys. Lett. 85, 4145 (2004); http://dx.doi.org/10.1063/1.1811789 (3 pages) | Cited 30 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We studied small-signal modulation characteristics of 1.3 μm InAs∕GaAs self-assembled quantum-dot lasers in terms of the modulation efficiency and the K factor as a function of the photon lifetime. We could explain the measured photon-lifetime dependence based on the rate equation model considering explicitly the carrier-capture process and Pauli blocking in quantum dots. Our model shows how the modulation bandwidth of quantum-dot lasers is limited by the carrier-capture time and by the maximum modal gain via the K factor. We present prerequisite designs of quantum-dot active regions for over 10 GHz modulation.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
73.21.La Quantum dots

Measurement of interface potential change and space charge region across metal/organic/metal structures using Kelvin probe force microscopy

O. Tal, W. Gao, C. K. Chan, A. Kahn, and Y. Rosenwaks

Appl. Phys. Lett. 85, 4148 (2004); http://dx.doi.org/10.1063/1.1811805 (3 pages) | Cited 12 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on high-resolution potential measurements across complete metal/organic molecular semiconductor/metal structures using Kelvin probe force microscopy in inert atmosphere. It is found that the potential distribution at the metal/organic interfaces is in agreement with an interfacial abrupt potential changes and the work function of the different metals. The potential distribution across the organic layer strongly depends on its purification. In pure Alq3 the potential profile is flat, while in nonpurified layers there is substantial potential bending probably due to the presence of deep traps. The effect of the measuring tip is calculated and discussed.
Show PACS
73.40.Sx Metal-semiconductor-metal structures
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ps Atomic force microscopy (AFM)
73.30.+y Surface double layers, Schottky barriers, and work functions
73.61.Ph Polymers; organic compounds

Controlling Er–Tm interaction in Er and Tm codoped silicon-rich silicon oxide using nanometer-scale spatial separation for efficient, broadband infrared luminescence

Se-Young Seo and Jung H. Shin

Appl. Phys. Lett. 85, 4151 (2004); http://dx.doi.org/10.1063/1.1812578 (3 pages) | Cited 9 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of nanometer-scale spatial separation between Er3+ and Tm3+ ions in Er and Tm codoped silicon-rich silicon oxide (SRSO) films is investigated. Er and Tm codoped SRSO films, which consist of nanocluster Si (nc-Si) embedded inside SiO2 matrix, were fabricated with electron cyclotron resonance-plasma enhanced chemical vapor deposition of SiH4 and O2 with concurrent sputtering of Er and Tm metal targets. Spatial separation between Er3+ and Tm3+ ions was achieved by depositing alternating layers of Er- and Tm-doped layers of varying thickness while keeping the total film thickness the same. The films display broadband infrared photoluminescence (PL) from 1.5 to 2.0 μm under a single source excitation due to simultaneous excitation of Er3+ and Tm3+ ions by nc-Si. Increasing the layer thickness from 0 to 72 nm increases the Er3+ PL intensity nearly 50-fold while the Tm3+ PL intensity is unaffected. The data are well-explained by a model assuming a dipole–dipole interaction between excited Er3+ and Tm3+ ions, and suggest that by nanoscale engineering, efficient, ultrabroadband infrared luminescence can be obtained in an optically homogeneous material using a single light source.
Show PACS
78.66.Nk Insulators
68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology
78.55.Hx Other solid inorganic materials
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Multispectral operation of self-assembled InGaAs quantum-dot infrared photodetectors

Seongsin M. Kim and James S. Harris

Appl. Phys. Lett. 85, 4154 (2004); http://dx.doi.org/10.1063/1.1810208 (3 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report two-color InGaAs quantum-dot infrared photodetectors. The InGaAs self-assembled quantum dots were grown on InGaP matrix via metalorganic chemical vapor deposition and fabricated as intersubband photoconductive structure. Bias controlled two-color photoconductive responses were obtained at two different infrared window, mid-infrared (IR) of λ=5.5 μm and far-IR of λ=9.2 μm at 77 K. Our devices were operated with low dark currents and high optical gains, and resulted in peak detectivity, D*, of 4.7×109 cm Hz1∕2∕W at λ=5.5 μm with bias of −2.0 V, and 7.2×108 cm Hz1∕2∕W at λ=9.2 μm with bias of −0.8 V.
Show PACS
85.60.Gz Photodetectors (including infrared and CCD detectors)
68.65.Hb Quantum dots (patterned in quantum wells)
78.67.Hc Quantum dots
78.30.Fs III-V and II-VI semiconductors
72.40.+w Photoconduction and photovoltaic effects

Real-time detection of ambient oxidation of steps and terraces on Si(111)-(1×1):H by scanning force microscopy

Abbas Khan and Peter Hess

Appl. Phys. Lett. 85, 4157 (2004); http://dx.doi.org/10.1063/1.1813632 (3 pages) | Cited 1 time

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The initial stage of oxide formation on Si(111)-(1×1):H, a highly controversial problem, has been studied using scanning force microscopy under ambient conditions (25% relative humidity at 20 °C). Real-time monitoring of changes in the root-mean-squared (rms) roughness of the broad terraces and step heights was performed at the same surface spots. The height of the bilayer steps increased by 0.2–0.3 nm with a maximum after about 22 h and decreased afterward due to further oxidation of the terrace on a longer time scale. This finding clearly suggests fast bilayer step oxidation, as opposed to terrace oxidation, contrary to previous reports.
Show PACS
81.05.Cy Elemental semiconductors
81.65.Mq Oxidation
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ps Atomic force microscopy (AFM)

Combined “heat transfer and power dissipation” optimization of nanofluid flows

Louis Gosselin and Alexandre K. da Silva

Appl. Phys. Lett. 85, 4160 (2004); http://dx.doi.org/10.1063/1.1813642 (3 pages) | Cited 24 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter exercises the importance of maximizing the thermal performance of nanofluid flows under appropriate constraints. Laminar and turbulent boundary layer flows in forced and natural convection are considered. The objective is to maximize the heat transfer rate removed from a warm plate by the nanofluid. In forced convection, the power dissipation is constrained to highlight the competing effects of the thermal conductivity and viscosity variations due to the presence of the particles. In natural convection, the competition is intrinsic to the problem formulation. The amount of particles is optimized in each case.
Show PACS
47.27.T- Turbulent transport processes
47.27.nb Boundary layer turbulence
66.25.+g Thermal conduction in nonmetallic liquids
66.20.-d Viscosity of liquids; diffusive momentum transport

Two-beam interferometric encoding of photoluminescent gratings in LiF crystals by high-brightness tabletop soft x-ray laser

G. Tomassetti, A. Ritucci, A. Reale, L. Arrizza, F. Flora, R. M. Montereali, A. Faenov, and T. Pikuz

Appl. Phys. Lett. 85, 4163 (2004); http://dx.doi.org/10.1063/1.1812841 (3 pages) | Cited 8 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Two-beam interferometric encoding of periodic lines of permanent color centers in LiF has been obtained by use of an intense and high spatially coherent soft x-ray laser beam. A spatial resolution of the lines less than 1 μm is demonstrated. We have used the 46.9 nm laser pulses (0.3 mJ, 1.7 ns at 0.2 Hz) produced in compact capillary discharges. Due to the low penetration depth of their radiation, their high brightness and spatial coherence, soft x-ray lasers can represent a powerful tool to encode integrated optical devices having low dimensionality and high spatial resolution inside optically transparent dielectrics, in extremely short exposure times.
Show PACS
42.79.Dj Gratings
42.82.Cr Fabrication techniques; lithography, pattern transfer
61.72.J- Point defects and defect clusters
61.82.Ms Insulators
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

In situ real time process characterization in nanoimprint lithography using time-resolved diffractive scatterometry

Zhaoning Yu, He Gao, and Stephen Y. Chou

Appl. Phys. Lett. 85, 4166 (2004); http://dx.doi.org/10.1063/1.1811396 (3 pages) | Cited 15 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
To optimize nanoimprint lithography (NIL), it is essential to be able to characterize and control the NIL process in situ and in real time. Here, we present a method for in situ real-time NIL process characterization using time-resolved diffractive scatterometry (TRDS). A surface relief diffraction grating is used as the imprint mold, and the diffracted light intensity is monitored continuously during the imprint process. We use a scalar diffraction model to calculate the diffraction intensity as a function of the mold penetration ratio. Simulations show good agreement with the experimental results. Our results indicate that TRDS offers a powerful characterization tool that can be used for in situ, real-time NIL process control.
Show PACS
81.16.Nd Micro- and nanolithography
42.79.Dj Gratings

Förster energy transfer from blue-emitting polymers to colloidal CdSe∕ZnS core shell quantum dots

M. Anni, L. Manna, R. Cingolani, D. Valerini, A. Cretí, and M. Lomascolo

Appl. Phys. Lett. 85, 4169 (2004); http://dx.doi.org/10.1063/1.1814795 (3 pages) | Cited 53 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied the interactions in the solid phase between a blue-light-emitting organic conjugated polymer {poly[(9,9-dihexylfluorenyl-2,7-diyl)-alt-co-(9,ethyl-3,6-carbazole)]} and colloidal CdSe∕ZnS core shell quantum dots. We demonstrate by time resolved photoluminescence measurements that efficient Förster energy transfer takes place from the polymer acting as the donor and the CdSe∕ZnS dots, acting as the acceptors. A Förster radius of about 80±15 math is extracted from the analysis of the relaxation dynamics based on the solution of the donor-acceptor coupled rate equations. This value is in good agreement with the value extracted from the steady state spectra and indicates that efficient energy tranfer from a polymeric host to a nanocrystal guest can occur. Our results are relevant to the application of hybrid organic/inorganic systems to light-emitting devices.
Show PACS
81.07.Pr Organic-inorganic hybrid nanostructures
78.67.Hc Quantum dots
78.66.Qn Polymers; organic compounds
78.55.Et II-VI semiconductors
78.55.Qr Amorphous materials; glasses and other disordered solids
78.55.Kz Solid organic materials
78.66.Hf II-VI semiconductors
78.47.-p Spectroscopy of solid state dynamics
82.70.Dd Colloids

1∕f noise in single-walled carbon nanotube devices

E. S. Snow, J. P. Novak, M. D. Lay, and F. K. Perkins

Appl. Phys. Lett. 85, 4172 (2004); http://dx.doi.org/10.1063/1.1812838 (3 pages) | Cited 48 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the scaling behavior of 1∕f noise in single-walled carbon nanotube devices. In this study we use two-dimensional carbon nanotube networks to explore the geometric scaling of 1∕f noise and find that for devices of a given resistance the noise scales inversely with device size. We have established an empirical formula that describes this behavior over a wide range of device parameters that can be used to assess the noise characteristics of carbon nanotube-based electronic devices and sensors.
Show PACS
85.35.Kt Nanotube devices
72.70.+m Noise processes and phenomena
73.63.Fg Nanotubes

Manipulation of nanowires in suspension by ac electric fields

D. L. Fan, F. Q. Zhu, R. C. Cammarata, and C. L. Chien

Appl. Phys. Lett. 85, 4175 (2004); http://dx.doi.org/10.1063/1.1812364 (3 pages) | Cited 24 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nanowires are potential building blocks for nanoscale devices. Manipulation of nanowires in suspension has been a formidable problem. Using ac electric fields applied to strategically designed microelectrodes, nanowires in suspension can be driven to align, to chain, to accelerate in directions parallel and perpendicular to its orientation, to concentrate onto designated places, and to disperse in a controlled manner with high efficiency despite an extremely low Reynolds number at the level of 10−5. The manipulation of nanowires can also be applied to other small elongated entities such as carbon nanotubes.
Show PACS
81.07.Bc Nanocrystalline materials
82.70.Kj Emulsions and suspensions
61.46.-w Structure of nanoscale materials

Metal-semiconductor transition in armchair carbon nanotubes by symmetry breaking

Yan Li, Slava V. Rotkin, and Umberto Ravaioli

Appl. Phys. Lett. 85, 4178 (2004); http://dx.doi.org/10.1063/1.1811792 (3 pages) | Cited 7 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electronic band structure of armchair carbon nanotubes may be considerably modified by potentials with angular dependence. Different angular modes Vq∼cos qθ have been studied within a tight-binding scheme. Using symmetry arguments, we demonstrate a bandgap opening in these metallic nanotubes when certain selection rules are satisfied for both potential and nanotube structure. We estimate the bandgap opening as a function of both the external potential strength and the nanotube radius and suggest an effective mechanism of metal-semiconductor transition by combination of different forms of perturbations.
Show PACS
73.63.Fg Nanotubes
71.30.+h Metal-insulator transitions and other electronic transitions
73.22.Gk Broken symmetry phases
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)

Strain-relieved, dislocation-free InxGa1−xAs∕GaAs(001) heterostructure by nanoscale-patterned growth

S. C. Lee, L. R. Dawson, B. Pattada, S. R. J. Brueck, Y.-B. Jiang, and H. F. Xu

Appl. Phys. Lett. 85, 4181 (2004); http://dx.doi.org/10.1063/1.1811799 (3 pages) | Cited 8 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A strain-relieved, dislocation-free InxGa1−xAs layer is selectively grown on nanoscale SiO2-patterned GaAs(001) by molecular beam epitaxy. By localizing the epitaxial area to a periodic array of nanoscale circular holes opened in a SiO2 mask and allowing the InxGa1−xAs epilayers selectively grown on adjacent holes to coalesce over the SiO2 mask by lateral overgrowth, the strain of the resulting InxGa1−xAs layer (x=0.06) is relieved with a dramatically decreased generation of misfit dislocations. These experimental results qualitatively support the basic idea of the Luryi-Suhir proposal [Appl. Phys. Lett. 49, 140 (1986)].
Show PACS
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Multiple-exposure holographic lithography with phase shift

Jun Hyuk Moon, Seung-Man Yang, David J. Pine, and Won-Seok Chang

Appl. Phys. Lett. 85, 4184 (2004); http://dx.doi.org/10.1063/1.1813644 (3 pages) | Cited 11 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrated a multiple-exposure holographic lithography with phase shift. The phase shift was utilized to translate two-dimensional (2D) and three-dimensional (3D) interference patterns. The multiple exposure of the interference patterns with a controlled phase shift created partially overlapped patterns, resulting in 2D and 3D polymer lattices of shape-anisotropic atoms. This approach can be used to design directly the unit atoms in periodic patterns for tunable optical properties.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
42.40.Kw Holographic interferometry; other holographic techniques

Photoluminescence properties of lamellar aggregates of titania nanosheets accommodating rare earth ions

Hao Xin, Renzhi Ma, Lianzhou Wang, Yasuo Ebina, Kazunori Takada, and Takayoshi Sasaki

Appl. Phys. Lett. 85, 4187 (2004); http://dx.doi.org/10.1063/1.1812811 (3 pages) | Cited 27 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Fluorescent semiconductor materials doped with rare earth ions have been synthesized by flocculation of colloidal titania nanosheets, Ti0.91O2, with Eu3+ or Tb3+ ions. The composites had a lamellar structure with a gallery height of 1.06 nm, accommodating rare earth ions between the nanosheets with a doping concentration as high as 10±1 mol %. The composite with Eu3+ exhibited intense characteristic emission from Eu3+ either by exciting the Ti0.91O2 host with UV light (λ<350 nm) or by directly exciting Eu3+ at a longer wavelength where there was no absorption by Ti0.91O2. This indicates that nonradiative energy transfer from the Ti0.91O2 host to Eu3+ can take place in this system. In contrast, no energy transfer was observed in the composite with Tb3+.
Show PACS
81.07.Bc Nanocrystalline materials
81.05.Hd Other semiconductors
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.55.Hx Other solid inorganic materials
82.70.Dd Colloids
61.46.-w Structure of nanoscale materials
61.72.S- Impurities in crystals

Synthesis and piezoresponse of highly ordered Pb(Zr0.53Ti0.47)O3 nanowire arrays

X. Y. Zhang, X. Zhao, C. W. Lai, J. Wang, X. G. Tang, and J. Y. Dai

Appl. Phys. Lett. 85, 4190 (2004); http://dx.doi.org/10.1063/1.1814427 (3 pages) | Cited 56 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the synthesis and characterization of ferroelectric lead zirconate titanate Pb(Zr0.53Ti0.47)O3 (PZT) nanowires. The PZT nanowires, with diameters of about 45 nm and lengths of about 6 μm, were fabricated by means of a sol-gel method utilizing nanochannel alumina templates. After postannealing at 700 °C, the PZT nanowires exhibit a polycrystalline microstructure, and x-ray diffraction and transmission electron microscopy study revealed their perovskite crystal structure. The piezoelectric characteristics of individual PZT nanowires were demonstrated by piezoresponse force microscopy.
Show PACS
81.07.Bc Nanocrystalline materials
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
68.65.La Quantum wires (patterned in quantum wells)
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)
77.65.-j Piezoelectricity and electromechanical effects
61.46.-w Structure of nanoscale materials
81.40.Gh Other heat and thermomechanical treatments
61.66.Fn Inorganic compounds
78.30.Hv Other nonmetallic inorganics
68.37.Ps Atomic force microscopy (AFM)
68.37.Lp Transmission electron microscopy (TEM)

Effect of anharmonicity of the strain energy on band offsets in semiconductor nanostructures

Olga L. Lazarenkova, Paul von Allmen, Fabiano Oyafuso, Seungwon Lee, and Gerhard Klimeck

Appl. Phys. Lett. 85, 4193 (2004); http://dx.doi.org/10.1063/1.1814810 (3 pages) | Cited 13 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Anharmonicity of the interatomic potential is taken into account for the quantitative simulation of the conduction and valence band offsets for strained semiconductor heterostructures. The anharmonicity leads to a weaker compressive hydrostatic strain than that obtained with the commonly used quasiharmonic approximation of the Keating model. Compared to experiment, inclusion of the anharmonicity in the simulation of strained InAs∕GaAs nanostructures results in an improvement of the electron band offset computed on an atomistic level by up to 100 meV.
Show PACS
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.20.At Surface states, band structure, electron density of states

High-sensitivity microwave vector detection at extremely low-power levels for low-dimensional electron systems

W. H. Hsieh, C. H. Kuan, Y. W. Suen, S. Y. Chang, L. C. Li, B. C. Lee, and C. P. Lee

Appl. Phys. Lett. 85, 4196 (2004); http://dx.doi.org/10.1063/1.1814797 (3 pages) | Cited 2 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a high-sensitivity microwave vector detection system for studying the low-dimensional electron system embedded in the gaps of a coplanar waveguide at low temperatures. Using this system, we have achieved 0.005% and 0.001° resolutions in amplitude and phase variations, respectively, at 10 GHz in a magnetotransport measurement on a quantum-wire array with an average signal power less than −75 dBm into the sample at 0.3 K. From the measured phase variation, we can distinguish a very tiny change in the induced dipole moment of each quantum wire.
Show PACS
84.40.Az Waveguides, transmission lines, striplines
85.25.Pb Superconducting infrared, submillimeter and millimeter wave detectors

Electrochemically deposited nanowhiskers of nickel oxide as a high-power pseudocapacitive electrode

K. Rajendra Prasad and Norio Miura

Appl. Phys. Lett. 85, 4199 (2004); http://dx.doi.org/10.1063/1.1814816 (3 pages) | Cited 50 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High performance pseudocapacitive characteristics of potentiodynamically deposited NiO are reported here. Three-dimensional nanowhiskers of NiO were prepared by potentiodynamically depositing nickel hydroxide on stainless steel (SS) and heating the hydroxide in air at 300 °C for 3 h. The scan rate used for the deposition was 200 mV s−1 and the electrolyte solution used was 100 mM NiCl2⋅6H2O at a pH 8.0. The NiO-covered SS electrodes were characterized by cyclic voltammetry (CV) in 1 M KOH electrolyte for the redox supercapacitor application. A maximum specific capacitance (SC) of 138 F g−1 was obtained from the CV at a scan rate of 100 mV s−1. A SC value of 82 F g−1 was obtained even at the very high CV scan rate of 500 mV s−1, demonstrating the high-power characteristics of NiO. Long cycle-life of the NiO nanowhiskers was also demonstrated. High specific capacitance, high power, high stability, and low cost of the electrode materials are favorable factors for commercial applications.
Show PACS
81.07.Bc Nanocrystalline materials
82.80.Fk Electrochemical methods
84.32.Tt Capacitors
82.47.Uv Electrochemical capacitors; supercapacitors
82.45.Fk Electrodes
82.45.Rr Electroanalytical chemistry
68.70.+w Whiskers and dendrites (growth, structure, and nonelectronic properties)
61.46.-w Structure of nanoscale materials
82.45.Gj Electrolytes
81.15.Pq Electrodeposition, electroplating
82.45.Qr Electrodeposition and electrodissolution

Power broadening of the exciton linewidth in a single InGaAs∕GaAs quantum dot

Stefan Stufler, Patrick Ester, Artur Zrenner, and Max Bichler

Appl. Phys. Lett. 85, 4202 (2004); http://dx.doi.org/10.1063/1.1815373 (3 pages) | Cited 25 times

Online Publication Date: 3 November 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We use high-resolution photocurrent spectroscopy to investigate the ground state of a single quantum dot. In the limit of low optical excitation power, we observe a ground state linewidth down to 4 μeV. With increasing excitation intensities, the linewidth shows a characteristic power broadening. This effect is a direct consequence of the saturation of the absorption in a two-level system under conditions of high excitation intensities. From a comparison of both effects, we conclude that power-dependent dephasing is negligible in our system.
Show PACS
73.21.La Quantum dots
73.50.Pz Photoconduction and photovoltaic effects
73.63.Kv Quantum dots
71.35.-y Excitons and related phenomena
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close