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

24 Aug 2009

Volume 95, Issue 8, Articles (08xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 95, 082507 (2009); http://dx.doi.org/10.1063/1.3186782 (3 pages)

Sang-Koog Kim, Ki-Suk Lee, and Dong-Soo Han
Enlarge Image | Read More
Page 1 of 2 Pages Return to All Sections Next Page
back to top
RSS Feeds

Electrical control of singlet-triplet entanglement in lateral quantum dot molecules

Fanyao Qu, G. L. Iório, V. Lopez-Richard, and G. E. Marques

Appl. Phys. Lett. 95, 083101 (2009); http://dx.doi.org/10.1063/1.3210786 (3 pages) | Cited 5 times

Online Publication Date: 24 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study effects of spin-orbit coupling and electron-electron correlation, which can be electrically tuned, on the singlet-triplet entanglement in double lateral quantum dots charged with two electrons. We have found that the magnetic character of a double-dot system can be changed from diamagnetic to paramagnetic, only by adjusting the strength of spin-orbit coupling. Coulomb interaction leads to an unusual singlet-triplet energy splitting, accompanied by a shift of this transition energy to the lower magnetic field side in the energy spectrum.
Show PACS
73.21.La Quantum dots
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
75.20.Ck Nonmetals
75.50.Pp Magnetic semiconductors

Temperature dependence of electronic energy transfer in PbS quantum dot films

Wei Lü, Itaru Kamiya, Masao Ichida, and Hiroaki Ando

Appl. Phys. Lett. 95, 083102 (2009); http://dx.doi.org/10.1063/1.3213349 (3 pages) | Cited 8 times

Online Publication Date: 24 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Colloidal PbS quantum dots dispersed as close-packed film and in polystyrene (PS) matrix are prepared and photoluminescence (PL) spectra are measured in the temperature range of 5–300 K. The integrated PL intensity of the close-packed film increases as the temperature is raised from 5 to 120 K, and then decreases to 300 K, while that of the PS film decreases monotonously. This abnormal behavior of the close-packed film can be explained by a thermally activated electronic energy transfer model, which is supported by time resolved PL measurements.
Show PACS
73.63.Kv Quantum dots
73.61.Le Other inorganic semiconductors
78.66.Li Other semiconductors
78.55.Hx Other solid inorganic materials
68.55.ag Semiconductors
73.21.La Quantum dots

Fabrication of graphene layers from multiwalled carbon nanotubes using high dc pulse

Woo Sik Kim, Sook Young Moon, Sin Young Bang, Bong Geun Choi, Heon Ham, Tohru Sekino, and Kwang Bo Shim

Appl. Phys. Lett. 95, 083103 (2009); http://dx.doi.org/10.1063/1.3213350 (3 pages) | Cited 13 times

Online Publication Date: 24 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Graphene layers are fabricated from multiwalled carbon nanotubes (MWCNTs) with a high direct current pulse through a pulsed current sintering process. We confirm the transformation of the structure from MWCNTs to graphene layers. Graphene layers are analyzed by field emission scanning electron microscopy, high resolution transmission electron microscopy, high resolution Raman, and x-ray diffraction.
Show PACS
81.05.U- Carbon/carbon-based materials
81.05.ub Fullerenes and related materials
81.16.-c Methods of micro- and nanofabrication and processing
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
78.30.Na Fullerenes and related materials

System investigation of a rolled-up metamaterial optical hyperlens structure

E. J. Smith, Z. Liu, Y. F. Mei, and O. G. Schmidt

Appl. Phys. Lett. 95, 083104 (2009); http://dx.doi.org/10.1063/1.3211115 (3 pages) | Cited 14 times

Online Publication Date: 24 August 2009

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
An investigation of the material makeup and surrounding medium of an optical rolled-up hyperlens is presented. A working spectral range of the hyperlens for different material combinations is studied along with an examination of hyperlens immersion, which suppresses the diffraction of waves exiting the lens due to impedance matching, leading to a higher intensity output. This hyperlens immersion technique can be implemented into cell culture and molecular analysis.
Show PACS
42.79.Bh Lenses, prisms and mirrors
42.70.-a Optical materials

Raman stress mapping of CdS nanosheets

Mohammad Montazeri, Leigh M. Smith, Howard E. Jackson, Jan M. Yarrison-Rice, Young-Jin Choi, and Jae-Gwan Park

Appl. Phys. Lett. 95, 083105 (2009); http://dx.doi.org/10.1063/1.3211121 (3 pages) | Cited 5 times

Online Publication Date: 24 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spatially resolved Raman scattering is used to probe the strain distribution in CdS nanosheets. We observe both significant strains and a significant strain gradient across the nanosheets. The magnitude of the strain suggests that electronic properties of the CdS nanosheets will be influenced as well. Using spatially resolved photoluminescence spectroscopy, we show that the band gap of the nanosheet experiences changes in the energy gap of 20 meV across the width of the nanosheet, which are consistent with our observations of the strain.
Show PACS
78.30.Fs III-V and II-VI semiconductors
78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
73.22.-f Electronic structure of nanoscale materials and related systems

Stable and reproducible electronic conduction through DNA molecular junctions

Ajit K. Mahapatro, Gil U. Lee, Kyung J. Jeong, and David B. Janes

Appl. Phys. Lett. 95, 083106 (2009); http://dx.doi.org/10.1063/1.3186056 (3 pages) | Cited 4 times

Online Publication Date: 24 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter presents the observation of stable and reproducible electronic conduction through double stranded (ds) DNA molecules in a nominally dry state. Stable conduction was realized by immobilizing 15 base-pair guanine:cytosine rich dsDNA within gold nanogap junctions, stabilizing the dsDNA with a polycation, and characterizing in nitrogen. In air, the current levels decrease with successive voltage scans likely due to oxidation of the guanine bases under bias. In nitrogen, reproducible current-voltage traces are observed and the current levels at specific bias points are stable with time. The stability allows comprehensive electrical studies and could enable conductance-based DNA sensors.
Show PACS
85.65.+h Molecular electronic devices
87.85.Rs Nanotechnologies-applications
85.35.-p Nanoelectronic devices

Modulating the surface states of electric field assembled CuO nanowires by electrochemical deposition method

Lixiang Wang, Gang Cheng, Xiaohong Jiang, Shujie Wang, Xingtang Zhang, and Zuliang Du

Appl. Phys. Lett. 95, 083107 (2009); http://dx.doi.org/10.1063/1.3213551 (3 pages) | Cited 4 times

Online Publication Date: 24 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this paper, the electrochemical deposition and anneal method has been developed to modulate the contact performance of electric field assembled CuO nanowires. After modulation, the current increases about two orders. The I-V curves indicate that before and after modulation, the current transport properties are both dominated by the reverse current of Schottky barriers under image force model. The current increase results from the formation of another current pathway, i.e., the CuO nanowire@nanoparticles/Pt electrode structure, in which the surface states in metal-semiconductor interface are largely reduced by passivating dangling bonds, and the barrier height decreases about 105 meV.
Show PACS
73.20.At Surface states, band structure, electron density of states
73.21.Hb Quantum wires
81.05.Hd Other semiconductors
82.45.Fk Electrodes
81.16.-c Methods of micro- and nanofabrication and processing
73.63.Bd Nanocrystalline materials
73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts
61.72.Cc Kinetics of defect formation and annealing
81.07.Bc Nanocrystalline materials
82.45.Yz Nanostructured materials in electrochemistry
82.45.Qr Electrodeposition and electrodissolution

Excellent field emission from semialigned carbon nanofibers grown on cylindrical copper surface

P. Mahanandia, V. Arya, P. V. Bhotla, S. V. Subramanyam, J. J. Schneider, and K. K. Nanda

Appl. Phys. Lett. 95, 083108 (2009); http://dx.doi.org/10.1063/1.3212728 (3 pages) | Cited 2 times

Online Publication Date: 24 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the field emission from carbon nanofibers (CNFs) grown directly on cylindrical copper by a simple pyrolysis technique. The turn-on field is 0.17 V/μm and the emission current density is 0.9 mA/cm2 at 0.35 V/μm. The emission current is stable at a field of 0.35 V/μm and 6.5×10−6 Torr. The excellent field emission behavior is attributed to the sp2 phase in CNFs and the stable emission is due to the direct growth. The direct growth on cylindrical cathode is advantageous for field emission.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
81.16.Be Chemical synthesis methods
81.07.-b Nanoscale materials and structures: fabrication and characterization
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)

P-N junction with donor and acceptor encapsulated single-walled carbon nanotubes

Toshiaki Kato, Rikizo Hatakeyama, Jun Shishido, Wataru Oohara, and Kazuyuki Tohji

Appl. Phys. Lett. 95, 083109 (2009); http://dx.doi.org/10.1063/1.3207742 (3 pages) | Cited 5 times

Online Publication Date: 25 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ultimate one-dimensional heterojunctions of electron donor and acceptor materials have been realized within the inner hollow space of a single-walled carbon nanotube (SWNT). The heterojunction structures of Cs/I and Cs/C60 inside SWNTs (Cs/I@SWNTs, Cs/C60@SWNTs) yield the air-stable rectifying performance. Clear tunneling currents through the p-n junction barrier could be also detected only for Cs/I@SWNTs, which is explained by the difference of depletion layer structures. Based on a potential calculation, symmetrical and asymmetrical depletion layers were found to be formed in Cs/I@SWNTs and Cs/C60@SWNTs, respectively. Low temperature measurements also supply evidence of asymmetric depletion layer formation in Cs/C60@SWNTs.
Show PACS
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Ei Rectification
73.40.Gk Tunneling
73.63.Fg Nanotubes

Modeling lattice expansion and cohesive energy of nanostructured materials

Y. F. Zhu, W. T. Zheng, and Q. Jiang

Appl. Phys. Lett. 95, 083110 (2009); http://dx.doi.org/10.1063/1.3212858 (3 pages) | Cited 12 times

Online Publication Date: 25 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The lattice constants and cohesive energies of nanostructured materials (NSs) are modeled using a hard-sphere approach and the model for size-dependent interface energy. The lattice constant of NSs will expand opposite to that of nanoparticles (NPs) as the grain size of NSs and the diameter of NPs decrease. Associated with it, the cohesive energies increase in both cases. However, the increment is less obvious for NSs because the bond deficit at grain boundaries is smaller than that at surfaces. The predictions agree fairly well with the available experimental or computer simulation results of nanostructured metals and semiconductors.
Show PACS
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
61.50.Lt Crystal binding; cohesive energy
61.72.Mm Grain and twin boundaries

Photocurrent and photoconductance properties of a GaAs nanowire

S. Thunich, L. Prechtel, D. Spirkoska, G. Abstreiter, A. Fontcuberta i Morral, and A. W. Holleitner

Appl. Phys. Lett. 95, 083111 (2009); http://dx.doi.org/10.1063/1.3193540 (3 pages) | Cited 17 times

Online Publication Date: 26 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on photocurrent and photoconductance processes in a freely suspended p-doped single GaAs nanowire. The nanowires are grown by molecular beam epitaxy, and they are electrically contacted by a focused ion beam deposition technique. The observed photocurrent is generated at the Schottky contacts between the nanowire and metal source-drain electrodes, while the observed photoconductance signal can be explained by a photogating effect induced by optically generated charge carriers located at the surface of the nanowire. Both optoelectronic effects are sensitive to the polarization of the exciting laser field, enabling polarization dependent photodetectors.
Show PACS
79.60.Jv Interfaces; heterostructures; nanostructures
61.72.uj III-V and II-VI semiconductors
78.67.Lt Quantum wires
72.40.+w Photoconduction and photovoltaic effects
73.30.+y Surface double layers, Schottky barriers, and work functions
81.16.-c Methods of micro- and nanofabrication and processing

A torsional parametric oscillator based on carbon nanotubes

Byeong-Woo Jeong and Susan B. Sinnott

Appl. Phys. Lett. 95, 083112 (2009); http://dx.doi.org/10.1063/1.3211123 (3 pages) | Cited 4 times

Online Publication Date: 26 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Parametric oscillations are observed in torsional electromechanical oscillators based on carbon nanotubes via molecular dynamics simulations. The stretch of nanotube torsion springs due to the vertical translational-electrostatic force acting on the paddle makes possible the parametric oscillations. The electrostatic force can provide control over nanotube stretching that allows it to parametrically modulate the torsional spring constant at twice the resonance frequency. This reveals potential building blocks for a variety of applications of the devices.
Show PACS
84.30.Ng Oscillators, pulse generators, and function generators
85.35.Kt Nanotube devices

Real time estimation of equivalent cantilever parameters in tapping mode atomic force microscopy

Pranav Agarwal and Murti V. Salapaka

Appl. Phys. Lett. 95, 083113 (2009); http://dx.doi.org/10.1063/1.3206740 (3 pages) | Cited 7 times

Online Publication Date: 26 August 2009

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
In this article, a method of imaging is developed, where during tapping-mode operation, equivalent resonant frequency and quality factor can be obtained in real time. It involves exciting the cantilever near its resonant frequency and two other frequencies chosen close to the resonant frequency. It is shown that changes in equivalent cantilever parameters can be registered for topography changes that are less than 1 nm in height and within 400 μs of the change occurring. The estimation time is two orders of magnitude better than current techniques.
Show PACS
07.79.Lh Atomic force microscopes

Photocurrent generation in random networks of multiwall-carbon-nanotubes grown by an “all-laser” process

M. A. El Khakani, V. Le Borgne, B. Aïssa, F. Rosei, C. Scilletta, E. Speiser, M. Scarselli, P. Castrucci, and M. De Crescenzi

Appl. Phys. Lett. 95, 083114 (2009); http://dx.doi.org/10.1063/1.3211958 (3 pages) | Cited 9 times

Online Publication Date: 26 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report photocurrent generation in entangled networks of multiwall-carbon nanotubes (MWCNTs) grown on TiN/Si substrates by an all-laser process. By integrating these MWCNTs into planar devices, we demonstrate that they generate photocurrent over all the visible and near-ultraviolet range, with maximum efficiency around 420 nm. Photocurrent is obtained even at zero applied voltage, pointing to a true photovoltaic (PV) effect. The extracted photocurrent as a function of applied voltage exhibits nonlinear behavior for voltages ≥ 2 V, suggesting that the devices do not behave as pure photoresistances. Other mechanisms (e.g., Schottky barriers imbalance) are invoked to describe current flow in these PV devices.
Show PACS
73.63.Fg Nanotubes
81.16.-c Methods of micro- and nanofabrication and processing
42.62.-b Laser applications
72.40.+w Photoconduction and photovoltaic effects
61.46.Fg Nanotubes
81.07.De Nanotubes

Electronic structures of silicon nanoribbons

Yi Ding and Jun Ni

Appl. Phys. Lett. 95, 083115 (2009); http://dx.doi.org/10.1063/1.3211968 (3 pages) | Cited 37 times

Online Publication Date: 26 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using first principles calculations, we investigate the electronic properties of silicon nanoribbons (SiNRs). We find that the armchair SiNRs can be metals or semiconductors depending on width. For the zigzag SiNRs, the antiferromagnetic semiconducting state is the most stable one. Under transverse electric field, the zigzag SiNRs become half-metals. These results show that SiNRs have both rich electronic and magnetic properties with potential applications in silicon-based electronic and spintronic nanodevices.
Show PACS
73.22.-f Electronic structure of nanoscale materials and related systems
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
81.05.Cy Elemental semiconductors
75.50.Pp Magnetic semiconductors
75.50.Ee Antiferromagnetics
71.20.Mq Elemental semiconductors

Atomic resolution on a metal single crystal with dynamic force microscopy

T. König, G. H. Simon, H.-P. Rust, and M. Heyde

Appl. Phys. Lett. 95, 083116 (2009); http://dx.doi.org/10.1063/1.3189282 (3 pages) | Cited 5 times

Online Publication Date: 26 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Atomically resolved frequency modulation dynamic force microscope (FM-DFM) images taken by a tuning fork setup on an Ag(001) surface are presented. The necessity of well chosen tip surface interaction parameters is demonstrated making atomically resolved FM-DFM images on metal surfaces scarce. The capability of our setup to measure frequency shift and simultaneously tunneling current gives insight into different tip trajectories and possible contrast formation mechanisms in FM-DFM and scanning tunneling microscopy. One explanation is related to local variations in the decaying signals, which may originate from different density of states contributions to tip-sample force and tunneling current.
Show PACS
68.37.Ps Atomic force microscopy (AFM)
07.79.Cz Scanning tunneling microscopes
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
07.79.Lh Atomic force microscopes

Selective probing of mRNA expression levels within a living cell

D. Nawarathna, T. Turan, and H. Kumar Wickramasinghe

Appl. Phys. Lett. 95, 083117 (2009); http://dx.doi.org/10.1063/1.3213343 (3 pages) | Cited 1 time

Online Publication Date: 27 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on a selective and nondestructive measurement of mRNA (messenger ribonucleic acid) expression levels within a living cell. We first modify an atomic force microscope tip to create a tapered nanoscale coaxial cable. Application of an ac (alternating potential) between the inner and outer electrodes of this cable creates a dielectrophoretic force attracting mRNA molecules toward the tip-end which is pretreated with gene specific primers. We selectively extracted and analyzed both high ( ∼ 2500) and extremely low (1math0) copy number mRNA from a living cell mRNA in less than 10 s.
Show PACS
87.85.fk Biosensors
87.64.Dz Scanning tunneling and atomic force microscopy
87.15.Tt Electrophoresis
87.16.Yc Regulatory genetic and chemical networks

Three-dimensional micronanofabrication via two-photon-excited photoisomerization

Hong Xia, Wen-Yi Zhang, Fang-Fang Wang, Dong Wu, Xiang-Wei Liu, Lei Chen, Qi-Dai Chen, Yu-Guang Ma, and Hong-Bo Sun

Appl. Phys. Lett. 95, 083118 (2009); http://dx.doi.org/10.1063/1.3213351 (3 pages) | Cited 3 times

Online Publication Date: 27 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, laser micronanofabrication via two-photon absorption initiated isomerization was proposed and explored. Experimentally a cis-form rich poly[2,5-dihexyloxy-1,4-phenylene] vinylene)-alt-(2,5-diphenyl-1,4-phenylene vinylene)] (DPO-PPV) was used as the precursory material, which underwent pinpoint molecular conformational change upon the near-infrared femtosecond laser irradiation. Due to pronouncedly reduced solubility of trans-configuration molecules, the precipitate at the tiny volumes was implemented as voxels to construct two- and three-dimensional micronanostructures. This mechanism may provide an alternative enabling tool other than two-photon absorption initiated polymerization of resins for designable micronanofabrication of photonic or optoelectronic devices including organic electroluminescent devices, particularly those based on PPV and its derivatives.
Show PACS
81.16.-c Methods of micro- and nanofabrication and processing
82.30.Qt Isomerization and rearrangement
64.75.Bc Solubility
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
82.35.-x Polymers: properties; reactions; polymerization
82.50.Bc Processes caused by infrared radiation

Experimental study of microwave radiation of carbon nanotube arrays

Qi Zhu, Weifeng Liu, Hualiang Zhang, and Hao Xin

Appl. Phys. Lett. 95, 083119 (2009); http://dx.doi.org/10.1063/1.3213395 (3 pages)

Online Publication Date: 27 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Microwave radiation effects of carbon nanotube (CNT) arrays are investigated experimentally by placing them on the surface of microstrip patch antennas. The radiation intensities of different patch antenna configurations with and without CNT arrays are measured and compared. The experimental results indicate that the addition of CNT arrays significantly enhances the electromagnetic radiation of the antenna.
Show PACS
61.46.Fg Nanotubes
84.40.Ba Antennas: theory, components and accessories
41.20.Jb Electromagnetic wave propagation; radiowave propagation

Processing route for size distribution narrowing of ion beam synthesized nanoclusters

C. W. Yuan, Cosima N. Boswell, S. J. Shin, C. Y. Liao, J. Guzman, J. W. Ager, III, E. E. Haller, and D. C. Chrzan

Appl. Phys. Lett. 95, 083120 (2009); http://dx.doi.org/10.1063/1.3211193 (3 pages) | Cited 3 times

Online Publication Date: 27 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ion beam synthesis of nanocrystals is explored using a recently developed kinetic Monte Carlo model for the process. The model suggests that temperature can be used to engineer nanocrystal size distributions. Specifically, by initiating implants at low temperature and then ramping the temperature upward, one can both tune the average size of the nanocrystals and restrict size distribution widths to less than 20% of the average size.
Show PACS
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
81.16.-c Methods of micro- and nanofabrication and processing
61.72.up Other materials

Capillarity-driven deformation of ordered nanoporous silica

Johannes Prass, Dirk Müter, Peter Fratzl, and Oskar Paris

Appl. Phys. Lett. 95, 083121 (2009); http://dx.doi.org/10.1063/1.3213564 (3 pages) | Cited 9 times

Online Publication Date: 27 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ordered nanoporous silica is seen to contract reversibly during the condensation and evaporation of fluids in the pores, forming a capillarity-driven actuation system. In situ x-ray diffraction is used to measure the strain of the ordered pore lattice in dependence on the relative vapor pressure of different fluids. Elastic moduli extracted from these strain isotherms are independent of the fluid used, and do therefore constitute real nanomechanical properties of the solid porous framework. The relationship between this pore-load modulus and the Young’s modulus of the silica walls is analyzed with simple analytical considerations and with finite element calculations.
Show PACS
62.25.-g Mechanical properties of nanoscale systems
62.20.F- Deformation and plasticity
62.20.de Elastic moduli
61.43.Gt Powders, porous materials
47.61.Fg Flows in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS)
47.56.+r Flows through porous media

Cascaded exciton emission of an individual strain-induced quantum dot

F. J. R. Schülein, A. Laucht, J. Riikonen, M. Mattila, M. Sopanen, H. Lipsanen, J. J. Finley, A. Wixforth, and H. J. Krenner

Appl. Phys. Lett. 95, 083122 (2009); http://dx.doi.org/10.1063/1.3216807 (3 pages) | Cited 1 time

Online Publication Date: 27 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Single strain-induced quantum dots are isolated for optical experiments by selective removal of the inducing InP islands from the sample surface. Unpolarized emission of single exciton, biexciton, and triexciton transitions are identified by power-dependent photoluminescence spectroscopy. Employing time-resolved experiments performed at different excitation powers, we find a pronounced shift of the rise and decay times of these different transitions as expected from cascaded single photon emissions. Good agreement is found for a rate equation model for a three step cascade.
Show PACS
71.35.-y Excitons and related phenomena
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
73.21.La Quantum dots
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors

Terahertz sensing with a carbon nanotube/two-dimensional electron gas hybrid transistor

Yukio Kawano, Takao Uchida, and Koji Ishibashi

Appl. Phys. Lett. 95, 083123 (2009); http://dx.doi.org/10.1063/1.3205125 (3 pages) | Cited 10 times

Online Publication Date: 28 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on a highly sensitive terahertz (THz) detector based on a carbon nanotube (CNT) transistor, which is integrated with a two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure. The operation principle of this device is that the CNT transistor senses electrical polarization induced by terahertz-excited electron-hole pairs in the 2DEG. The magnetic field dependence of the terahertz response signal (CNT current) is shown to follow features of cyclotron resonance of the 2DEG, indicating the validity of the above mechanism. The utilization of the present device structure and mechanism has enabled the detection of a small number of terahertz photons.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.35.-p Nanoelectronic devices
85.35.Gv Single electron devices

Interconnected Si nanocrystals forming thin films with controlled bandgap values

T. Nychyporuk, Yu. Zakharko, V. Lysenko, and M. Lemiti

Appl. Phys. Lett. 95, 083124 (2009); http://dx.doi.org/10.1063/1.3216072 (3 pages) | Cited 3 times

Online Publication Date: 28 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Interconnected Si nanocrystals forming homogeneous thin films with controlled bandgap values from 1.2 to 2.9 eV were formed by pulsed plasma enhanced chemical vapor deposition technique under dusty plasma conditions. The chosen values of plasma duration time correspond to specific phases of the dust nanoparticle growth. Structural and optical properties of the deposited nanostructured films are described in details. These nanocrystalline Si thin films seem to be promising candidates for all-Si tandem solar cell applications.
Show PACS
68.55.ag Semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
84.60.Jt Photoelectric conversion
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
81.07.Bc Nanocrystalline materials
81.05.Cy Elemental semiconductors
78.66.Db Elemental semiconductors and insulators
81.16.-c Methods of micro- and nanofabrication and processing

Size-induced metal-to-semiconductor transition and room temperature sequential resonant tunneling in La0.5Sr0.5CoO3−δ quantum dots embedded in La0.5Sr0.5CoO3−δ nanotubes

Wei Liu, Yu Chen, Zuci Quan, Shishang Guo, Meiya Li, and Xing-Zhong Zhao

Appl. Phys. Lett. 95, 083125 (2009); http://dx.doi.org/10.1063/1.3202759 (3 pages) | Cited 1 time

Online Publication Date: 28 August 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The sequential resonant tunneling in La0.5Sr0.5CoO3−δ (LSCO) semiconductor quantum dots (QDs) arrays were observed by current-voltage measurements under room temperature. A series of spikelike current peaks are found, which are resulted from the accumulation and depletion of electrons tunneling through the QDs embedded in insulated barriers. Temperature dependent onset-voltage blueshift and number variation in current peaks are also observed. These results confirm the size-induced metal-to-semiconductor transition in LSCO.
Show PACS
72.60.+g Mixed conductivity and conductivity transitions
73.40.Gk Tunneling
Page 1 of 2 Pages Return to All Sections Next Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close