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

14 Oct 2002

Volume 81, Issue 16, pp. 2917-3103

Return to All Sections
back to top
RSS Feeds

Anomalous localization effects associated with excess volume of cobalt catalyst in multiwalled carbon nanotubes

Junji Haruyama, Izumi Takesue, and Tetsuro Hasegawa

Appl. Phys. Lett. 81, 3031 (2002); http://dx.doi.org/10.1063/1.1511535 (3 pages) | Cited 5 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the anomalous localization effects strongly associated with excess volume of a cobalt catalyst in multiwalled carbon nanotubes (MWNTs) synthesized in nanoporous alumina membranes. These effects bring about the following anomalies in bulk MWNTs: (a) A slight increase in the volume of excess cobalt changes antilocalization (AL) to weak localization (WL), (b) a further increase in excess changes this WL back to the AL, but only in magnetoresistance (MR) oscillation, and (c) even under this AL in MR, AL can not be observed in the conductance versus logarithmic temperature relation. Mechanisms for these anomalies were discussed based on the unique MWNT structures. © 2002 American Institute of Physics.
Show PACS
73.22.-f Electronic structure of nanoscale materials and related systems
81.07.De Nanotubes
61.46.-w Structure of nanoscale materials
81.16.Hc Catalytic methods
73.63.Fg Nanotubes
82.30.Vy Homogeneous catalysis in solution, polymers and zeolites
73.20.Fz Weak or Anderson localization
72.20.My Galvanomagnetic and other magnetotransport effects
71.55.Jv Disordered structures; amorphous and glassy solids

Second-harmonic spectroscopy of two-dimensional Si nanocrystal layers embedded in SiO2 films

Y. Jiang, L. Sun, and M. C. Downer 

Appl. Phys. Lett. 81, 3034 (2002); http://dx.doi.org/10.1063/1.1510963 (3 pages) | Cited 6 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present observations of optical second-harmonic generation (SHG) from dense (1010 or 6×1011 cm−2) layers of 5 or 8 nm average diameter silicon nanocrystals (NCs) embedded in thin (6–15 nm) SiO2 films on silicon substrates. Time-dependent SHG monitors optically-driven electrostatic charging of the Si NC layer as well as subsequent charge leakage, and thus provides noncontact electrical characterization of Si-NC-based device structures. SHG intensity and phase spectra of Si NCs are distinguished from contributions of the Si substrate by polarization-dependent and frequency-domain interferometric SH spectroscopy, which reveal a NC-size-dependent blueshift of the E1 resonance consistent with quantum confinement. © 2002 American Institute of Physics.
Show PACS
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.66.Db Elemental semiconductors and insulators

High-resolution atomic force microscope nanotip grown by self-field emission

C. H. Oon, J. T. L. Thong, Y. Lei, and W. K. Chim

Appl. Phys. Lett. 81, 3037 (2002); http://dx.doi.org/10.1063/1.1515120 (3 pages) | Cited 11 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A technique to grow a single tungsten filament tip on a tapping mode atomic force microscope (AFM) tip by a process of self-field emission in the presence of tungsten carbonyl is demonstrated. Such filaments have a tip radius of 1–2 nm and are grown to lengths ranging from 400 nm to 3 μm and a shank diameter of about 60–90 nm. Images of germanium nanocrystals and porous alumina membranes show much higher resolution and definition than standard AFM tips. The tip shows no degradation even after 10 h of scanning, demonstrating its utility as a practical tip. The self-aligned nature of the growth makes it a very simple nanotip fabrication technique. © 2002 American Institute of Physics.
Show PACS
07.79.Lh Atomic force microscopes
68.37.Ps Atomic force microscopy (AFM)
81.07.Lk Nanocontacts
79.70.+q Field emission, ionization, evaporation, and desorption
81.16.Be Chemical synthesis methods

Space-selective precipitation of metal nanoparticles inside glasses

Jianrong Qiu, Mitsuru Shirai, Takayuki Nakaya, Jinhai Si, Xiongwei Jiang, Congshan Zhu, and Kazuyuki Hirao

Appl. Phys. Lett. 81, 3040 (2002); http://dx.doi.org/10.1063/1.1509095 (3 pages) | Cited 53 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the precipitation and control of metal nanoparticles inside transparent glasses. An Ag+-doped silicate glass sample was first irradiated by using an 800 nm femtosecond laser at room temperature and then annealed at 550 °C. The area near the focal point of the laser beam became gray after laser irradiation and yellow after further annealing at 550 °C for 10 min. Absorption and electron spin resonance spectra of the glass sample showed that a portion of silver ions near the focused part of the laser beam inside the glass were reduced to silver atoms after the laser irradiation. These silver atoms aggregated to form nanoparticles after further annealing at temperatures above 500 °C. A mechanism is suggested that consists of multiphoton reduction, which is induced by the fundamental light of the laser beam and supercontinuum white light, and diffusion of silver atoms driven by heat energy to form nanoparticles. The observed phenomenon may have promising applications for the fabrication of three-dimensional multicolored images inside a transparent material and for integrative micro-optical switches. © 2002 American Institute of Physics.
Show PACS
81.30.Mh Solid-phase precipitation
64.75.-g Phase equilibria
42.70.Ce Glasses, quartz
42.82.Cr Fabrication techniques; lithography, pattern transfer
61.46.-w Structure of nanoscale materials
66.30.Pa Diffusion in nanoscale solids
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
81.40.Gh Other heat and thermomechanical treatments
76.30.He Platinum and palladium group (4d and 5d) ions and impurities (Zr-Ag and Hf-Au)
81.07.Bc Nanocrystalline materials
78.30.-j Infrared and Raman spectra
78.40.-q Absorption and reflection spectra: visible and ultraviolet

Electrical measurements of a dithiolated electronic molecule via conducting atomic force microscopy

Adam M. Rawlett, Theresa J. Hopson, Larry A. Nagahara, Raymond K. Tsui, Ganesh K. Ramachandran, and Stuart M. Lindsay

Appl. Phys. Lett. 81, 3043 (2002); http://dx.doi.org/10.1063/1.1512815 (3 pages) | Cited 67 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We describe a method of measuring the electrical properties of a molecule via conducting atomic force microscopy (AFM). A dithiolated molecule is chemically inserted into defect sites in an insulating self-assembled monolayer formed on an epitaxial Au substrate and the top thiol terminus of the molecule is reacted with a Au nanoparticle. A Au-coated AFM probe is used to contact the molecule through the nanoparticle, thus electrical data can be obtained. We report preliminary transport measurements of two test molecules. Our data shows qualitative agreement with previously published results for similar molecules deposited in a nanopore containing approximately a thousand molecules. This work indicates that the measured negative differential resistance is not an intermolecular phenomenon. © 2002 American Institute of Physics.
Show PACS
72.80.Le Polymers; organic compounds (including organic semiconductors)
68.37.Ps Atomic force microscopy (AFM)
81.07.Nb Molecular nanostructures
72.20.Ht High-field and nonlinear effects
73.40.Sx Metal-semiconductor-metal structures
81.16.Dn Self-assembly
73.50.Fq High-field and nonlinear effects
73.61.Ph Polymers; organic compounds

Site-specific growth of Zno nanorods using catalysis-driven molecular-beam epitaxy

Y. W. Heo, V. Varadarajan, M. Kaufman, K. Kim, D. P. Norton, F. Ren, and P. H. Fleming

Appl. Phys. Lett. 81, 3046 (2002); http://dx.doi.org/10.1063/1.1512829 (3 pages) | Cited 136 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on catalyst-driven molecular beam epitaxy of ZnO nanorods. The process is site specific, as single crystal ZnO nanorod growth is realized via nucleation on Ag films or islands that are deposited on a SiO2-terminated Si substrate surface. Growth occurs at substrate temperatures on the order of 300–500 °C. The nanorods are uniform cylinders, exhibiting diameters of 15–40 nm and lengths in excess of 1 μm. With this approach, nanorod placement can be predefined via location of metal catalyst islands or particles. This, coupled with the relatively low growth temperatures needed, suggests that ZnO nanorods could be integrated on device platforms for numerous applications, including chemical sensors and nanoelectronics. © 2002 American Institute of Physics.
Show PACS
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Dz II-VI semiconductors
81.07.Bc Nanocrystalline materials
61.46.-w Structure of nanoscale materials
68.55.-a Thin film structure and morphology

Size and location control of Si nanocrystals at ion beam synthesis in thin SiO2 films

Torsten Müller, Karl-Heinz Heinig, and Wolfhard Möller

Appl. Phys. Lett. 81, 3049 (2002); http://dx.doi.org/10.1063/1.1512952 (3 pages) | Cited 33 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Binary collision simulations of high-fluence 1 keV Si+ ion implantation into 8-nm-thick SiO2 films on (001)Si were combined with kinetic Monte Carlo simulations of Si nanocrystal (NC) formation by phase separation during annealing. For nonvolatile memory applications, these simulations help to control the size and location of NCs. For low concentrations of implanted Si, NCs form via nucleation, growth, and Ostwald ripening, whereas for high concentrations Si separates by spinodal decomposition. In both regimes, NCs form above a thin NC free-oxide layer at the SiO2/Si interface. This, self-adjusted layer has just a thickness appropriate for NC charging by direct electron tunneling. Only in the nucleation regime the width of the tunneling oxide and the mean NC diameter remain constant during a long annealing period. This behavior originates from the competition of Ostwald ripening and Si loss to the Si/SiO2 interface. The process simulations predict that, for nonvolatile memories, the technological demands on NC synthesis are fulfilled best in the nucleation regime. © 2002 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
81.07.Bc Nanocrystalline materials
61.72.up Other materials
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
68.55.A- Nucleation and growth

Engineering the nanocrystalline structure of TiO2 films by aerodynamically filtered cluster deposition

E. Barborini, I. N. Kholmanov, P. Piseri, C. Ducati, C. E. Bottani, and P. Milani

Appl. Phys. Lett. 81, 3052 (2002); http://dx.doi.org/10.1063/1.1510579 (3 pages) | Cited 35 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have produced nanocrystalline titanium dioxide films with different structures (anatase or rutile) by depositing mass selected clusters from the gas phase. Nanoparticles are produced by a pulsed microplasma cluster source and are selected by aerodynamic separation effects. We have characterized nanocrystalline films by Raman spectromicroscopy and transmission electron microscopy, showing that the films assembled with very small clusters have a predominant rutile phase, whereas larger clusters form films with anatase structure. Our observations suggest that phonon confinement effects are responsible for a significant shift and broadening observed for the Raman peaks. © 2002 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
68.55.-a Thin film structure and morphology
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.30.Hv Other nonmetallic inorganics

Dynamic characteristics of high-speed In0.4Ga0.6As/GaAs self-organized quantum dot lasers at room temperature

S. Ghosh, S. Pradhan, and P. Bhattacharya

Appl. Phys. Lett. 81, 3055 (2002); http://dx.doi.org/10.1063/1.1514823 (3 pages) | Cited 45 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have measured the room-temperature modulation characteristics of self-organized In0.4Ga0.6As/GaAs quantum dot lasers in which electrons are injected into the dot lasing states by tunneling. A small-signal modulation bandwidth of f−3 dB = 22 GHz is measured. Values of differential gain at 288 K of dg/dn ≅ 8.85×10−14 cm2 and gain compression factor ε = 7.2×10−16 cm3 are derived from the modulation data. Extremely low values of linewidth enhancement factor α ∼ 1 and chirp <0.6 Å were also measured in the devices. © 2002 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.60.Fc Modulation, tuning, and mode locking

Gradient nanostructures for interfacing microfluidics and nanofluidics

Han Cao, Jonas O. Tegenfeldt, Robert H. Austin, and Stephen Y. Chou

Appl. Phys. Lett. 81, 3058 (2002); http://dx.doi.org/10.1063/1.1515115 (3 pages) | Cited 65 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is difficult to introduce long genomic DNA molecules into nanometer scale fluidic channels directly from the macroscale world because of the steep entropic barrier caused by necessary stretching of the polymer. We present a very simple technique using optical lithography to fabricate continuous spatial gradient structures which smoothly narrow the cross section of a volume from the micron to the nanometer length scale, greatly reducing the local entropic barrier to nanochannel entry. This technique, diffraction gradient lithography, can be very valuable for the fabrication of micro/nano total analysis systems. © 2002 American Institute of Physics.
Show PACS
81.16.Nd Micro- and nanolithography
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
47.60.-i Flow phenomena in quasi-one-dimensional systems
47.85.Np Fluidics

Phase diagram for the interaction of oxygen with SiC

Y. Song and F. W. Smith

Appl. Phys. Lett. 81, 3061 (2002); http://dx.doi.org/10.1063/1.1514397 (3 pages) | Cited 12 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on experimental studies of the interactions of oxygen with the 4H– and 6H–SiC surfaces at high temperatures. It is observed that these interactions lead to the growth of passivating SiO2 layers at high O2 pressures, etching of the surfaces at lower pressures, and enhancements of the surface segregation of carbon at still lower pressures. A pressure–temperature phase diagram for the oxidation of SiC containing these three experimentally observed regions is presented. © 2002 American Institute of Physics.
Show PACS
81.65.Mq Oxidation
81.65.Rv Passivation
81.65.Cf Surface cleaning, etching, patterning
68.35.Dv Composition, segregation; defects and impurities
64.70.-p Specific phase transitions

GaN islanding by spontaneous rearrangement of a strained two-dimensional layer on (0001) AlN

C. Adelmann, N. Gogneau, E. Sarigiannidou, J.-L. Rouvière, and B. Daudin

Appl. Phys. Lett. 81, 3064 (2002); http://dx.doi.org/10.1063/1.1515114 (3 pages) | Cited 37 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is shown that a two-dimensional GaN layer grown on (0001) AlN under Ga-rich conditions remains two-dimensional while annealing under a Ga flux due to a surfactant effect of Ga. In contrast, further annealing under vacuum without the Ga flux leads to evaporation of excess Ga and to spontaneous transformation of the GaN layer into islands if the initial layer is thicker than about 2.5 monolayers. The resulting morphology is studied by atomic force microscopy and transmission electron microscopy. The latter reveals that these islands sit on top of a continuous 2.5 monolayer thick wetting layer, i.e., they represent a Stranski–Krastanow structure. © 2002 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
61.72.Cc Kinetics of defect formation and annealing
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Temperature dependence of the photoluminescence of InGaAs/GaAs quantum dot structures without wetting layer

S. Sanguinetti, T. Mano, M. Oshima, T. Tateno, M. Wakaki, and N. Koguchi

Appl. Phys. Lett. 81, 3067 (2002); http://dx.doi.org/10.1063/1.1516632 (3 pages) | Cited 31 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We analyze the photoluminescence temperature behavior of InGaAs/GaAs quantum dots grown by heterogeneous droplet epitaxy. Morphologically, these dots are nanocrystal InGaAs inclusions in the GaAs matrix, with a concave disk shape and, more important, no wetting layer is connecting the dots. The photoluminescence of the dots does not show any of the typical of the Stranski–Krastanov dots temperature properties, such as sigmoidal peak energy position and linewidth narrowing. We demonstrate that such behavior stems from the lacking of the thermally activated dot–dot coupling channel provided by the wetting layer thus preventing the establishment of a common quasiequilibrium in the whole dot ensemble. © 2002 American Institute of Physics.
Show PACS
78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
81.07.Ta Quantum dots
68.65.Hb Quantum dots (patterned in quantum wells)
61.46.-w Structure of nanoscale materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
61.72.Qq Microscopic defects (voids, inclusions, etc.)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Stressed metal probes for atomic force microscopy

Thomas Hantschel, Eugene M. Chow, Dirk Rudolph, and David K. Fork

Appl. Phys. Lett. 81, 3070 (2002); http://dx.doi.org/10.1063/1.1514830 (3 pages) | Cited 3 times

Online Publication Date: 7 October 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Common scanning probes with straight cantilevers and micrometer-sized tips are not suited for substrates with very high topography. Therefore, we have developed stressed metal probes that use bent cantilevers and can have a tip height of hundreds of micrometers. The use of a transparent substrate allows the laser beam light to shine through the probe chip in atomic force microscopy (AFM). This letter describes the stressed probe concept and presents first measurements on thin film samples and on the bottom of deep structures. Our probe concept extends the functionality of AFM systems and is an alternative to straight cantilever probes in many applications. © 2002 American Institute of Physics.
Show PACS
07.79.Lh Atomic force microscopes
68.37.Ps Atomic force microscopy (AFM)
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close