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4 Feb 2002

Volume 80, Issue 5, pp. 707-899

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Observation of a magic discrete family of ultrabright Si nanoparticles

G. Belomoin, J. Therrien, A. Smith, S. Rao, R. Twesten, S. Chaieb, M. H. Nayfeh, L. Wagner, and L. Mitas

Appl. Phys. Lett. 80, 841 (2002); http://dx.doi.org/10.1063/1.1435802 (3 pages) | Cited 120 times

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We demonstrate that electrochemically etched, hydrogen capped SinHx clusters with n larger than 20 are obtained within a family of discrete sizes. These sizes are 1.0 (Si29), 1.67 (Si123), 2.15, 2.9, and 3.7 nm in diameter. We characterize the particles via direct electron imaging, excitation and emission optical spectroscopy, and colloidal crystallization. The band gaps and emission bands are measured. The smallest four are ultrabright blue, green, yellow and red luminescent particles. The availability of discrete sizes and distinct emission in the red, green and blue (RGB) range is useful for biomedical tagging, RGB displays, and flash memories. © 2002 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
78.55.Ap Elemental semiconductors
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
81.07.Bc Nanocrystalline materials
78.66.Db Elemental semiconductors and insulators
81.65.Cf Surface cleaning, etching, patterning
82.45.-h Electrochemistry and electrophoresis
82.70.Dd Colloids

Controlled two-dimensional distribution of nanoparticles by spin-coating method

Young-Kyu Hong, Hanchul Kim, Geunseop Lee, Wondong Kim, Jong-Il Park, Jinwoo Cheon, and Ja-Yong Koo

Appl. Phys. Lett. 80, 844 (2002); http://dx.doi.org/10.1063/1.1445811 (3 pages) | Cited 38 times

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We demonstrate that the controlled distribution of nanoparticles can be achieved by employing the spin-coating method. The Co and Ag nanoparticles were uniformly distributed on the Si and SiO2 substrates with this method. The particle density was controllable by varying the concentration of colloids. The spatial distribution of the nanoparticles within the patterned area was also shown to be uniform with small boundary effect, which is favorable for current microelectronics technology. We propose that the spin-coating method can be utilized in developing mass production processes for future nanodevices. © 2002 American Institute of Physics.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.A- Nucleation and growth
61.46.-w Structure of nanoscale materials
85.35.-p Nanoelectronic devices
81.07.Bc Nanocrystalline materials
82.70.Dd Colloids

Nanoscale organic transistors based on self-assembled monolayers

J. H. Schön and Z. Bao

Appl. Phys. Lett. 80, 847 (2002); http://dx.doi.org/10.1063/1.1445804 (3 pages) | Cited 1 time

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See Also: RETRACTION

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A device structure is reported for the fabrication of nanoscale organic transistors. In this structure, a self-assembled monolayer is used to define the channel length, as well as acting as the semiconducting material. High current modulation and high current output are demonstrated with 4,4′-dithiolbiphenylene. Various dielectric materials, such as SiO2, Al2O3, and a self-assembled silane monolayer, have been shown to result in high-performance transistors. Finally, nanopatterning can also be achieved by using an insulating alkanethiol to define the channel length of a conventional organic field-effect transistor. © 2002 American Institute of Physics.
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85.30.Tv Field effect devices
85.35.-p Nanoelectronic devices

Comparison of catalytically grown and arc-discharge carbon nanotube tips

Lê Thiên-Nga, Jean-Marc Bonard, Richard Gáal, László Forró, and Klara Hernadi

Appl. Phys. Lett. 80, 850 (2002); http://dx.doi.org/10.1063/1.1432748 (3 pages) | Cited 6 times

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We have performed a detailed transmission electron microscopy study of the tip of carbon nanotubes prepared by chemical vapor deposition (CVD) and by arc discharge. We found that a large proportion of the CVD-grown tubes have well-formed caps but that the graphitization of the walls is far from perfect. The tip shapes are also more rounded and the tip radius is higher when compared to arc-discharge tube tips. These features are discussed in relation with the growth mechanism and with the consequences they might have for applications in scanning probe microscopies. © 2002 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
81.07.De Nanotubes
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Diode and transistor behaviors of three-terminal ballistic junctions

H. Q. Xu

Appl. Phys. Lett. 80, 853 (2002); http://dx.doi.org/10.1063/1.1447316 (3 pages) | Cited 60 times

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We propose new applications of three-terminal ballistic junctions (TBJs) in nanoelectronics. It is found that for a TBJ with one of its three branch contacts, say the right branch contact, being grounded, the output voltage, Vc, from the central branch as a function of the voltage, Vl, applied to the left branch shows a diode characteristic: Vc approximately follows Vl linearly when Vl is negative, and saturates at a small positive value when Vl becomes positive. It is also found that the saturation level of Vc as well as the threshold value of Vl, beyond which Vc saturates, can be modulated by application of a voltage, Vr, to the right branch contact of the TBJ. Thus, the TBJ can also be used as a transistor. TBJ diodes and TBJ transistors with dimensions on the order of sub 100 nm, or much less, can be made from standard high-quality electronic materials with state-of-the-art nanofabrication technology. © 2002 American Institute of Physics.
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85.30.De Semiconductor-device characterization, design, and modeling
85.30.Kk Junction diodes
85.35.-p Nanoelectronic devices

In situ imaging of field emission from individual carbon nanotubes and their structural damage

Zhong L. Wang, Rui Ping Gao, Walt A. de Heer, and P. Poncharal

Appl. Phys. Lett. 80, 856 (2002); http://dx.doi.org/10.1063/1.1446994 (3 pages) | Cited 72 times

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Field emission of individual carbon nanotubes was observed by in situ transmission electron microscopy. A fluctuation in emission current was due to a variation in distance between the nanotube tip and the counter electrode owing to a “head-shaking” effect of the nanotube during field emission. Strong field-induced structural damage of a nanotube occurs in two ways: a piece-by-piece and segment-by-segment pilling process of the graphitic layers, and a concentrical layer-by-layer stripping process. The former is believed owing to a strong electrostatic force, and the latter is likely due to heating produced by emission current that flowed through the most outer graphitic layers. © 2002 American Institute of Physics.
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79.70.+q Field emission, ionization, evaporation, and desorption
61.46.-w Structure of nanoscale materials

Metal-encapsulated icosahedral superatoms of germanium and tin with large gaps: ZnGe12 and CdSn12

Vijay Kumar and Yoshiyuki Kawazoe

Appl. Phys. Lett. 80, 859 (2002); http://dx.doi.org/10.1063/1.1447315 (3 pages) | Cited 50 times

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Metal (M)-encapsulated clusters of Ge and Sn, ZnGe12 and CdSn12, are obtained from total energy calculations using ab initio pseudopotential plane wave method and generalized gradient approximation for the exchange-correlation energy. These have perfect icosahedral symmetry and large highest occupied–lowest unoccupied molecular orbital gap of about 2 eV. It lies in the optical region and makes these species attractive for cluster assembled optoelectronic materials. Calculations on silicon clusters doped with Be show a different behavior. © 2002 American Institute of Physics.
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36.40.Cg Electronic and magnetic properties of clusters
71.23.Ft Quasicrystals
71.15.Nc Total energy and cohesive energy calculations
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)
71.15.Dx Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction)
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