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

8 Apr 2002

Volume 80, Issue 14, pp. 2433-2611

Return to All Sections
back to top
RSS Feeds

Gas-phase thermodynamic models of nitrogen-induced nanocrystallinity in chemical vapor-deposited diamond

Raymond B. Corvin, Joseph G. Harrison, Shane A. Catledge, and Yogesh K. Vohra

Appl. Phys. Lett. 80, 2550 (2002); http://dx.doi.org/10.1063/1.1467618 (3 pages) | Cited 15 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Gas-phase thermodynamic equilibrium calculations involving H2/CH4/N2 mixtures were performed to investigate the chemical interactions leading to nitrogen-induced nanocrystallinity in microwave plasma chemical vapor deposition of diamond films. The strong influence of the CN radical in causing nanocrystallinity is confirmed by the correlation of its modeled composition in the gas phase with the degree of nanocrystallinity as determined experimentally for diamond films grown with different N2 additions. For a given CH4 feedgas concentration, there exists a critical N2 feedgas concentration, above which the change in the CH3/CN ratio is minimal and further induced nanocrystallinity is diminished. This is verified experimentally where it is observed that the same critical N2 feedgas concentration exists, above which a further decrease in diamond crystallinity and surface roughness of the grown diamond films is minimal. © 2002 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.35.B- Structure of clean surfaces (and surface reconstruction)

Raman scattering and thermogravimetric analysis of iodine-doped multiwall carbon nanotubes

Weiya Zhou, Sishen Xie, Lianfeng Sun, Dongsheng Tang, Yubao Li, Zuqin Liu, Lijie Ci, Xiaoping Zou, Gang Wang, Pingheng Tan, Xiaoli Dong, Bo Xu, and Boru Zhao

Appl. Phys. Lett. 80, 2553 (2002); http://dx.doi.org/10.1063/1.1468269 (3 pages) | Cited 10 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Iodine-doped multiwall carbon nanotubes (I-MWNTs) were characterized by means of Raman scattering and thermogravimetric analysis. The results show that multiwall carbon nanotubes (MWNTs) can be effectively doped by iodine and exchange electrons with iodine. Iodine atoms form charged polyiodide chains inside tubes of different inner diameter, which is similar to the iodine-doped single-wall carbon nanotubes (I-SWNTs), but can not intercalate into the graphene walls of MWNTs. The Raman scattering behavior of I-MWNTs exhibits some differences from that of I-SWNTs and the low-dimensional conductive hydrocarbon-iodine complex perylene⋅I2.92. © 2002 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
78.67.Ch Nanotubes
65.80.-g Thermal properties of small particles, nanocrystals, nanotubes, and other related systems
78.30.Na Fullerenes and related materials

Local electrostatic potential and process-induced boron redistribution in patterned Si/SiGe/Si heterostructures

A. Orchowski, W.-D. Rau, H. Rücker, B. Heinemann, P. Schwander, B. Tillack, and A. Ourmazd

Appl. Phys. Lett. 80, 2556 (2002); http://dx.doi.org/10.1063/1.1467712 (3 pages) | Cited 3 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present microscopic maps of the electrostatic potential in Si/SiGe/Si patterned structures of the type used in heterostructure bipolar transistors. By obtaining such maps before and after anneals typically used in device processing, we directly reveal the “vertical” and “lateral” redistribution of boron during device fabrication. Such data can be compared with the results of process simulation to extract the fundamental parameters for dopant diffusion in complex device structures. © 2002 American Institute of Physics.
Show PACS
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.Cc Kinetics of defect formation and annealing
85.30.Pq Bipolar transistors
81.05.Cy Elemental semiconductors
61.72.uf Ge and Si
61.72.up Other materials
85.40.Ry Impurity doping, diffusion and ion implantation technology
61.72.S- Impurities in crystals

Hybridized boron–carbon nitride fibrous nanostructures on Ni substrates

Yoke Khin Yap, Masashi Yoshimura, Yusuke Mori, and Takatomo Sasaki

Appl. Phys. Lett. 80, 2559 (2002); http://dx.doi.org/10.1063/1.1468270 (3 pages) | Cited 13 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Stoichiometric BC2N films can be deposited on Si (100) at 800 °C, however, they are phase separated as pure carbon and BN phases. Likewise, hybridized boron–carbon nitride (BCN) films can be synthesized on Ni substrates. On Ni, the carbon and BN phases are hybridized through carbon nitride and boron carbide bonds. These films appeared as fibrous nanostructures. Evidence indicates that the Ni substrate acts as a sink for the carbon and forces the carbon composites to grow on top of the B and N atoms. However, as these films are grown thicker, phase separation occurs again. These results indicate that hybridized BCN phases should now be regarded as semiconducting or superhard nanostructures. High-temperature deposition on Ni substrates might be a solution to the obstacle of preparing hybridized BCN phases. © 2002 American Institute of Physics.
Show PACS
81.07.Bc Nanocrystalline materials
68.55.-a Thin film structure and morphology
61.46.-w Structure of nanoscale materials
68.55.Nq Composition and phase identification
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
81.15.Fg Pulsed laser ablation deposition
81.16.Mk Laser-assisted deposition
52.77.Dq Plasma-based ion implantation and deposition
64.75.-g Phase equilibria
78.30.Hv Other nonmetallic inorganics

Conceptual design of nanostructures for efficient photoinduced phase transitions

Tohru Kawamoto and Shuji Abe

Appl. Phys. Lett. 80, 2562 (2002); http://dx.doi.org/10.1063/1.1468263 (3 pages) | Cited 10 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
By means of Monte Carlo simulations on a kinetic model, we demonstrate that the efficiency of a photoinduced phase change can in general be enhanced drastically by using a superstructure of an appropriate combination of two components. This is due to the accelerated nucleation of converted domains in the structural blocks relatively close to local instability. The present mechanism provides a general guideline on the design of photocontrollable materials with potential applications for memory and storage devices. © 2002 American Institute of Physics.
Show PACS
64.70.Nd Structural transitions in nanoscale materials
64.60.-i General studies of phase transitions
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Nanopatterning of alkyl monolayers covalently bound to Si(111) with an atomic force microscope

Masato Ara, Harald Graaf, and Hirokazu Tada

Appl. Phys. Lett. 80, 2565 (2002); http://dx.doi.org/10.1063/1.1467973 (3 pages) | Cited 30 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Alkyl monolayers covalently bound to silicon were prepared through the reaction between 1-alkene molecules and hydrogen-terminated Si. The surfaces were anodized in nanometer scale with a contact-mode atomic force microscope (AFM) by applying positive bias voltage to the surface with respect to a conducting cantilever under ambient conditions. Following the anodization, patterned areas were selectively modified by chemical etching and coating with different molecules. The alkyl monolayers showed high resistance against chemical etching and protected Si surfaces from oxidation. AFM lithography of monolayers on Si was found to be useful for nanofabrication of organic/inorganic interfaces based on the Si–C covalent bond. © 2002 American Institute of Physics.
Show PACS
81.16.Rf Micro- and nanoscale pattern formation
81.16.Ta Atom manipulation
81.65.Cf Surface cleaning, etching, patterning
81.65.Kn Corrosion protection
68.35.B- Structure of clean surfaces (and surface reconstruction)

Enhanced tunneling across nanometer-scale metal–semiconductor interfaces

G. D. J. Smit, S. Rogge, and T. M. Klapwijk

Appl. Phys. Lett. 80, 2568 (2002); http://dx.doi.org/10.1063/1.1467980 (3 pages) | Cited 50 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have measured electrical transport across epitaxial, nanometer-sized metal–semiconductor interfaces by contacting CoSi2 islands grown on Si(111) with the tip of a scanning tunneling microscope. The conductance per unit area was found to increase with decreasing diode area. Indeed, the zero-bias conductance was found to be ∼ 104 times larger than expected from downscaling a conventional diode. These observations are explained by a model, which predicts a narrower barrier for small diodes and, therefore, a greatly increased contribution of tunneling to the electrical transport. © 2002 American Institute of Physics.
Show PACS
73.40.Ns Metal-nonmetal contacts
73.30.+y Surface double layers, Schottky barriers, and work functions
85.30.Kk Junction diodes
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)

Quasiregular quantum-dot-like structure formation with postgrowth thermal annealing of InGaN/GaN quantum wells

Yen-Sheng Lin, Kung-Jen Ma, Cheng Hsu, Yi-Yin Chung, Chih-Wen Liu, Shih-Wei Feng, Yung-Chen Cheng, C. C. Yang, Ming-Hua Mao, Hui-Wen Chuang, Cheng-Ta Kuo, Jian-Shihn Tsang, and Thomas E. Weirich

Appl. Phys. Lett. 80, 2571 (2002); http://dx.doi.org/10.1063/1.1467983 (3 pages) | Cited 42 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Postgrowth thermal annealing of an InGaN/GaN quantum-well sample with a medium level of nominal indium content (19%) was conducted. From the analyses of high-resolution transmission electron microscopy and energy filter transmission electron microscopy, it was found that thermal annealing at 900 °C led to a quasiregular quantum-dot-like structure. However, such a structure was destroyed when the annealing temperature was raised to 950 °C. Temperature-dependent photoluminescence (PL) measurements showed quite consistent results. Blueshift of the PL peak position and narrowing of the PL spectral width after thermal annealing were observed. © 2002 American Institute of Physics.
Show PACS
68.65.Fg Quantum wells
68.65.Hb Quantum dots (patterned in quantum wells)
68.35.Ct Interface structure and roughness
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
78.67.De Quantum wells
81.07.St Quantum wells
78.67.Hc Quantum dots
81.07.Ta Quantum dots
81.40.Gh Other heat and thermomechanical treatments
68.37.Lp Transmission electron microscopy (TEM)

Controlled placement of an individual carbon nanotube onto a microelectromechanical structure

P. A. Williams, S. J. Papadakis, M. R. Falvo, A. M. Patel, M. Sinclair, A. Seeger, A. Helser, R. M. Taylor, S. Washburn, and R. Superfine

Appl. Phys. Lett. 80, 2574 (2002); http://dx.doi.org/10.1063/1.1467701 (3 pages) | Cited 38 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the precise placement of a single carbon nanotube (CNT) onto a microlectromechanial system (MEMS) structure. Using a hybrid atomic force microscope/scanning electron microscope (AFM/SEM) system, an individual multiwalled CNT was retrieved from a cartridge by the AFM tip, translated to a MEMS device, and then placed across a gap between an actuating and a stationary structure. Progress toward a resistance versus stress/strain measurement on a CNT will be discussed, including SEM images of a MEMS structure we have designed specifically for such a measurement. © 2002 American Institute of Physics.
Show PACS
81.16.Ta Atom manipulation
81.07.De Nanotubes
85.35.Kt Nanotube devices
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Few-electron filling effect in laterally coupled spherical InAs/GaAs quantum-dot system

Zhen-Hong Dai, Li-De Zhang, Jin-Zuo Sun, Zuo-Hong Li, and Shi-Yong Huang

Appl. Phys. Lett. 80, 2577 (2002); http://dx.doi.org/10.1063/1.1468262 (3 pages) | Cited 2 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Artificial molecules, i.e., systems of excess electrons confined in multiple semiconductor InAs/GaAs quantum dots, are studied with the unrestricted Hartree–Fock–Roothaan method. We focus our attention on calculating the chemical potential for two laterally coupled spherical quantum dots. The confinement potential in each quantum dot of the molecule is assumed in a form of three-dimensional spherical finite potential well of radius R and depth V0. The chemical potential is found to depend strongly on the proportionality of the radii of the two quantum dots. This method can be extended to study large quantum-dot arrays. © 2002 American Institute of Physics.
Show PACS
73.21.La Quantum dots
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)

Nanoparticle-templated carbon nanotube ring nucleus formation

James R. Hester and Oleg A. Louchev

Appl. Phys. Lett. 80, 2580 (2002); http://dx.doi.org/10.1063/1.1465112 (3 pages) | Cited 7 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A mechanism for nanotube ring nucleus formation via the interaction of a carbon nanosheet with a nanoparticle is proposed based on consideration of both short-range covalent and long-range interactions. In nanosheet–nanoparticle interaction, the potential barrier for nanosheet folding into a nanoring segment caused by covalent bonds distortions can be significantly decreased by long-range interaction with the nanoparticle. This effect, alone or in combination with the kinetic energy of collision, is shown to be able to fold the nanosheet around the nanoparticle and lead to the eventual formation of a nanotube ring nucleus. © 2002 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials

Exchange-coupled FePt nanoparticle assembly

Hao Zeng, Shouheng Sun, T. S. Vedantam, J. P. Liu, Z.-R. Dai, and Z.-L. Wang

Appl. Phys. Lett. 80, 2583 (2002); http://dx.doi.org/10.1063/1.1467976 (3 pages) | Cited 70 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have produced exchange-coupled FePt nanoparticle assemblies by chemical synthesis and subsequent thermal annealing. As the interparticle distances decrease by tuning the annealing conditions, interparticle interactions change from dipolar type to exchange type, and the magnetization reversal mechanism switches from rotation controlled to domain-nucleation controlled. With increasing annealing temperature, the coercivity first increases due to improved chemical ordering, and then drops significantly, resulting from excessive interparticle exchange coupling. For the samples exhibiting exchange coupling, both the remanence ratio and coercive squareness increase. © 2002 American Institute of Physics.
Show PACS
75.50.Tt Fine-particle systems; nanocrystalline materials
75.50.Bb Fe and its alloys
75.30.Et Exchange and superexchange interactions
75.60.Jk Magnetization reversal mechanisms
75.50.Vv High coercivity materials
81.07.Bc Nanocrystalline materials
75.60.Ch Domain walls and domain structure
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Ww Permanent magnets

Microscopic surface photovoltage spectroscopy

S. Saraf, R. Shikler, J. Yang, and Y. Rosenwaks

Appl. Phys. Lett. 80, 2586 (2002); http://dx.doi.org/10.1063/1.1468275 (3 pages) | Cited 5 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a microscopic surface photovoltage spectroscopy method. It is based on a tunable illumination system combined with a kelvin probe force microscope, which measures the contact potential difference between a sample surface and a tip of an atomic force microscope. By measuring the contact potential difference as a function of illumination wavelength, the whole surface photovoltage spectrum of a semiconductor sample is obtained with submicrometer spatial resolution. This resolution can be as high as 100 nm, in regions where the minority carrier transport is controlled by drift rather than by diffusion. © 2002 American Institute of Physics.
Show PACS
72.40.+w Photoconduction and photovoltaic effects
73.25.+i Surface conductivity and carrier phenomena
68.37.Ps Atomic force microscopy (AFM)
73.40.Cg Contact resistance, contact potential
07.79.Lh Atomic force microscopes
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Effect of substitutional atoms in the tip on field-emission properties of capped carbon nanotubes

Gang Zhang, Wenhui Duan, and Binglin Gu

Appl. Phys. Lett. 80, 2589 (2002); http://dx.doi.org/10.1063/1.1469213 (3 pages) | Cited 30 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
By use of first-principles calculations, we investigate the effect of introducing substitutional boron or nitrogen atom in the tip on field-emission properties of capped single-wall carbon nanotubes. We find that the substitution in the tip can significantly enhance the localized density of states at the Fermi level, which is important for field emission. The substitution of nitrogen introduces unsaturated dangling bond states at the tip, yielding a reduction of the work function of the tip. Our results suggest that the capped tube with substitutional nitrogen or boron atom in the tip could have much larger field-emission current than the tube without substitution. © 2002 American Institute of Physics.
Show PACS
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.20.Fz Weak or Anderson localization
79.70.+q Field emission, ionization, evaporation, and desorption
73.22.-f Electronic structure of nanoscale materials and related systems
73.30.+y Surface double layers, Schottky barriers, and work functions
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

Mechanism of atomic force microscopy anodization lithography on a mixed Langmuir–Blodgette resist of palmitic acid and hexadecylamine on silicon

Sang Jung Ahn, Yun Kyeong Jang, Haeseong Lee, and Haiwon Lee

Appl. Phys. Lett. 80, 2592 (2002); http://dx.doi.org/10.1063/1.1467984 (3 pages) | Cited 28 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A degradation process of a resist was observed by an atomic force microscope (AFM) during AFM anodization lithography on a mixed Langmuir–Blodgett resist of palmitic acid and hexadecylamine. Based on the observation, we proposed a two-step mechanism as follows: (i) a partial degradation of the resist was first achieved and (ii) silicon oxide started to be grown in the presence of a resist. Lateral force microscopy was accomplished on the patterned area before and after the resist was stripped in order to confirm when the silicon oxide started to be grown in the area. This result provides us with the actual information on the mechanism of the anodization lithography on an organic resist. © 2002 American Institute of Physics.
Show PACS
68.47.Pe Langmuir-Blodgett films on solids; polymers on surfaces; biological molecules on surfaces
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
68.37.Ps Atomic force microscopy (AFM)
81.65.Cf Surface cleaning, etching, patterning

Adsorbate-induced one-dimensional long-range modulation of an epitaxial insulator film

W. Ernst, M. Eichmann, H. Pfnür, K.-L. Jonas, V. von Oeynhausen, and K. H. Meiwes-Broer

Appl. Phys. Lett. 80, 2595 (2002); http://dx.doi.org/10.1063/1.1467624 (3 pages) | Cited 5 times

Online Publication Date: 2 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using low-energy electron diffraction and scanning tunneling micrsocopy, we found that epitaxial NaCl films grown on Ge(100) with thicknesses up to (at least) 15 monolayers can be modulated with a period of six lattice constants and an amplitude directed mainly normal to their surface. The (6×1) periodicity on the NaCl films is induced by a preadsorbed Na layer at very low coverages (Θ ≈ 0.06), that form chain structures with a sixfold periodicity in one dimension. At 10 monolayers thickness of NaCl a modulation amplitude of 0.28 Å was obtained. © 2002 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
68.43.Fg Adsorbate structure (binding sites, geometry)
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close