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

6 Aug 2001

Volume 79, Issue 6, pp. 705-888

Page 2 of 3 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Spatial distribution of space charge in conjugated polymers

F. Feller, D. Geschke, and A. P. Monkman

Appl. Phys. Lett. 79, 779 (2001); http://dx.doi.org/10.1063/1.1391399 (3 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate the pyroelectric effect in a conjugated polymer, poly(2,5-pyridinediyl) (PPY), and we use the laser intensity modulation method (LIMM) to resolve the spatial distribution of electric field and space charges inside a 5 μm Au/PPY/Au sandwich device. The pyroelectric signal shows hysteresis behavior with respect to the applied bias indicating permanent storage of injected charges. From the analysis of the LIMM spectra we conclude that application of a bias leads to the accumulation of space charges near the electrodes, while a zone of opposite space charge may establish in a distance of about 1 μm from it. The charged state retains after removing the bias and can lead to an internal electric field that is opposite to the external poling field in the bulk of the polymer film. © 2001 American Institute of Physics.
Show PACS
77.22.Jp Dielectric breakdown and space-charge effects
77.84.Jd Polymers; organic compounds
73.61.Ph Polymers; organic compounds
77.70.+a Pyroelectric and electrocaloric effects

Direct-to-indirect band gap crossover for the BexZn1−xTe alloy

O. Maksimov and M. C. Tamargo

Appl. Phys. Lett. 79, 782 (2001); http://dx.doi.org/10.1063/1.1390327 (3 pages) | Cited 19 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the growth and optical properties of a set of BexZn1−xTe epitaxial layers having different composition, with x ranging from 0–0.7. Comparison of the reflectivity and the photoluminescence spectra allowed us to locate the direct-to-indirect band gap crossover for this alloy at x ≈ 0.28. The Γ→Γ direct band gap exhibits a linear dependence on composition over the entire compositional range and can be fitted to the equation EΓg(x) = 2.26∗(1−x)+4.1∗x. It increases linearly with BeTe content at a rate of 18 meV for a change of 1% in BeTe content. The Γ→X indirect band gap for BexZn1−xTe can be fitted to the equation EXg(x) = 3.05∗(1−x)+2.8∗x−0.5∗x∗(1−x), suggesting that the energy of the indirect Γ→X transition for ZnTe is about 3.05 eV. © 2001 American Institute of Physics.
Show PACS
71.20.Nr Semiconductor compounds
78.66.Hf II-VI semiconductors
81.05.Dz II-VI semiconductors
68.55.Nq Composition and phase identification
78.55.Et II-VI semiconductors
78.40.Fy Semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Aluminum-doped n-type ZnTe layers grown by molecular-beam epitaxy

J. H. Chang, T. Takai, B. H. Koo, J. S. Song, T. Handa, and T. Yao

Appl. Phys. Lett. 79, 785 (2001); http://dx.doi.org/10.1063/1.1390481 (3 pages) | Cited 25 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
N-type ZnTe layers with high electron concentration are grown by molecular-beam epitaxy using aluminum as the donor species. The ZnTe:Al layers show a high structural quality with a narrow x-ray diffraction linewidth (24 arcsec) and a high carrier concentration up to n = 4×1018 cm−3 with low resistivity (ρ=0.017 Ω cm). The dependence of the electron mobility on the carrier concentration suggests that the dominant scattering mechanisms in the ZnTe:Al layers are ionized impurity scattering and polar optical phonon scattering. The photoluminescence spectrum of moderately doped ZnTe layers shows strong Al–donor-related bound exciton lines: I2 (2.378 eV) and donor–acceptor pair emission (zero phonon energy=2.324 eV) with a weak deep-level emission (2.19 eV). Highly Al-doped layers show an increase in the deep-level emission intensity and a decrease in carrier mobility, which are interpreted in terms of the increase in the carrier compensation. © 2001 American Institute of Physics.
Show PACS
81.05.Dz II-VI semiconductors
78.66.Hf II-VI semiconductors
73.61.Ga II-VI semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
71.55.Gs II-VI semiconductors
78.55.Et II-VI semiconductors

Transport through a nine period silicon/oxygen superlattice

Yong-Jin Seo, John C. Lofgrene, and Raphael Tsu

Appl. Phys. Lett. 79, 788 (2001); http://dx.doi.org/10.1063/1.1394162 (3 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The silicon/adsorbed oxygen superlattice was introduced as an epitaxial barrier for silicon quantum devices. A barrier height of ∼0.5 eV with a thin layer of silicon sandwiched between two adsorbed oxygen layers has been achieved. This work describes a similar structure with nine periods which may serve as a replacement of the present amorphous silicon dioxide gate for metal oxide semiconductor field effect transistor. The insulating property derived from our current–voltage (I–V) and conductance–voltage (G–V) measurements indicates that the scheme may serve as a replacement of silicon on insulator. © 2001 American Institute of Physics.
Show PACS
73.63.Rt Nanoscale contacts
85.35.Ds Quantum interference devices
73.23.-b Electronic transport in mesoscopic systems
85.30.Tv Field effect devices
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Localized charge injection in SiO2 films containing silicon nanocrystals

Elizabeth A. Boer, Mark L. Brongersma, Harry A. Atwater, Richard C. Flagan, and L. D. Bell

Appl. Phys. Lett. 79, 791 (2001); http://dx.doi.org/10.1063/1.1383574 (3 pages) | Cited 41 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An atomic-force microscope (AFM) is used to locally inject, detect, and quantify the amount and location of charge in SiO2 films containing Si nanocrystals (size ∼2–6 nm). By comparison with control samples, charge trapping is shown to be due to nanocrystals and not ion-implantation-induced defects in samples containing ion-beam-synthesized Si nanocrystals. Using an electrostatic model and AFM images of charge we have estimated the amount of charge injected in a typical experiment to be a few hundred electrons and the discharge rate to be ∼35±15 e/min. © 2001 American Institute of Physics.
Show PACS
73.61.Ng Insulators
71.55.Ht Other nonmetals
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
81.05.Cy Elemental semiconductors
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
68.65.Hb Quantum dots (patterned in quantum wells)
73.63.Kv Quantum dots
81.07.Ta Quantum dots
61.46.-w Structure of nanoscale materials
73.22.-f Electronic structure of nanoscale materials and related systems
73.63.Bd Nanocrystalline materials
81.07.Bc Nanocrystalline materials
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.16.-c Methods of micro- and nanofabrication and processing
68.37.Ps Atomic force microscopy (AFM)
61.72.up Other materials
61.80.Jh Ion radiation effects
61.82.Ms Insulators
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
85.40.Ry Impurity doping, diffusion and ion implantation technology
back to top
RSS Feeds

Domain wall pinning on strain relaxation defects in FePt(001)/Pt thin films

J. P. Attané, Y. Samson, A. Marty, D. Halley, and C. Beigné

Appl. Phys. Lett. 79, 794 (2001); http://dx.doi.org/10.1063/1.1390321 (3 pages) | Cited 22 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thin FePt (001) films, grown by molecular-beam epitaxy on Pt(001), exhibit a very large perpendicular magnetic anisotropy (Ku = 5×106 J m−3) and a 100% magnetic remanence in perpendicular field. The lattice misfit between FePt and Pt (1.5%) relaxes through the pileup of a/6 〈112〉 partial dislocations along {111} planes, leading to the formation of microtwins. Atomic force microscopy images demonstrate that this process induces a spontaneous rectangular nanostructuration of the sample, while magnetic force microscopy shows that the microtwins act as pinning sites for the magnetic walls. This leads to square magnetic domains and explains the large coercivity associated with the domain wall propagation. © 2001 American Institute of Physics.
Show PACS
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.50.Bb Fe and its alloys
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
75.30.Gw Magnetic anisotropy
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Mm Grain and twin boundaries
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
75.60.Ch Domain walls and domain structure

Partitioning behavior and the effect of Co on the Curie temperature of nanocomposite PrFeCoB hard magnetic alloys

Y. Zhang, P. J. Warren, A. Cerezo, C. L. Harland, and H. A. Davies

Appl. Phys. Lett. 79, 797 (2001); http://dx.doi.org/10.1063/1.1388879 (3 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The microstructure and phase chemistry of melt-spun nanocomposite Pr9.7Fe76.6Co7.8B5.9 and Pr9.2Fe69.4Co15.4B6.0 ribbons have been studied using three-dimensional atom probe (3DAP) and transmission electron microscopy. The microstructure of these alloys consists of two phases, bcc α-Fe–Co and tetragonal Pr2(FeCo)14B. Practically all of the B and Pr atoms are rejected from the α-Fe–Co phase and are concentrated into the 2/14/1 hard magnetic phase. However, no significant difference of Co concentration between the two phases is observed. From the measured Co concentration in the 2/14/1 phase, it is explained why the effect of Co content on Curie temperature (Tc) is greater in the nanocomposite alloys than in single phase alloys. Predictions of Tc for the nanocomposite alloys based on the 3DAP composition data show excellent agreement with experimental measurements. © 2001 American Institute of Physics.
Show PACS
75.50.Ww Permanent magnets
75.50.Bb Fe and its alloys
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
81.05.Bx Metals, semimetals, and alloys
75.50.Tt Fine-particle systems; nanocrystalline materials
back to top
RSS Feeds

Studies of thin film growth and oxidation processes for conductive Ti–Al diffusion barrier layers via in situ surface sensitive analytical techniques

A. M. Dhote, O. Auciello, D. M. Gruen, and R. Ramesh

Appl. Phys. Lett. 79, 800 (2001); http://dx.doi.org/10.1063/1.1391237 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Conducting diffusion barrier layers play a critical role in high-density memory integration. We recently demonstrated that Ti–Al can be used as a diffusion barrier layer for the integration of ferroelectric capacitors with complementary metal–oxide semiconductor devices for the fabrication of nonvolatile ferroelectric random access memories (NVFRAMs). Here, we discuss results from systematic studies designed to understand Ti–Al film growth and oxidation processes using in situ ion beam sputter deposition in conjunction with complementary in situ atomic layer-resolution mass spectroscopy of recoil ion (MSRI) and surface sensitive x-ray photoelectron spectroscopy (XPS). The concurrent MSRI/XPS analysis revealed that amorphous Ti–Al layers produced by tailored sputter-deposition methods are resistant to oxidation to at least 600 °C, and that oxidation occurs only when the a-Ti–Al layers are exposed to oxygen at >600 °C, via the segregation of Ti species to the surface and TiO2 formation. The a-Ti–Al layers discussed in this letter could be used in the double functionality of a bottom electrode/diffusion barrier for the integration of ferroelectric capacitors with Si substrates for the fabrication of NVFRAMs and other devices. © 2001 American Institute of Physics.
Show PACS
68.35.Fx Diffusion; interface formation
85.40.Ls Metallization, contacts, interconnects; device isolation
85.50.Gk Non-volatile ferroelectric memories
81.05.Bx Metals, semimetals, and alloys
81.65.Mq Oxidation
81.15.Cd Deposition by sputtering
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
79.60.Jv Interfaces; heterostructures; nanostructures

Ultralow-k dielectrics prepared by plasma-enhanced chemical vapor deposition

A. Grill and V. Patel

Appl. Phys. Lett. 79, 803 (2001); http://dx.doi.org/10.1063/1.1392976 (3 pages) | Cited 102 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Carbon-doped oxide materials (SiCOH films) with ultralow dielectric constants have been prepared by plasma-enhanced chemical vapor deposition (PECVD) from mixtures of SiCOH precursors with organic materials. The films have been characterized by Rutherford backscattering and forward recoil elastic scattering analysis, Fourier transform infrared spectroscopy and index of refraction measurements, and measurement of step heights in the films. The electrical properties of the films have been measured on metal–insulator–silicon structures. By proper choice of the precursor and deposition conditions, the dielectric constants of the SiCOH films can be reduced to values below 2.1, demonstrating the extendibility of PECVD-prepared carbon-doped oxides as the interconnect dielectrics for future generation of very large scale integrated chips. © 2001 American Institute of Physics.
Show PACS
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.Nk Insulators
85.40.Ls Metallization, contacts, interconnects; device isolation
77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
78.30.Hv Other nonmetallic inorganics
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Electrical properties of LaAlO3/Si and Sr0.8Bi2.2Ta2O9/LaAlO3/Si structures

Byung-Eun Park and Hiroshi Ishiwara

Appl. Phys. Lett. 79, 806 (2001); http://dx.doi.org/10.1063/1.1380246 (3 pages) | Cited 66 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Lanthanum aluminate (LaAlO3) films were deposited on Si(100) substrates by evaporating single-crystal pellets in vacuum using an electron-beam gun. Then, they were annealed in N2 ambience at 700 °C for 10 min using an electric furnace. X-ray diffraction analysis showed that the LaAlO3 films were amorphous even after the annealing process. No hysteretic characteristics were observed in the capacitance–voltage (C–V) measurement and the dielectric constant of the LaAlO3 films was estimated to be 21–25. It was also found that the leakage current density decreased by about three orders of magnitude after the annealing process. On these films, Sr0.8Bi2.2Ta2O9 films with 210 nm thickness were deposited by a sol–gel method. All samples annealed in O2 atmosphere at temperatures ranging from 650 to 750 °C showed hysteretic C–V characteristics, and the memory window width in the sample annealed at 750 °C for 30 min was about 3.0 V for a voltage sweep of ±10 V. It was also found that the capacitance values biased in the hysteresis loop were unchanged over 12 h. © 2001 American Institute of Physics.
Show PACS
77.80.Dj Domain structure; hysteresis
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.40.Gh Other heat and thermomechanical treatments
77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
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)
85.50.Gk Non-volatile ferroelectric memories

Stability of electrodeless ferroelectric domains near a ferroelectric/dielectric interface

X. Li, A. Mamchik, and I.-W. Chen

Appl. Phys. Lett. 79, 809 (2001); http://dx.doi.org/10.1063/1.1390326 (3 pages) | Cited 17 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The stability of an electrodeless near-surface ferroelectric domain, such as the one written by the tip of an atomic-force microscope, is considered. The analysis takes into account the domain-wall energy, depolarization energy, and coercive field. The domain is found unstable unless the surface charge is compensated, which was experimentally verified. A high-dielectric substrate is found to stabilize the domain while a low-dielectric substrate has the opposite effect. © 2001 American Institute of Physics.
Show PACS
77.80.Dj Domain structure; hysteresis
68.37.Ps Atomic force microscopy (AFM)
77.22.Ej Polarization and depolarization

Investigation of Li-doped ferroelectric and piezoelectric ZnO films by electric force microscopy and Raman spectroscopy

H. Q. Ni, Y. F. Lu, Z. Y. Liu, H. Qiu, W. J. Wang, Z. M. Ren, S. K. Chow, and Y. X. Jie

Appl. Phys. Lett. 79, 812 (2001); http://dx.doi.org/10.1063/1.1391225 (3 pages) | Cited 16 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have grown Li-doped ZnO films on silicon (100) using the rf planar magnetron sputtering method. The surface charges induced piezoelectrically by defect and by polarization can be observed by electric force microscopy. The Li-doped ZnO films have been proven to be ferroelectric. The Raman spectra of ZnO and Li-doped ZnO films have been measured. © 2001 American Institute of Physics.
Show PACS
78.66.Hf II-VI semiconductors
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.65.-j Piezoelectricity and electromechanical effects
77.55.-g Dielectric thin films
78.30.Fs III-V and II-VI semiconductors
77.80.-e Ferroelectricity and antiferroelectricity
77.22.Ej Polarization and depolarization

Enhancement of dielectric constant and associated coupling of polarization behavior in thin film relaxor superlattices

M. H. Corbett, R. M. Bowman, J. M. Gregg, and D. T. Foord

Appl. Phys. Lett. 79, 815 (2001); http://dx.doi.org/10.1063/1.1391233 (3 pages) | Cited 27 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thin film capacitor structures in which the dielectric is composed of superlattices of the relaxors [0.2Pb(Zn1/3Nb2/3)O3–0.8BaTiO3] and Pb(Mg1/3Nb2/3)O3 have been fabricated by pulsed laser deposition. Superlattice wavelength (Λ) was varied between ∼3 and ∼600 nm, and dielectric properties were investigated as a function of Λ. Progressive enhancement of the dielectric constant was observed on decreasing Λ, and, in contrast to previous work, this was not associated with the onset of Maxwell–Wagner behavior. Polarization measurements as a function of temperature suggested that the observed enhancement in dielectric constant was associated with the onset of a coupled response. The superlattice wavelength (Λ = 20 nm) at which coupled functional behavior became apparent is comparable to that found in literature for the onset of coupled structural behavior (between Λ = 5 nm and Λ = 10 nm). © 2001 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ch Permittivity (dielectric function)
77.22.Ej Polarization and depolarization
81.15.Fg Pulsed laser ablation deposition

Dielectric relaxation and conduction in SrTiO3 thin films under dc bias

Chen Ang, Zhi Yu, L. E. Cross, Ruyan Guo, and A. S. Bhalla

Appl. Phys. Lett. 79, 818 (2001); http://dx.doi.org/10.1063/1.1389771 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The dielectric and conduction behavior of SrTiO3 thin films deposited on a SrTiO3 single-crystal substrate is studied. Without dc bias, an obvious dielectric “defect mode” in the dielectric loss is observed in the temperature range of ∼100–200 K; however, no noticeable corresponding dielectric constant peak is observed. By applying a high dc bias (⩾40 kV/cm), a dielectric constant peak with frequency dispersion appears in the same temperature range, the dielectric loss is increased, and simultaneously high dc conduction is observed. The induced dielectric constant peak is related to dc conduction and attributed to the coupling effect of the mobile carriers with the dielectric defect mode. © 2001 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Gm Dielectric loss and relaxation
73.61.Ng Insulators
77.22.Ch Permittivity (dielectric function)

Characteristics of ferroelectric Pb(Zr,Ti)O3 thin films having Pt/PtOx electrode barriers

Kwangbae Lee, Byung Roh Rhee, and Chanku Lee

Appl. Phys. Lett. 79, 821 (2001); http://dx.doi.org/10.1063/1.1391226 (3 pages) | Cited 14 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the feasibility of the Pt/PtOx multilayer as an electrode barrier for Pb(Zr,Ti)O3 (PZT)-based ferroelectric random access memories. PtOx and Pt layers were prepared on polycrystalline-Si/SiO2/Si substrates by means of the sputtering method in Ar and O2 ambience, and the Pb(Zr0.53Ti0.47)O3 layer was prepared by the sol-gel method. A capacitor consisting of Pt/PtOx/PZT/PtOx/Pt/PtOx/poly-Si had a remanent polarization of 18 μC/cm2 and a low coercive field of 32 kV/cm. The polarization fatigue behavior of test capacitors was improved as compared with that of Pt/PZT/Pt, which showed negligible fatigue loss of 15% after 1011 switching repetitions with a frequency of 1 MHz. © 2001 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
85.50.Gk Non-volatile ferroelectric memories
77.80.Dj Domain structure; hysteresis
77.22.Ej Polarization and depolarization
77.80.Fm Switching phenomena
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)
back to top
RSS Feeds

Fabrication of epitaxial CoSi2 nanowires

P. Kluth, Q. T. Zhao, S. Winnerl, S. Lenk, and S. Mantl

Appl. Phys. Lett. 79, 824 (2001); http://dx.doi.org/10.1063/1.1390318 (3 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed a method for fabricating epitaxial CoSi2 nanowires using only conventional optical lithography and standard silicon processing steps. This method was successfully applied to ultrathin epitaxial CoSi2 layers grown on Si(100) and silicon-on-insulator substrates. A nitride mask induces a stress field near its edges into the CoSi2/Si heterostructure and leads to the separation of the CoSi2 layer in this region during a rapid thermal oxidation step. A subsequent etching step and a second oxidation generate highly homogenous silicide wires with dimensions down to 50 nm. © 2001 American Institute of Physics.
Show PACS
85.40.Ls Metallization, contacts, interconnects; device isolation
81.16.Nd Micro- and nanolithography
81.07.Lk Nanocontacts
85.40.Sz Deposition technology
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
85.40.Hp Lithography, masks and pattern transfer
81.16.Pr Micro- and nano-oxidation
81.65.Cf Surface cleaning, etching, patterning

Coherent nanoscale islands on La0.5Ca0.5MnO3 thin films and the enhancement of magnetoresistance

W. Z. Gong, B. R. Zhao, C. Cai, and Y. Lin

Appl. Phys. Lett. 79, 827 (2001); http://dx.doi.org/10.1063/1.1384003 (3 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A low cost reproducible fabrication process has been developed to prepare La0.5Ca0.5MnO3 (LCMO) films with well distributed uniform nanoscale dots using pulsed-laser deposition. It was found that the growth of the dots was closely related to the strain in the film during the growth process. The diameter and density of dots could be controlled within the range of 30–120 nm and 2×108–2×109/cm2, respectively. The magnetoresistance effect of such LCMO films is also enhanced, which may be caused by the spin-dependent scattering of carriers due to the existence of the dots. © 2001 American Institute of Physics.
Show PACS
75.47.Gk Colossal magnetoresistance
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
75.50.Dd Nonmetallic ferromagnetic materials
68.55.-a Thin film structure and morphology
75.75.-c Magnetic properties of nanostructures
81.15.Fg Pulsed laser ablation deposition
81.16.Mk Laser-assisted deposition
72.25.Rb Spin relaxation and scattering

Continuous-wave two-photon excitation of individual CdS nanocrystallites

A. M. van Oijen, R. Verberk, Y. Durand, J. Schmidt, J. N. J. van Lingen, A. A. Bol, and A. Meijerink

Appl. Phys. Lett. 79, 830 (2001); http://dx.doi.org/10.1063/1.1391231 (3 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
By use of low-temperature confocal microscopy, continuous-wave two-photon fluorescence images are obtained of individual CdS nanocrystallites embedded in a polymer matrix. The quadratic dependence of the emission rate on the applied laser power proves that the observed fluorescence originates from the simultaneous absorption of two photons. From the experimental data the two-photon absorption cross-section σ(2) could be determined, resulting in a value smaller than that known from literature. The work presented is a first step towards high-resolution fluorescence-excitation spectroscopy on the electronic states in the band edge, inaccessible by conventional one-photon spectroscopy. © 2001 American Institute of Physics.
Show PACS
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.55.Et II-VI semiconductors
73.22.Dj Single particle states

Ultraviolet–visible near-field microscopy of phase-separated blends of polyfluorene-based conjugated semiconductors

R. Stevenson, R. Riehn, R. G. Milner, D. Richards, E. Moons, D.-J. Kang, M. Blamire, J. Morgado, and F. Cacialli

Appl. Phys. Lett. 79, 833 (2001); http://dx.doi.org/10.1063/1.1389822 (3 pages) | Cited 27 times

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
We have used fluorescence scanning near-field microscopy to characterize polymer blends for electroluminescent applications, and thereby identify compositional nonhomogeneities. In particular, we have focused on the binary system constituted by poly(9,9′-dioctylfluorenealt-benzothiadiazole) and poly(9,9′-dioctylfluorene) (PFO), known to give efficiencies of up to 22 cd/A in light-emitting devices with suitable electrodes. Our primary aim was the assignment of the morphological features revealed in shear-force and atomic-force images of spin-coated films, and suggestive of phase separation on a 300-nm-length scale. From analysis of the fluorescence images (325 and 488 nm excitation), and quantitative correlation of optical and topographic data, we identify the raised features with PFO-rich regions. However, the limited variation in fluorescence intensity reveals a high extent of mixing within each phase on the length scale accessible in our experiment, approximately 100 nm for our focused-ion-beam-processed probe apertures. © 2001 American Institute of Physics.
Show PACS
61.41.+e Polymers, elastomers, and plastics
68.55.-a Thin film structure and morphology
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
78.55.Kz Solid organic materials
64.75.-g Phase equilibria
78.66.Qn Polymers; organic compounds

Dimensional effects on field emission properties of the body for single-walled carbon nanotube

Gang Zhou, Wenhui Duan, and Binglin Gu

Appl. Phys. Lett. 79, 836 (2001); http://dx.doi.org/10.1063/1.1388871 (3 pages) | Cited 29 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, by use of the first-principles calculations, field emission properties of the body are investigated for a series of dimension-variational single-walled carbon nanotubes (SWNTs). We find that in the course of increasing tube diameter, at low emission currents, field emission properties worsen, chemical stability enhances and binding energy increases, which indicates that optimized field emitter could be achieved; while at high applied voltages, the highest emission current density may appear for the SWNT with some peculiar dimension. We predict that the body of the SWNT could behave as a peculiar field emitter with high threshold voltage and high current density. © 2001 American Institute of Physics.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
73.22.-f Electronic structure of nanoscale materials and related systems
71.15.-m Methods of electronic structure calculations

Ordered indium-oxide nanowire arrays and their photoluminescence properties

M. J. Zheng, L. D. Zhang, G. H. Li, X. Y. Zhang, and X. F. Wang

Appl. Phys. Lett. 79, 839 (2001); http://dx.doi.org/10.1063/1.1389071 (3 pages) | Cited 110 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ordered semiconductor In2O3 nanowire arrays are uniformly assembled into hexagonally ordered nanochannels of anodic alumina membranes (AAMs) by electrodeposition and oxidizing methods. Their microstructures were characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. A blue-green photoluminescence (PL) band in the wavelength range of 300–650 nm was observed in the In2O3/AAM assembly system. The PL intensity and peak position depend on the annealing temperature, which is mainly attributed to the singly ionized oxygen vacancy in the In2O3 nanowire array system. © 2001 American Institute of Physics.
Show PACS
81.07.Bc Nanocrystalline materials
81.16.Pr Micro- and nano-oxidation
61.46.-w Structure of nanoscale materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
73.22.-f Electronic structure of nanoscale materials and related systems
81.15.Pq Electrodeposition, electroplating
78.55.Hx Other solid inorganic materials
71.55.Ht Other nonmetals
61.72.Cc Kinetics of defect formation and annealing

Selective thermal desorption of ultrathin aluminum oxide layers induced by electron beams

Manisha Kundu, Noriyuki Miyata, and Masakazu Ichikawa

Appl. Phys. Lett. 79, 842 (2001); http://dx.doi.org/10.1063/1.1391236 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The mechanism of electron-beam-induced selective thermal desorption of ultrathin aluminum-oxide layer (∼0.4 nm) on Si(001) surface was investigated by using scanning reflection electron microscopy, reflection high-energy electron diffraction, and Auger electron spectroscopy. We found that the change in the aluminum-oxide layer composition induced by electron-stimulated oxygen desorption accounted for the selective thermal desorption of the oxide layer. A systematic increase in the vacuum-annealing temperature to 500 °C, 600 °C and 720 °C resulted in the formation of three-dimensional metal aluminum clusters, desorption of these clusters, and creation of a nanometer-scale clean Si(001)-2×1 open window in the selected electron-beam-irradiated area. © 2001 American Institute of Physics.
Show PACS
68.43.Rs Electron stimulated desorption
79.20.La Photon- and electron-stimulated desorption
79.20.Fv Electron impact: Auger emission
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.43.Hn Structure of assemblies of adsorbates (two- and three-dimensional clustering)

Multilevel nanoimprint lithography with submicron alignment over 4 in. Si wafers

Wei Zhang and Stephen Y. Chou

Appl. Phys. Lett. 79, 845 (2001); http://dx.doi.org/10.1063/1.1391400 (3 pages) | Cited 25 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate that multilevel nanoimprint lithography (NIL) with submicron alignment over an entire 4 in. Si wafer can be achieved. Average alignment accuracy of 1 μm with a standard deviation 0.4 μm in both X and Y directions was obtained in ten consecutive tests of multilevel NIL. The multilevel alignment was achieved by aligning the wafer and the mask with an aligner, fixing them with a holder, and imprinting in an imprint machine. The issues that are critical to the alignment accuracy, such as relative movement during the press, relative thermal expansion, wafer bending, and resist, are discussed. The alignment accuracy currently achieved on the system is limited by the aligning accuracy of the aligner, instead of the process of multilevel NIL. © 2001 American Institute of Physics.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
06.60.Sx Positioning and alignment; manipulating, remote handling

Double textured cylindrical block copolymer domains via directional solidification on a topographically patterned substrate

Cheolmin Park, Joy Y. Cheng, Michael J. Fasolka, Anne M. Mayes, C. A. Ross, Edwin L. Thomas, and Claudio De Rosa

Appl. Phys. Lett. 79, 848 (2001); http://dx.doi.org/10.1063/1.1389766 (3 pages) | Cited 28 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Directional solidification of cylinder forming block copolymer films confined between a directionally crystallizing solvent (benzoic acid) and a topographically patterned silicon substrate imparts a particular orientation to the block copolymer microdomains that is dependent of the solidification direction and the local film thickness. The substrate features (30 nm high, 2μm wide square mesas on a 4μm sq lattice) shape the film morphology by periodically modulating the local film thickness. Thicker regions between substrate features (plateaus) exhibit in-plane cylinders aligned in the crystallization direction and thinner regions over the substrate features (mesas) display vertically aligned cylindrical domains. This approach is a simple and general technique for engineering an intended domain orientation in specific areas of a block copolymer film. Development of this method for nanolithographic applications is demonstrated through oxygen plasma reactive ion etching of the patterned cylindrical domains. © 2001 American Institute of Physics.
Show PACS
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.30.Fb Solidification
81.65.Cf Surface cleaning, etching, patterning
81.16.Nd Micro- and nanolithography
61.41.+e Polymers, elastomers, and plastics

Modification of the three-phonon Umklapp process in a quantum wire

A. Khitun and K. L. Wang

Appl. Phys. Lett. 79, 851 (2001); http://dx.doi.org/10.1063/1.1391230 (3 pages) | Cited 12 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the modification of the three-phonon Umklapp process in a quantum wire caused by the effect of phonon confinement. Our formalism rigorously takes into account variations in phonon group velocity as well as the presence of an energy gap between the phonon modes due to the quantization of the radial phonon wave vector. Numerical calculations of the Umklapp relaxation rate were carried out for Si wires. Based on the obtained results we predict the suppression of the acoustic phonon modes decay at low temperatures that can lead to the unusual thermal conductivity increase. We also present a simplified empiric formula for the Umklapp relaxation rate calculation in a quantum wire. © 2001 American Institute of Physics.
Show PACS
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
63.20.K- Phonon interactions
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
68.65.La Quantum wires (patterned in quantum wells)
Page 2 of 3 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close