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

21 Aug 2000

Volume 77, Issue 8, pp. 1071-1232

Page 1 of 3 Pages Next Page | Jump to Page
back to top
RSS Feeds

Scanning near-field optical microscopy in the near-infrared region using light emitting cantilever probes

S. Heisig, O. Rudow, and E. Oesterschulze

Appl. Phys. Lett. 77, 1071 (2000); http://dx.doi.org/10.1063/1.1289261 (3 pages) | Cited 14 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present an application of an active emitting cantilever probe for scanning near-field optical microscopy and scanning force microscopy. A vertical cavity surface emitting laser (VCSEL) integrated in a galliumarsenide (GaAs) cantilever serves as a light source at 980 nm emission wavelength that is below the band gap energy of the GaAs substrate material. The VCSEL of 8 μm diameter is centered with respect to the metalized GaAs tip and illuminates a small near-field aperture at its apex. Aperture fabrication is accomplished by a proper thermal metal evaporation process. Optical measurements on a Fischer projection pattern revealed an edge resolution of about 80 nm. © 2000 American Institute of Physics.
Show PACS
07.79.Fc Near-field scanning optical microscopes
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
07.79.Lh Atomic force microscopes
81.05.Ea III-V semiconductors
78.66.Fd III-V semiconductors
42.62.-b Laser applications

Gray-track damage in potassium titanyl phosphate under a picosecond regime at 532 nm

Lionel Carrion and Jean-Pierre Girardeau-Montaut

Appl. Phys. Lett. 77, 1074 (2000); http://dx.doi.org/10.1063/1.1289501 (3 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report studies of gray-track damage formation in flux-grown potassium titanyl phosphate exposed to 532 nm, picosecond pulses. We investigate the time evolution of damage formation and the evolution of gray-track susceptibility as a function of laser intensity. We demonstrate that the energy loss in the crystal is for the most part due to the formation of the centers of absorption. For 26 ps pulses, the intensity damage threshold was found to be much higher than for nanosecond pulses. Evidence is found that the mechanism of gray-track formation is nonlinear as a function of intensity and as a function of pulse duration. © 2000 American Institute of Physics.
Show PACS
78.47.-p Spectroscopy of solid state dynamics
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.65.An Optical susceptibility, hyperpolarizability
42.70.Mp Nonlinear optical crystals

Self-aligned coupled cavity GaAs/AlGaAs midinfrared quantum-cascade laser

L. Hvozdara, A. Lugstein, S. Gianordoli, W. Schrenk, G. Strasser, K. Unterrainer, E. Bertagnolli, and E. Gornik

Appl. Phys. Lett. 77, 1077 (2000); http://dx.doi.org/10.1063/1.1289499 (3 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A monolithic GaAs/AlGaAs quantum-cascade laser with self-aligned focused ion beam-cut coupled cavities, emitting in the range of λ = 9.4 μm is demonstrated. Separate pulsing of two optically coupled laser sections enables control of the lasing in single-mode and in multimode regimes. Side mode suppression ratios better than 25 dB are shown. Mode control over two single modes spaced by 3.6 cm−1 is presented. An optical output intensity modulation in a range of 20 dB is achieved. The laser exhibits a peak output power in the range of 180 mW at cryogenic temperatures. The observed mode spacing is in a good agreement with the calculation. © 2000 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Narrowing of high power diode laser arrays using reflection feedback from an etalon

M. V. Romalis

Appl. Phys. Lett. 77, 1080 (2000); http://dx.doi.org/10.1063/1.1289652 (2 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The spectrum of a high power multielement laser array is narrowed using reflection feedback from an 100 μm etalon placed in front of the laser. The full width at half maximum (FWHM) of the laser array is reduced by a factor of 2 with only 6% power loss. This reduction in FWHM is useful for optical pumping of alkali metals in the presence of high density buffer gas. © 2000 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
32.80.Xx Level crossing and optical pumping
42.79.Bh Lenses, prisms and mirrors
07.60.Ly Interferometers

Subcycle high electron acceleration by crossed laser beams

Yousef I. Salamin and Christoph H. Keitel

Appl. Phys. Lett. 77, 1082 (2000); http://dx.doi.org/10.1063/1.1289649 (3 pages) | Cited 31 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present an exact plane-wave-based analysis of the vacuum acceleration, to energy gradients in the TeV/m range, of a single electron, using two laser beams crossing at an arbitrary angle. Our analysis of the dynamics evolves from analytic solutions to the relativistic equations of motion and predicts that, for a given laser intensity, a unique crossing angle maximizes the energy gain due to constructive interference. © 2000 American Institute of Physics.
Show PACS
41.75.Jv Laser-driven acceleration
29.20.-c Accelerators
42.62.-b Laser applications

Frequency domain spectroscopy of free-space terahertz radiation

Hironori Takahashi and Makoto Hosoda

Appl. Phys. Lett. 77, 1085 (2000); http://dx.doi.org/10.1063/1.1289805 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate frequency domain spectroscopy of free-space terahertz (THz) radiation by using a vibrating optical delay and a rf spectrum analyzer. When the timing of the pump pulses is repeatedly varied at several Hz and an optical chopper at a frequency of several kHz simultaneously modulates the pump pulse, the spectrum analyzer directly obtains the THz spectrum as a sideband of the chopping frequency. This method can be used to measure in real time the transient change in the THz spectrum at a specific frequency corresponding to the water absorption. © 2000 American Institute of Physics.
Show PACS
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques

Electronic distribution in superlattice quantum cascade lasers

Mariano Troccoli, Gaetano Scamarcio, Vincenzo Spagnolo, Alessandro Tredicucci, Claire Gmachl, Federico Capasso, Deborah L. Sivco, Alfred Y. Cho, and Marinella Striccoli

Appl. Phys. Lett. 77, 1088 (2000); http://dx.doi.org/10.1063/1.1289798 (3 pages) | Cited 18 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electron population in the excited miniband of quantum cascade structures with intrinsic superlattice active regions is extracted from the fine structure analysis of spontaneous interminiband electroluminescence spectra. At current densities typical of laser thresholds, the electrons injected into the excited miniband of a (GaInAs)6 nm/(AlInAs)1.8 nm superlattice are described by a nonequilibrium thermal distribution characterized by temperatures Te>200 K, much higher than the lattice temperature TL = 15 K. © 2000 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.66.Fd III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.60.Fi Electroluminescence

2.12 μm InGaAs–InGaAlAs–InP diode lasers grown in solid-source molecular-beam epitaxy

G. K. Kuang, G. Böhm, M. Grau, G. Rösel, R. Meyer, and M.-C. Amann

Appl. Phys. Lett. 77, 1091 (2000); http://dx.doi.org/10.1063/1.1289799 (2 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have fabricated InGaAs–InGaAlAs–InP strained quantum well lasers with wavelength as long as 2.12 μm in solid-source molecular-beam epitaxy. A continuous-wave threshold current density of 780 A/cm2 at room temperature and a characteristic temperature of 48 K have been achieved. © 2000 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
81.05.Ea III-V semiconductors
42.60.By Design of specific laser systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
42.86.+b Optical workshop techniques
42.60.Pk Continuous operation

Improved band alignment for hole injection by an interfacial layer in organic light emitting devices

L. Chkoda, C. Heske, M. Sokolowski, and E. Umbach

Appl. Phys. Lett. 77, 1093 (2000); http://dx.doi.org/10.1063/1.1289804 (3 pages) | Cited 23 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate that a thin organic interfacial layer of 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) can be utilized to improve the band alignment of N,N′-di-(3-methylphenyl)N,N′diphenyl-4,4′diaminobiphenyl (TPD) films on [indium–tin–oxide (ITO)] (InSnO) substrates in, e.g., organic electroluminescent devices. A photoemission study of the highest occupied molecular orbital (HOMO) and vacuum level position as a function of the organic overlayer thickness reveals that due to chemisorptive bonding a thin PTCDA interlayer results in a reduced barrier between the Fermi level of ITO and the HOMO of TPD. Furthermore we detect a new molecular state 0.6 eV below the Fermi level at the PTCDA/ITO interface. Both effects are expected to improve the hole injection from the ITO anode into the TPD hole transport layer, e.g., in organic light emitting devices. © 2000 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices
73.20.At Surface states, band structure, electron density of states
79.60.Fr Polymers; organic compounds
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
back to top
RSS Feeds

Negative ion formation in the scattering of CF3+ from graphite

M. A. Gleeson, M. Kropholler, and A. W. Kleyn

Appl. Phys. Lett. 77, 1096 (2000); http://dx.doi.org/10.1063/1.1289808 (3 pages) | Cited 2 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The scattering of CF3+ from highly oriented pyrolytic graphite results in the formation of CF3−. Comparison is made with CF3+ scattering from a metal and from an insulator surface, which do not yield negative molecular ions. The outcome of the charge transfer processes that occur as CF3+ approaches a surface is critically dependent on the electronic properties of that surface. The ability to produce a stable negative ion close to a surface may be an important factor in the etching efficiency of the CF3 molecule. © 2000 American Institute of Physics.
Show PACS
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
34.35.+a Interactions of atoms and molecules with surfaces
81.65.Cf Surface cleaning, etching, patterning
34.70.+e Charge transfer
73.20.At Surface states, band structure, electron density of states
back to top
RSS Feeds

Transmittance and resistivity of semicontinuous copper films prepared by pulsed-laser deposition

S. K. So, H. H. Fong, C. F. Yeung, and N. H. Cheung

Appl. Phys. Lett. 77, 1099 (2000); http://dx.doi.org/10.1063/1.1289259 (3 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thin copper films were grown on glass by pulsed-laser deposition. The simultaneous in situ monitoring of the electrical resistance and optical transmittance of the growing film yielded highly reproducible and consistent data about percolation onset and film conductivity, both being useful indicators of film quality. When prepared under favorable conditions, films as thin as 1.5 nm would percolate, and became fully continuous at 5 nm, with conductivity reaching 30% of that of bulk copper. © 2000 American Institute of Physics.
Show PACS
78.66.Bz Metals and metallic alloys
73.61.At Metal and metallic alloys
68.55.-a Thin film structure and morphology
81.15.Fg Pulsed laser ablation deposition
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys

Nanoquasicrystallization of binary Zr–Pd metallic glasses

B. S. Murty, D. H. Ping, and K. Hono

Appl. Phys. Lett. 77, 1102 (2000); http://dx.doi.org/10.1063/1.1289271 (3 pages) | Cited 52 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The formation of an icosahedral phase during crystallization of Zr–Pd binary amorphous alloys is reported. The icosahedral phase forms in the nanocrystalline state with a grain size of about 10 nm as a metastable transient phase during the transformation from an amorphous to a crystalline state in Zr70Pd30 and Zr65Pd35 alloys. The amorphous phase coexists with the nanoquasicrystalline phase before complete crystallization to Zr2Pd occurs. © 2000 American Institute of Physics.
Show PACS
61.43.Fs Glasses
61.44.Br Quasicrystals
64.70.K- Solid-solid transitions
81.30.Bx Phase diagrams of metals, alloys, and oxides

Reduction of threading defects in GaN grown on vicinal SiC(0001) by molecular-beam epitaxy

M. H. Xie, L. X. Zheng, S. H. Cheung, Y. F. Ng, Huasheng Wu, S. Y. Tong, and N. Ohtani

Appl. Phys. Lett. 77, 1105 (2000); http://dx.doi.org/10.1063/1.1289266 (3 pages) | Cited 27 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We observe a significant reduction of threading dislocations in GaN grown on vicinal substrates of SiC(0001). Using scanning tunneling microscopy, we find films grown on vicinal substrates maintain the surface misorientation of the substrate and display terraces with straight edges. On top of the terraces there is no spiral mound, which is the main feature found for films grown on singular substrates. Transmission electron microscopy studies confirm that threading screw dislocations are reduced by two orders of magnitude while edge dislocations are reduced by one order. © 2000 American Institute of Physics.
Show PACS
81.05.Ea III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.35.B- Structure of clean surfaces (and surface reconstruction)

Dispersive rotation of dipoles in amorphous media

D. J. Binks and D. P. West

Appl. Phys. Lett. 77, 1108 (2000); http://dx.doi.org/10.1063/1.1289258 (3 pages) | Cited 9 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The dispersive rotation of dipoles under the influence of an applied electric field is described simply and accurately using a time-dependent diffusion coefficient. There is excellent agreement between theory and measurement. This analysis shows that the dispersive rotational dynamic is described well by a power law in time and hence has no characteristic lifetime, unlike the conventional biexponential description. This has important implications for the characterization of the transient response of any electro-optic process or device based on the rotation of dipoles in an amorphous material such as a polymer or glass. © 2000 American Institute of Physics.
Show PACS
61.43.-j Disordered solids

Temperature dependence of the electron–hole-plasma electroluminescence from metal–oxide–silicon tunneling diodes

C. W. Liu, Miin-Jang Chen, I. C. Lin, M. H. Lee, and Ching-Fuh Lin

Appl. Phys. Lett. 77, 1111 (2000); http://dx.doi.org/10.1063/1.1289491 (3 pages) | Cited 21 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The temperature performance of metal–oxide–silicon tunneling light-emitting diodes was studied. An electron–hole-plasma model can be used to fit all the emission spectra from room temperature to 98 K. At constant voltage bias in the accumulation region, the normalized integral emission intensity slightly increases at low temperature with activation energy as low as 12 meV. From room temperature down to 98 K, the extracted band gaps are ∼80 meV lower than the value of Varshni equation, and the linewidth drops from 65 to 30 meV. The transverse optical and longitudinal optical phonons are involved in the light-emission process due to the reduction of extracted band gaps and the resemblance between electroluminescence and photoluminescence spectra at similar temperature. © 2000 American Institute of Physics.
Show PACS
78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices
78.66.Db Elemental semiconductors and insulators
81.05.Cy Elemental semiconductors
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
85.30.Tv Field effect devices
72.30.+q High-frequency effects; plasma effects
73.50.Mx High-frequency effects; plasma effects

Newtonian viscosity of supercooled liquid in a Pd40Ni40P20 metallic glass

Yoshihito Kawamura and Akihisa Inoue

Appl. Phys. Lett. 77, 1114 (2000); http://dx.doi.org/10.1063/1.1289502 (3 pages) | Cited 41 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The Newtonian viscosity of the supercooled liquid measured by the continuous-strain-rate tensile test was investigated in the Pd40Ni40P20 metallic glass. It was found that continuous-strain-rate tests were applicable to determine the viscosity over a wide strain-rate region, and that the measured Newtonian viscosity η0 corresponded to the equilibrium one. The viscosity η over the entire strain-rate interval could be well described by one master curve expressed with a stretched exponential function η/η0 = 1−exp(C/mathβ) in which β was 0.82. The free-volume-theory relation proposed by Cohen and Grest reproduced the equilibrium viscosity data over the entire temperature region better than the famous Vogel–Fulcher–Tammann relation. The supercooled liquid of the Pd40Ni40P20 metallic glass was classified into the relatively strong liquids as well as the other metallic glasses. The Pd40Ni40P20 metallic glass that is a metal-metalloid alloy exhibited to be more fragile than metal–metal glasses. © 2000 American Institute of Physics.
Show PACS
66.20.-d Viscosity of liquids; diffusive momentum transport
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
61.25.Mv Liquid metals and alloys

Band gap engineering in amorphous AlxGa1−xN: Experiment and ab initio calculations

Hong Chen, Kuiying Chen, D. A. Drabold, and M. E. Kordesch

Appl. Phys. Lett. 77, 1117 (2000); http://dx.doi.org/10.1063/1.1289496 (3 pages) | Cited 25 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Amorphous alloys of aluminum nitride and gallium nitride deposited at 100 K at compositions ranging from pure AlN to pure GaN with optical band gaps which vary linearly with composition from 3.27 eV (a-GaN) to 5.95 eV (a-AlN) have been synthesized. Ab initio molecular dynamics calculations for these alloys reproduce the band gap versus composition data and give specific information on the electronic localization of the band tail states. There are no midgap states in amorphous AlxGa1−xN alloys. The calculated models have mixed four-fold and three-fold coordination and have no wrong (homopolar nuclear) bonds, demonstrating the strong ionicity in amorphous AlxGa1−xN alloys. It has been found that the valence band tail states are mostly localized on the three-fold coordinated N sites while the conduction band tail states are mostly localized on the three-fold coordinated Ga or Al sites. © 2000 American Institute of Physics.
Show PACS
71.23.Cq Amorphous semiconductors, metallic glasses, glasses
78.66.Jg Amorphous semiconductors; glasses
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.15.Pd Molecular dynamics calculations (Car-Parrinello) and other numerical simulations
71.55.Jv Disordered structures; amorphous and glassy solids
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
78.66.Fd III-V semiconductors

Ultrafast polarized fluorescence dynamics in an organic dendrimer

O. Varnavski, G. Menkir, T. Goodson, and P. L. Burn

Appl. Phys. Lett. 77, 1120 (2000); http://dx.doi.org/10.1063/1.1289495 (3 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
The excited state relaxation processes of a nitrogen-cored distyrylbenzene-stilbene (A-DSB) dendrimers and the analogous linear model compound (bis-MSB) were investigated by polarized fluorescence upconversion spectroscopy. The fluorescence anisotropy (FA) of A-DSB was found to decay to a value close to zero in less than 200 fs after excitation. For the model compound bis-MSB the FA initial value was close to 0.4 and showed a relatively slow decay (82 ps) corresponding to the overall rotational diffusion of the molecule. The results are interpreted in terms of fast transition dipole reorientation during relaxation of the excited states of the branched molecules. © 2000 American Institute of Physics.
Show PACS
36.20.Kd Electronic structure and spectra
33.15.Hp Barrier heights (internal rotation, inversion, rotational isomerism, conformational dynamics)
33.50.Dq Fluorescence and phosphorescence spectra
31.50.Df Potential energy surfaces for excited electronic states
36.20.Ey Conformation (statistics and dynamics)

Codoping characteristics of Zn with Mg in GaN

K. S. Kim, M. S. Han, G. M. Yang, C. J. Youn, H. J. Lee, H. K. Cho, and J. Y. Lee

Appl. Phys. Lett. 77, 1123 (2000); http://dx.doi.org/10.1063/1.1289494 (3 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The doping characteristics of Mg–Zn codoped GaN films grown by metalorganic chemical vapor deposition are investigated. By means of the concept of Mg–Zn codoping technique, we have grown p-GaN showing a low electrical resistivity (0.72 Ω cm) and a high hole concentration (8.5×1017 cm−3) without structural degradation of the film. It is thought that the codoping of Zn atoms with Mg raises the Mg activation ratio by reducing the hydrogen solubility in p-GaN. In addition, the measured specific contact resistance of Mg–Zn codoped GaN film is 5.0×10−4 Ω cm2, which is one order of magnitude lower than that of Mg doped only GaN film (1.9×10−3 Ω cm2). © 2000 American Institute of Physics.
Show PACS
81.05.Ea III-V semiconductors
61.72.uj III-V and II-VI semiconductors
73.40.Cg Contact resistance, contact potential
73.61.Ey III-V semiconductors

In situ transmission electron microscopy study of dislocations in a polycrystalline Cu thin film constrained by a substrate

Gerhard Dehm and Eduard Arzt

Appl. Phys. Lett. 77, 1126 (2000); http://dx.doi.org/10.1063/1.1289488 (3 pages) | Cited 32 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dislocation plasticity in a thin Cu film on a SiNx/SiOx coated silicon wafer was observed by transmission electron microscopy (TEM) during thermal cycling of a cross-sectional specimen. While the in situ TEM study revealed jerky dislocation motion at low homologous temperatures, continuous dislocation glide occurred at elevated temperatures. Furthermore, dislocations were pulled into the Cu/SiNx interface, where dislocation contrast disappeared. It is assumed from these preliminary observations that the limited mobility of dislocations at low homologous temperatures rather than interfacial dislocation segments may be responsible for the high yield stress of the Cu film. © 2000 American Institute of Physics.
Show PACS
68.60.Bs Mechanical and acoustical properties
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep

Dielectric function of V2O5 nanocrystalline films by spectroscopic ellipsometry: Characterization of microstructure

Maria Losurdo, Giovanni Bruno, Davide Barreca, and Eugenio Tondello

Appl. Phys. Lett. 77, 1129 (2000); http://dx.doi.org/10.1063/1.1289658 (3 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spectroscopic ellipsometry over the photon energy 1.5–5.0 eV is used to derive the dielectric function of V2O5 nanocrystalline films deposited by plasma-enhanced chemical vapor deposition. The dispersion in the optical response is described by a combination of Lorentzian oscillators. The results are obtained from a microstructure-dependent model, which considers the anisotropy of the V2O5 crystallites into the bulk film, as well as the presence of interface and surface roughness layers. The variation of the V2O5 thin-film dielectric function upon film crystallinity, going from pure nanocrystalline to amorphous material, is also investigated. © 2000 American Institute of Physics.
Show PACS
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.Jg Amorphous semiconductors; glasses
68.55.-a Thin film structure and morphology
61.46.-w Structure of nanoscale materials
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
07.60.Fs Polarimeters and ellipsometers
78.40.Fy Semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)

Sintering, structure, and mechanical properties of nanophase SiC: A molecular-dynamics and neutron scattering study

Alok Chatterjee, Rajiv K. Kalia, Aiichiro Nakano, Andrey Omeltchenko, Kenji Tsuruta, Priya Vashishta, Chun-Keung Loong, Markus Winterer, and Sylke Klein

Appl. Phys. Lett. 77, 1132 (2000); http://dx.doi.org/10.1063/1.1289661 (3 pages) | Cited 16 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Structure, mechanical properties, and sintering of nanostructured SiC (n-SiC) are investigated with neutron scattering and molecular-dynamics (MD) techniques. Both MD and the experiment indicate the onset of sintering around 1500 K. During sintering, the pores shrink while maintaining their morphology: the fractal dimension is ∼2 and the surface roughness exponent is ∼0.45. Structural analyses reveal that interfacial regions in n-SiC are disordered with nearly the same number of three- and fourfold coordinated Si atoms. The elastic moduli scale with the density as ∼ ρμ, where μ = 3.4±0.1. © 2000 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
61.66.Fn Inorganic compounds
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations
68.35.B- Structure of clean surfaces (and surface reconstruction)
02.70.Ns Molecular dynamics and particle methods
71.15.Pd Molecular dynamics calculations (Car-Parrinello) and other numerical simulations

Huge differences between low- and high-angle twist grain boundaries: The case of ultrathin (001) Si films bonded to (001) Si wafers

J. L. Rouviere, K. Rousseau, F. Fournel, and H. Moriceau

Appl. Phys. Lett. 77, 1135 (2000); http://dx.doi.org/10.1063/1.1289656 (3 pages) | Cited 16 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ultrathin (001) Si films bonded onto (001) Si wafers, inducing grain boundaries with twist angles varying from 0.5° to 12°, were studied by transmission electron microscopy. A great structural difference between low (ψ<5°) and high (ψ>6°) twist angles was observed. In low twist angle grain boundaries, “twist interfacial dislocations” are dissociated and produce rough interfaces with no oxide precipitates. It is the opposite in high-angle grain boundaries: there is no dissociation, the interfaces are smoother but contain oxide precipitates. These differences are not attributed to the thin thickness of one grain, but to the large atomic differences between high- and low-angle twist grain boundaries, which is not the case for tilt grain boundaries. © 2000 American Institute of Physics.
Show PACS
61.72.Mm Grain and twin boundaries
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
64.75.-g Phase equilibria
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Optical evidence of intrinsic quantum wells in the transparent conducting oxide β-Ga2O3

Laurent Binet and Didier Gourier

Appl. Phys. Lett. 77, 1138 (2000); http://dx.doi.org/10.1063/1.1289655 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A peculiar peak structure is observed in the optical absorption edge of β-Ga2O3 at low temperature. These peaks appear in an energy range corresponding to the excitation of the acceptor defects. It is suggested that some of these acceptors be assembled in low dimensional clusters with size about 30–40 Å and forming potential wells with depth about 0.5 eV. The extra peaks are interpreted as transitions between the discrete energy levels of these potential wells and the conduction band. © 2000 American Institute of Physics.
Show PACS
78.66.Li Other semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.40.Fy Semiconductors

Polyparaphenylene-based low-temperature carbons studied by transmission electron microscopy

T. Hayashi, M. Endo, and M. S. Dresselhaus

Appl. Phys. Lett. 77, 1141 (2000); http://dx.doi.org/10.1063/1.1289653 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A comparison of the microtexture and structure of the low temperature heat-treated polyparaphenylene (PPP)-based carbons which are promising for the Li ion battery has been performed using high-resolution transmission electron microscopy and electron energy loss spectroscopy. It is found that the PPP-based carbon prepared by Kovacic method remains in suitable microtexture for high Li storage over a wider temperature range relative to that obtained by Yamamoto method. This characteristic of the Kovacic PPP-based carbon could lead to a more controlled microtexture for obtaining a higher Li storage capacity for Li ion battery applications. © 2000 American Institute of Physics.
Show PACS
81.05.ub Fullerenes and related materials
61.66.Bi Elemental solids
81.40.Gh Other heat and thermomechanical treatments
82.47.-a Applied electrochemistry
61.43.Er Other amorphous solids
79.20.Kz Other electron-impact emission phenomena
Page 1 of 3 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close