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

31 May 1999

Volume 74, Issue 22, pp. 3245-3412

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

Observation of neodymium electroluminescence

Yuichiro Kawamura, Yuji Wada, Yasuchika Hasegawa, Mitsunori Iwamuro, Takayuki Kitamura, and Shozo Yanagida

Appl. Phys. Lett. 74, 3245 (1999); http://dx.doi.org/10.1063/1.123357 (3 pages) | Cited 41 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Organic electroluminescence devices using a neodymium(III) complex as an emitting layer were fabricated. The cell structure of glass substrate/indium–tin–oxide/N,N′-diphenyl-N,N′-di(m-tolyl)-benzidine/tris(dibenzoylmethanato)(monobathophenanthroline)neodymium(III) complex/tris(8-quinolinolato)aluminum(III)complex/Mg:Ag was employed. Sharp near-infrared emission bands assigned to f–f transitions of neodymium ion were obtained at dc bias voltage of over 15 V. © 1999 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices

Nonlinear thin-layer theory for stratified Kerr medium

T. A. Laine and A. T. Friberg

Appl. Phys. Lett. 74, 3248 (1999); http://dx.doi.org/10.1063/1.123309 (3 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Exact theory of field propagation in stratified Kerr media is developed. Making use of thin-layer approximation applied to plane waves, we solve the nonlinear Maxwell–Kerr equation within a thin slab. From this we construct the characteristic matrix of the Kerr medium and derive the amplitude-dependent wave vectors. The advantages of the method are that the equations are rigorous, simple to implement, and analogous with the linear theory. We also present a thick-layer approximation and solve a layered example numerically. Both polarizations, transverse electric (TE) and transverse magnetic (TM), are considered separately. © 1999 American Institute of Physics.
Show PACS
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.25.Bs Wave propagation, transmission and absorption
42.25.Ja Polarization

Epitaxially-stacked multiple-active-region 1.55μm lasers for increased differential efficiency

J. K. Kim, E. Hall, O. Sjölund, and L. A. Coldren

Appl. Phys. Lett. 74, 3251 (1999); http://dx.doi.org/10.1063/1.123310 (3 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Semiconductor lasers emitting at 1.55 μm with external differential efficiencies >1 have been created by monolithically connecting several active regions in series within a single optical waveguide. This is accomplished by epitaxially stacking a number of p–i–n multiquantum well active regions with intermediate n++–p++ back diodes, which enable the entire terminal current to flow through each active region stages in series. Such lasers should also improve the impedance match as well as provide for low-noise, high-efficiency microwave links. © 1999 American Institute of Physics.
Show PACS
42.60.By Design of specific laser systems
42.55.Px Semiconductor lasers; laser diodes
42.82.Bq Design and performance testing of integrated-optical systems
42.79.Sz Optical communication systems, multiplexers, and demultiplexers

Third-order susceptibilities of asymmetric pentaazadentate porphyrin-like metal complexes

Wenfang Sun, Clare C. Byeon, Chris M. Lawson, Gary M. Gray, and Duoyuan Wang

Appl. Phys. Lett. 74, 3254 (1999); http://dx.doi.org/10.1063/1.123311 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The third-order nonlinear optical properties of a series of asymmetric pentaazadentate porphyrin-like metal complexes ([(R–APPC)M]Cln) with different conjugated R groups and metal centers have been investigated by degenerate four wave mixing experiments using 40 ps laser pulses at 532 nm. The molecular second-order hyperpolarizabilities (γ) for these complexes range from 1.1×10−31 to 1.2×10−30 esu and depend strongly on both the nature of the metal and the R group. The γ values of the [(R–APPC)Cd]Cl complexes are 2–7 times larger than those of PbPc(CP)4 and SiNc, two of the most promising nonlinear optical materials for optical limiting applications. Measurements of the individual components of the χ(3) tensor indicate that the nonlinearity is predominantly electronic in origin when 40 ps laser pulses are used. © 1999 American Institute of Physics.
Show PACS
42.65.An Optical susceptibility, hyperpolarizability
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
33.15.Kr Electric and magnetic moments (and derivatives), polarizability, and magnetic susceptibility
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Distributed feedback ridge waveguide lasers fabricated by nanoscale printing and molding on nonplanar substrates

John A. Rogers, Martin Meier, Ananth Dodabalapur, Edward J. Laskowski, and Mark A. Cappuzzo

Appl. Phys. Lett. 74, 3257 (1999); http://dx.doi.org/10.1063/1.123312 (3 pages) | Cited 38 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter describes the use of printing and molding techniques to fabricate plastic photopumped laser that use distributed feedback resonators on ridge waveguides. The results indicate (i) potential optoelectronic applications of a set of emerging low cost lithographic techniques that can pattern a range of materials with submicron resolution on nonplanar substrates, (ii) a new type of plastic laser based on molded organic gain materials, and (iii) that thresholds of plastic distributed feedback ridge waveguide lasers are similar to their planar counterparts. © 1999 American Institute of Physics.
Show PACS
42.55.Rz Doped-insulator lasers and other solid state lasers
42.82.Cr Fabrication techniques; lithography, pattern transfer

Disordered dielectric high reflectors with broadband from visible to infrared

Hongqiang Li, Guochang Gu, Hong Chen, and Shiyao Zhu

Appl. Phys. Lett. 74, 3260 (1999); http://dx.doi.org/10.1063/1.123313 (3 pages) | Cited 14 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
With proper structure, one-dimensional (1D) binary nonperiodic dielectric multilayers can own compact strucuture and provide widely extended stop band from visible to infrared which is insensitive to the angle of incidence. The striking phenomenon attributes to the combining effect of Bragg reflection and light localization induced by disorder. The characteristic parameters to describe 1D binary nonperiodic dielectric multilayers are well defined. Material parameters of MgF2 and GaP are used to model 1D realistic device. Optimal design is suggested by comparison to binary λ0/4 stack reflectors with the same optical length, number of layers and degree of disorder. © 1999 American Institute of Physics.
Show PACS
42.79.Wc Optical coatings
42.70.Qs Photonic bandgap materials

Laser-machined layer-by-layer metallic photonic band-gap structures

N. Katsarakis, E. Chatzitheodoridis, G. Kiriakidis, M. M. Sigalas, C. M. Soukoulis, W. Y. Leung, and G. Tuttle

Appl. Phys. Lett. 74, 3263 (1999); http://dx.doi.org/10.1063/1.123314 (3 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Metallic photonic band-gap crystals operating in the microwave frequency range were fabricated by laser precision machining. They consist of stainless steel plates with a tetragonal lattice of holes and a lattice constant of 15 mm. Transmission measurements show that periodic crystals exhibit a cutoff frequency in the 8–18 GHz range, below which no propagation is allowed. The cutoff frequency can be easily tuned by varying the interlayer distance or the filling fraction of the metal. Combinations of plates with different hole diameters create defect modes with relatively sharp peaks, which are tunable. The experimental measurements are in good agreement with theoretical calculations. © 1999 American Institute of Physics.
Show PACS
42.70.Qs Photonic bandgap materials
42.62.-b Laser applications

Polarization self-modulated lasers with circular eigenstates

M. Vallet, M. Brunel, F. Bretenaker, M. Alouini, A. Le Floch, and G. P. Agrawal

Appl. Phys. Lett. 74, 3266 (1999); http://dx.doi.org/10.1063/1.123315 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A polarization self-modulated laser made of a semiconductor laser with an external cavity containing a Faraday rotator is investigated theoretically and experimentally. It is shown that the Faraday rotator yields circularly polarized eigenstates for the laser. Stable optical pulses at a frequency equal to one half of the free spectral range are observed through a polarizer, independently of the Faraday rotator orientation. The pulses are generated through beating between the phase-locked lasing modes associated with the two circular eigenstates of the laser. © 1999 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.25.Ja Polarization
78.20.Ls Magneto-optical effects
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Organic electroluminescent devices by high-temperature processing and crystalline hole transporting layer

Z. Q. Gao, W. Y. Lai, T. C. Wong, C. S. Lee, I. Bello, and S. T. Lee

Appl. Phys. Lett. 74, 3269 (1999); http://dx.doi.org/10.1063/1.123316 (3 pages) | Cited 32 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Crystallization and interdiffusion of organic layers have been widely considered to be important causes for performance degradation of organic electroluminescent devices. By using high substrate temperature during vapor deposition, we have fabricated organic electroluminescent devices with crystalline organic layers. Contrary to the common belief, substantial increases in luminescent efficiency and brightness have been observed in the device thus fabricated. Such devices also showed much improved storage stability against high humidity compared to the conventional ones with amorphous organic layers. © 1999 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
68.55.-a Thin film structure and morphology
85.60.Pg Display systems
back to top
RSS Feeds

Application of plasma columns to radiofrequency antennas

Gerard G. Borg, Jeffrey H. Harris, David G. Miljak, and Noel M. Martin

Appl. Phys. Lett. 74, 3272 (1999); http://dx.doi.org/10.1063/1.123317 (3 pages) | Cited 26 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Plasma offers a promising alternative to metal for a wide variety of radiofrequency antenna applications. In this letter we report measurements of efficiencies up to 50% and radiation patterns for plasma column antenna elements. It is demonstrated that the current distribution along the antenna can be controlled by the plasma density. Plasma columns can be used instead of metal elements in communications antennas. © 1999 American Institute of Physics.
Show PACS
52.40.Fd Plasma interactions with antennas; plasma-filled waveguides
84.40.Ba Antennas: theory, components and accessories
52.35.Hr Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid)
back to top
RSS Feeds

Monte Carlo simulation of reentrant reflection high-energy electron diffraction intensity oscillation observed during low-temperature GaAs growth

Haruyuki Yasuda and Hideo Ohno

Appl. Phys. Lett. 74, 3275 (1999); http://dx.doi.org/10.1063/1.123318 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Reentrant behavior of intensity oscillation of reflection high-energy electron diffraction (RHEED) observed during low-temperature GaAs homoepitaxy on GaAs (001) substrates is studied by a Monte Carlo simulation using cubic solid-on-solid configuration. By assuming that an excess As overlayer acts as surfactant which enhances the migration of Ga adatoms at low temperature, temperature as well as V/III ratio dependence of step density oscillation (i.e., RHEED intensity oscillation) is successfully reproduced. © 1999 American Institute of Physics.
Show PACS
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
81.05.Ea III-V semiconductors
68.55.-a Thin film structure and morphology
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Fx Diffusion; interface formation
68.08.-p Liquid-solid interfaces
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Light emission properties of crystalline SiO2 coated with LiNbO3/LiTaO3 multilayers

X. L. Wu and G. G. Siu

Appl. Phys. Lett. 74, 3278 (1999); http://dx.doi.org/10.1063/1.123319 (3 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Photoluminescence (PL) properties of the crystalline SiO2 coated with LiNbO3/LiTaO3 multilayers were studied using the 514.5 nm line excitation. The 2.25 eV PL band observed at room temperature can be Gaussian divided into two subbands at 2.19 and 2.30 eV, which can be clearly resolved in the 77 K PL spectrum. The 2.30 eV band is z polarized with a polarization degree of 0.25 and its intensity has a linear dependence on the excitation power. No similar behavior was observed for the 2.19 eV band. Spectral analysis indicates that the two PL bands arise from optical transitions of the self-trapped excitons and E′ defect pairs in the crystalline SiO2 surface, which are induced by the photorefractive effect of the coated multilayers. © 1999 American Institute of Physics.
Show PACS
78.55.Hx Other solid inorganic materials
78.66.Nk Insulators
42.79.Wc Optical coatings
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.35.Aa Frenkel excitons and self-trapped excitons
73.20.Hb Impurity and defect levels; energy states of adsorbed species
71.55.Ht Other nonmetals

Local vibrational modes in Mg-doped GaN grown by molecular beam epitaxy

A. Kaschner, H. Siegle, G. Kaczmarczyk, M. Straßburg, A. Hoffmann, C. Thomsen, U. Birkle, S. Einfeldt, and D. Hommel

Appl. Phys. Lett. 74, 3281 (1999); http://dx.doi.org/10.1063/1.123320 (3 pages) | Cited 45 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Local vibrational modes in the region of the acoustic and optical phonons are reported for Mg-doped GaN grown by molecular beam epitaxy. The modes, studied by Raman spectroscopy, appear in addition to the known modes in the high-energy region around 2200 cm−1. We suggest disorder-activated scattering and scattering from Mg-related lattice vibrations to be the origin of the low-energy modes. Our assignment is supported by calculations based on a modified valence-force model of Kane. Temperature-dependent measurements between 4 and 300 K exclude an electronic Raman-scattering mechanism. We also report a new line at 2129 cm−1 and discuss the origin of all five observed high-energy modes. © 1999 American Institute of Physics.
Show PACS
63.20.Pw Localized modes
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
61.72.S- Impurities in crystals
68.60.Wm Other nonelectronic physical properties

Reflection high-energy electron diffraction intensity oscillation during layer-by-layer oxidation of Si(001) surfaces

Heiji Watanabe, Toshio Baba, and Masakazu Ichikawa

Appl. Phys. Lett. 74, 3284 (1999); http://dx.doi.org/10.1063/1.123308 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied initial layer-by-layer oxidation of Si(001)-2×1 surfaces by using reflection high-energy electron diffraction (RHEED). We observed an intensity oscillation and a change in the streaky profile of a specular reflection spot in RHEED patterns during initial oxidation. These results indicate that layer-by-layer oxidation of Si surfaces is promoted by nucleation and lateral growth of two-dimensional oxide islands. We have also confirmed that a 1-monolayer-thick oxide has an ordered structure originating from the initial 2×1 reconstruction. © 1999 American Institute of Physics.
Show PACS
81.05.Cy Elemental semiconductors
81.65.Mq Oxidation

Quantitative characterization of GaN quantum-dot structures in AlN by high-resolution transmission electron microscopy

M. Arlery, J. L. Rouvière, F. Widmann, B. Daudin, G. Feuillet, and H. Mariette

Appl. Phys. Lett. 74, 3287 (1999); http://dx.doi.org/10.1063/1.123321 (3 pages) | Cited 55 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
GaN/AlN heterostructures grown by molecular beam epitaxy are studied by high-resolution transmission electron microscopy (HRTEM). The two-dimensional/three-dimensional Stranski–Krastanow growth mode transition of GaN allows the formation of GaN quantum-dot structures embedded in AlN. The nature of the wetting layer associated with these dots is determined by quantitative HRTEM analysis, based on comparison between interplanar distortion profiles of experimental and simulated images. This study demonstrates a low intermixing between GaN and AlN materials. Such result is also evidenced for the GaN dots. © 1999 American Institute of Physics.
Show PACS
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Interpretation of x-ray photoelectron spectra of elastic amorphous carbon nitride thin films

B. C. Holloway, O. Kraft, D. K. Shuh, M. A. Kelly, W. D. Nix, P. Pianetta, and S. Hagström

Appl. Phys. Lett. 74, 3290 (1999); http://dx.doi.org/10.1063/1.123362 (3 pages) | Cited 25 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the synthesis and characterization of amorphous carbon nitride (CNx) thin films using a direct current magnetron reactive sputter system. Nanoindentation of the CNx films and amorphous carbon films deposited under similar conditions shows the CNx films are extremely elastic, that the addition of nitrogen fundamentally changes the mechanical properties of the films, and that traditional methods of calculating the hardness and Young’s modulus may not be valid. X-ray photoelectron spectroscopy (XPS) of the N(1s) and C(1s) core levels show multiple bonding arrangements. In a new interpretation of the XPS data, the two predominant N(1s) spectral features have been identified, based on comparison to reference data in the literature, as those belonging to nitrogen in a four-bond arrangement and nitrogen in a three-bond arrangement, independent of hybridization. The formation of a fourth bond allows nitrogen to substitute for C atoms in a carbon-based graphitic system without the formation of dangling bonds or unfilled states. The relationship between nitrogen incorporation in a carbon-based ring structure and measured film properties is rationalized based on previously published models. © 1999 American Institute of Physics.
Show PACS
81.15.Cd Deposition by sputtering
61.43.Er Other amorphous solids
79.60.Bm Clean metal, semiconductor, and insulator surfaces
68.60.Bs Mechanical and acoustical properties
62.20.Qp Friction, tribology, and hardness
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations
71.55.Ht Other nonmetals
68.55.-a Thin film structure and morphology

Effects of a low-energy ion beam on the growth of titanium nitride layers near the interface of a polyimide

Peter Abramowitz, Michael Kiene, and Paul S. Ho

Appl. Phys. Lett. 74, 3293 (1999); http://dx.doi.org/10.1063/1.123322 (3 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter two different growth methods, reactive evaporation and ion-assisted reactive evaporation, were used to grow titanium nitride films on the polyimide biphenyl tetracarboxylic acid dianhydride-para phenylene diamine. The films were examined with x-ray photoemission spectroscopy and it was found that the chemical properties of the film depend on the distance from the polyimide/titanium nitride interface. While both techniques produced very similar films at distances greater than 5 nm from the interface, only the ion-assisted grown film had a significant amount of nitride near the interface. This is due to the ability of low-energy (100 eV) nitrogen ions to break the initial titanium/polyimide bonds which would otherwise prevent the growth of titanium nitride at the interface. © 1999 American Institute of Physics.
Show PACS
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
85.40.Ls Metallization, contacts, interconnects; device isolation
81.15.Jj Ion and electron beam-assisted deposition; ion plating
85.40.Sz Deposition technology
68.35.Ct Interface structure and roughness

Tapping-mode atomic force microscopy and phase-imaging in higher eigenmodes

Robert W. Stark, Tanja Drobek, and Wolfgang M. Heckl

Appl. Phys. Lett. 74, 3296 (1999); http://dx.doi.org/10.1063/1.123323 (3 pages) | Cited 40 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Tapping-mode atomic force microscopy (TM-AFM) is a powerful tool to study soft biological samples. Higher eigenmodes of the vibrating cantilever offer enhanced signal and smaller time constants increasing the sensitivity of the tapping probe as compared to conventional TM-AFM. The first five eigenmodes of a v-shaped silicon cantilever were investigated with respect to their suitability for imaging. Stable imaging was possible in the first and third modes. Phase imaging in the third mode was extremely sensitive to surface inhomogeneities and surface contamination particles not visible in standard TM-AFM. © 1999 American Institute of Physics.
Show PACS
07.79.Lh Atomic force 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
87.64.Dz Scanning tunneling and atomic force microscopy
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Dv Composition, segregation; defects and impurities

Optical properties of doped InGaN/GaN multiquantum-well structures

J. Dalfors, J. P. Bergman, P. O. Holtz, B. E. Sernelius, B. Monemar, H. Amano, and I. Akasaki

Appl. Phys. Lett. 74, 3299 (1999); http://dx.doi.org/10.1063/1.123324 (3 pages) | Cited 29 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A systematic investigation of the photoluminescence spectra from InGaN/GaN multiquantum-well structures with different levels of Si doping in the quantum well has been carried out, in order to study the screening of the strain induced piezoelectric field and potential fluctuations. It is found that the emission energy strongly depends on the carrier concentration, originating from the doping or photogeneration. The observed strong shift with Si doping can only partly be explained by the screening of the piezoelectric field. The main shift is suggested to be related to the screening of the localization potentials. © 1999 American Institute of Physics.
Show PACS
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
77.65.Ly Strain-induced piezoelectric fields

Solvent-induced phase transition in thermally evaporated pentacene films

D. J. Gundlach, T. N. Jackson, D. G. Schlom, and S. F. Nelson

Appl. Phys. Lett. 74, 3302 (1999); http://dx.doi.org/10.1063/1.123325 (3 pages) | Cited 101 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a solvent-induced phase transition in pentacene thin films, from a “thin film” phase to a bulk-like phase. X-ray diffraction indicates that as-deposited thermally evaporated pentacene films consist mainly of (001)-oriented pentacene with an elongated (001) plane spacing of 15.5±0.1 Å, and a minor amount with a (001) plane spacing of 14.5±0.1 Å. When such films are exposed to solvents such as acetone, isopropanol, or ethanol, the plane spacing of the entire layer shifts abruptly from the elongated (001) plane spacing to the bulk value and this shift is accompanied by a macroscopic change in film morphology. While molecular ordering is maintained as indicated by x-ray diffraction, thin film transistor performance is severely degraded, most likely as a result of the morphological changes in the film. © 1999 American Institute of Physics.
Show PACS
64.70.K- Solid-solid transitions
68.55.-a Thin film structure and morphology
85.30.Tv Field effect devices

Irradiation-induced growth of nanoquasicrystals from amorphous matrix in the equilibrium immiscible Fe–Cu system

G. W. Yang, W. S. Lai, C. Lin, and B. X. Liu

Appl. Phys. Lett. 74, 3305 (1999); http://dx.doi.org/10.1063/1.123326 (3 pages) | Cited 26 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A microstructure of nanosized quasicrystals embedded in an amorphous matrix was formed in the Fe70Cu30 multilayered films upon room temperature 200 keV xenon ion irradiation. The initial Fe and Cu crystalline phases in the as-deposited multilayers transformed into a unique amorphous phase at a dose of 8×1014 Xe+ cm−2 and further irradiation, i.e., up to a dose of 5×1015 Xe+ cm−2, induced the growth of the quasicrystals in some local areas in the amorphous matrix. High-resolution electron microscopy examination revealed that the compositions of the quasicrystals and amorphous matrix were close to Fe50Cu50 and Fe70Cu30, respectively. Apparently, the above microstructure was formed through a two-step phase transition along the increase of ion dose and the amorphous-to-quasicrystal transition was discussed in terms of the similarity in the atomic configuration between the icosahedral and amorphous short-range orders. © 1999 American Institute of Physics.
Show PACS
61.44.Br Quasicrystals
61.46.-w Structure of nanoscale materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
61.80.Jh Ion radiation effects
61.72.-y Defects and impurities in crystals; microstructure
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Evidence for relaxed and high-quality growth of GaN on SiC(0001)

F. Boscherini, R. Lantier, A. Rizzi, F. D’Acapito, and S. Mobilio

Appl. Phys. Lett. 74, 3308 (1999); http://dx.doi.org/10.1063/1.123327 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
By using polarization-dependent x-ray absorption spectroscopy at the Ga edge, we study the growth of GaN on SiC(0001) in the thickness range 0.7–150 nm. We find that the growth is always relaxed (i.e., nonpseudomorphic) even for the thinnest epilayers, i.e., below the expected critical thickness. No evidence is found for a mixed Ga/Si interface plane, while a C/N mixed interface plane cannot be ruled out. The results are discussed with reference to the electronic structure of the SiC/GaN heterojunction and in particular to band offsets and strain-induced piezoelectric polarization. © 1999 American Institute of Physics.
Show PACS
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.70.Dm X-ray absorption spectra
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
68.55.-a Thin film structure and morphology
73.20.At Surface states, band structure, electron density of states

High temperature proton implantation induced photosensitivity of Ge-doped SiO2 planar waveguides

P. J. Hughes, A. P. Knights, B. L. Weiss, S. Kuna, P. G. Coleman, and S. Ojha

Appl. Phys. Lett. 74, 3311 (1999); http://dx.doi.org/10.1063/1.123328 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The possibility of using keV proton implantation at 800 °C to enhance the photosensitivity of Ge-doped silica has been investigated. Room temperature implantation induced defects indicated by absorption at ultraviolet (UV) (<200 nm) and visible wavelengths (>550 nm) were annealed during implantation at 800 °C to leave stable photosensitive neutral oxygen vacancy (NOV) centers with an absorption peak at ∼ 240 nm. The stable NOV defects were photochemically bleached after UV exposure, a process which is accompanied by a change in UV absorption. Positron annihilation spectroscopy demonstrated the effectiveness of implantation at 800 °C in annealing the implantation induced damage. © 1999 American Institute of Physics.
Show PACS
42.65.Wi Nonlinear waveguides
42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
61.82.Ms Insulators
61.80.Jh Ion radiation effects
61.72.up Other materials
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
78.70.Bj Positron annihilation
61.72.J- Point defects and defect clusters

Study of wet treatment of polyimide by sum-frequency vibrational spectroscopy

Doseok Kim and Y. R. Shen

Appl. Phys. Lett. 74, 3314 (1999); http://dx.doi.org/10.1063/1.123329 (3 pages) | Cited 21 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A polyimide surface treated with a strong NaOH solution for improvement of adhesion with metals was investigated using ultraviolet absorption and sum-frequency vibrational spectroscopy. Conversion of imide groups to amide groups at the polyimide surface was observed. This conversion and subsequent etching of the polyimide film by the solution seems to be more effective in the amorphous part of the film. Drying of the film converts the surface amides back to imides. © 1999 American Institute of Physics.
Show PACS
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.Cf Surface cleaning, etching, patterning
63.50.-x Vibrational states in disordered systems
78.40.Me Organic compounds and polymers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Deformation of carbon nanotubes in nanotube–polymer composites

C. Bower, R. Rosen, L. Jin, J. Han, and O. Zhou

Appl. Phys. Lett. 74, 3317 (1999); http://dx.doi.org/10.1063/1.123330 (3 pages) | Cited 193 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Composites of uniaxially oriented multiwalled carbon nanotubes embedded in polymer matrices were fabricated and investigated by transmission electron microscopy. In strained composite films, buckling was ubiquitously observed in bent nanotubes with large curvatures. By analyses of a large number of bent nanotubes, the onset buckling strain and fracture strain were estimated to be ≈5% and ⩾18%, respectively. The buckling wavelengths are proportional to the dimensions of the nanotubes. Examination of the fracture surface showed adherence of the polymer to the nanotubes. © 1999 American Institute of Physics.
Show PACS
81.40.Lm Deformation, plasticity, and creep
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
62.20.F- Deformation and plasticity
62.20.M- Structural failure of materials
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
Page 1 of 3 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close