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

19 Apr 1999

Volume 74, Issue 16, pp. 2253-2392

Page 1 of 2 Pages Next Page | Jump to Page
back to top
RSS Feeds

Direct observation of orientation limit in a fast photorefractive polymer composite

J. A. Herlocker, K. B. Ferrio, E. Hendrickx, B. D. Guenther, S. Mery, B. Kippelen, and N. Peyghambarian

Appl. Phys. Lett. 74, 2253 (1999); http://dx.doi.org/10.1063/1.123816 (3 pages) | Cited 51 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on a photorefractive polymer with a 4-ms-response time in transient four-wave mixing experiments at 0.5 W/cm2 writing irradiance, 95 V/μm applied electric field, and a grating period of 3.1 μm. Complementary transient ellipsometry, however, reveals orientational birefringence response which leads the four-wave mixing response all the way to its saturation, despite complex dynamics in these processes. Orientation does not limit the dynamic formation of photorefractive gratings in this polymer, which suggests that even faster photorefractive responses are possible for polymer composites with improved charge generation and transport properties. © 1999 American Institute of Physics.
Show PACS
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.70.Jk Polymers and organics
42.70.Gi Light-sensitive materials
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.79.Dj Gratings
78.20.Fm Birefringence
78.20.Jq Electro-optical effects
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
78.47.-p Spectroscopy of solid state dynamics

Light-emitting diodes with 31% external quantum efficiency by outcoupling of lateral waveguide modes

R. Windisch, P. Heremans, A. Knobloch, P. Kiesel, G. H. Döhler, B. Dutta, and G. Borghs

Appl. Phys. Lett. 74, 2256 (1999); http://dx.doi.org/10.1063/1.123817 (3 pages) | Cited 73 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The external quantum efficiency of light-emitting diodes (LEDs) is usually limited by total internal reflection at the semiconductor–air interface. This problem can be overcome by a combination of light scattering at a textured top surface and reflection on a backside mirror. With this design, we achieve 22% external quantum efficiency. One of the main loss mechanisms in such nonresonant cavity (NRC) light-emitting diodes is coupling into an internal waveguide. Texturing the surface of this waveguide allows the partial extraction of the confined light. In this way, we demonstrate an increase in the external quantum efficiency of NRC-LEDs to 31%. © 1999 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices
42.79.Gn Optical waveguides and couplers

Broad-range, latchable reconfiguration of Bragg wavelength in optical gratings

S. Jin, H. Mavoori, R. P. Espindola, and T. A. Strasser

Appl. Phys. Lett. 74, 2259 (1999); http://dx.doi.org/10.1063/1.123818 (3 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Tunability of optical signal filters such as fiber Bragg gratings is important for high volume data communications. A magnetically tunable and latchable optical fiber Bragg grating structure has been devised, and a fine wavelength control as well as a broad-range wavelength tunability has been demonstrated. A spinodally decomposed, anisotropically elongated microstructure was induced in Fe–Cr–Co alloys to fabricate square-loop, programmable magnets. The adjustable attractive force between the magnetic poles was used to controllably strain the grating and induce a very large shift in the Bragg reflection wavelength by as much as 15 nm (which is equivalent to more than 36-channel span in a high density optical communication system). This novel approach can be useful not only for a variety of optical communication networking applications, but also for imparting latchable reconfiguration of structural periodicity and functional properties in a wide class of materials and devices. © 1999 American Institute of Physics.
Show PACS
42.81.Wg Other fiber-optical devices
42.79.Dj Gratings
42.79.Ci Filters, zone plates, and polarizers
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
84.40.Ua Telecommunications: signal transmission and processing; communication satellites

Blue luminescence from amorphous GaN nanoparticles synthesized in situ in a polymer

Yi Yang, Valerie J. Leppert, Subhash H. Risbud, Brendan Twamley, Phillip P. Power, and Howard W. H. Lee

Appl. Phys. Lett. 74, 2262 (1999); http://dx.doi.org/10.1063/1.123819 (3 pages) | Cited 31 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Amorphous GaN nanoparticles were synthesized by the in situ thermal decomposition of cyclotrigallazane incorporated into a polystyrene–poly(N,N-dimethyl-4-vinylaniline) copolymer. Transmission electron microscopy, energy dispersive x-ray spectrometry, and x-ray photoelectron spectroscopy show that the composite material consists of amorphous GaN nanoparticles (average diameter ∼40 nm) well dispersed in the copolymer. The photoluminescence spectra show blue light emission from the amorphous GaN nanoparticles, peaked at ∼426 nm. © 1999 American Institute of Physics.
Show PACS
78.55.Cr III-V semiconductors
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

High performance organic polymer light-emitting heterostructure devices

Y. He, S. Gong, R. Hattori, and J. Kanicki

Appl. Phys. Lett. 74, 2265 (1999); http://dx.doi.org/10.1063/1.123862 (3 pages) | Cited 61 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a high performance electroluminescence device based on bi-layer conjugated polymer structures consisting of a hole transporting (amine-fluorene) and an emissive (benzothiadiazole-fluorene) polymer layers prepared by the spin-coating technique on the glass substrate. Devices showed green emission with an electroluminescence peak located at around 545 nm and a full width at half maximum of about 80 nm. Our devices have also shown a high brightness ( ∼ 10 000 cd/m2 at 0.84 mA/mm2), good emission efficiency ( ∼ 14.5 cd/A) and luminous efficiency (2.26 lm/W), a large external quantum efficiency (3.8%), and a reasonable forward-to-reverse bias current rectification ratio (>103 at ±25 V). © 1999 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
78.66.Qn Polymers; organic compounds
73.61.Ph Polymers; organic compounds
73.40.Ei Rectification

Sub-5-fs visible pulse generation by pulse-front-matched noncollinear optical parametric amplification

A. Shirakawa, I. Sakane, M. Takasaka, and T. Kobayashi

Appl. Phys. Lett. 74, 2268 (1999); http://dx.doi.org/10.1063/1.123820 (3 pages) | Cited 125 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Sub-5-fs pulses are generated in the visible region. A pulse-front-matched noncollinear optical parametric amplifier is operated with the full bandwidth by precompression of the seeded continuum with a customized ultrabroadband chirped mirror (UBCM) pair. The signal is compressed down to a nearly transform-limited 4.7±0.1 fs duration by a prism pair and another UBCM pair with a 5-μJ pulse energy. © 1999 American Institute of Physics.
Show PACS
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.65.Yj Optical parametric oscillators and amplifiers
42.79.Bh Lenses, prisms and mirrors
42.60.Fc Modulation, tuning, and mode locking

Ultrafast (GaIn)(NAs)/GaAs vertical-cavity surface-emitting laser for the 1.3 μm wavelength regime

C. Ellmers, F. Höhnsdorf, J. Koch, C. Agert, S. Leu, D. Karaiskaj, M. Hofmann, W. Stolz, and W. W. Rühle

Appl. Phys. Lett. 74, 2271 (1999); http://dx.doi.org/10.1063/1.123821 (3 pages) | Cited 42 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
(GaIn)(NAs) vertical-cavity surface-emitting lasers for room-temperature emission at 1.3 μm wavelength are designed and grown by metal-organic vapor-phase epitaxy using dimethylhydrazine and tertiarybutylarsine. Room-temperature operation at wavelengths up to 1.285 μm is achieved with low optical pumping thresholds between 1.6 and 2.0 kW/cm2. Stimulated emission dynamics after femtosecond optical pumping are measured and compare favorably with results on (GaIn)As/Ga(PAs)-based structures. © 1999 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
78.45.+h Stimulated emission
78.66.Fd III-V semiconductors

Polarization modal noise and dichroism in vertical-cavity semiconductor lasers

M. P. van Exter, M. B. Willemsen, and J. P. Woerdman

Appl. Phys. Lett. 74, 2274 (1999); http://dx.doi.org/10.1063/1.123822 (3 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We show quantitatively how the limited polarization stability of vertical-cavity semiconductor lasers is related to the small dichroism and large quantum noise in these lasers. We introduce several techniques to measure this dichroism and noise. Suitable polarization projections are shown to yield either the heterodyne beat or the partition noise of the two polarization modes. © 1999 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Mi Dynamical laser instabilities; noisy laser behavior
42.50.Lc Quantum fluctuations, quantum noise, and quantum jumps
78.20.Fm Birefringence
78.66.Fd III-V semiconductors

Clamping of the linewidth enhancement factor in narrow quantum-well semiconductor lasers

J. Hader, D. Bossert, J. Stohs, W. W. Chow, S. W. Koch, and J. V. Moloney

Appl. Phys. Lett. 74, 2277 (1999); http://dx.doi.org/10.1063/1.123823 (3 pages) | Cited 21 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The linewidth enhancement factor in single quantum-well graded index separate confinement heterostructure semiconductor lasers is investigated theoretically and experimentally. For thin wells, a small linewidth enhancement factor is obtained which clamps with increasing carrier density, in contrast to the monotonous increase observed for thicker wells. Microscopic many-body calculations reproduce the experimental observations attributing the clamping to excitation dependent gain shifts and the influence of the population of off-resonant states on the refractive index. © 1999 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.79.Ry Gradient-index (GRIN) devices
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
back to top
RSS Feeds

Lateral ordering of quantum dots by periodic subsurface stressors

A. E. Romanov, P. M. Petroff, and J. S. Speck

Appl. Phys. Lett. 74, 2280 (1999); http://dx.doi.org/10.1063/1.123824 (3 pages) | Cited 54 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the possibility of using subsurface dislocation arrays as a tool for controlling the nucleation of self-assembled quantum dots (SAQDs). A quantitative model predicts that periodic nonuniform elastic fields on the surface induced by dislocations may control the lateral ordering SAQDs. The effect of dislocations is shown to be comparable to the interaction between buried and surface dots which leads to vertical dot stacking. The periodic subsurface dislocation arrays necessary for dot ordering can be produced by twist wafer bonding and backside substrate removal. © 1999 American Institute of Physics.
Show PACS
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
64.60.Q- Nucleation
81.15.Aa Theory and models of film growth
61.72.Bb Theories and models of crystal defects
61.72.Lk Linear defects: dislocations, disclinations
68.35.Gy Mechanical properties; surface strains

Fermi-level-dependent defect formation in Cu-chalcopyrite semiconductors

A. Klein and W. Jaegermann

Appl. Phys. Lett. 74, 2283 (1999); http://dx.doi.org/10.1063/1.123825 (3 pages) | Cited 39 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Valence-band photoelectron spectroscopy of CuInSe2, CuInS2, and CuGaSe2 surfaces and interfaces give evidence for the formation of Cu vacancies when the Fermi level moves upwards in the band gap due to contact formation. The effect might be a key issue in understanding basic properties of solar cell devices based on these materials. © 1999 American Institute of Physics.
Show PACS
73.20.Hb Impurity and defect levels; energy states of adsorbed species
81.05.Hd Other semiconductors
61.72.J- Point defects and defect clusters
71.20.Nr Semiconductor compounds
79.60.Bm Clean metal, semiconductor, and insulator surfaces
79.60.Jv Interfaces; heterostructures; nanostructures
73.20.At Surface states, band structure, electron density of states
71.55.Ht Other nonmetals

Deposition-temperature-dependent stress of capping oxide and its effect on Pt/Pb(Zr1−xTix)O3/Pt ferroelectric capacitor

Bon Jae Koo, Yoon Jong Song, Sung Yung Lee, Dong Jin Jung, Byung Hee Kim, Kinam Kim, Youngsoo Park, and June Key Lee

Appl. Phys. Lett. 74, 2286 (1999); http://dx.doi.org/10.1063/1.123826 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Two different interlayer dielectric (ILD) materials, electron cyclotron resonance chemical vapor deposition oxide (ECR-OXIDE) and plasma enhanced chemical vapor deposition TEOS oxide (PE-TEOS), were prepared at 400 and 200 °C respectively, on silicon substrates and Pt/Pb(Zr1−xTix)O3 (PZT)/Pt capacitors. It was found that the ILD deposition temperature is a most important parameter for minimizing the degradation of remnant polarization (Pr) during the ILD deposition. Since the stress of PZT capacitor strongly depends on the ILD deposition temperature, the PZT capacitor with PE-TEOS showed more compressive stress than that with ECR-OXIDE, which results in severe Pr degradation of PZT capacitor with PE-TEOS. This large stress effect of PE-TEOS was confirmed by x-ray diffraction (XRD) patterns in which the d spacing of (111) PZT films with PE-TEOS was much larger than that of PZT films with ECR-OXIDE. Therefore, the low ILD deposition temperature is a key parameter for achieving an ILD integration without any Pr degradation. © 1999 American Institute of Physics.
Show PACS
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
84.32.Tt Capacitors
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
77.22.Ej Polarization and depolarization

Ohmic contact formation mechanism of nonalloyed Pd contacts to p-type GaN observed by positron annihilation spectroscopy

Jong-Lam Lee, Marc Weber, Jong Kyu Kim, Jae Won Lee, Yong Jo Park, Taeil Kim, and Kelvin Lynn

Appl. Phys. Lett. 74, 2289 (1999); http://dx.doi.org/10.1063/1.123827 (3 pages) | Cited 37 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The change of the Fermi energy level at the interface of Pd/p-type GaN by surface treatment was investigated using positron annihilation spectroscopy, and the results were used to provide interpretation of the electrical properties of the contact. Changes in the positron parameters at the interface in the aqua regia-treated GaN are more pronounced than that in the HCl-treated one. This provides evidence that the surface treatment with aqua regia prior to Pd metal deposition removes surface oxides, resulting in the shift of the Fermi level position from a middle of the bandgap to near the valence band. Thus, the barrier for hole injection from metal to p-type GaN is lowered, subsequent to the decrease of contact resistivity by two orders of magnitude. © 1999 American Institute of Physics.
Show PACS
78.70.Bj Positron annihilation
81.05.Ea III-V semiconductors
73.40.Ns Metal-nonmetal contacts
73.20.At Surface states, band structure, electron density of states
73.40.Cg Contact resistance, contact potential

Suppressed diffusion of implanted boron in 4H–SiC

Michael Laube, Gerhard Pensl, and Hisayoshi Itoh

Appl. Phys. Lett. 74, 2292 (1999); http://dx.doi.org/10.1063/1.123828 (3 pages) | Cited 25 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Transient-enhanced diffusion of boron (B) during anneals at 1700 °C is experimentally observed in B-implanted 4H–SiC samples. This enhanced diffusion can strongly be suppressed by coimplantation of carbon or by a preanneal at 900 °C. It is proposed that B in 4H–SiC diffuses via the kick-out mechanism with the assistance of silicon interstitials in analogy to the B diffusion in Si. From the Fickian diffusion tail into the undamaged bulk, the preexponential factor D0 and the activation energy EA of the B diffusion coefficient D(B,T) are determined. © 1999 American Institute of Physics.
Show PACS
66.30.J- Diffusion of impurities
61.72.J- Point defects and defect clusters
61.72.Cc Kinetics of defect formation and annealing
61.72.up Other materials

Light-emitting diodes based on an alternating copolymer containing triphenylamine and phenylene units

Gui Yu, Yunqi Liu, Xia Wu, Min Zheng, Fenglian Bai, Daoben Zhu, Linpei Jin, Mingzhao Wang, and Xiuni Wu

Appl. Phys. Lett. 74, 2295 (1999); http://dx.doi.org/10.1063/1.123829 (3 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The optical and electroluminescence properties of a light-emitting poly(arylene vinylene) derivative comprising triphenylamine as the arylene unit (TPA–PPV) are demonstrated. TPA–PPV is soluble in common organic solvents, and has a high photoluminescent (PL) quantum yield (ΦPL = 0.94 in benzene). A single-layer light-emitting diode Indium–tin–oxide/TPA–PPV/Al utilizing blue–green light-emitting TPA–PPV as the emissive layer is fabricated, and luminance in excess of 612 cd/m2, turn-on voltages of 1.5 V, and high luminous efficiency (3.0 lm/w) are reported. © 1999 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices
42.70.Jk Polymers and organics
78.66.Qn Polymers; organic compounds
78.60.Fi Electroluminescence
78.55.Kz Solid organic materials

Improved blue luminescence in Ag-codoped SrS:Ce thin films made by atomic layer epitaxy and ion implantation

Wei-Min Li, Mikko Ritala, Markku Leskelä, Reijo Lappalainen, Erkki Soininen, Lauri Niinistö, Carlos Barthou, Paul Benalloul, and Jacques Benoit

Appl. Phys. Lett. 74, 2298 (1999); http://dx.doi.org/10.1063/1.123830 (3 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Silver ions were implanted into SrS:Ce3+ thin films grown by atomic layer epitaxy (ALE) to examine the effects of Ag+ codoping on the luminescence of SrS:Ce3+ used in thin-film electroluminescent (TFEL) devices. High-temperature annealing (800 °C) of the standard ALE SrS:Ce prepared at 510 °C caused a pronounced blueshift of the photoluminescence (PL) emission, but the intensity was decreased. Codoping by ion implantation of Ag+ and high-temperature annealing (800 °C) caused no further blueshift but the PL intensity was more than double that of the nonimplanted samples. The implanted SrS:Ce, Ag also exhibited the longest decay value (SN = 22 ns at 520 nm with 420 nm excitation) reported for ALE SrS:Ce thin films. The improved PL properties show that codoping with Ag+ can be advantageous in ALE SrS:Ce3+ thin films used for electroluminescent multicolor and full-color flat panel displays. The results also suggest the potential of the ion implantation technique in TFEL device preparation. © 1999 American Institute of Physics.
Show PACS
78.55.Hx Other solid inorganic materials
61.72.Cc Kinetics of defect formation and annealing
61.72.up Other materials
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
85.60.Jb Light-emitting devices
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.66.Li Other semiconductors

Dislocation-induced changes in quantum dots: Step alignment and radiative emission

R. Leon, J. O. Okuno, R. A. Lawton, M. Stevens-Kalceff, M. R. Phillips, J. Zou, D. J. H. Cockayne, and C. Lobo

Appl. Phys. Lett. 74, 2301 (1999); http://dx.doi.org/10.1063/1.123831 (3 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A transition between two types of step alignment was observed in a multilayered InGaAs/GaAs quantum-dot (QD) structure. A change to larger QD sizes in smaller concentrations occurred after formation of a dislocation array. Cathodoluminescence (CL) spectra show a bimodal peak with lower energy peak enhancement when probing at lower e-beam energies. The two peaks separate as a result of QD interdiffusion. CL imaging and cross-sectional transmission electron microscopy showed contrast from a dislocation array formed at the interface between GaAs and the first InGaAs QD layer. Strong QD emission in the near infrared (800–1100 nm) was obtained despite the presence of dislocations. © 1999 American Institute of Physics.
Show PACS
78.66.Fd III-V semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Deactivation and diffusion of boron in ion-implanted silicon studied by secondary electron imaging

Martin R. Castell, Todd W. Simpson, Ian V. Mitchell, D. D. Perovic, and J.-M. Baribeau

Appl. Phys. Lett. 74, 2304 (1999); http://dx.doi.org/10.1063/1.123832 (3 pages) | Cited 9 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Secondary electron (SE) imaging in a scanning electron microscope is used to map electrically active dopant distributions of B-doped superlattices in Si. By comparing SE contrast profiles with secondary ion mass spectroscopy data, it is shown that B is electrically deactivated when the damage caused during Si implantation falls onto a doped region. Following a 450 °C anneal, the effect of the implantation damage is severely reduced in the SE profiles and the B is partially reactivated. An 815 °C anneal results in transient enhanced diffusion of some of the B with the remainder trapped in an inactive immobile peak. © 1999 American Institute of Physics.
Show PACS
61.72.uf Ge and Si
61.80.Jh Ion radiation effects
66.30.J- Diffusion of impurities
79.20.Hx Electron impact: secondary emission
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
61.82.Fk Semiconductors
61.72.Cc Kinetics of defect formation and annealing

Hydrogen adsorption and cohesive energy of single-walled carbon nanotubes

Y. Ye, C. C. Ahn, C. Witham, B. Fultz, J. Liu, A. G. Rinzler, D. Colbert, K. A. Smith, and R. E. Smalley

Appl. Phys. Lett. 74, 2307 (1999); http://dx.doi.org/10.1063/1.123833 (3 pages) | Cited 306 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Hydrogen adsorption on crystalline ropes of carbon single-walled nanotubes (SWNT) was found to exceed 8 wt. %, which is the highest capacity of any carbon material. Hydrogen is first adsorbed on the outer surfaces of the crystalline ropes. At pressures higher than about 40 bar at 80 K, however, a phase transition occurs where there is a separation of the individual SWNTs, and hydrogen is physisorbed on their exposed surfaces. The pressure of this phase transition provides a tube-tube cohesive energy for much of the material of 5 meV/C atom. This small cohesive energy is affected strongly by the quality of crystalline order in the ropes. © 1999 American Institute of Physics.
Show PACS
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
64.70.K- Solid-solid transitions

Reflection spectroscopy on the photoinduced local metallic phase of Pr0.7Ca0.3MnO3

M. Fiebig, K. Miyano, Y. Tomioka, and Y. Tokura

Appl. Phys. Lett. 74, 2310 (1999); http://dx.doi.org/10.1063/1.123834 (3 pages) | Cited 24 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Optical spectroscopy and topography techniques were used to study the local photoinduced insulator-metal transition (IMT) in a Pr0.7Ca0.3MnO3 crystal. Although the change of reflectivity due to the transition exhibits features which are characteristic for the IMT, the spectrum reveals strong modifications as compared to the magnetic-field induced bulk IMT. The different nature of the photoinduced IMT is attributed to the competition of the ferromagnetic metallic region with its antiferromagnetic insulating surrounding, which possibly leads to a filamentary metallic phase. Modifications also include a pronounced broadband electrochromism in the >1.8 eV spectral range. © 1999 American Institute of Physics.
Show PACS
71.30.+h Metal-insulator transitions and other electronic transitions
78.20.Jq Electro-optical effects
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
78.30.Hv Other nonmetallic inorganics
72.60.+g Mixed conductivity and conductivity transitions

Instability of nanocavities in amorphous silicon

Xianfang Zhu, J. S. Williams, D. J. Llewellyn, and J. C. McCallum

Appl. Phys. Lett. 74, 2313 (1999); http://dx.doi.org/10.1063/1.123835 (3 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter demonstrates that, whereas nanocavities are quite stable in crystalline Si (c-Si), they are unstable in amorphous Si (a-Si). This behavior is illustrated by introducing a band of nanocavities into c-Si by H implantation, followed by annealing at 850 °C. Amorphization of the c-Si surrounding the nanocavities led to their disappearance. Transmission electron microscopy, Rutherford backscattering, and channeling and time resolved (optical) reflectivity were used to provide details of the cavity instability process by studying the amorphous Si after implantation and subsequent crystallization. Two possible reasons are suggested for the instability of nanocavities in a-Si. © 1999 American Institute of Physics.
Show PACS
61.43.Dq Amorphous semiconductors, metals, and alloys
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
78.40.Fy Semiconductors
61.46.-w Structure of nanoscale materials
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
78.47.-p Spectroscopy of solid state dynamics
61.72.uf Ge and Si

Adjustable emissions from silicon-rich oxide films prepared by plasma-enhanced chemical-vapor deposition

J. F. Tong, H. L. Hsiao, and H. L. Hwang

Appl. Phys. Lett. 74, 2316 (1999); http://dx.doi.org/10.1063/1.123836 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Observation of sequentially adjustable, intense, and stable emissions at room temperature from amorphous silicon-rich oxide thin films without any thermal annealing is reported. Hydrogenated amorphous silicon-rich oxide (SiOx:N:H, 0<x<2) thin films were deposited by plasma-enhanced chemical-vapor deposition with a mixture of 5% silane in argon and nitrous oxide gases. The strong naked-eye-seeing photoluminescence (blue–white–orange) could be adjusted by changing the process gases flow rate ratio Γ ( = [SiH4]/[N2O]). The degree of silicon richness was determined from secondary ion mass spectrometry. The microstructure-bonding configuration was examined by Fourier transform infrared spectroscopy. The implications of these studies for understanding the origins of silicon-based luminescence are discussed. © 1999 American Institute of Physics.
Show PACS
78.66.Jg Amorphous semiconductors; glasses
78.55.Hx Other solid inorganic materials
68.55.Nq Composition and phase identification
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
61.43.Er Other amorphous solids
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Surface energetics, pit formation, and chemical ordering in InGaN alloys

J. E. Northrup, L. T. Romano, and J. Neugebauer

Appl. Phys. Lett. 74, 2319 (1999); http://dx.doi.org/10.1063/1.123837 (3 pages) | Cited 95 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present first-principle calculations of the structure and energetics of the GaN(10math1) surface, and present models for the reconstructions. A strong preference for In surface segregation and occupation of specific surface sites is demonstrated. We argue that inverted pyramid defect formation is enhanced by segregation of In on (10math1) facets. We propose that the chemical ordering recently observed in InGaN alloys is driven by the preference for In incorporation at the sites of reduced N coordination present at step edges during growth on the (0001) and (000math) surfaces. © 1999 American Institute of Physics.
Show PACS
68.35.Fx Diffusion; interface formation
68.35.Md Surface thermodynamics, surface energies
68.35.B- Structure of clean surfaces (and surface reconstruction)

Silicon microcolumn arrays grown by nanosecond pulsed-excimer laser irradiation

A. J. Pedraza, J. D. Fowlkes, and D. H. Lowndes

Appl. Phys. Lett. 74, 2322 (1999); http://dx.doi.org/10.1063/1.123838 (3 pages) | Cited 72 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Arrays of high aspect ratio silicon microcolumns that protrude well above the initial surface have been formed by cumulative nanosecond pulsed-excimer laser irradiation of silicon. Microcolumn growth is strongly affected by the gas environment, being enhanced in air or other oxygen-containing ambient. It is proposed that microcolumn growth occurs through a combination of pulsed-laser melting of the tips of the columns and deposition of silicon from the intense flux of silicon-rich vapor produced by ablation of the surface regions between columns. The molten tips of the columns are strongly preferred sites for deposition, resulting in a very high axial growth rate. The growth process is conceptually similar to the vapor–liquid–solid method used to grow silicon whiskers. However, in the present case the pulsed-laser radiation fulfills two roles almost simultaneously, viz., providing the flux of silicon-containing molecules and melting the tips of the columns. © 1999 American Institute of Physics.
Show PACS
81.05.Cy Elemental semiconductors
81.15.Fg Pulsed laser ablation deposition
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
64.70.D- Solid-liquid transitions
back to top
RSS Feeds

Reduced thermal conductivity in low-temperature-grown GaAs

A. W. Jackson, J. P. Ibbetson, A. C. Gossard, and U. K. Mishra

Appl. Phys. Lett. 74, 2325 (1999); http://dx.doi.org/10.1063/1.123839 (3 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thermal conductivity of low-temperature-grown GaAs(LT GaAs) was measured at room temperature using a self-heated photolithographically patterned platinum wire on the surface of the sample. Finite element calculations were performed to extract the thermal conductivity from the nonlinear I–V characteristic of the wires. For LT GaAs grown at a substrate temperature of 240 °C, the thermal conductivity was found to be only 23% of the value for stoichiometric GaAs. Rapid thermal annealing of the sample at 650 °C for 30 s increased the thermal conductivity to 46% of the GaAs value. Strong phonon scattering by point defects could account for reduced thermal conductivity in the as-grown material. The reduced thermal conductivity in the annealed material, however, is not consistent with our current understanding of the defects in annealed LT GaAs. © 1999 American Institute of Physics.
Show PACS
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
61.72.Cc Kinetics of defect formation and annealing
63.20.kp Phonon-defect interactions
02.70.Dh Finite-element and Galerkin methods
Page 1 of 2 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close