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

18 Mar 2002

Volume 80, Issue 11, pp. 1859-2034

Return to All Sections
back to top
RSS Feeds

Modification of optical properties by strain-induced piezoelectric effects in ultrahigh-quality V-groove AlGaAs/GaAs single quantum wire

Xing-Quan Liu, Xue-Lun Wang, Mutsuo Ogura, Thierry Guillet, Valia Voliotis, and Roger Grousson

Appl. Phys. Lett. 80, 1894 (2002); http://dx.doi.org/10.1063/1.1459761 (3 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report tiny strain-induced piezoelectric effects in an ultrahigh-quality AlGaAs/GaAs V-groove quantum wire structure. Zero photoluminescence excitation (PLE) absorption intensities are observed at low temperatures. Excitation power density-dependent optical properties provide evidence that the zero PLE absorption intensities are due to an internal electric field created by tiny strain-induced piezoelectric polarization along the wires, which causes complete spatial separation of the electron and hole wave functions along the wires. Absorption is enhanced by shining a He–Ne laser as a background in order to screen the electric field, which confirms the existence of piezoelectric field effects. © 2002 American Institute of Physics.
Show PACS
78.67.Lt Quantum wires
78.55.Cr III-V semiconductors
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
77.65.Ly Strain-induced piezoelectric fields

Thermodynamic stability of high-K dielectric metal oxides ZrO2 and HfO2 in contact with Si and SiO2

Maciej Gutowski, John E. Jaffe, Chun-Li Liu, Matt Stoker, Rama I. Hegde, Raghaw S. Rai, and Philip J. Tobin

Appl. Phys. Lett. 80, 1897 (2002); http://dx.doi.org/10.1063/1.1458692 (3 pages) | Cited 135 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present theoretical and experimental results regarding the thermodynamic stability of the high-k dielectrics ZrO2 and HfO2 in contact with Si and SiO2. The HfO2/Si interface is found to be stable with respect to formation of silicides whereas the ZrO2/Si interface is not. The metal–oxide/SiO2 interface is marginally unstable with respect to formation of silicates. Cross-sectional transmission electron micrographs expose formation of nodules, identified as silicides, across the polycrystalline silicon/ZrO2/Si interfaces but not for the interfaces with HfO2. For both ZrO2 and HfO2, the x-ray photoemission spectra illustrate formation of silicate-like compounds in the MO2/SiO2 interface. © 2002 American Institute of Physics.
Show PACS
68.37.Lp Transmission electron microscopy (TEM)
79.60.Jv Interfaces; heterostructures; nanostructures
68.35.Fx Diffusion; interface formation
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
82.60.Cx Enthalpies of combustion, reaction, and formation

Growth and characterization of GaInNxAs1−x thin films with band-gap energies in the red-blue portion of the visible spectrum

Jairo A. Cardona-Bedoya, Fernando Gordillo-Delgado, Orlando Zelaya-Angel, Alfredo Cruz-Orea, and Julio G. Mendoza-Álvarez

Appl. Phys. Lett. 80, 1900 (2002); http://dx.doi.org/10.1063/1.1454209 (3 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using the radio-frequency (rf) sputtering deposition technique, we have grown GaInNxAs1−x thin films on glass substrates at room temperature. The concentration of nitrogen in the films was found to depend mainly on the rf power used to excite the growth plasma. X-ray diffractograms show that the films have small grain sizes and present a broad diffraction band centered close to the (002) diffraction peak of hexagonal GaN. Electron dispersive spectroscopy measurements report N concentrations of x ∼ 0.8 and In concentrations of about 3% indicating that we have grown GaInNxAs1−x alloys in the GaN-rich side. The absorption spectra measured by the photoacoustic technique show that these semiconductor films have band-gap energies ranging between 1.69 and 2.56 eV, when the rf sputtering power is varied in the range 30–80 W. Thus, we show the feasibility to grow GaInNxAs1−x thin films with high N concentrations in which we can tune the band-gap energy in the red-blue portion of the visible spectrum, by a careful control of the growth parameters. © 2002 American Institute of Physics.
Show PACS
81.05.Ea III-V semiconductors
81.15.Cd Deposition by sputtering
78.66.Fd III-V semiconductors
71.20.Nr Semiconductor compounds
68.55.Nq Composition and phase identification
78.40.Fy Semiconductors
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects

On the effective thermal diffusivity of fiber-reinforced composites

A. Salazar, J. M. Terrón, A. Sánchez-Lavega, and R. Celorrio

Appl. Phys. Lett. 80, 1903 (2002); http://dx.doi.org/10.1063/1.1461422 (3 pages) | Cited 12 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Modulated photothermal techniques provide useful methods based on linear relations between measurable quantities to obtain the thermal diffusivity of homogeneous materials. In this letter the applicability of such linear relations in the case of unidirectional fiber-reinforced composites (UFRC) is analyzed. Based on the solution of the propagation of plane thermal waves in a material with aligned buried cylinders, we found that the linear relation valid for homogeneous materials still holds for UFRC. However, its slope does not give the effective thermal diffusivity as derived from the effective thermal conductivity measured by steady-state experiments. Anyway, as the number of cylinder rows increases the thermal diffusivity measured by modulated methods approaches the steady value asymptotically. The model is validated by photothermal measurements performed on calibrated samples. © 2002 American Institute of Physics.
Show PACS
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
07.20.-n Thermal instruments and apparatus

Microstructures and mechanical properties of tungsten wire/particle reinforced Zr57Nb5Al10Cu15.4Ni12.6 metallic glass matrix composites

Haein Choi-Yim, Jan Schroers, and William L. Johnson

Appl. Phys. Lett. 80, 1906 (2002); http://dx.doi.org/10.1063/1.1459766 (3 pages) | Cited 31 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Tungsten wire or particle reinforced metallic glass matrix composites are produced by infiltrating liquid Zr57Nb5Al10Cu15.4Ni12.6 (Vit106) into tungsten reinforcements at 1150 and at 1425 K. X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy are carried out to characterize the composite. The matrix of the composite processed at 1150 K is mostly amorphous, with some embedded crystals. During processing, tungsten dissolves in the glass-forming melt and upon quenching precipitates over a relatively narrow zone near the interface between the tungsten and matrix. In the composites processed at 1425 K, tungsten dissolves in the melt and diffuses through the liquid medium, and then reprecipitates upon quenching. The faster kinetics at this high temperature results in a uniform distribution of the crystals throughout the matrix. Mechanical properties of the differently processed composites containing wires and particles are compared and discussed. The composites exhibit a plastic strain failure of up to 16% without sacrificing the high-failure strength, which is comparable to monolithic Vit106. © 2002 American Institute of Physics.
Show PACS
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.F- Deformation and plasticity
81.30.Mh Solid-phase precipitation
62.20.M- Structural failure of materials
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
61.43.Fs Glasses
64.75.-g Phase equilibria

Nitrogen-related local vibrational modes in ZnO:N

A. Kaschner, U. Haboeck, Martin Strassburg, Matthias Strassburg, G. Kaczmarczyk, A. Hoffmann, C. Thomsen, A. Zeuner, H. R. Alves, D. M. Hofmann, and B. K. Meyer

Appl. Phys. Lett. 80, 1909 (2002); http://dx.doi.org/10.1063/1.1461903 (3 pages) | Cited 141 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study the influence of nitrogen, a potential acceptor in ZnO, on the lattice dynamics of ZnO. A series of samples grown by chemical vapor deposition (CVD) containing different nitrogen concentrations, as determined by secondary ion mass spectroscopy (SIMS), was investigated. The Raman spectra revealed vibrational modes at 275, 510, 582, 643, and 856 cm−1 in addition to the host phonons of ZnO. The intensity of these additional modes correlates linearly with the nitrogen concentration and can be used as a quantitative measure of nitrogen in ZnO. These modes are interpreted as local vibrational modes. Furthermore, SIMS showed a correlation between the concentration of incorporated nitrogen and unintentional hydrogen, similar to the incorporation of the p-dopant magnesium and hydrogen in GaN during metalorganic CVD. © 2002 American Institute of Physics.
Show PACS
78.66.Hf II-VI semiconductors
78.30.Fs III-V and II-VI semiconductors
63.20.Pw Localized modes
61.72.S- Impurities in crystals
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Band gap changes of GaN shocked to 13 GPa

M. D. McCluskey, Y. M. Gupta, C. G. Van de Walle, D. P. Bour, M. Kneissl, and N. M. Johnson

Appl. Phys. Lett. 80, 1912 (2002); http://dx.doi.org/10.1063/1.1455148 (3 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The band gap of GaN under uniaxial-strain compression was determined using time-resolved optical transmission measurements in shock-wave experiments. Shock waves were generated by impacting the GaN samples with c-cut sapphire impactors mounted on projectiles fired by a gas gun. Impact velocities were varied to provide longitudinal stresses ranging from 4.5 to 13 GPa. An abrupt increase of the band gap is observed upon shock-wave compression, followed by a slower increase. By measuring the absorption threshold before and during shock compression of the GaN layer, the band-gap shift for a particular longitudinal stress was obtained. A linear fit to the data yields a band-gap shift of 0.02 eV/GPa. Comparison with ab initio calculations show that this slope lies between the calculated bounds for isotropic and uniaxial compression. Potential reasons for the differences are indicated. © 2002 American Institute of Physics.
Show PACS
71.20.Nr Semiconductor compounds
62.50.-p High-pressure effects in solids and liquids
78.47.-p Spectroscopy of solid state dynamics

Direct crystallization of the peritectic Nd2Fe14B1 phase by undercooling of bulk alloy melts

Thomas Volkmann, Jianrong Gao, and Dieter M. Herlach

Appl. Phys. Lett. 80, 1915 (2002); http://dx.doi.org/10.1063/1.1461430 (3 pages) | Cited 19 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electromagnetic levitation was used to melt and solidify containerlessly Nd–Fe–B alloys. A method was developed to reduce and evaporate stable solid Nd oxides at the surface of the liquid samples. The oxides otherwise limit the undercoolability of the highly reactive Nd-based alloys. In such a way, undercoolings up to 150 K of the levitation processed samples were achieved. Owing to the large undercooling range, the intermetallic Nd2Fe14B1 phase with the hard magnetic properties was primarily crystallized at undercoolings exceeding 50 K. Solidification of the pro-peritectic γ-Fe with soft magnetic properties was successfully suppressed. At the largest undercoolings, a metastable phase, likely to be of the composition Nd2Fe17Bx (x ≈ 1) is primarily formed while the crystallization of Nd2Fe14B1 phase is followed up in a subsequent step. © 2002 American Institute of Physics.
Show PACS
64.70.D- Solid-liquid transitions
64.75.-g Phase equilibria
75.50.Ww Permanent magnets

Phase stabilities of “morphotropic” phases in Pb(Zn1/3Nb2/3)O3–PbTiO3 single crystals

Yu Lu, D.-Y. Jeong, Z.-Y. Cheng, T. Shrout, and Q. M. Zhang

Appl. Phys. Lett. 80, 1918 (2002); http://dx.doi.org/10.1063/1.1461902 (3 pages) | Cited 41 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Based on the optic and dielectric data acquired under different mechanical and electric conditions and temperature, we show that an orthorhombic phase exists near the morphotropic phase boundary (MPB) (on both the rhombohedral and tetragonal sides of MPB). Because of the proximity of the free energy of this phase to the two other morphotropic phases, i.e., the rhombohedral and tetragonal phases, the experimentally observed phases and phase diagrams near MPB depend crucially on the mechanical and electric conditions as well as the sample history. © 2002 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.B- Phase transitions and Curie point
81.30.Dz Phase diagrams of other materials

Growth of single-crystal SiO2 film on Ni(111) surface

Manisha Kundu and Yoshitada Murata

Appl. Phys. Lett. 80, 1921 (2002); http://dx.doi.org/10.1063/1.1461052 (3 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We grew a single-crystal SiO2 film on a Ni(111) surface. Atomic hydrogen during initial growth of an amorphous SiO2 film and an ambient oxygen atmosphere during annealing of this film were essential in forming this single-crystal SiO2 film. The film grew with a (√3×√3) R30° crystallographic orientation, and its structure was the high-temperature phase of quartz, i.e., β quartz. In addition, a polycrystalline silicide phase was formed at the SiO2/Ni(111) interface. © 2002 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.35.Fx Diffusion; interface formation

Time-resolved and time-integrated photoluminescence in ZnO epilayers grown on Al2O3(0001) by metalorganic vapor phase epitaxy

S. W. Jung, W. I. Park, H. D. Cheong, Gyu-Chul Yi, Hyun M. Jang, S. Hong, and T. Joo

Appl. Phys. Lett. 80, 1924 (2002); http://dx.doi.org/10.1063/1.1461051 (3 pages) | Cited 79 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on photoluminescence (PL) spectra of ZnO films grown by low pressure metalorganic vapor phase epitaxy. For PL measurements, high quality ZnO thin films were epitaxially grown on Al2O3(0001) substrates. Time-integrated PL spectra of the films at 10 K clearly exhibited free A and B excitons at 3.376 and 3.382 eV and bound exciton peaks at 3.360, 3.364, and 3.367 eV. With increasing temperature, intensities of the bound exciton peaks drastically decreased and a free exciton peak was dominant above 40 K. Furthermore, time-resolved PL measurements at the free exciton peak were carried out at room temperature. The decay profiles were of double-exponential form, and the decay time constants of 180 ps and 1.0 ns were obtained using a least-square fit of the data. © 2002 American Institute of Physics.
Show PACS
78.66.Hf II-VI semiconductors
78.55.Et II-VI semiconductors
78.47.-p Spectroscopy of solid state dynamics
81.05.Dz II-VI semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
71.35.Cc Intrinsic properties of excitons; optical absorption spectra

Nanoencapsulation of ZnS:Ag particulates with indium tin oxide for field emission displays

M. Ollinger, V. Craciun, and R. K. Singh

Appl. Phys. Lett. 80, 1927 (2002); http://dx.doi.org/10.1063/1.1453477 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Cathodoluminescence degradation measurements showed that by applying a nanometer-scale indium tin oxide (ITO) coating on micron-sized ZnS:Ag particles, the degradation lifetime was dramatically improved. X-ray photoelectron spectroscopy (XPS) analysis showed that the Zn 2p3/2 and S 2p peaks of the electron beam irradiated ZnS:Ag were shifted to higher binding energies, which correspond to oxidized elements with respect to those found for the commercial ZnS:Ag particulates. The XPS analysis for the ITO coated ZnS:Ag showed a broadening of the Zn 2p3/2 and S 2p peaks, which were a convolution of several peaks. In this case, the Zn 2p3/2 and S 2p peaks corresponding to ZnS were still present together with another shoulder corresponding to the oxidized elements. This difference in the XPS results shows that the ITO coating reduced the degradation rate by slowing the surface chemical changes on the ZnS:Ag powder. © 2002 American Institute of Physics.
Show PACS
78.66.Vs Fine-particle systems
78.60.Hk Cathodoluminescence, ionoluminescence
85.45.Fd Field emission displays (FEDs)
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
79.60.Jv Interfaces; heterostructures; nanostructures
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close