jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter UniPHY Group iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 May 2003

Volume 93, Issue 10, pp. 5855-8792

Page 1 of 35 Pages Next Page | Jump to Page
back to top
RSS Feeds

Epitaxially grown GaAsN random laser

B. Q. Sun, M. Gal, Q. Gao, H. H. Tan, C. Jagadish, T. Puzzer, L. Ouyang, and J. Zou

J. Appl. Phys. 93, 5855 (2003); http://dx.doi.org/10.1063/1.1568533 (4 pages) | Cited 6 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied the photoluminescence properties of as-grown GaAs1−xNx epitaxial layers grown on GaAs containing 0.6%, 1.77%, and 2.8% nitrogen. We found laser emission from thick (d>200 nm) GaAs0.972N0.028 layers exhibiting the characteristic lasing properties of random lasers. This is unusual because random lasers have so far only been associated with highly disordered or random media. We believe that high gain in combination with structural inhomogeneities that are evident in these GaAs0.972N0.028 layers, can explain the random lasing in such epitaxial layers. © 2003 American Institute of Physics.
Show PACS
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
68.55.-a Thin film structure and morphology
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)

Asymptotic analysis of dispersion characteristics in two-dimensional metallic photonic band gap structures

Evgenya I. Smirnova and Chiping Chen

J. Appl. Phys. 93, 5859 (2003); http://dx.doi.org/10.1063/1.1568530 (7 pages) | Cited 1 time

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a self-consistent technique for the asymptotic analysis of dispersion curves in two-dimensional metallic photonic band gap structures representing square and triangular arrays of metal rods. The technique is applicable for the structures with rod radii (a), which are small compared to the distance between the rods (b) and to the wavelength (λ). The induced current and charge distributions on the rods are expressed self-consistently in terms of the electromagnetic wave field. The dispersion characteristics are calculated for the TE and TM modes. The results are in agreement with those obtained previously using the Photonic Band Gap Structure Simulator code. © 2003 American Institute of Physics.
Show PACS
42.70.Qs Photonic bandgap materials

Fabrication of photonic band gap crystal using microtransfer molded templates

W. Y. Leung, H. Kang, K. Constant, D. Cann, C.-H. Kim, R. Biswas, M. M. Sigalas, and K.-M. Ho

J. Appl. Phys. 93, 5866 (2003); http://dx.doi.org/10.1063/1.1568548 (5 pages) | Cited 8 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have proposed and demonstrated an economical technique to fabricate a three-dimensional layer-by-layer photonic band gap structure in the infrared wavelengths. An organic polymer template structure, an inverse layer-by-layer photonic crystal structure, is assembled using the microtransfer molding technique. This template is infiltrated with sol-gel or nanoparticle titanium oxide slurry, then later removed by heat treatment at a temperature range of 550–800 °C. This method can be extended to fabricate photonic crystals operating at optical and ultraviolet frequencies. © 2003 American Institute of Physics.
Show PACS
42.70.Qs Photonic bandgap materials
42.86.+b Optical workshop techniques

Aperture shape effect on the performance of very small aperture lasers

Fang Chen, D. D. Stancil, and T. E. Schlesinger

J. Appl. Phys. 93, 5871 (2003); http://dx.doi.org/10.1063/1.1568150 (5 pages) | Cited 7 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the effect of different aperture shapes on the power output of a very small aperture laser (VSAL) fabricated from commercial edge-emitting laser diodes and correlate the results to the layer structure and polarization of the optical field. A waveguide theory is used to explain the experimental observations. We show that the shape of the aperture has a significant effect on the VSAL output power. In particular shapes exploiting the asymmetry of the laser can achieve much higher throughput over square apertures while keeping the aperture area constant. This work also indicates the validity of analyzing near-field small apertures as cutoff waveguide structures. © 2003 American Institute of Physics.
Show PACS
42.60.By Design of specific laser systems
42.55.Px Semiconductor lasers; laser diodes
back to top
RSS Feeds

Dynamics of ozone and OH radicals generated by pulsed corona discharge in humid-air flow reactor measured by laser spectroscopy

Ryo Ono and Tetsuji Oda

J. Appl. Phys. 93, 5876 (2003); http://dx.doi.org/10.1063/1.1567796 (7 pages) | Cited 34 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The dynamics of ozone and OH radicals are studied in pulsed corona discharge plasma in a humid-air environment. Ozone density is measured by the laser absorption method, and OH density is measured by the laser-induced fluorescence (LIF) method. A 100-ns pulsed corona discharge occurs between a series of 25 needle electrodes and a plate electrode. After the pulsed discharge, the time evolutions of ozone and OH densities are measured in humid air or a humid nitrogen-oxygen mixture. Results show that the addition of 2.4% water vapor to dry air reduces ozone production by a factor of about 6, and shortens the ozone formation time constant from 30 to 6 μs. Water vapor may reduce atomic oxygen levels leading to the decreased production of ozone by O+O2 reaction. The LIF measurement for OH radicals shows that OH density is approximately constant for 10 μs after the pulsed discharge, then decays by recombination reaction and reactions with the discharge products of oxygen, such as ozone or atomic oxygen. Absolute OH density is estimated; it is about 3×1015 cm−3 in streamers at 10 μs after discharge in the H2O(2.4%)/N2 mixture. © 2003 American Institute of Physics.
Show PACS
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
52.80.Hc Glow; corona
33.50.Dq Fluorescence and phosphorescence spectra

Effects of assistant anode on planar inductively coupled magnetized argon plasma in plasma immersion ion implantation

Deli Tang and Paul K. Chu

J. Appl. Phys. 93, 5883 (2003); http://dx.doi.org/10.1063/1.1568151 (5 pages) | Cited 6 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The enhancement of planar radio frequency (RF) inductively coupled argon plasma is studied in the presence of an assistant anode and an external magnetic field at low pressure. The influence of the assistant anode and magnetic field on the efficiency of RF power absorption and plasma parameters is investigated. An external axial magnetic field is coupled into the plasma discharge region by an external electromagnetic coil outside the discharge chamber and an assistant cylindrical anode is inserted into the discharge chamber to enhance the plasma discharge. The plasma parameters and density profile are measured by an electrostatic Langmuir probe at different magnetic fields and anode voltages. The RF power absorption by the plasma can be effectively enhanced by the external magnetic field compared with the nonmagnetized discharge. The plasma density can be further increased by the application of a voltage to the assistant anode. Owing to the effective power absorption and enhanced plasma discharge by the assistant anode in a longitudinal magnetic field, the plasma density can be enhanced by more than a factor of two. Meanwhile, the nonuniformity of the plasma density is less than 10% and it can be achieved in a process chamber with a diameter of 600 mm. © 2003 American Institute of Physics.
Show PACS
52.80.Dy Low-field and Townsend discharges
52.77.Dq Plasma-based ion implantation and deposition
52.70.Ds Electric and magnetic measurements
52.25.-b Plasma properties

Time- and space-resolved electric potentials in a parallel-plate radio-frequency plasma

Kungen Teii, Michinobu Mizumura, Shousaku Matsumura, and Shinriki Teii

J. Appl. Phys. 93, 5888 (2003); http://dx.doi.org/10.1063/1.1568158 (5 pages) | Cited 2 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A low-input capacitance emissive probe heated by a CO2 laser has been used to investigate frequency-modulated electric potentials in a radio-frequency (rf) glow discharge plasma. An excellent time-response ability of our probe system to a sharp potential change was confirmed by potential measurements with applying a step function voltage to the plasma. The electric field distribution as the first derivative of the potential distribution obtained by the probe method was compared with that by the laser optogalvanic spectroscopy to ensure the reliability of the measurements in the sheath region. The probe method was applied to directly monitor a temporal variation of axial potential and electric field distributions between two parallel-plate electrodes in a rf argon plasma. The formation of ion sheath regions on both electrode surfaces was confirmed at any phase in a rf cycle. The results were consistent with a one-dimensional model for potential and electric field distributions in the sheath region. © 2003 American Institute of Physics.
Show PACS
52.80.Pi High-frequency and RF discharges
52.80.Hc Glow; corona
52.70.Ds Electric and magnetic measurements
back to top
RSS Feeds

Predictive Monte Carlo ion implantation simulator from sub-keV to above 10 MeV

Shiyang Tian

J. Appl. Phys. 93, 5893 (2003); http://dx.doi.org/10.1063/1.1565690 (12 pages) | Cited 9 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this paper is reported a general and accurate binary-collision-approximation- (BCA-)based Monte Carlo ion implantation model for implants into crystalline silicon. The combination of an improved semiempirical electronic stopping power model and Ziegler-Biersack-Littmark universal potential enables us to simulate a wide variety of implant species with only two different electronic stopping parameters for different implant species. With the model parameters fixed for a given implant species, excellent agreement is found with experimental secondary ion mass spectroscopy data for the energy range from sub-keV to above 10 MeV, and for different implant directions including random equivalent orientation, 〈100〉, 〈111〉, and 〈110〉 channeling directions. When compared with other BCA-based Monte Carlo simulators, it is demonstrated that more accurate results can be obtained for ultralow energy and very high energy implants. Furthermore, it is shown that, while the existing ion implantation simulators with the electronic stopping power based on the effective charge theory fail to predict the long tails of the deeply channeled implant species (such as Al), our model can predict these long tails successfully. Finally, an efficient damage model is also presented, which requires only one additional free parameter to accurately account for the damage accumulation and dechanneling effect. For high dose implants, substantial speed improvement over MARLOWE-based Monte Carlo simulators is observed. © 2003 American Institute of Physics.
Show PACS
61.72.uf Ge and Si
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
02.70.Uu Applications of Monte Carlo methods

Effects of ion implantation on electron centers in hydrogenated amorphous carbon films

A. A. Konchits, M. Ya. Valakh, B. D. Shanina, S. P. Kolesnik, I. B. Yanchuk, J. D. Carey, and S. R. P. Silva

J. Appl. Phys. 93, 5905 (2003); http://dx.doi.org/10.1063/1.1564280 (6 pages) | Cited 4 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron spin resonance (ESR) and Raman spectra measurements are carried out on a-C:H and a-C:H:N films both as grown and implanted with W and Ni ions with doses ranged from 0.5×1015 to 1.2×1016 cm−2. The as-grown films have small concentration of paramagnetic centers with a spin density Ns of 1017 cm−3. Upon implantation a significant increase in Ns of (0.5–22)×1019 cm−3 centers with g(Si)=2.0055 and g(C)=2.0025 was observed. These defects are ascribed to dangling bonds in the silicon substrate and in the carbon film, respectively. The correlation between variation of Ns value with implantation dose and behavior of D and G band position and their intensity ratio in the visible Raman spectra is observed. The effects are attributed to changes in the sp2–sp3 systems and hydrogen loss due to ion induced annealing of the carbon films at high ion doses. The temperature and concentration dependencies of the ESR line shape and linewidth are explained using the mechanism of motional narrowing over the temperature range 4.2–300 K. Low temperature anisotropy of the g value is found in the ESR spectra and is explained as arising from the dipole–dipole interaction in the infinitely thin films. © 2003 American Institute of Physics.
Show PACS
61.72.up Other materials
71.55.Jv Disordered structures; amorphous and glassy solids
81.05.Cy Elemental semiconductors
81.05.Gc Amorphous semiconductors
81.05.U- Carbon/carbon-based materials
61.43.Dq Amorphous semiconductors, metals, and alloys
71.23.Cq Amorphous semiconductors, metallic glasses, glasses
78.66.Jg Amorphous semiconductors; glasses
71.55.Cn Elemental semiconductors
78.66.Db Elemental semiconductors and insulators
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
76.30.-v Electron paramagnetic resonance and relaxation
78.35.+c Brillouin and Rayleigh scattering; other light scattering
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
85.40.Ry Impurity doping, diffusion and ion implantation technology
61.72.Cc Kinetics of defect formation and annealing

Hypersonic shock waves and hybridization of a-C:H thin films

A. Golanski, J. P. Stoquert, F. Piazza, P. Kern, E. Laemmer, A. Deruyver, F. S. Schulze, and L. McDonnell

J. Appl. Phys. 93, 5911 (2003); http://dx.doi.org/10.1063/1.1567060 (9 pages) | Cited 4 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A distributed electron cyclotron resonance plasma reactor powered by a microwave generator operating at 2.45 GHz was used to deposit a-C:H films at room temperature on rf biased 〈100〉 Si substrates. Modifying substrate bias, substrate current density and composition of the precursor gas enabled the average deposited energy density to be varied. The physical properties of a-C:H were investigated using atomic force microscopy (AFM), x-ray photoelectron spectroscopy, and electron energy loss spectroscopy (EELS). The experimental results were correlated with the predictions of the binary collision theory. The influence of the deposited energy density on the nucleation and growth processes was investigated using both pure C2H2 and C2H2 mixed with Ar. The sp3 nucleation process is shown to be stimulated by high energy density cascades generated by (C2H2)+ and Ar+ ions. For the pure acetylene plasma, the AFM topography displays a random network of circular, crater-like objects close to 1 μm in diameter. These objects are associated with plastic flow of a-C:H and are attributed to the transversal hypersonic shock waves generated by overlapping binary collision cascades. EELS analysis shows that an increasing ion current density applied under constant substrate bias leads to an increased sp3 hybridized carbon fraction. The effect is attributed to interference between the shock waves triggered by individual ions and the corresponding high pressure transients. The probability Pi of a dynamic overlap of order i between shock waves is estimated under the assumption that in order to modify the quantum state and bonding type, the overlap must occur during the wave propagation time τ. The observed evolution of the sp3 hybridized fraction is consistent with theoretical predictions for i=2 and a propagation time τ≈1 ps, indicating that shock waves are generated during the cascade’s lifetime. Analysis of the AFM images shows that once the shock wave comes to rest, the subsequent nucleation of the sp3 hybridized component is controlled by the tensile stress-mediated nucleation process. © 2003 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
62.50.-p High-pressure effects in solids and liquids
68.60.Bs Mechanical and acoustical properties
52.77.Dq Plasma-based ion implantation and deposition
68.37.Ps Atomic force microscopy (AFM)
79.20.Uv Electron energy loss spectroscopy

Discrete dislocation analysis of size effects in thin films

Lucia Nicola, Erik Van der Giessen, and Alan Needleman

J. Appl. Phys. 93, 5920 (2003); http://dx.doi.org/10.1063/1.1566471 (9 pages) | Cited 68 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A discrete dislocation plasticity analysis of plastic deformation in metal thin films caused by thermal stress is carried out. The calculations use a two-dimensional plane-strain formulation with only edge dislocations. Single crystal films with a specified set of slip systems are considered. The film-substrate system is subjected to a prescribed temperature history and a boundary value problem is formulated and solved for the evolution of the stress field and for the evolution of the dislocations structure in the film. A hard boundary layer forms at the interface between the film and the substrate, which does not scale with the film thickness and thus gives rise to a size effect. It is found that a reduction in the rate of dislocation nucleation can occur abruptly, which gives rise to a two-stage hardening behavior. © 2003 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
62.20.F- Deformation and plasticity
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)

Temperature quenching of exciton luminescence intensity in ZnO/(Mg,Zn)O multiple quantum wells

T. Makino, K. Tamura, C. H. Chia, Y. Segawa, M. Kawasaki, A. Ohtomo, and H. Koinuma

J. Appl. Phys. 93, 5929 (2003); http://dx.doi.org/10.1063/1.1563295 (5 pages) | Cited 26 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The temperature-dependent behavior of excitonic photoluminescence observed in ZnO/MgZnO multiple quantum wells (MQWs) in the temperature range of 5–300 K is described. In a ZnO/Mg0.27Zn0.73O MQW grown by laser molecular-beam epitaxy, the luminescence was dominated by localized exciton (LE) emission throughout the whole temperature range studied. Luminescence of free excitons (FEs) was not observed. A simple rate equation is used to describe the quenching of LE emission. The activation energy for LE luminescence quenching is of the order of the localization energy of excitons, suggesting that the thermionic emission of the LEs out of the localization potentials leads to nonradiative recombination. In a ZnO/Mg0.12Zn0.88O MQW having lower barriers, the luminescence was dominated by LE emissions at low temperatures, while the FE transition was dominating emissions at temperatures above 175 K. A rate equation assuming one nonradiative recombination channel is used to describe the quenching of the transitions observed. The activation energy for LE luminescence quenching deduced in this sample is also of the order of the localization energy of excitons. The temperature dependences of FE emission intensities are also discussed by using a simple rate equation in which a thermal release effect of LEs toward FEs is taken into account. © 2003 American Institute of Physics.
Show PACS
78.67.De Quantum wells
73.21.Fg Quantum wells
78.55.Et II-VI semiconductors
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
79.40.+z Thermionic emission

Electrical activation of the ion-implanted phosphorus in 4H-SiC by excimer laser annealing

Yasunori Tanaka, Hisao Tanoue, and Kazuo Arai

J. Appl. Phys. 93, 5934 (2003); http://dx.doi.org/10.1063/1.1565190 (3 pages) | Cited 2 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We developed the annealing method for the activation of the ion-implanted dopants in silicon carbide using excimer laser irradiation. The electrical activation efficiency of the dopants drastically improved while the substrate temperature was kept in the range of 500–700 °C during laser irradiation. A “multiple energy irradiation method” realized the annealing of the implanted layer without ablation of the surface atoms and without redistribution of the dopants that were usually observed in the case of furnace annealing above 1500 °C. We have obtained a very low sheet resistance Rs, namely, 164.7 Ω/□, of the phosphorus ion-implanted layer in 4H-SiC by excimer laser annealing. This value is comparable to that of the furnace-annealed substrate at 1500 °C. © 2003 American Institute of Physics.
Show PACS
61.72.up Other materials
61.72.Cc Kinetics of defect formation and annealing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Structural study of the Al/Ni interface in ultrathin polycrystalline multilayers

E. Fonda, F. Petroff, and A. Traverse

J. Appl. Phys. 93, 5937 (2003); http://dx.doi.org/10.1063/1.1565174 (8 pages) | Cited 8 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Several Al–Ni multilayers were prepared where the Ni thickness was varied in order to (i) detect Ni diffusion in Al and Al diffusion in Ni and (ii) determine the compounds that form at the interface during deposition at room temperature. X-ray absorption spectroscopy was carried out at the K edge of Ni to identify the local atomic arrangement around this atom. Magnetic measurements allowed the detection of pure Ni among nonmagnetic AlxNi1−x compounds. At the Al/Ni interface, Ni diffuses in Al whereas no Al diffusion in Ni was observed at the Ni/Al interface. Ni diffusion in Al results in the formation of a disordered aluminide over a thickness of about 1.7 nm, then pure Ni growth takes place in the form of islands. © 2003 American Institute of Physics.
Show PACS
68.65.Ac Multilayers
68.35.Ct Interface structure and roughness
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
78.70.Dm X-ray absorption spectra

Interfacial properties of ZrO2 on silicon

Y.-S. Lin, R. Puthenkovilakam, J. P. Chang, C. Bouldin, I. Levin, N. V. Nguyen, J. Ehrstein, Y. Sun, P. Pianetta, T. Conard, W. Vandervorst, V. Venturo, and S. Selbrede

J. Appl. Phys. 93, 5945 (2003); http://dx.doi.org/10.1063/1.1563844 (8 pages) | Cited 28 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The interface of zirconium oxide thin films on silicon is analyzed in detail for their potential applications in the microelectronics. The formation of an interfacial layer of ZrSixOy with graded Zr concentration is observed by the x-ray photoelectron spectroscopy and secondary ion mass spectrometry analysis. The as-deposited ZrO2/ZrSixOy/Si sample is thermally stable up to 880 °C, but is less stable compared to the ZrO2/SiO2/Si samples. Post-deposition annealing in oxygen or ammonia improved the thermal stability of as-deposited ZrO2/ZrSixOy/Si to 925 °C, likely due to the oxidation/nitridation of the interface. The as-deposited film had an equivalent oxide thickness of ∼1.3 nm with a dielectric constant of ∼21 and a leakage current of 3.2×10−3 A/cm2 at −1.5 V. Upon oxygen or ammonia annealing, the formation of SiOx and SiHxNyOz at the interface reduced the overall dielectric constants. © 2003 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
68.35.Ct Interface structure and roughness
68.47.Fg Semiconductor surfaces
68.37.Xy Scanning Auger microscopy, photoelectron microscopy
79.20.Uv Electron energy loss spectroscopy
68.49.Jk Electron scattering from surfaces
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
68.60.Dv Thermal stability; thermal effects
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
81.65.Mq Oxidation
77.22.Ch Permittivity (dielectric function)
81.40.Gh Other heat and thermomechanical treatments

Self-assembled InAs quantum dots formed by molecular beam epitaxy at low temperature and postgrowth annealing

H. H. Zhan, R. Nötzel, G. J. Hamhuis, T. J. Eijkemans, and J. H. Wolter

J. Appl. Phys. 93, 5953 (2003); http://dx.doi.org/10.1063/1.1566457 (6 pages) | Cited 3 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Self-assembled InAs quantum dots are grown at low temperature (LT) by molecular beam epitaxy (MBE) on GaAs substrates. The growth is in situ monitored by reflection high-energy electron diffraction, and ex situ evaluated by atomic force microscopy for the morphological properties, and by high-resolution x-ray diffraction for the structural properties. While two monolayers as-grown LT (250 °C) InAs layers exhibit shallow mounds due to the low adatom migration length at low temperature, well-developed InAs dots are formed after postgrowth annealing above 450 °C. The structural quality of the LT GaAs matrix grown on top and of the embedded InAs dot layer is improved when a 3 nm GaAs interlayer is deposited (at 480 °C) on the InAs dots and subsequently annealed at 580 °C before LT GaAs overgrowth. These high structural quality LT-grown InAs dots are considered for applications in high-speed optical modulators and switches operating at low power by combining the high optical nonlinearity of quantum dots with the ultrafast optical response provided by LT growth in MBE. © 2003 American Institute of Physics.
Show PACS
68.65.Hb Quantum dots (patterned in quantum wells)
81.07.Ta Quantum dots
78.67.Hc Quantum dots
61.72.Cc Kinetics of defect formation and annealing
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.16.Dn Self-assembly
68.37.Ps Atomic force microscopy (AFM)

Resonant ionization of laser desorbed silicon

T. Gibert and T. Gonthiez

J. Appl. Phys. 93, 5959 (2003); http://dx.doi.org/10.1063/1.1567057 (7 pages) | Cited 1 time

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Soft ultraviolet laser desorption of neutral and ionized Si atoms was investigated at 355 nm for fluences ranging from the desorption threshold (85 mJ/cm2) up to 165 mJ/cm2. The sensitivity of resonance ionization mass spectrometry enabled the number of sputtered particles to be studied at a very low emission level corresponding to only several 100 atoms. For such a low emission yield, the ejected atoms keeps the memory of the laser–surface interaction mechanism during their flight in the ultrahigh vacuum condition. The velocity distribution of neutrals was measured for different fluences and were well fitted by a set of 2 Maxwellian functions at each fluence. From these fits it appears that the primary mechanisms involved in laser desorption are both a thermal process and an electronic one. © 2003 American Institute of Physics.
Show PACS
68.43.Tj Photon stimulated desorption
79.20.La Photon- and electron-stimulated desorption
79.20.Ds Laser-beam impact phenomena
81.65.Cf Surface cleaning, etching, patterning
52.38.Mf Laser ablation
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Fk Semiconductors

Sequence of Mg segregation, grain growth, and interfacial MgO formation in Cu–Mg alloy films on SiO2 during vacuum annealing

M. J. Frederick, R. Goswami, and G. Ramanath

J. Appl. Phys. 93, 5966 (2003); http://dx.doi.org/10.1063/1.1566451 (7 pages) | Cited 27 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Cu-alloy films are being explored for integrated circuits, for creating low-resistivity interconnects with stabilized metal/dielectric interfaces via solute segregation, and for interfacial reactions. Here, we describe the pathways of microstructure evolution in supersaturated Cu– 5–12 at. % Mg films, and phase formation at the film/SiO2 interface during annealing. The as-deposited films consist primarily of a Cu–Mg solid solution with trace amounts of orthorhombic CuMg2. Upon annealing to 400 °C, Mg segregates to the surface and the Cu–Mg grains grow from an average size of 20 to 60 nm, resulting in a ∼25%–40% decrease in film resistivity. In the same temperature regime, CuMg2 phase dissolves and fcc Cu2Mg forms. Upon annealing to higher temperatures, Mg segregates to the film/silica interface, reduces SiO2, and forms fcc MgO on the silica side of the interface. The Si released by this interfacial reaction diffuses into the metal film resulting in a ∼40%–190% increase in resistivity, for films with 8–12 at. % Mg, respectively. These results are of relevance for understanding microstructure evolution in alloy films and exploring the use of Cu alloys as interconnects in integrated circuits. © 2003 American Institute of Physics.
Show PACS
68.55.Nq Composition and phase identification
85.40.Ls Metallization, contacts, interconnects; device isolation
73.61.At Metal and metallic alloys
81.05.Bx Metals, semimetals, and alloys
61.72.Cc Kinetics of defect formation and annealing
81.40.Rs Electrical and magnetic properties related to treatment conditions
81.40.Gh Other heat and thermomechanical treatments
64.75.-g Phase equilibria
81.30.Mh Solid-phase precipitation
73.40.Ns Metal-nonmetal contacts
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Recombination kinetics in wide gap electroluminescent conjugated polymers with on-chain emissive defects

V. R. Nikitenko and J. M. Lupton

J. Appl. Phys. 93, 5973 (2003); http://dx.doi.org/10.1063/1.1566091 (5 pages) | Cited 8 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We analyze the experimental dependence of temporally and spectrally resolved electroluminescence (EL) from polyfluorene-based light-emitting diodes on electric field and temperature. The blue band in the EL spectrum is caused by emission from the polymer backbone, while the low-energy green emission results from on-chain keto defects, which act as traps for electrons. Although the time and temperature dependencies of the blue and green emission could be explained by the kinetics of redistribution of trapped holes and electrons in energy and space, the increase of the blue-to-green delayed emission ratio with increasing field strength appears to result from a difference in the nature of recombination. We propose that the formation of blue-emitting singlet excitons from close electron–hole pairs after turn-off is impeded by an energy barrier, in contrast to the formation of green-emitting excitons. © 2003 American Institute of Physics.
Show PACS
78.60.Fi Electroluminescence
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
85.60.Jb Light-emitting devices
78.47.-p Spectroscopy of solid state dynamics
71.55.Jv Disordered structures; amorphous and glassy solids
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
71.35.-y Excitons and related phenomena

Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes

H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy

J. Appl. Phys. 93, 5978 (2003); http://dx.doi.org/10.1063/1.1567803 (5 pages) | Cited 29 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Micro-light emitting diode (LED) arrays with diameters of 4 to 20 μm have been fabricated and were found to be much more efficient light emitters compared to their broad-area counterparts, with up to five times enhancement in optical power densities. The possible mechanisms responsible for the improvement in performance were investigated. Strain relaxation in the microstructures as measured by Raman spectroscopy was not observed, arguing against theories of an increase in internal quantum efficiency due to a reduction of the piezoelectric field put forward by other groups. Optical microscope images show intense light emission at the periphery of the devices, as a result of light scattering off the etched sidewalls. This increases the extraction efficiency relative to broad area devices and boosts the forward optical output. In addition, spectra of the forward emitted light reveal the presence of resonant cavity modes [whispering gallery (WG) modes in particular] which appear to play a role in enhancing the optical output. © 2003 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.67.De Quantum wells
78.60.Fi Electroluminescence
78.60.Hk Cathodoluminescence, ionoluminescence
78.30.Fs III-V and II-VI semiconductors
68.65.Fg Quantum wells

Dynamic failure of steel under hypervelocity impact of polycarbonate up to 9 km/s

Tatsumi Moritoh, Shohei Matsuoka, Toshiyuki Ogura, Kazutaka G. Nakamura, Ken-ichi Kondo, Masahide Katayama, and Masatake Yoshida

J. Appl. Phys. 93, 5983 (2003); http://dx.doi.org/10.1063/1.1569979 (6 pages) | Cited 3 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We performed hypervelocity impact experiments on SS400 steel with a polycarbonate projectile at velocities up to 9 km/s. Spall fracture damages were observed near a rear surface of the impacted target. The microstructure and microdamages were examined using optical microscopy and scanning electron microscopy. The α−ε phase transition region was observed near the crater. Cracks parallel to the impact direction were observed below the crater, and radial cracks grew from the α−ε phase interface at high velocity impact tests, especially above 6 km/s. Cleavage was the dominant mechanism for a spall fracture surface, and ductile fracture structures were also observed at the edge of spall plane. Geometric spall behaviors were well reproduced by numerical simulations using a hydrocode. These simulation results also showed that the cracks below the crater would be due to dynamic tensile stresses. The calculated results using the value of 13 GPa as the transition pressure showed that the duration necessary for the phase transition is about 150 ns for impact velocity of 8.8 km/s. © 2003 American Institute of Physics.
Show PACS
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.M- Structural failure of materials
81.70.Bt Mechanical testing, impact tests, static and dynamic loads

Surface alloying of metals by nanosecond laser pulses under transparent overlays

V. Yu. Fominski, R. I. Romanov, I. Smurov, and A. L. Smirnov

J. Appl. Phys. 93, 5989 (2003); http://dx.doi.org/10.1063/1.1568149 (11 pages) | Cited 1 time

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A thorough study was made of the processes determining the formation of metastable surface alloys in a film–substrate system [using Au(110 nm)–Ni and Sn(40 nm)–Cr systems as an example] irradiated by laser pulses of nanosecond duration. The irradiation was performed in conventional conditions (in air) and, following the applied method, through a transparent overlay. Scanning/transmission electron microscopy and Rutherford backscattering spectroscopy investigations of alloys were complemented by the measurements of acoustic signals initiated by laser pulses in the substrate. It has been ascertained that the alloy formation in air is accompanied by two competitive processes: laser sputtering of the film substance and its diffusion into the molten substrate layer. As the irradiation intensity goes up, the hydrodynamical sputtering mechanism is replaced by the atomic vaporization. As a result, sufficiently high vapor pressure (up to 102 bar) is generated above the film surface, the film is pressed to the substrate, and the heat and mass transport through the film–substrate interface is realized. However, no more than 20% of the atoms (of their total amount in the film) penetrate into the substrate, and the depth of alloying is within 100 nm. The experiments on the irradiation of the same systems through transparent overlays (water or “liquid glass”) have demonstrated a marked change in the pattern of processes: alloying atoms efficiently penetrate from the film into the substrate, the depth of alloying increases to 400 nm, and defects are formed in deep layers of the substrate. © 2003 American Institute of Physics.
Show PACS
81.05.Bx Metals, semimetals, and alloys
81.65.-b Surface treatments
68.49.Sf Ion scattering from surfaces (charge transfer, sputtering, SIMS)
68.37.Lp Transmission electron microscopy (TEM)
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)

First-principles calculations and experimental study for effect of different inorganic components on solid acid-base properties of inorganic/organic hybrids

Shingo Katayama, Keiji Iwata, Yuji Kubo, Noriko Yamada, and Yasushi Nonaka

J. Appl. Phys. 93, 6000 (2003); http://dx.doi.org/10.1063/1.1567822 (6 pages) | Cited 6 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Solid acidity was found to be generated in methylsiloxane-based inorganic/organic hybrids by incorporating inorganic components other than Si, such as Al and Nb, into methylsiloxane networks by combining theoretical first-principles calculations based on the density functional theory (DFT) with experimental synthesis and characterization. First-principles calculations based on the DFT indicated that the dissociation energy of protons at the surface followed the order Si<Al<Nb. The calculation led to the conclusion that methylsiloxane-based inorganic/organic hybrids were synthesized from metal alkoxides. The solid acidity followed the same order: Si<Al<Nb. The Fourier-transform infrared measurements of pyridine adsorbed on the methylsiloxane-based inorganic/organic hybrids showed that the solid acidity can be attributed to Brønsted acid sites. © 2003 American Institute of Physics.
Show PACS
68.43.Fg Adsorbate structure (binding sites, geometry)
82.80.Dx Analytical methods involving electronic spectroscopy

Spectroscopic characterization of chromium (IV, V, VI) in Cr:Li2MSiO4 (M=Mg,Zn)

C. Jousseaume, D. Vivien, A. Kahn-Harari, J. Derouet, F. Ribot, and F. Villain

J. Appl. Phys. 93, 6006 (2003); http://dx.doi.org/10.1063/1.1568152 (10 pages) | Cited 2 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
To understand the exceptionally long fluorescence lifetime of CrIV in Li2MSiO4 (M=Mg,Zn), several spectroscopic investigations are performed on Cr:Li2MSiO4 (M=Mg,Zn) crystals. X-ray absorption near-edge structure investigations attest that chromium is localized in tetrahedral sites and that CrVI is the major species while CrIV is the minor one in both compounds. Electron paramagnetic resonance studies confirm the occurrence of CrV in elongated tetrahedral environment (dx2−y2 ground state), corresponding probably to the silicon site, and suggest the presence of several charge compensation schemes. Fluorescence and fluorescence dynamics of CrIV:Li2MSiO4 are reported. The very long CrIV excited state lifetime previously observed on powders samples is confirmed for the crystals (117 μs at room temperature, 305 μs at 30 K for Cr:Li2MgSiO4) and is explained by combined contributions to the emission from both 1E level and the lowest component of the 3T2 level, in thermal equilibrium. Contrary to the situation found in most CrIV activated compounds, the 1E level lies below the 3T2 one. © 2003 American Institute of Physics.
Show PACS
78.55.Hx Other solid inorganic materials
78.70.Dm X-ray absorption spectra
76.30.Fc Iron group (3d) ions and impurities (Ti-Cu)
71.55.Ht Other nonmetals
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Characterization of isolated hydrogen traps by hydrogen permeation experiments

Tong-Yi Zhang and Iva Wat

J. Appl. Phys. 93, 6016 (2003); http://dx.doi.org/10.1063/1.1565493 (9 pages)

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The present work analyzes hydrogen permeation through a slab sample containing isolated hydrogen traps. The analysis is based on a flux continuity model that considers both the absorption and desorption processes. An analytical solution in series is derived for a dilute system with a low trap coverage fraction. According to this solution, we are able to characterize isolated hydrogen traps using only hydrogen permeation tests on two groups of samples with each group having different thicknesses. One group of samples, serving as a reference, is made of a pure matrix material without any hydrogen traps, while the other group of samples is made of the same matrix material with traps. The proposed multisample method is demonstrated by numerical calculations and plots, from which we determine the hydrogen diffusion coefficient, the desorption rate, the absorption parameter, the trap density, and the trap enthalpy from the permeation data of the steady flux and the time lag. The maximum error caused by the numerical calculations is less than 7%. © 2003 American Institute of Physics.
Show PACS
68.43.Mn Adsorption kinetics
66.30.J- Diffusion of impurities
Page 1 of 35 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Your Recent History Recent History Help

Recently Viewed

  1. Comparison of a density functional theory and a Hartree treatment of silicon quantum dot
  2. High-frequency impedance of driven superlattices
  3. Deposition kinetics on particles in a dusty plasma reactor
  4. Composition dependence of thermoelectric properties of AlPdRe icosahedral quasicrystals
  5. Large sonic band gaps in 12-fold quasicrystals
Go to AIP Home
Copyright © American Institute of Physics
close