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12 Aug 2002

Volume 81, Issue 7, pp. 1157-1360

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Photoacoustic trace gas detection of ethane using a continuously tunable, continuous-wave optical parametric oscillator based on periodically poled lithium niobate

M. M. J. W. van Herpen, Shaocheng Li, S. E. Bisson, and F. J. M. Harren

Appl. Phys. Lett. 81, 1157 (2002); http://dx.doi.org/10.1063/1.1500410 (3 pages) | Cited 19 times

Online Publication Date: 5 August 2002

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A 1.2 W, continuous-wave, continuously-tunable, singly-resonant optical parametric oscillator (OPO) (idler tuning range 3.0–3.8 μm), pumped by a 10 W continuous-wave Nd:YAG laser, is used in combination with a photoacoustic cell for the detection of ethane. An intracavity solid-state etalon (thickness 400 μm) was used to stabilize the OPO cavity and could be used to mode-hop tune the idler wavelength over 10 cm−1. The usefulness of the system was demonstrated by determining a detection limit for ethane down to 10 parts per trillion. The selectivity was achieved by making a 24 GHz wide pump laser scan over the ethane absorption line at 2996.9 cm−1, after which a Lorentzian fit determined the total area of the absorption signal. Both area value and peak value proved to be linearly depending on the ethane concentration. © 2002 American Institute of Physics.
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82.80.Kq Energy-conversion spectro-analytical methods (e.g., photoacoustic, photothermal, and optogalvanic spectroscopic methods)
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
42.65.Yj Optical parametric oscillators and amplifiers

Use of polarization sensitivity for three-dimensional optical data storage in polymer dispersed liquid crystals under two-photon illumination

Dennis McPhail and Min Gu

Appl. Phys. Lett. 81, 1160 (2002); http://dx.doi.org/10.1063/1.1499988 (3 pages) | Cited 14 times

Online Publication Date: 5 August 2002

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We report on the use of the polarization-dependent fluorescence property in photorefractive polymer dispersed liquid crystals for three-dimensional (3D) optical data storage under two-photon absorption. The liquid crystals, which have optical anisotropy, exhibit an alignment-based fluorescence feature that depends on the polarization state of an excitation field. Such a polarization sensitivity can be confined to the small focal region under two-photon excitation, allowing the stable recording of a 3D bit array. A 3D data density of 204.8 Gbits/cm3 is achieved using ultrashort pulsed illumination at a wavelength of 900 nm. It is also demonstrated that the recorded data can be erased in bulk or as single bits and then rerecorded. © 2002 American Institute of Physics.
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42.70.Df Liquid crystals
42.70.Gi Light-sensitive materials
61.30.Pq Microconfined liquid crystals: droplets, cylinders, randomly confined liquid crystals, polymer dispersed liquid crystals, and porous systems
42.70.Ln Holographic recording materials; optical storage media
61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures
78.55.Bq Liquids

Effective index method for heterostructure-slab-waveguide-based two-dimensional photonic crystals

Min Qiu

Appl. Phys. Lett. 81, 1163 (2002); http://dx.doi.org/10.1063/1.1500774 (3 pages) | Cited 103 times

Online Publication Date: 5 August 2002

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The validity of the two-dimensional approximation by the effective index method for heterostructure-slab-waveguide-based two-dimensional photonic crystals is tested against the full-vectorial three-dimensional finite-difference time-domain calculations. A good agreement over a wide frequency range is obtained for the band structures of two-dimensional photonic crystals in a low-index-contrast heterostructure. For high-index-contrast heterostructures, the effective index method is still valid, but only for much narrower frequency range. © 2002 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.65.Wi Nonlinear waveguides

6 W InGaAsSb(Gd)/InAsSbP double-heterostructure diode lasers emitting at λ=3.3 μm

M. Aydaraliev, N. V. Zotova, S. A. Karandashov, B. A. Matveev, M. A. Remennyi, N. M. Stus’, G. N. Talalakin, W. W. Bewley, J. R. Lindle, and J. R. Meyer

Appl. Phys. Lett. 81, 1166 (2002); http://dx.doi.org/10.1063/1.1499219 (2 pages) | Cited 10 times

Online Publication Date: 5 August 2002

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An InGaAsSb/InAsSbP double-heterostructure laser (λ=3.3 μm) with Gd-doped active region exhibited 6 W (35 A and 150 ns) of output power in pulsed mode at 78 K. The power, spectral, and electrical characteristics are presented, along with their temperature dependences. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes

Achieving very-low-loss group velocity reduction without electromagnetically induced transparency

L. Deng, E. W. Hagley, M. Kozuma, D. Akamatsu, and M. G. Payne

Appl. Phys. Lett. 81, 1168 (2002); http://dx.doi.org/10.1063/1.1499995 (3 pages) | Cited 6 times

Online Publication Date: 5 August 2002

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A Raman method is studied experimentally for potential optical-wave group velocity reduction in resonant medium. Specifically, we show that the proposed method can achieve significant group velocity reduction comparable to the conventional electromagnetically induced transparency (EIT) method that had been exclusively used to date. In addition, we show that this method has a significantly lower loss compared to the EIT method, and has rich dynamics such as probe pulse narrowing. Such features have applications in the domain of telecommunication technology. © 2002 American Institute of Physics.
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42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency

Light scattering in transparent glass ceramics

S. Hendy

Appl. Phys. Lett. 81, 1171 (2002); http://dx.doi.org/10.1063/1.1499989 (3 pages) | Cited 25 times

Online Publication Date: 5 August 2002

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Transparent glass ceramic materials, with microstructures comprised of dispersed nanocrystallites in a residual glass matrix, offer the prospect of nonlinear optical properties. However, good transparency requires low optical scattering and low atomic absorption. The attenuation of light due to scattering (turbidity) will depend upon the difference in refractive index of the two phases and the size and distribution of crystals in the glass. Here, we model the glass ceramic as a late-stage phase-separated structure, and compute scattering in this model. We find that the turbidity follows a k8R7 relationship, where k is the wave vector of light in the glass ceramic and R is the average radius of the crystals in the glass. © 2002 American Institute of Physics.
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78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
61.46.-w Structure of nanoscale materials
42.65.-k Nonlinear optics

Terahertz frequency difference from vertically integrated low-temperature-grown GaAs photodetector

E. Peytavit, S. Arscott, D. Lippens, G. Mouret, S. Matton, P. Masselin, R. Bocquet, J. F. Lampin, L. Desplanque, and F. Mollot

Appl. Phys. Lett. 81, 1174 (2002); http://dx.doi.org/10.1063/1.1499517 (3 pages) | Cited 23 times

Online Publication Date: 5 August 2002

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We report on the development of a photoconductive detector based on low-temperature-grown GaAs which is vertically integrated with terahertz spiral antennas. A non steady-state velocity overshoot effect was expected in the photoresponse with a responsivity of 0.04 A/W at a bias voltage of 8 V. Photomixing experiments using two optical 0.8 μm beating lasers show a 3 dB bandwith of 700 GHz with a radiation power at terahertz frequency of 0.5 μW under 2×30 mW optical pumping. © 2002 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)

Ultrafast switch-off of an electrically pumped quantum-dot laser

A. V. Platonov, C. Lingk, J. Feldmann, M. Arzberger, G. Böhm, M.-C. Amann, and G. Abstreiter

Appl. Phys. Lett. 81, 1177 (2002); http://dx.doi.org/10.1063/1.1500431 (3 pages) | Cited 5 times

Online Publication Date: 5 August 2002

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We report on the subpicosecond switch-off of the emission of an electrically pumped quantum-dot (QD) laser with perturbation by a 100 fs optical pulse. The observed effect is in contrast to known ones for quantum-well laser diodes. This is explained by unique properties of the QDs, namely by the fast modal gain saturation and localization-enhanced intraband absorption. The QD laser response can be described in terms of hot carrier absorption in the barrier states via intraband optical transitions leading to the transient suppression of the laser mode and, hence, to the switch-off. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
42.60.Fc Modulation, tuning, and mode locking
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Effects of sampling and limited data in optical tomography

Vadim A. Markel and John C. Schotland

Appl. Phys. Lett. 81, 1180 (2002); http://dx.doi.org/10.1063/1.1495543 (3 pages) | Cited 14 times

Online Publication Date: 5 August 2002

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We consider the image reconstruction problem for optical tomography in the transmission geometry. We investigate the effects of sampling and limited data on this inverse problem and derive an explicit inversion which is computationally efficient and stable in the presence of noise. © 2002 American Institute of Physics.
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42.30.Wb Image reconstruction; tomography
87.63.L- Visual imaging
87.57.N- Image analysis
02.30.Zz Inverse problems
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Magnetic field effect on the sheath thickness in plasma immersion ion implantation

M. Keidar, O. R. Monteiro, A. Anders, and I. D. Boyd

Appl. Phys. Lett. 81, 1183 (2002); http://dx.doi.org/10.1063/1.1499516 (3 pages) | Cited 26 times

Online Publication Date: 5 August 2002

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The sheath thickness in plasma immersion ion implantation has been investigated in the presence of a transverse magnetic field. It has been found that the steady-state sheath thickness increases with increasing magnetic field strength. This result is in line with a simplified model of the sheath in which the steady-state sheath thickness is determined by the plasma density and ion velocity at the sheath edge. These results suggest that a magnetic field may be used to control the high-voltage sheath in plasma immersion ion implantation. © 2002 American Institute of Physics.
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52.40.Kh Plasma sheaths
52.77.Dq Plasma-based ion implantation and deposition
85.40.Ry Impurity doping, diffusion and ion implantation technology
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Photoluminescence of strained and relaxed multilayered Ge islands on Si(001)

E. Palange, L. Di Gaspare, A. Notargiacomo, G. Capellini, and F. Evangelisti

Appl. Phys. Lett. 81, 1186 (2002); http://dx.doi.org/10.1063/1.1500776 (3 pages) | Cited 2 times

Online Publication Date: 5 August 2002

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In this letter, we report on the optical properties of multistacked Ge quantum dots grown on Si(001). We demonstrate that the two emission bands observed in the photoluminescence spectra are related to the presence of strained and relaxed islands. Within both types of islands, the experimental findings support the hypothesis of the presence of quantum confining regions whose dimensions are governed by the strain relaxation process. © 2002 American Institute of Physics.
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78.67.Hc Quantum dots
78.55.Ap Elemental semiconductors
68.65.Hb Quantum dots (patterned in quantum wells)

Structure transformations and superhardness effects in V/Ti nanostructured multilayers

Junhua Xu, Masao Kamiko, Yaomin Zhou, Guanghong Lu, Ryoichi Yamamoto, Lihua Yu, and Isao Kojima

Appl. Phys. Lett. 81, 1189 (2002); http://dx.doi.org/10.1063/1.1500435 (3 pages) | Cited 9 times

Online Publication Date: 5 August 2002

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An anomalous enhancement of hardness has been found in the V/Ti nanostructured multilayer films, in which the constituent materials have the same elastic modulus. The high-resolution transmission electron microscopy results showed that the V layers take bcc structure at all modulation periods from 2.8 to 150.0 nm. The Ti layers are bcc structured at modulation periods less than 3.0 nm. The Ti layers are hcp structured at modulation periods of more than 5.9 nm. There is a Burgers orientation relation between the bcc V and the hcp Ti. Coherent stress hardening between the interfaces of bcc V and hcp Ti layers and the different crystal structures appear to be one likely reason for the hardness enhancement in V/Ti nanostructured multilayers. © 2002 American Institute of Physics.
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68.65.Ac Multilayers
68.60.Bs Mechanical and acoustical properties
64.70.Nd Structural transitions in nanoscale materials
68.35.Gy Mechanical properties; surface strains
61.46.-w Structure of nanoscale materials
81.07.Bc Nanocrystalline materials
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity

Evidence of ductile response of alumina ceramic under shock wave compression

E. B. Zaretsky and G. I. Kanel

Appl. Phys. Lett. 81, 1192 (2002); http://dx.doi.org/10.1063/1.1499992 (3 pages) | Cited 4 times

Online Publication Date: 5 August 2002

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An experimental technique for controlled variation of the transversal stress in specimens subjected to planar impact has been developed to study the inelastic response mode of materials under one-dimensional shock compression. That technique was employed in order to test alumina ceramic at zero and 0.3 GPa confining pressure. The results unambiguously exhibit the ductile response of the ceramic under conditions of one-dimensional shock compression. © 2002 American Institute of Physics.
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62.50.-p High-pressure effects in solids and liquids
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep

Influence of a thin GaAs cap layer on structural and optical properties of InAs quantum dots

Fariba Ferdos, Shumin Wang, Yongqiang Wei, Anders Larsson, Mahdad Sadeghi, and Qingxiang Zhao

Appl. Phys. Lett. 81, 1195 (2002); http://dx.doi.org/10.1063/1.1500778 (3 pages) | Cited 25 times

Online Publication Date: 5 August 2002

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In this letter we investigate the changes in the surface morphology and emission wavelength of InAs quantum dots (QDs) during initial GaAs encapsulation by atomic force microscopy and photoluminescence. The density (2.9×1010 cm−2) and height (7.9±0.4 nm) of the uncapped QDs decrease and saturate at 0.6×1010 cm−2 and 4 nm, respectively, after the deposition of 4 monolayers (MLs) of GaAs. A model for the evolution of surface morphology is proposed. Photoluminescence spectra of the surface dots show a wavelength shift from 1.58 to 1.22 μm when the GaAs capping layer thickness increases from 0 to 8 MLs. © 2002 American Institute of Physics.
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78.66.Fd III-V semiconductors
68.65.Hb Quantum dots (patterned in quantum wells)
78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
68.37.Ps Atomic force microscopy (AFM)
68.35.B- Structure of clean surfaces (and surface reconstruction)

Viscoelasticity of silica aerogels at ultrasonic frequencies

T. E. Gómez Álvarez-Arenas, F. R. Montero de Espinosa, M. Moner-Girona, E. Rodríguez, A. Roig, and E. Molins

Appl. Phys. Lett. 81, 1198 (2002); http://dx.doi.org/10.1063/1.1499225 (3 pages) | Cited 14 times

Online Publication Date: 5 August 2002

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In this letter, the possibility to use a technique based on the analysis of thickness resonances of air-surrounded aerogel plates at ultrasonic frequencies to obtain viscoelastic properties is investigated. These resonances were excited and sensed by airborne ultrasonic waves. Toward this purpose, specially designed air-coupled, high-sensitivity, and broadband piezoelectric transducers were used. Precise and simultaneous measurements of the velocity and attenuation of longitudinal and shear waves at different frequencies, as well as aerogel density, were obtained. It allowed us to afford a full characterization of the viscoelastic properties of these materials at ultrasonic frequencies. © 2002 American Institute of Physics.
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82.70.Gg Gels and sols
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products
43.38.Fx Piezoelectric and ferroelectric transducers
81.40.Jj Elasticity and anelasticity, stress-strain relations
81.70.Cv Nondestructive testing: ultrasonic testing, photoacoustic testing

Threading dislocation reduction via laterally overgrown nonpolar (11math0) a-plane GaN

M. D. Craven, S. H. Lim, F. Wu, J. S. Speck, and S. P. DenBaars

Appl. Phys. Lett. 81, 1201 (2002); http://dx.doi.org/10.1063/1.1498010 (3 pages) | Cited 84 times

Online Publication Date: 5 August 2002

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Threading dislocation density reduction of nonpolar (11math0) a-plane GaN films was achieved by lateral epitaxial overgrowth (LEO). We report on the dependence of morphology and defect reduction on crystallographic stripe orientation. Stripes aligned along [0001] and [math100], the most favorable a-plane GaN LEO stripe orientations, possessed well-behaved, symmetric morphologies. Threading dislocation reduction via mask blocking was observed by transmission electron microscopy for [math100] stripes which had optimal rectangular cross-sections. Cathodoluminescence studies showed increased light emission for the overgrown regions in comparison to the window regions. The extent of lateral overgrowth of these stripes was asymmetric due to the opposing polarities of the vertical c-plane sidewalls. Conversely, threading dislocations propagated into the symmetric overgrown regions of [0001] stripes which possessed coexisting inclined and vertical {10math0} facets. © 2002 American Institute of Physics.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.Fd III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
78.60.Hk Cathodoluminescence, ionoluminescence

Intrinsic tensile stress and grain boundary formation during Volmer–Weber film growth

Ashok Rajamani, Brian W. Sheldon, Eric Chason, and Allan F. Bower

Appl. Phys. Lett. 81, 1204 (2002); http://dx.doi.org/10.1063/1.1494459 (3 pages) | Cited 20 times

Online Publication Date: 5 August 2002

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The finite element calculations in this letter present a detailed picture of tensile stress evolution during island coalescence in polycrystalline films. Earlier models suggest that these stresses are produced only when islands initially coalesce. In contrast, our model predicts that stress evolution is an inherent part of the growth process when two neighboring surfaces grow together to form a grain boundary. This view of coalescence stress is also consistent with experimental observations. © 2002 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Aa Theory and models of film growth
61.72.Mm Grain and twin boundaries
02.70.Dh Finite-element and Galerkin methods

Structural and optical properties of InGaN/GaN layers close to the critical layer thickness

S. Pereira, M. R. Correia, E. Pereira, C. Trager-Cowan, F. Sweeney, K. P. O’Donnell, E. Alves, N. Franco, and A. D. Sequeira

Appl. Phys. Lett. 81, 1207 (2002); http://dx.doi.org/10.1063/1.1499220 (3 pages) | Cited 40 times

Online Publication Date: 5 August 2002

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In this work, we investigate structural and optical properties of metalorganic chemical vapor deposition grown wurtzite InxGa1−xN/GaN epitaxial layers with thicknesses that are close to the critical layer thickness (CLT) for strain relaxation. CLT for InxGa1−xN/GaN structures was calculated as a function of the InN content, x, using the energy balance model proposed by People and Bean [Appl. Phys. Lett. 47, 322 (1985)]. Experimentally determined CLT are in good agreement with these calculations. The occurrence of discontinuous strain relaxation (DSR), when the CLT is exceeded, is revealed in the case of a 120 nm thick In0.19Ga0.89N layer by x-ray reciprocal space mapping of an asymmetrical reflection. The effect of DSR on the luminescence of this layer is clear: The luminescence spectrum shows two peaks centered at ∼2.50 and ∼2.67 eV, respectively. These two components of the luminescence of the sample originate in regions of different strain, as discriminated by depth-resolving cathodoluminescence spectroscopy. DSR leads directly to the emergence of the second, lower-energy, peak. Based on this experimental evidence, it is argued that the appearance of luminescence doublets in InGaN is not evidence of “quantum dotlike In-rich” or “phase separated” regions, as commonly proposed. © 2002 American Institute of Physics.
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68.55.-a Thin film structure and morphology
78.66.Fd III-V semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
68.60.Bs Mechanical and acoustical properties
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances

Improved structure and properties of single-wall carbon nanotube spun fibers

Brigitte Vigolo, Philippe Poulin, Marcel Lucas, Pascale Launois, and Patrick Bernier

Appl. Phys. Lett. 81, 1210 (2002); http://dx.doi.org/10.1063/1.1497706 (3 pages) | Cited 72 times

Online Publication Date: 5 August 2002

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This letter describes a method to improve the alignment of single-wall carbon nanotubes in macroscopic fibers produced by a simple spinning process. By contrast to classical composite fibers, where the nanotubes are embedded in a polymeric matrix, they consist of an interconnected network of polymers and nanotubes. This network can be swollen and stretched when the fibers are immersed in an appropriate solvent. The nanotubes alignment, studied by x-ray scattering, is significantly improved by the treatment. The fiber Young’s modulus can also be increased by a factor of 4. © 2002 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
62.25.-g Mechanical properties of nanoscale systems
81.07.De Nanotubes
62.20.D- Elasticity
78.70.Ck X-ray scattering

Optical switching properties from isotherms of Gd and GdMg hydride mirrors

M. Di Vece, S. J. M. Zevenhuizen, and J. J. Kelly

Appl. Phys. Lett. 81, 1213 (2002); http://dx.doi.org/10.1063/1.1499765 (3 pages) | Cited 9 times

Online Publication Date: 5 August 2002

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Concentration–pressure isotherms were measured together with the optical transmission in polycrystalline Gd and GdMg thin-film switchable mirrors. Formation plateaus in GdMg alloys, corresponding to gadolinium dihydride and trihydride as well as magnesium dihydride have been found. From these, the formation enthalpies could be calculated. These results show that the GdMg alloys are phase separated. From the onset of the transmission we conclude that the formation of gadolinium trihydride is the final stage in the switching process. © 2002 American Institute of Physics.
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42.79.Bh Lenses, prisms and mirrors
82.60.Cx Enthalpies of combustion, reaction, and formation

Thermal contact conductance of actuated interfaces

Woo-Bin Song, Michael S. Sutton, and Joseph J. Talghader

Appl. Phys. Lett. 81, 1216 (2002); http://dx.doi.org/10.1063/1.1499518 (3 pages) | Cited 6 times

Online Publication Date: 5 August 2002

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The thermal contact conductance (TCC) of microactuated mechanical interfaces has been characterized using an electronic technique, where micromachined test structures were heated with a current and the TCC was inferred from the change in resistance. For every device tested, the TCC was higher in vacuum than in air. This is in stark contrast to the behavior of bulk interfaces, and several experiments suggest that it may be the result of a decreased solid–solid contact area in air caused by the pressure of the interstitial gas. The average effective TCC of a polysilicon/nitride interface brought together by electrostatic actuation varies about values of 6.0×104 W/(K m2) in air and 9.5×104 W/(K m2) under vacuum for applied pressures of 1 MPa. These values are significantly higher than commonly reported for nonmetallic materials and probably reflect the very smooth surfaces of deposited thin films. © 2002 American Institute of Physics.
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66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
46.55.+d Tribology and mechanical contacts
68.35.Ct Interface structure and roughness
73.40.Cg Contact resistance, contact potential

Proposed model for calculating the standard formation enthalpy of binary transition-metal systems

R. F. Zhang and B. X. Liu

Appl. Phys. Lett. 81, 1219 (2002); http://dx.doi.org/10.1063/1.1499510 (3 pages) | Cited 21 times

Online Publication Date: 5 August 2002

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In this letter, we present a proposed model for calculating the standard formation enthalpy of binary transition-metal systems by adding a prefactor S(c) to the well-documented formula developed by Miedema. The main idea is to take into account the significant effect of the atomic size difference on the contact surface while two dissimilar metals approaching together. Employing this model, the standard formation enthalpies of some 260 intermetallic compounds were calculated and compared with the experimentally measured data. It was found that the precision of the calculated values by the proposed model could be improved 13%–65% and that statistically, over 95% of the calculated values were in agreement with the experimental ones within an error of ±23 kJ/mol, while employing the Miedema’s formula the agreement was about 80%. © 2002 American Institute of Physics.
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82.60.Cx Enthalpies of combustion, reaction, and formation

Electric-field-induced birefringence in LiNbO3 measured by generalized transmission ellipsometry

G. E. Jellison, C. O. Griffiths, and D. E. Holcomb

Appl. Phys. Lett. 81, 1222 (2002); http://dx.doi.org/10.1063/1.1498497 (3 pages) | Cited 8 times

Online Publication Date: 5 August 2002

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Transmission generalized ellipsometry has been used to measure electric-field-induced birefringence in LiNbO3. By stepping an imaging lens over the end of an optical fiber attached to the detector, images of the retardation, fast axis, diattenuation, and depolarization can be obtained with a resolution of ∼ 31 μm. It is shown that the retardation and the fast axis in z-cut LiNbO3 under bias is not constant throughout the material, but can vary as much as a factor of 2. Furthermore, this retardation is a function of the magnitude and duration of the applied voltage. © 2002 American Institute of Physics.
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78.20.Fm Birefringence
78.20.Jq Electro-optical effects

Quantification of substitutional carbon loss from Si0.998C0.002 due to silicon self-interstitial injection during oxidation

M. S. Carroll and J. C. Sturm

Appl. Phys. Lett. 81, 1225 (2002); http://dx.doi.org/10.1063/1.1500411 (3 pages) | Cited 9 times

Online Publication Date: 5 August 2002

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The empirical reaction of substitutional carbon with silicon self-interstitials in Si0.998C0.002 layers pseudomorphically grown on Si (100) substrates has been quantified at 850 °C. During annealing of a sample with a thin Si0.998C0.002 layer capped with a thin crystalline silicon layer, in either oxygen or nitrogen ambient, carbon diffuses from the surface edge of the Si0.998C0.002 layer towards and out of the silicon surface. The extra number of carbon atoms lost during oxidation is found equal to the number of silicon interstitials injected by the oxidation process, strongly suggesting that each substitutional carbon reacts with a single self-interstitial to form a mobile interstitial carbon, whereby it diffuses to the surface. The mechanism appears the same in Si1−x−yGexCy and Si1−xCx films. © 2002 American Institute of Physics.
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81.65.Mq Oxidation
61.72.J- Point defects and defect clusters
61.72.Cc Kinetics of defect formation and annealing
66.30.J- Diffusion of impurities

Comparison of the birefringence in an azobenzene-side-chain copolymer induced by pulsed and continuous-wave irradiation

Věra Cimrová, Dieter Neher, Ralf Hildebrandt, Manuel Hegelich, Arend von der Lieth, Gerd Marowsky, Rainer Hagen, Sergej Kostromine, and Thomas Bieringer

Appl. Phys. Lett. 81, 1228 (2002); http://dx.doi.org/10.1063/1.1499766 (3 pages) | Cited 13 times

Online Publication Date: 5 August 2002

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A comparative study of photoinduced birefringence in azobenzene-side-chain copolymers under continuous-wave (cw) and pulsed irradiation is presented. Absolute refractive index changes were determined by the attenuated total reflection spectroscopy. We clearly demonstrated that pulsed, similarly to cw, irradiation induces a three-dimensional reorientation of azobenzene chromophores. For the same light dose, pulsed irradiation using ns pulses of appropriate pulse energy led to higher values of birefringence, which can be attributed to a cooperative motion of azobenzene side chains and thermal effects induced by the laser pulses. © 2002 American Institute of Physics.
Show PACS
78.20.Fm Birefringence
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
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