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10 Feb 2003

Volume 82, Issue 6, pp. 841-996

Issue Cover Spotlight Figure

Appl. Phys. Lett. 82, 913 (2003); http://dx.doi.org/10.1063/1.1542686 (3 pages)

F. Gao and W. J. Weber
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Thermal stability of ion-irradiated InGaAs with (sub-) picosecond carrier lifetime

L. Joulaud, J. Mangeney, J.-M. Lourtioz, P. Crozat, and G. Patriarche

Appl. Phys. Lett. 82, 856 (2003); http://dx.doi.org/10.1063/1.1543231 (3 pages) | Cited 20 times

Online Publication Date: 4 February 2003

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Pump-probe experiments have been used to measure the (sub-) picosecond carrier lifetimes in Au+- and proton-irradiated InGaAs samples, subsequently annealed at various temperatures. For both types of irradiation, the carrier lifetime increases with the annealing temperature. After 600 °C annealing, the defects are totally recovered in proton-irradiated samples, whereas they are still present in Au+-irradiated samples. The defect annealing kinetics observed in proton-irradiated samples is described well by a Frenkel pair recombination model, thereby indicating the dominance of isolated point defects. In contrast, the model is not adapted to describe the thermal behavior of Au+-irradiation-induced defects that are clusters of point defects as observed via transmission electronic microscopy. It is clearly shown that heavy-ion irradiated InGaAs exhibits a much higher thermal stability than proton-irradiated InGaAs. © 2003 American Institute of Physics.
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68.60.Dv Thermal stability; thermal effects
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
61.72.Cc Kinetics of defect formation and annealing
61.72.J- Point defects and defect clusters
68.37.Lp Transmission electron microscopy (TEM)

Electron-beam-induced damage in wurtzite InN

K. A. Mkhoyan and J. Silcox

Appl. Phys. Lett. 82, 859 (2003); http://dx.doi.org/10.1063/1.1543642 (3 pages) | Cited 15 times

Online Publication Date: 4 February 2003

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Knock-on type damage with ejection of nitrogen atoms from a sample was observed in wurtzite InN during irradiation by 100 keV electron beam in scanning transmission electron microscope. Comparison of the measured integrated intensities of nitrogen K and indium M4,5 edges with calculated mass-loss provided a method to measure the energy of vacancy-enhanced displacement in InN for nitrogen atoms, which was found to be 4.6 eV. The results were also applied to predict the rate of electron beam induced damage that will occur in InN specimens with different thicknesses. © 2003 American Institute of Physics.
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61.80.Fe Electron and positron radiation effects
61.82.Fk Semiconductors
61.72.J- Point defects and defect clusters
68.49.Jk Electron scattering from surfaces

Direct observation of a concealed glass transition in a Mg–Ni–Nd metallic glass

Z. P. Lu, C. T. Liu, C. H. Kam, and Y. Li

Appl. Phys. Lett. 82, 862 (2003); http://dx.doi.org/10.1063/1.1544441 (3 pages) | Cited 4 times

Online Publication Date: 4 February 2003

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Glass transition and crystallization behavior of Mg75Ni10Nd15 metallic glass has been studied by a temperature-modulated differential scanning calorimeter (TMDSC) and a normal differential scanning calorimeter (DSC). The truly vitreous state of the as-spun Mg75Ni10Nd15 alloy was confirmed by the direct observation of the glass transition through TMDSC measurements, which was not perceptible in the normal DSC heating scans. It was concluded that the glass transition signal was concealed by the relatively strong concurrent signal of the primary crystallization. This was further confirmed by the fact that the glass transition was revealed by both TMDSC and DSC for the samples with negligible heat release from the primary crystallization. © 2003 American Institute of Physics.
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64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
61.43.Fs Glasses

Temperature dependence of the surface roughness evolution during hydrogenated amorphous silicon film growth

A. H. M. Smets, W. M. M. Kessels, and M. C. M. van de Sanden

Appl. Phys. Lett. 82, 865 (2003); http://dx.doi.org/10.1063/1.1543237 (3 pages) | Cited 35 times

Online Publication Date: 4 February 2003

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The scaling behavior of the surface morphology of hydrogenated amorphous silicon deposited from a SiH3 dominated plasma has been studied using atomic force microscopy and in situ ellipsometry. The observed substrate temperature dependence of growth exponent β reflects a crossover behavior from random deposition at 100 °C to a surface diffusion controlled smoothening around 250 °C to full surface relaxation around 500 °C. This crossover behavior has been reproduced by Monte Carlo simulations assuming a site dependent surface diffusion process, revealing an activation energy of ∼ 1.0 eV for the ruling surface smoothening mechanism. The implications for a-Si:H growth are discussed. © 2003 American Institute of Physics.
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68.55.-a Thin film structure and morphology
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Fx Diffusion; interface formation
68.37.Ps Atomic force microscopy (AFM)

Intraband absorptions in GaN/AlN quantum dots in the wavelength range of 1.27–2.4 μm

Kh. Moumanis, A. Helman, F. Fossard, M. Tchernycheva, A. Lusson, F. H. Julien, B. Damilano, N. Grandjean, and J. Massies

Appl. Phys. Lett. 82, 868 (2003); http://dx.doi.org/10.1063/1.1543238 (3 pages) | Cited 31 times

Online Publication Date: 4 February 2003

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GaN/AlN quantum-dot superlattices grown by molecular-beam epitaxy on silicon (111) or sapphire (0001) substrate have been investigated using high-resolution transmission electron microscopy, photoluminescence, and photo-induced absorption spectroscopy. Under interband excitation at λ ≈ 351 nm, three resonances are observed, respectively peaked at 2.1 μm (2.36 μm), 1.46 μm (1.69 μm), and 1.28 μm (1.27 μm) for the sample grown on silicon (sapphire) substrate. We show that the absorptions involve conduction-band interlevel transitions from the ground state to p-like or d-like states, and that their energy is governed mainly by the magnitude of the internal field in the GaN dots. © 2003 American Institute of Physics.
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78.67.Hc Quantum dots
73.21.La Quantum dots
78.55.Cr III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
68.37.Lp Transmission electron microscopy (TEM)

Orientation of self-assembled block copolymer cylinders perpendicular to electric field in mesoscale film

S. Elhadj, J. W. Woody, V. S. Niu, and R. F. Saraf

Appl. Phys. Lett. 82, 871 (2003); http://dx.doi.org/10.1063/1.1543253 (3 pages) | Cited 9 times

Online Publication Date: 4 February 2003

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The possibility of using self-assembled films of block polymers as templates to fabricate nanoscale structures for devices has attracted great attention towards this class of material. Self-assembly of a block copolymer can be directed by using an electric field to orient features (i.e., ∼10-nm-diam cylinders) parallel to the electric field, making the material more attractive as a nanoscale lithography mask. In this letter we describe an approach to influence the electric field orientation phenomena by interfacial effects. As a result, the 15-nm-diam polystyrene cylinders of the polystyrene–polyisoprene–polystyrene triblock copolymer orient perpendicular to the electric field. The described approach along with the previous method can produce a directed self-assembly to fabricate complex nanoscale structures with orthogonally oriented nanoscale width lines. © 2003 American Institute of Physics.
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81.16.Dn Self-assembly
68.47.Pe Langmuir-Blodgett films on solids; polymers on surfaces; biological molecules on surfaces
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
61.41.+e Polymers, elastomers, and plastics
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials

Microstructures of phases in indented silicon: A high resolution characterization

I. Zarudi, J. Zou, and L. C. Zhang

Appl. Phys. Lett. 82, 874 (2003); http://dx.doi.org/10.1063/1.1544429 (3 pages) | Cited 40 times

Online Publication Date: 4 February 2003

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This letter investigates the structural changes in monocrystalline silicon caused by microindentation with the aid of the high-resolution transmission electron microscopy. It shows that the transformation zone is amorphous when the maximum indentation load, Pmax, is low, but a crystalline phase of high-pressure R8/BC8 can appear when Pmax increases. The nanodeformation of the pristine silicon outside the transformation zone proceeds with the mechanical bending and distortion of the crystalline planes. Certain extent of plastic deformation took place due to dislocation slipping. The results seem to indicate that the shear stress component played an important role in the deformation of the transformation zone. © 2003 American Institute of Physics.
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62.20.F- Deformation and plasticity
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Dislocation-enhanced ionic conductivity of yttria-stabilized zirconia

Kazuya Otsuka, Akihide Kuwabara, Atsutomo Nakamura, Takahisa Yamamoto, Katsuyuki Matsunaga, and Yuichi Ikuhara

Appl. Phys. Lett. 82, 877 (2003); http://dx.doi.org/10.1063/1.1544440 (3 pages) | Cited 23 times

Online Publication Date: 4 February 2003

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The ionic conductivity of yttria-stabilized zirconia (YSZ) single crystals (10 mol %Y2O3–ZrO2) was enhanced by introducing high density of dislocations. YSZ single crystals were systematically deformed by compression tests at 1300 °C, and their electrical conductivity was measured by an AC impedance method. It was confirmed that a great number of dislocations were introduced in YSZ by the high-temperature deformation, and the density reached up to more than 8×1012 m−2, depending on the compression strains imposed on the samples. The electrical conductivity of the deformed samples was found to be larger than that of undeformed samples. Furthermore, samples with larger strains exhibited higher electrical conductivity, which indicates that dislocations generated by the plastic deformation play an important role to enhance the ionic conductivity of YSZ. © 2003 American Institute of Physics.
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66.30.H- Self-diffusion and ionic conduction in nonmetals
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
61.72.Lk Linear defects: dislocations, disclinations

Converse piezoelectric effect and photoelastic effect in InGaN/GaN multiple quantum wells

T. Y. Lin

Appl. Phys. Lett. 82, 880 (2003); http://dx.doi.org/10.1063/1.1543639 (3 pages) | Cited 10 times

Online Publication Date: 4 February 2003

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We present microphotoluminescence and microRaman measurements with different optical excitation intensities in InGaN/GaN multiple quantum wells (MQWs). When the optical excitation density was increased, the InGaN A1(LO) phonon was found to show a redshift in frequency and a blueshift in photoluminescence spectra has been observed. The change in the refractive index of MQWs was found to be strongly related to the blueshift of photoluminescence spectra and the redshift of the InGaN A1(LO) phonon. Our results firmly establish that a converse piezoelectric effect responsible for a considerable photoelastic effect (change in refractive index produced by a strain) arising from the optical modulation does exist in InGaN/GaN MQWs. © 2003 American Institute of Physics.
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78.67.De Quantum wells
77.65.Ly Strain-induced piezoelectric fields
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
78.55.Cr III-V semiconductors
73.21.Fg Quantum wells
78.30.Fs III-V and II-VI semiconductors
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Binding and surface diffusion of SiH3 radicals and the roughness of hydrogenated amorphous silicon

R. Dewarrat and J. Robertson

Appl. Phys. Lett. 82, 883 (2003); http://dx.doi.org/10.1063/1.1544439 (3 pages) | Cited 9 times

Online Publication Date: 4 February 2003

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Local density formalism pseudopotential calculations find that the growth radical SiH3 binds to the hydrogen-terminated (111)Si surface. The bound site is not the three-center Si–H–Si bridging site previously assumed. It has a direct Si–Si bond between the SiH3 and the surface Si, and the terminal hydrogen is displaced to a bond center of a lateral surface Si–Si bond. This site is more stable as the unpaired electron can delocalize over more Si–Si bonds. A bound site validates the standard model of the growth of hydrogenated amorphous silicon (a-Si:H) and microcrystalline Si, in which a mobile growth species allows surface diffusion and creates smooth surfaces. © 2003 American Institute of Physics.
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68.43.Jk Diffusion of adsorbates, kinetics of coarsening and aggregation
68.35.Fx Diffusion; interface formation
68.35.Ct Interface structure and roughness
61.50.Lt Crystal binding; cohesive energy
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
71.15.Dx Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction)
68.47.Fg Semiconductor surfaces
61.43.Dq Amorphous semiconductors, metals, and alloys

Acoustic nonlinearity parameter measurements in solids using the collinear mixing of elastic waves

Xavier Jacob, Christophe Barrière, and Daniel Royer

Appl. Phys. Lett. 82, 886 (2003); http://dx.doi.org/10.1063/1.1541100 (3 pages) | Cited 8 times

Online Publication Date: 4 February 2003

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An alternative method for measuring the nonlinearity parameter β of longitudinal acoustic waves propagating in solids is presented. The method is based on the detection of the phase modulation resulting from the parametric interaction between a high frequency acoustic wave and a lower frequency acoustic pulse. Results are reported for various materials: fused quartz, duraluminum, titanium, and polystyrene. © 2003 American Institute of Physics.
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62.30.+d Mechanical and elastic waves; vibrations
62.65.+k Acoustical properties of solids
43.25.Ed Effect of nonlinearity on velocity and attenuation
43.20.Gp Reflection, refraction, diffraction, interference, and scattering of elastic and poroelastic waves
43.20.Jr Velocity and attenuation of elastic and poroelastic waves
46.40.Cd Mechanical wave propagation (including diffraction, scattering, and dispersion)

Chemical composition and local structure of plasma enhanced chemical vapor-deposited Si nanodots and their embedding silica matrix

G. Dalba, N. Daldosso, P. Fornasini, R. Grisenti, L. Pavesi, F. Rocca, G. Franzò, F. Priolo, and F. Iacona

Appl. Phys. Lett. 82, 889 (2003); http://dx.doi.org/10.1063/1.1543641 (3 pages) | Cited 8 times

Online Publication Date: 4 February 2003

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X-ray absorption measurements in total electron yield mode have been carried out on Si nanodots embedded in amorphous silica produced by plasma enhanced chemical vapor deposition (PECVD). The amount of Si atoms composing the Si nanodots and the chemical composition of the amorphous host matrix has been determined thanks to the comparison with Rutherford backscattering spectrometry data. The influence of nitrogen, incorporated during the PECVD procedure, on the structure of the host silica matrix has been discussed. © 2003 American Institute of Physics.
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68.65.Hb Quantum dots (patterned in quantum wells)
81.07.Ta Quantum dots
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.70.Dm X-ray absorption spectra
52.77.Dq Plasma-based ion implantation and deposition
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
61.46.-w Structure of nanoscale materials

Nonlinear optical crystal-line writing in glass by yttrium aluminum garnet laser irradiation

Tsuyoshi Honma, Yasuhiko Benino, Takumi Fujiwara, Takayuki Komatsu, and Ryuji Sato

Appl. Phys. Lett. 82, 892 (2003); http://dx.doi.org/10.1063/1.1544059 (3 pages) | Cited 41 times

Online Publication Date: 4 February 2003

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Crystal lines with second-order optical nonlinearity have been successfully fabricated at the surface of 10Sm2O3.35Bi2O3.55B2O3 glass by continuous irradiation of Nd:YAG laser. The laser-induced crystalline phase was confirmed to be Bi0.7Sm0.3BO3 by x-ray diffraction measurements, and second-harmonic generation (SHG) from the phase was clearly observed. An array structure of crystal lines was fabricated by laser writing under automatic computer control, and Maker fringe patterns of SHG were observed, indicating that the direction of polarization in the structure with a crystal line array was parallel to the sample surface. In addition, we measured polarization optical microphotographs, and found uniform phase retardation for a whole length of crystal lines. It is strongly suggested from these results that crystal lines by laser irradiation are formed in single-domain crystalline phase (single crystal) with second-order nonlinearity. © 2003 American Institute of Physics.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.70.Ce Glasses, quartz
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
61.43.Fs Glasses
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Ms Insulators

Enhanced oxidation and segregation in plasma source ion implanted alloy

M. Bolduc and B. Terreault

Appl. Phys. Lett. 82, 895 (2003); http://dx.doi.org/10.1063/1.1544432 (3 pages) | Cited 2 times

Online Publication Date: 4 February 2003

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Segregation of surprising magnitude and depth was discovered in oxygen plasma-implanted Mg-containing Al alloys. In order to identify the respective roles of diffusional kinetics and oxidation energetics in the effect, pure Al and an Al–Mg–Zn–Cu–Cr alloy were implanted for various times, or oxidized in air, at 700 K. Examination of depth profiles and chemical states of O, Al, and Mg by x-ray photoelectron spectroscopy reveals a potent synergy between the chemical potential drive and the radiation-enhanced diffusion. © 2003 American Institute of Physics.
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61.72.up Other materials
52.77.Dq Plasma-based ion implantation and deposition
81.65.Mq Oxidation
64.75.-g Phase equilibria
79.60.Bm Clean metal, semiconductor, and insulator surfaces
66.30.Fq Self-diffusion in metals, semimetals, and alloys

Metalorganic molecular-beam epitaxy and characterization of GaAsNSe/GaAs superlattices emitting around 1.5-μm-wavelength region

K. Uesugi, I. Suemune, H. Machida, and N. Shimoyama

Appl. Phys. Lett. 82, 898 (2003); http://dx.doi.org/10.1063/1.1544656 (3 pages) | Cited 2 times

Online Publication Date: 4 February 2003

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GaAsNSe/GaAs superlattices (SLs) were grown on GaAs(001) substrates by metalorganic molecular-beam epitaxy. Strong photoluminesence (PL) emission around the 1.5-μm-wavelength region was observed from these SLs without thermal annealing, which suggests that high electron concentrations in GaAsNSe layers increase the radiative recombination rate, making the nonradiative recombination relatively unimportant. It is also demonstrated that (GaAsNSe/GaAs SLs)/(GaAsN/GaAsSb SLs)/GaAs heterostructures are effective to reduce the strain accumulation in the layers, which will also form effective separated confinement heterostructure. The temperature dependence of the PL peak intensity is drastically improved by combining the GaAsN/GaAsSb SLs with the GaAsNSe/GaAs SLs following this scheme. The PL peak intensity observed at 300 K was as large as 20% of that observed at 19 K. This improvement of the optical property will be attributed to the elimination of nonradiative defects by minimizing average strain in the samples. © 2003 American Institute of Physics.
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78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
68.65.Cd Superlattices
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Cr III-V semiconductors
73.21.Cd Superlattices
81.07.-b Nanoscale materials and structures: fabrication and characterization

Composite cathode based on yttria stabilized bismuth oxide for low-temperature solid oxide fuel cells

Changrong Xia, Yuelan Zhang, and Meilin Liu

Appl. Phys. Lett. 82, 901 (2003); http://dx.doi.org/10.1063/1.1542933 (3 pages) | Cited 25 times

Online Publication Date: 4 February 2003

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Composites consisting of silver and yttria stabilized bismuth oxide (YSB) have been investigated as cathodes for low-temperature honeycomb solid oxide fuel cells with stabilized zirconia as electrolytes. At 600 °C, the interfacial polarization resistances of a porous YSB–Ag cathode is about 0.3 Ω cm2, more than one order of magnitude smaller than those of other reported cathodes on stabilized zirconia. For example, the interfacial resistances of a traditional YSZ–lanthanum maganites composite cathode is about 11.4 Ω cm2 at 600 °C. Impedance analysis indicated that the performance of an YSB–Ag composite cathode fired at 850 °C for 2 h is severely limited by gas transport due to insufficient porosity. The high performance of the YSB–Ag cathodes is very encouraging for developing honeycomb fuel cells to be operated at temperatures below 600 °C. © 2003 American Institute of Physics.
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82.47.Ed Solid-oxide fuel cells (SOFC)
82.45.Fk Electrodes
81.05.Mh Cermets, ceramic and refractory composites
82.80.Fk Electrochemical methods

Photomodulated thermoreflectance detection of hydrogen at elevated temperatures: a detection limit

Andreas Othonos and Constantinos Christofides

Appl. Phys. Lett. 82, 904 (2003); http://dx.doi.org/10.1063/1.1543254 (3 pages) | Cited 2 times

Online Publication Date: 4 February 2003

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Laser photomodulated thermoreflectance has been used as a means of detecting, at elevated temperatures, low concentration of hydrogen using an optically thin film of palladium. Data indicate that concentrations as low as a few parts per billion can easily be detected at 100 °C. A semi-quantitative interpretation of the photothermal signal has been achieved using a Langmurian isothermic model. © 2003 American Institute of Physics.
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78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
82.80.Dx Analytical methods involving electronic spectroscopy
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
68.47.De Metallic surfaces

Nanoscale stiffness of individual dendritic molecules and their aggregates

Vladimir V. Tsukruk, Hennady Shulha, and Xiaowen Zhai

Appl. Phys. Lett. 82, 907 (2003); http://dx.doi.org/10.1063/1.1544056 (3 pages) | Cited 13 times

Online Publication Date: 4 February 2003

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We demonstrate that carefully designed micromapping of the surface stiffness with nanoscale resolution could reveal quantitative data on the elastic properties of compliant, dendritic organic molecules with nanoparticulate dimensions below 3 nm. Much higher elastic modulus was observed for individual, fourth generation dendritic molecules due to their more shape persistent conformation. Large, reversible, elastic deformation is a distinct characteristic of the nanomechanical response observed for individual dendritic molecules. Such a “rubbery” response could be an indication of spatial constraints imposed on vitrification of dendritic molecules tethered to the functionalized interface. Surprisingly, an increased stiffness was also found for the third generation dendritic molecules within long aggregates. © 2003 American Institute of Physics.
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62.25.-g Mechanical properties of nanoscale systems
62.20.D- Elasticity
61.43.Hv Fractals; macroscopic aggregates (including diffusion-limited aggregates)
61.46.-w Structure of nanoscale materials
36.20.Ey Conformation (statistics and dynamics)
64.70.Nd Structural transitions in nanoscale materials
61.41.+e Polymers, elastomers, and plastics
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition

Thermal conductivity of elemental crystalline silicon clathrate Si136

G. S. Nolas, M. Beekman, J. Gryko, G. A. Lamberton, T. M. Tritt, and P. F. McMillan

Appl. Phys. Lett. 82, 910 (2003); http://dx.doi.org/10.1063/1.1544640 (3 pages) | Cited 26 times

Online Publication Date: 4 February 2003

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The thermal conductivity and heat capacity of a guest-free polycrystalline silicon clathrate with the type-II hydrate crystal structure is reported. The magnitude of the thermal conductivity at room temperature is only slightly larger than that of vitreous silica, and is thirty times lower than that of diamond structured Si. The temperature dependence of the thermal conductivity of Si136 follows the well-known Debye form, and is dissimilar to that of clathrates with “guest” atoms inside their polyhedra. The Debye temperature of Si136, estimated from low temperature heat capacity measurements, is 470 K. The potential of guest-free clathrates for thermoelectric applications is discussed. © 2003 American Institute of Physics.
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66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
65.40.Ba Heat capacity
63.70.+h Statistical mechanics of lattice vibrations and displacive phase transitions

Atomic-level study of ion-induced nanoscale disordered domains in silicon carbide

F. Gao and W. J. Weber

Appl. Phys. Lett. 82, 913 (2003); http://dx.doi.org/10.1063/1.1542686 (3 pages) | Cited 9 times

Online Publication Date: 4 February 2003

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Atomic-level simulations have been employed to study the nanoscale disordering induced in 3C–SiC by energetic Si and Au ions (up to 50 keV). Topologically disordered nanoscale domains are generated with low frequency in the cascades produced by Au ions, whereas Si ions create only a few small defect clusters, with most defects being single interstitials and monovacancies. The structural image simulations of the nanoscale domains provide for atomic-level insights into disordered states. The simulations suggest that it is possible to design and fabricate nanoscale optoelectronic devices based on SiC using ion-beam-induced order–disorder transformation. © 2003 American Institute of Physics.
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61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
64.70.K- Solid-solid transitions
61.46.-w Structure of nanoscale materials
61.50.Ks Crystallographic aspects of phase transformations; pressure effects
61.72.J- Point defects and defect clusters

Photocurrent method for characterizing the interface of hydrophobically bonded Si wafers

L. S. Yu, P. Mages, D. Qiao, L. Jia, P. K. L. Yu, S. S. Lau, T. Suni, K. Henttinen, and I. Suni

Appl. Phys. Lett. 82, 916 (2003); http://dx.doi.org/10.1063/1.1544063 (3 pages) | Cited 1 time

Online Publication Date: 4 February 2003

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We report a simple and nondestructive photocurrent method for characterizing the bonding interface between two hydrophobically bonded Si wafers. The relationship of photocurrent versus wavelength was measured and analyzed. The direction of the photocurrent indicates the band-bending direction, and thus, the donor or acceptor nature of the interface states. The photocurrent is proportional to the electric field at the interface induced by band bending. Our results showed that the Si pairs bonded in air have much larger band bending at the interface than those bonded in dry nitrogen, and that both have donor-like interface states. © 2003 American Institute of Physics.
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73.20.At Surface states, band structure, electron density of states
72.40.+w Photoconduction and photovoltaic effects
85.30.De Semiconductor-device characterization, design, and modeling
81.05.Cy Elemental semiconductors
72.80.Cw Elemental semiconductors
68.47.Fg Semiconductor surfaces

GaN growth using a low-temperature GaNP buffer on sapphire by metalorganic chemical vapor deposition

M. Tsukihara, Y. Naoi, S. Sakai, and H. D. Li

Appl. Phys. Lett. 82, 919 (2003); http://dx.doi.org/10.1063/1.1544061 (3 pages) | Cited 4 times

Online Publication Date: 4 February 2003

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We developed a buffer layer to grow GaN epilayers by metalorganic chemical vapor deposition. The buffer layer consists of a thin GaN-rich GaNP layer deposited at low temperature (LT) (500 °C) on sapphire substrate, using phosphine (PH3) as the phosphorus source. For high-temperature GaN epilayers grown on this type of buffer, full-width at half maximum values from both (0002) and (10math2) x-ray rocking curves decrease as phosphorus composition in the GaNP buffer increases; a dislocation density observed by transmission electron microscopy is as low as 5×108 cm−2, which is a factor of 2 less compared to that in a conventional GaN buffer epilayer. These results reveal that LT GaNP can be used as an appropriate buffer for further improving quality of GaN-based films. © 2003 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
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