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Journal of Applied Physics

Issue 3 • Date Aug 2009

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Displaying Results 1 - 25 of 92
  • Photonic bands in two-dimensional metallodielectric photonic crystals composed of metal coated cylinders

    Page(s): 033101 - 033101-7
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    Photonic bands in two-dimensional metallodielectric (MD) periodic systems composed of metal coated cylinders are investigated theoretically based on frequency dependent plane-wave expansion method. For the case of E-polarization, although the thickness of metal coating is less than half of the cylinder’s radius, most of MD photonic bands are the same as photonic bands composed of pure metal cylinders. This property provides us with a way to substitute metal photonic crystals with MD photonic crystals in many applications. In addition, flatbands are discovered in MD photonic band structures, which can be tuned by changing the thickness of metal coating while other photonic bands do not change their positions. For the case of H-polarization, the lowest frequency band gap (between the first and the second bands) can open up when the thickness of metal coating is thick enough. According to approximate calculation based on Maxwell–Garnett type effective medium theory and comparison with recent studies on three-dimensional MD photonic band structures, we predict that the lowest frequency band gap is not because of Bragg scattering but result from the individual metal coated dielectric cylinders, so that the gap is independent on geometry of photonic crystal lattices. Then, numerical calculation validates that our prediction is right. View full abstract»

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  • Low-voltage onset of electroluminescence in nanocrystalline-Si/SiO2 multilayers

    Page(s): 033104 - 033104-8
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    Thin film metal-oxide-semiconductor light emitting devices (LEDs) based on nanocrystalline silicon multilayer structure were grown by plasma-enhanced chemical vapor deposition. Room temperature electroluminescence was studied under direct current and time-resolved pulsed-current injection schemes. Multilayer LEDs operating at voltages below 5 V and electroluminescence turn-on voltage of 1.4–1.7 V are demonstrated. The turn-on voltage is less than 3.2 V which corresponds to the barrier height at the silicon oxide interface for electrons. Electrical injection in the multilayer LED is controlled by direct tunneling of electrons and holes among silicon nanocrystals. This injection regime is different than the Fowler–Nordheim tunneling that controls the electron injection in single thick layer LED operating at high voltages. A comparison of the power efficiency for the multilayer based LED and a similar single thick layer LED shows larger power efficiency for the former than for the second. Our results open new directions in the development of highly efficient room temperature silicon based LED. View full abstract»

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  • Thermoluminescence properties of carbon doped Y3Al5O12 (YAG) crystal

    Page(s): 033105 - 033105-5
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    In this work, carbon doped yttrium aluminum garnet (YAG) (YAG:C) crystal was grown by the temperature gradient technique in a reducing atmosphere. The optical and thermoluminescence (TL) properties of the as-grown YAG:C crystal were investigated. Four absorption bands at 235, 255, 298, and 370 nm and a main blue emission peak at 400 nm are observed in the YAG:C crystal. The absorption coefficients of the bands at 235 and 370 nm, which are associated with the F+-center, increase sharply in YAG crystal by the introduction of carbon. As-grown YAG:C crystal shows high TL sensitivity, and three main glow peaks at 390 K (P1), 465 K (P2), 524 K (P3) and two weak glow peaks at 580 and 625 K are found. The TL dose responses of the three main glow peaks show linear-supralinear characteristic, and wide linearity dose response are found in P1 and P2 glow peaks. The temperature position and TL intensity of three main glow peaks show a strong dependence of heating rate in YAG:C crystal. View full abstract»

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  • Theoretical investigation of 1.3 μm dots-under-a-well and dots-in-a-well InAs/GaAs quantum dot vertical-cavity surface-emitting lasers

    Page(s): 033106 - 033106-8
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    The threshold characteristic and output power of 1.3 μm quantum dot (QD) vertical-cavity surface-emitting laser (VCSEL) with dots-under-a-well and dots-in-a-well InAs/GaAs QD structures are investigated by using rate equation model and output power model. The influence of VCSEL and QD structures on the modal gain of VCSEL is analyzed. Threshold current density, quantum efficiency, and characteristic temperature are simulated for different QD structures. The dependence of output power of 1.3 μm QD VCSEL on the QD structure, threshold current, quantum efficiency, and oxide-aperture size is investigated in detail. View full abstract»

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  • Control of plasma uniformity in a capacitive discharge using two very high frequency power sources

    Page(s): 033301 - 033301-7
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    Very high frequency (VHF) capacitively coupled plasma (CCP) discharges are being employed for dielectric etching due to VHF’s various benefits including low plasma potential, high electron density, and controllable dissociation. If the plasma is generated using multiple VHF sources, one can expect that the interaction between the sources can be important in determining the plasma characteristics. The effects of VHF mixing on plasma characteristics, especially its spatial profile, are investigated using both computational modeling and diagnostic experiments. The two-dimensional plasma model includes the full set of Maxwell equations in their potential formulation. The plasma simulation results show that electron density peaks at the center of the chamber at 180 MHz due to the standing electromagnetic wave. Electrostatic effects at the electrode edges tend to get stronger at lower VHFs such as 60 MHz. When the two rf sources are used simultaneously and power at 60 MHz is gradually increased, the ion flux becomes uniform and then transitions to peak at electrode edge. These results are corroborated by Langmuir probe measurements of ion saturation current. VHF mixing is therefore an effective method for dynamically controlling plasma uniformity. The plasma is stronger and more confined when the 60 MHz source is connected to the smaller bottom electrode compared to the top electrode. View full abstract»

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  • Plasma parameters of pulsed-dc discharges in methane used to deposit diamondlike carbon films

    Page(s): 033302 - 033302-11
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    Here we approximate the plasma kinetics responsible for diamondlike carbon (DLC) depositions that result from pulsed-dc discharges. The DLC films were deposited at room temperature by plasma-enhanced chemical vapor deposition (PECVD) in a methane (CH4) atmosphere at 10 Pa. We compared the plasma characteristics of asymmetric bipolar pulsed-dc discharges at 100 kHz to those produced by a radio frequency (rf) source. The electrical discharges were monitored by a computer-controlled Langmuir probe operating in time-resolved mode. The acquisition system provided the intensity-voltage (I-V) characteristics with a time resolution of 1 μs. This facilitated the discussion of the variation in plasma parameters within a pulse cycle as a function of the pulse waveform and the peak voltage. The electron distribution was clearly divided into high- and low-energy Maxwellian populations of electrons (a bi-Maxwellian population) at the beginning of the negative voltage region of the pulse. We ascribe this to intense stochastic heating due to the rapid advancing of the sheath edge. The hot population had an electron temperature Tehot of over 10 eV and an initial low density nehot which decreased to zero. Cold electrons of temperature Tecold∼1 eV represented the majority of each discharge. The density of cold electrons necold showed a monotonic increase over time within the negative pulse, peaking at almost 7×1010 cm-3, corresponding to the cooling of the hot electrons. The plasma potential Vp of ∼30 - ;V underwent a smooth increase during the pulse and fell at the end of the negative region. Different rates of CH4 conversion were calculated from the DLC deposition rate. These were explained in terms of the specific activation energy Ea and the conversion factor xdep associated with the plasma processes. The work deepens our understanding of the advantages of using pulsed power supplies for the PECVD of hard metallic and protective coatings for industrial applications (optics, biomedicine, and electronics). View full abstract»

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  • Effect of radio frequency discharge power on dusty plasma parameters

    Page(s): 033303 - 033303-6
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    The parameters of a two-dimensional dusty plasma consisting of six, 9 μm diameter particles trapped inside a radio frequency (rf) plasma sheath have been measured as a function of rf power in a 13.5 mtorr (1.8 Pa) argon discharge. The center-of-mass and breathing frequencies are found by projecting the cluster’s Brownian motion onto the associated normal mode. The center-of-mass frequency (i.e., radial confinement) is insensitive to rf power. The Debye shielding parameter κ, as found from the breathing frequency, increases from ≈0.5 to 2 as the square root of rf power. The Debye length decreases from ≈2.7 to 0.7 mm as the inverse of the square root of rf power. The average particle charge q≈-17 000e is effectively independent of rf power. These results are consistent with an electron temperature that is independent of rf power and an ion density that is directly proportional to rf power, where the Debye length is determined by the ion density in combination with the electron temperature. View full abstract»

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  • Mechanism of laser and rf plasma in vibrational nonequilibrium CON2 gas mixture

    Page(s): 033304 - 033304-7
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    This paper investigates the mechanism of plasma created by focused CO laser and rf electric field. The plasma is created in a CO/N2 environment, at a total pressure of 600 torr. Ionization of the gases occurs by an associative ionization mechanism, in collisions of two highly vibrationally excited molecules. These highly vibrationally excited states are populated by resonance absorption of the CO radiation followed by anharmonic vibration-vibration (V-V) pumping. Moreover N2 also becomes vibrationally excited due to collisions with vibrationally excited CO. The coupled rf reduced electric field E/N is sufficiently low to prevent electron impact ionization that may create plasma individually, so when a subbreakdown rf field is applied to the plasma, collisions between the free electrons heated by the field and the diatomic species create additional vibrational excitation both in the region occupied by the CO laser beam and outside of the laser beam region. The numerical results show plasma created in both regions (in and out of the CO laser beam region) with the associative ionization mechanism. This suggests a method for creating a stable nonequilibrium plasma. The calculation result is verified by comparison the synthetic spectrum to a measured one. View full abstract»

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  • Quantum cascade laser investigations of CH4 and C2H2 interconversion in hydrocarbon/H2 gas mixtures during microwave plasma enhanced chemical vapor deposition of diamond

    Page(s): 033305 - 033305-15
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    CH4 and C2H2 molecules (and their interconversion) in hydrocarbon/rare gas/H2 gas mixtures in a microwave reactor used for plasma enhanced diamond chemical vapor deposition (CVD) have been investigated by line-of-sight infrared absorption spectroscopy in the wavenumber range of 1276.5-1273.1 cm-1 using a quantum cascade laser spectrometer. Parameters explored include process conditions [pressure, input power, source hydrocarbon, rare gas (Ar or Ne), input gas mixing ratio], height (z) above the substrate, and time (t) after addition of hydrocarbon to a pre-existing Ar/H2 plasma. The line integrated absorptions so obtained have been converted to species number densities by reference to the companion two-dimensional (r,z) modeling of the CVD reactor described in Mankelevich etal [J. Appl. Phys. 104, 113304 (2008)]. The gas temperature distribution within the reactor ensures that the measured absorptions are dominated by CH4 and C2H2 molecules in the cool periphery of the reactor. Nonetheless, the measurements prove to be of enormous value in testing, tensioning, and confirming the model predictions. Under standard process conditions, the study confirms that all hydrocarbon source gases investigated (methane, acetylene, ethane, propyne, propane, and butane) are converted into a mixture dominated by CH4 and C2H2. The interconversion between these two species is high- ly dependent on the local gas temperature and the H atom number density, and thus on position within the reactor. CH4C2H2 conversion occurs most efficiently in an annular shell around the central plasma (characterized by 1400≪Tgas≪2200 K), while the reverse transformation C2H2CH4 is favored in the more distant regions where Tgas≪1400 K. Analysis of the multistep interconversion mechanism reveals substantial net consumption of H atoms accompanying the CH4C2H2 conversion, whereas the reverse C2H2CH4 process only requires H atoms to drive the reactions; H atoms are not consumed by the overall conversion. View full abstract»

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  • Temporal evolution of the laser-induced plasma generated by IR CO2 pulsed laser on carbon targets

    Page(s): 033306 - 033306-11
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    Time-resolved optical emission analysis was carried out for the plasma plume, produced by high-power tunable IR CO2 pulsed laser ablation of graphite, at λ=10.591 μm and in a regime of relatively high laser fluences (123–402 J/cm2). Wavelength-dispersed spectra of the plasma plume, at medium-vacuum conditions (4 Pa) and at 9.0 mm from the target, show ionized species (C+, C2+, C3+, C4+, N2+ , N+, and O+), neutral atoms (C, H, N, and O), and neutral diatomic molecules (C2, CN, OH, CH, and N2). In this work, we focus our attention on the temporal evolution of different atomic/ionic and molecular species over a broad spectral range from 190 to 1000 nm. The results show a faster decay for ionic fragments than for neutral atomic and molecular species. The velocity and kinetic energy distributions for different species were obtained from time-of-flight measurements using time-resolved optical emission spectroscopy. Possible mechanisms for the production of these distributions are discussed. Excitation temperature, electron density, and vibrational temperature in the laser-induced plasma were estimated from the analysis of spectral data at various times from the laser pulse incidence. View full abstract»

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  • Influence of electron velocity distribution on the plasma expansion features

    Page(s): 033309 - 033309-5
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    Collisionless plasma expansion into vacuum is addressed emphasizing on the kinetic effects associated with the plasma electrons. It is an important issue since there are situations in which the plasmas are in nonequilibrium state. Thus, the electron distribution function (DF) that is generally non-Maxwellian has to be modeled. For this purpose, the generalized Lorentzian (kappa) DF is used to simulate the electron DF. The Maxwellian and kappa distributions differ substantially in a high-energy tail. Thus, the electron dynamics is studied by the Vlasov equation. Neglecting the ion temperatures, fluid equations are used for them. It is shown that by increasing the population of energetic electrons, the expansion takes place faster, the resulting electric field is stronger, and the ions are accelerated to higher energy. View full abstract»

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  • Experimental scaling law for mass ablation rate from a Sn plasma generated by a 1064 nm laser

    Page(s): 033310 - 033310-5
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    The ablation depth in planar Sn targets irradiated with a pulsed 1064 nm laser was investigated over laser intensities from 3×1011 to 2×1012 W/cm2. The ablation depth was measured by irradiating a thin layer of Sn evaporated onto a Si wafer, and looking for signatures of Si ions in the expanding plasma with spectroscopic and particle diagnostics. It was found that ablation depth scales with laser intensity to the (5/9)th power, which is consistent with analytical models of steady-state laser ablation, as well as empirical formulae from previous studies of mass ablation rate in overlapping parameter space. In addition, the scaling of mass ablation rate with atomic number of the target as given by empirical formulae in previous studies using targets such as C and Al, are shown to remain valid for the higher atomic number of the target (Z=50) used in these experiments. View full abstract»

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  • First-principles study of structural, thermodynamic, elastic, and magnetic properties of Cr2GeC under pressure and temperature

    Page(s): 033501 - 033501-7
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    The dependences of the structural, thermodynamic, elastic, and magnetic properties of Cr2GeC on pressure and temperature were investigated with the quasiharmonic Debye model and the first-principles method based on the density functional theory. Our calculated data, which were obtained at different pressures and temperatures, are in good agreement with the experimental results. Cr2GeC is mechanically stable in the pressure range of 0–50 GPa and the compressibility along the a axis is greater than along the c axis indicating that the presence of C in the interstitial sites of the Cr octahedra can enhance the stability of the Cr–Ge bonds. It is also found that the antiferromagnetic state is the ground state of Cr2GeC and the total induced magnetic moment of the metastable ferromagnetic state decreases with pressure and completely vanishes at about 25 GPa. View full abstract»

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  • Power modulation based fiber-optic loop-sensor having a dual measurement range

    Page(s): 033502 - 033502-5
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    A fiber-optic sensor is investigated in this work for potential applications in structural health monitoring. The sensor, called fiber-loop-sensor, is based on bending an optical fiber beyond a critical radius to obtain intensity losses and calibrating the losses with respect to the applied force or displacement. Additionally, in the present case, the use of single-mode optical fibers allows the appearance of several resonance peaks in the transmitted power-displacement graph. The intensity of one of these resonances can be tracked in a narrow range to obtain high sensitivity. Experimental results show that the resolution of 10-4 N for force and 10-5 m for displacement can be obtained in these sensors. The sensors are calibrated for various loop radii and for various loading rates. They are also tested under loading-unloading conditions for over 104 cycles to observe their fatigue behavior. The sensors show very repeatable response and no degradation in performance under these test conditions. Simple construction and instrumentation, high sensitivity, and low cost are the advantages of these sensors. View full abstract»

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  • Water diffusion and fracture behavior in nanoporous low-k dielectric film stacks

    Page(s): 033503 - 033503-8
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    Among various low-dielectric constant (low-k) materials under development, organosilicate glasses (OSGs) containing nanometer-size pores are leading candidates for use as intrametal dielectrics in future microelectronics technologies. In this paper, we investigate the direct impact of water diffusion on the fracture behavior of film stacks that contain porous OSG coatings. We demonstrate that exposure of the film stacks to water causes significant degradation of the interfacial adhesion energy, but that it has negligible effect on the cohesive fracture energy of the nanoporous OSG layer. Isotope tracer diffusion experiments combined with dynamic secondary ion mass spectroscopy show that water diffuses predominantly along the interfaces, and not through the porous films. This unexpected result is attributed to the hydrophilic character of the interfaces. View full abstract»

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  • Chemical and physical sputtering effects on the surface morphology of carbon films grown by plasma chemical vapor deposition

    Page(s): 033504 - 033504-8
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    We have studied the influence of chemical and physical sputtering on the surface morphology of hydrogenated carbon films deposited on silicon substrates by bias-enhanced electron cyclotron resonance chemical vapor deposition. Atomic force microscopy based power spectrum density (PSD) and roughness analysis have been used to investigate the film morphology. This study has been possible due to the appropriate choice of the experimental variables, in particular, gas mixture, resulting in either nitrogen-free (a-C:H) or nitrogenated carbon (a-CN:H) films, and substrate bias (Vb). Under these conditions, chemical sputtering is present for a-CN:H deposition but it is negligible for a-C:H film growth, while physical sputtering processes appear for both systems for Vb≤-85 V. When physical sputtering does not operate, the film growth with simultaneous chemical sputtering leads to a characteristic a-CN:H granular surface morphology. Furthermore, PSD analysis reveals that a spatial correlation of the a-CN:H film surface roughness, up to distances ∼300 nm, becomes a fingerprint of the coexistence of growth and chemical erosion processes on the film morphology. However, once physical sputtering takes place, the influence of chemical sputtering by reactive nitrogen species on the final surface morphology becomes negligible and both a-CN:H and a-C:H film morphologies are ultrasmooth. View full abstract»

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  • Charged particle-display

    Page(s): 033505 - 033505-13
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    An optical shutter based on charged particles is presented. The output light intensity of the proposed device has an intrinsic dependence on the interparticle spacing between charged particles, which can be controlled by varying voltages applied to the control electrodes. The interparticle spacing between charged particles can be varied continuously and this opens up the possibility of particle based displays with continuous grayscale. View full abstract»

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  • Measurement and calculation of surface tension for undercooled liquid nickel and its alloy

    Page(s): 033506 - 033506-4
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    The surface tensions of metastable undercooled liquid nickel and its alloy are experimentally measured and theoretically calculated by electromagnetic levitation oscillating droplet method and molecular dynamics method, respectively. The experimental undercoolings for liquid Ni and Ni90.1Si9.9 alloy are 201 and 206 K, whereas the calculated undercoolings are up to 426 and 323 K. The measured surface tension displays the same undercooling dependence as the molecular dynamics calculation. The surface tension increases linearly with the increase in undercooling and no break occurs at the melting temperature. It is found that the correlation of surface tension with temperature predicted by molecular dynamics calculation agrees with the experimental results for both pure Ni and its alloy. View full abstract»

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  • Real time synchrotron x-ray diffraction measurements to determine material strength of shocked single crystals following compression and release

    Page(s): 033513 - 033513-9
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    We present a method to use real time, synchrotron x-ray diffraction measurements to determine the strength of shocked single crystals following compression and release during uniaxial strain loading. Aluminum and copper single crystals shocked along [111] were examined to peak stresses ranging from 2 to 6 GPa. Synchrotron x rays were used to probe the longitudinal lattice strains near the rear free surface (16 and 5 μm depths for Al and Cu, respectively) of the metal crystals following shock compression and release. The 111 diffraction peaks showed broadening indicating a heterogeneous microstructure in the released state. The diffraction peaks also shifted to lower Bragg angles relative to the ambient Bragg angle; the magnitude of the shift increased with increasing impact stress. The Bragg angle shifts and appropriate averaging procedures were used to determine the macroscopic or continuum strength following compression and release. For both crystals, the strengths upon release increased with increasing impact stress and provide a quantitative measure of the strain hardening that occurs in Al(111) and Cu(111) during the shock and release process. Our results for Al(111) are in reasonable agreement with a previous determination based solely on continuum measurements. Two points are noteworthy about the developments presented here: Synchrotron x rays are needed because they provide the resolution required for analyzing the data in the released state; the method presented here can be extended to the shocked state but will require additional measurements. View full abstract»

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  • Crystal structure, electric field gradient, and electronic charge densities in ReB2: A single crystal x-ray, 11B nuclear magnetic resonance, and first-principles study

    Page(s): 033514 - 033514-5
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    We have grown a single crystal of ReB2 and refined its crystal structure. Our structural studies confirmed the hexagonal structure (space group P63/mmc) with lattice parameters a=2.8982(1) Å and c=7.4723(3) Å. We also report the observation of first order satellites in the 11B nuclear magnetic resonance, which indicated the presence of a nonzero quadrupole coupling frequency, νQ=276±3 kHz, and an asymmetry parameter η=0 at the boron atom sites. These values are in excellent agreement with electric-field-gradient (EFG) tensor calculations based on first principles. These calculations showed that the principal axis of the most negative EFG-tensor component, VZZ, is parallel to the c-axis of the crystal. This behavior is in agreement with the observed excess of B pz charge (c direction) over the px and py charges and is related to stronger metal-boron bonds compared to previously studied YB12 and LaB6, where the B–B bonds are stronger. Finally, the bonding properties of ReB2 are discussed in terms of densities of states, valence-electron densities, and partial charges. View full abstract»

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  • Annealing effects on the optical properties of semiconducting boron carbide

    Page(s): 033515 - 033515-4
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    Infrared vibrations of as-deposited and annealed semiconducting boron carbide thin films were investigated by midinfrared spectroscopic ellipsometry. The strong boron-hydrogen resonance at ∼2560 cm-1 in as-deposited films reveals considerable hydrogen incorporation during plasma-enhanced chemical vapor deposition. Extended annealing at 600 °C caused significant reduction in film thickness, substantial reduction of boron-hydrogen bond resonance absorption, and development of distinct blue-shifted boron-carbon and icosahedral vibration mode resonances. Our findings suggest that annealing results in substantial loss of hydrogen and in development of icosahedral structure, accompanied by strain relaxation and densification. View full abstract»

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  • Large-area monocrystalline silicon thin films by annealing of macroporous arrays: Understanding and tackling defects in the material

    Page(s): 033516 - 033516-10
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    A concept that could provide a thin monocrystalline-silicon absorber layer without resorting to the expensive step of epitaxy would be very appealing for reducing the cost of solar cells. The empty-space-in-silicon technique by which thin films of silicon can be formed by reorganization of regular arrays of cylindrical voids at high temperature may be such a concept if the high quality of the thin film could be ensured on centimeter-large areas. While previous works mainly investigated the influence of the porous array on the final structure, this work focuses on the practical aspects of the high-temperature step and its application to large areas. An insight into the defects that may form is given and the origin of these defects is discussed, providing recommendations on how to avoid them. Surface roughening, pitting, formation of holes, and silicon pillars could be attributed to the nonuniform reactions between Si, SiO2, and SiO. Hydrogen atmospheres are therefore preferred for reorganization of macroporous arrays. Argon atmospheres, however, may provide high-quality silicon thin films as well, possibly even more easily transferable, as long as annealing is performed in controlled, clean, and oxygen-free conditions. Our experiments on large areas also highlight the importance of kinetics, which had not been considered up to now and which will require further understanding to ensure a complete reorganization over any wafer area. View full abstract»

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  • Coherent acoustic vibrations in silicon submicron spiral arrays

    Page(s): 033517 - 033517-5
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    Mechanical properties of complex silicon submicron structures have been studied both experimentally and theoretically using time resolved ultrafast spectroscopy and finite element analysis. Periodic and random arrays of single-turned silicon submircron spirals were grown using the oblique angle deposition technique. Resonant vibrational modes of the submicron spirals were coherently excited by femtosecond laser pulses. Excitation of multiple harmonics of the resonant vibrations has been observed, and the mode patterns of the excited vibrations in the submicron spirals have been calculated. View full abstract»

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  • Power dependent photoluminescence of ZnO

    Page(s): 033518 - 033518-5
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    The effect of excitation power on the photoluminescence (PL) of three types of ZnO samples, including a polycrystalline pellet, thin film, and nanowires, was investigated. The intensity ratio of the defect to band edge emission as well as the overall spectral line shape of the defect emission was strongly affected by the excitation power. A blueshift of the defect emissions at high excitation powers was observed, indicating that donor-acceptor transitions are responsible for the defect emissions. The power dependent PL also suggests that comparisons of defect concentrations among ZnO samples may be possible only if the PL spectra are measured under the same excitation power. View full abstract»

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  • Defect structure in Mg-doped LiNbO3: Revisited study

    Page(s): 033519 - 033519-5
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    We present and discuss the mechanism of incorporation of Mg ions in congruent lithium niobate where we assume the coexistence of both lithium and niobium vacancies induced for charge compensation. This model is supported by the site spectroscopy afforded by Raman scattering data. The dependence of the concentration of various intrinsic defects, derived from this description is then compared with corresponding experimental data. In particular this comparison shows that the Li and vacancy contents as well as the crystal density show similar behaviors versus Mg concentration, which reinforces the validity of our description. View full abstract»

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Aims & Scope

Journal of Applied Physics is the American Institute of Physics' (AIP) archival journal for significant new results in applied physics

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P. James Viccaro
Argonne National Laboratory