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Journal of Applied Physics

Issue 10 • Date May 2004

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Displaying Results 1 - 25 of 107
  • Issue Cover

    Page(s): c1
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  • Issue Table of Contents

    Page(s): toc1
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  • Faraday rotation spectra of bismuth-substituted rare-earth iron garnet crystals in optical communication band

    Page(s): 5267 - 5270
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    Bismuth-substituted rare-earth iron garnet (REBIG) crystals are used in optical isolators for optical communication. However, the Faraday rotation (FR) spectra of REBIG crystals in the wavelength region of 1.3–1.6 μm have not yet been theoretically studied. To interpret the spectra, we assumed that the FR in this wavelength range was dominated by the contribution of the electric dipole transitions, and calculated the FR spectra. REBIG bulk crystals were grown from the Bi2O3 self-fluxed melt by the top-seeded solution growth method. The experimental results agreed with the theoretical calculation of FR in (HoBi)3Fe5O12, (YbBi)3Fe5O12, (YYbBi)3Fe5O12, and (TbBi)3Fe5O12. The results indicate that the theoretical analysis method of the FR spectra of REBIG in the visible range of wavelengths can be applied in the optical communication band. © 2004 American Institute of Physics. View full abstract»

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  • Optical properties of Nd3+ ions in oxyfluoride glasses and glass ceramics comparing different preparation methods

    Page(s): 5271 - 5279
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    A study of optical properties of Nd3+ doped oxyfluoride glasses and glass ceramics prepared by three different methods has been carried out. These methods start from NdF3, Nd2O3, or a Nd3+ ion solution as doping agent. The alternative preparation method based on a preliminary dissolution of the Nd3+ ions is proposed in order to avoid nonhomogeneous dopant distribution and spontaneous devitrification during glass elaboration. In the frame of the Judd–Ofelt theory, main radiative parameters have been studied: transition probabilities, lifetimes, and stimulated emission cross sections. Fluorescence decay curves have been also analyzed in order to study the final distribution of the Nd3+ ions after the ceramming process, discerning between ions that reside in the fluoride nanocrystals precipitated during heat treatment and those remaining in the glassy phase. The NdF3 based glass ceramics present the best values for spectroscopic parameters as the stimulated cross section of the 4F3/24I11/2 laser transition. © 2004 American Institute of Physics. View full abstract»

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  • Femtosecond laser-pulse-induced birefringence in optically isotropic glass

    Page(s): 5280 - 5283
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    We used a regeneratively amplified Ti:sapphire femtosecond laser to create optical birefringence in an isotropic glass medium. Between two crossed polarizers, regions modified by the femtosecond laser show bright transmission with respect to the dark background of the isotropic glass. This observation immediately suggests that these regions possess optical birefringence. The angular dependence of transmission through the laser-modified region is consistent with that of an optically birefringent material. Laser-induced birefringence is demonstrated in different glasses, including fused silica and borosilicate glass. Experimental results indicate that the optical axes of laser-induced birefringence can be controlled by the polarization direction of the femtosecond laser. The amount of laser-induced birefringence depends on the pulse energy level and number of accumulated pulses. © 2004 American Institute of Physics. View full abstract»

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  • Kinetic pathways to visible emission from a moly–oxide–argon discharge bulb

    Page(s): 5284 - 5294
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    A low-pressure mercury-free moly-oxide–argon (MoO3Ar) electrodeless discharge is investigated with potential application to lighting. The inductive discharge is driven by a 13.56 MHz radio frequency (RF) generator at input powers between 100 and 200 W. Calibrated emission spectra in the near ultraviolet (UV), visible, and near infrared regions are recorded and the corresponding powers emitted as radiation are obtained. An extensive set of transition probabilities and rate coefficients for electron impact excitation between Mo states is assembled and a detailed collisional radiative model of the plasma is developed. The model includes 11 states of neutral Mo, the evaporative and recycling chemistry of MoO3 into Mo and back, and the relevant species and reactions in argon–oxygen plasma. The possible paths for visible and UV radiation are analyzed in detail. The measured light output at 200 W RF input power is ∼40 lumens per watt (lpw) with a potential to reach ∼60–80 lpw. Comparison of the model with data for various radiated powers and electron density shows reasonable agreement. © 2004 American Institute of Physics. View full abstract»

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  • Ion-beam mixing in an immiscible Fe/Ag multilayer film

    Page(s): 5295 - 5300
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    Ion-beam mixing of the thermally immiscible Fe/Ag system is studied by 90 keV Ar+-ion irradiation of Fe/Ag multilayer at 325 K and the evolution of microstructure is studied by x-ray diffraction (XRD), x-ray reflectivity, and transmission electron microscopy (TEM). XRD measurements did not show any evidence of a additional phase formation or increase in solubility due to mixing of Fe in Ag. X-ray reflectivity analysis shows an initial sharpening at the interface for a fluence of 1×1016ions/cm2 and the destruction of multilayer periodicity is observed for higher fluences. The microstructural studies by TEM show a reduction in Ag particle size with fluence. The size of Ag nanoclusters was optimum at a fluence of 7×1016ions/cm2 and was found to be in the range of 10–20 nm. The particle density decreases at low fluence and on further irradiation, the particle density increases at higher ion fluences. This indicates the nucleation of Ag particles presumably due to long-range transport of Ag atoms. These Ag atom clusters give rise to a granular microstructure. © 2004 American Institute of Physics. View full abstract»

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  • Characteristics of THz waves and carrier scattering in boron-doped epitaxial Si and Si1-xGex films

    Page(s): 5301 - 5304
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    The absorption and reflection characteristics of boron-doped silicon and silicon-germanium alloys have been investigated in the frequency range from 1.6 to 60 THz. The absorption increases with doping concentration, in agreement with free carrier effects, but saturates for wavelengths longer than about 20 μm. As compared to silicon, the attenuation increases with the Ge fraction in the alloy. Terahertz reflectance data has been analyzed to study the doping dependent plasma-edge frequency, which may play an important role for the design of emitters, detectors, and plasmon waveguides. The best fitting of the experimental data with Drude theory has been used to extract the hole scattering relaxation time in doped silicon. The results have been utilized to explain the doping-dependent attenuation characteristics of the THz radiation. © 2004 American Institute of Physics. View full abstract»

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  • Study of pinholes and nanotubes in AlInGaN films by cathodoluminescence and atomic force microscopy

    Page(s): 5305 - 5310
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    Cathodoluminescence (CL) in the scanning electron microscope and atomic force microscopy (AFM) have been used to study the formation of pinholes in tensile and compressively strained AlInGaN films grown on Al2O3 substrates by plasma-induced molecular beam epitaxy. Nanotubes, pits, and V-shaped pinholes are observed in a tensile strained sample. CL images show an enhanced emission around the pits and a lower intensity at the V-shaped pinholes. Rounded pinholes appear in compressively strained samples in island-like regions with higher In concentration. The grain structure near the pinholes is resolved by AFM. © 2004 American Institute of Physics. View full abstract»

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  • Simple theory of the optical absorption coefficient in nonparabolic semiconductors

    Page(s): 5311 - 5315
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    A simple theory is developed of the optical absorption coefficient (OAC) in nonparabolic semiconductors on the basis of the three-band model of Kane, by considering the wave-vector (k⃗) dependence of the optical matrix element. It has been found that the OAC is proportional to [(ħω)2-Eg2]1/2 (ħω and Eg are the energy of the incident radiation and the bandgap, respectively) instead of [(ħω)-Eg]1/2, the conventional form. It has been demonstrated, by taking n-InAs, n-InSb, Hg1-xCdxTe, and In1-xGaxAs1-yP1-y lattice matched to InP as examples, that the OAC increases with increasing photon energy and the value of the same coefficient in the three band model of Kane is greater than that in parabolic energy bands in all the cases. The well-known result for wide gap materials having parabolic energy bands has also been obtained from our generalized formulation under certain limiting condition. © 2004 American Institute of Physics.   View full abstract»

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  • Environmental effects of H2O on fracture initiation in silicon: A hybrid electronic-density-functional/molecular-dynamics study

    Page(s): 5316 - 5323
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    A hybrid quantum-mechanical/molecular-dynamics simulation is performed to study the effects of environmental molecules on fracture initiation in silicon. A (110) crack under tension (mode-I opening) is simulated with multiple H2O molecules around the crack front. Electronic structure near the crack front is calculated with density functional theory. To accurately model the long-range stress field, the quantum-mechanical description is embedded in a large classical molecular-dynamics simulation. The hybrid simulation results show that the reaction of H2O molecules at a silicon crack tip is sensitive to the stress intensity factor K. For

    K=0.4 MPa m ,
    an H2O molecule either decomposes and adheres to dangling-bond sites on the crack surface or oxidizes Si, resulting in the formation of a Si–O–Si structure. For a higher K value of
    0.5 MPa m ,
    an H2O molecule either oxidizes or breaks a Si–Si bond. © 2004 American Institute of Physics. View full abstract»

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  • Separation of the first- and second-order contributions in magneto-optic Kerr effect magnetometry of epitaxial FeMn/NiFe bilayers

    Page(s): 5324 - 5329
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    The influence of second-order magneto-optic effects on Kerr effect magnetometry of epitaxial exchange coupled Fe50Mn50/Ni81Fe19-bilayers is investigated. A procedure for separation of the first-and second-order contributions is presented. The full angular dependence of both contributions during the magnetization reversal is extracted from the experimental data and presented using gray scaled magnetization reversal diagrams. The theoretical description of the investigated system is based on an extended Stoner–Wohlfarth model, which includes an induced unidirectional and fourfold anisotropy in the ferromagnet, caused by the coupling to the antiferromagnet. The agreement between the experimental data and the theoretical model for both the first- and second-order contributions are good, although a coherent reversal of the magnetization is assumed in the model. © 2004 American Institute of Physics. View full abstract»

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  • Cobalt valence states and origins of ferromagnetism in Co doped TiO2 rutile thin films

    Page(s): 5330 - 5333
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    Co doped rutile thin films were fabricated on α-Al2O3 (10-12) substrates by laser molecular beam epitaxy. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy indicated that the rutile thin films are (101) oriented and have smooth surfaces with no impurity phases. Co K-edge x-ray absorption near-edge structure, extended x-ray absorption fine structure, and x-ray photoelectron spectroscopy revealed the coexistence of different valence states of Co in the film. Magnetic circular dichroism studies suggest that the observed ferromagnetism is uniform and is related to the electron band structure of TiO2 rutile. Contribution of oxidized (Co2+) and metallic (Co0) cobalt to the ferromagnetism is discussed. © 2004 American Institute of Physics. View full abstract»

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  • Optical transitions, absorption intensities, and intermanifold emission cross sections of Pr3+(4f2) in Ca5(PO4)3F crystal host

    Page(s): 5334 - 5339
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    A spectroscopic Judd–Ofelt investigation has been performed on Pr3+ ions doped in calcium fluorapatite, Ca5(PO4)3F, belonging to the apatite structure family. The standard Judd–Ofelt analysis was applied to the room temperature absorption intensities of Pr3+ transitions to determine the phenomenological intensity parameters: Ω2, Ω4, and Ω6. Values of the intensity parameters were subsequently used to determine the decay rates (emission probabilities), radiative lifetimes, and branching ratios of the principal intermanifold transitions of Pr3+ from the 3P2, 1D2, and 3P0 manifold states to the lower-lying manifolds. In addition, the room temperature fluorescence lifetimes and emission cross sections of the 3P23H5, 1D23H4, and 3P03F2 transitions were measured; these values were compared with those of Nd3+:yttritium–aluminum–garnet and Pr3+:Sr5(PO4)3 (known as S–FAP). © 2004 American Institute of Physics. View full abstract»

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  • Low-temperature formation of CoSi2 in the presence of Au

    Page(s): 5340 - 5346
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    The formation of cobalt silicides was studied in the presence of interlayers and capping layers of Au, using both ex situ and in situ characterization techniques. The formation temperature of CoSi2 was found to be significantly lowered in the presence of Au. Two regimes can be discerned. For thin interlayers or capping layers, Au does not significantly affect the formation of Co2Si and CoSi, while it lowers the nucleation temperature of CoSi2. For thick interlayers, CoSi2 appears to form as the first phase at temperatures as low as 300 °C. The results are discussed within the context of classical nucleation theory and known models for phase selection during solid-state reactions. © 2004 American Institute of Physics. View full abstract»

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  • Strain relaxation and threading dislocation density in helium-implanted and annealed Si1-xGex/Si(100) heterostructures

    Page(s): 5347 - 5351
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    Strain relaxation and threading dislocation densities in Si1-xGex (0.15≪x≪0.30) produced by He implantation and annealing have been investigated using x-ray diffraction and transmission electron microscopy. The degree of strain relaxation is very sensitive to the SiGe layer thickness; only small differences in strain relaxation are obtained when the helium dose and energy are varied over a relatively wide range. In contrast, the threading dislocation density is strongly influenced by the implantation dose and depth. A composite parameter, the He dose in the SiGe layer (He(SiGe)), calculated from He profiles simulated using the program Stopping and Range of Ions in Matter (SRIM2000), correlates well with the threading dislocation density. We have found that to achieve a low threading dislocation density, ≪5×107cm-2, He(SiGe) must be less than 1×1015cm-2. © 2004 American Institute of Physics. View full abstract»

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  • Structural study of (CdS/ZnSe)/BeTe superlattices for λ=1.55 μm intersubband transition

    Page(s): 5352 - 5359
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    A (CdS/ZnSe)/BeTe superlattice (SL), based on wide band gap II–VI compounds, with a large band offset of 3.1 eV was grown on a GaAs (001) substrate using molecular-bean epitaxy and an intersubband transition (ISB-T) of 0.78 eV (λ=1.58 μm) with a full width at half maximum (FWHM) of 96 meV observed. We studied structural properties using high-resolution x-ray diffraction combined with dynamic simulation and found through the strain state in samples that a ZnSe/BeTe interface having a quaternary interface layer (ZnTe)0.45(BeSe)0.55 is preferentially formed despite the promotion of one molecular layer (ML) ZnTe interface formation. Be–Se bonds thus replace the Zn–Te bond in the transition region. For the CdS/ZnSe interface, an approximately 1 ML Zn0.75Cd0.25S ternary layer accompanied by ∼1 ML Zn0.85Cd0.15Se forms at the transition region due to Cd diffusion. X-ray (002) ω/2θ scan curves for (CdS/ZnSe)/BeTe SLs show sharp, intense satellite peaks exceeding ten orders, indicating high structure quality. We obtained excellent agreement between experimental diffraction patterns and the calculated curve via dynamic simulation for (CdS/ZnSe)/BeTe SLs. The good fits allows us to identify structure parameters in (CdS/ZnSe)/BeTe SLs, which are consistent with results of high-resolution transmission electron microscopy measurement. Based on dynamic simulated results, we obtained a structure of (CdS/ZnSe)/Be1-xMgxTe (x=1.2%) with an average lattice constant aSL matching the GaAs substrate. An ISB-T located at wavelength ;- b;=1.55 μm with a narrow FWHM of 90 meV was thus realized at room temperature. © 2004 American Institute of Physics. View full abstract»

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  • Lattice damage produced in GaN by swift heavy ions

    Page(s): 5360 - 5365
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    Wurtzite GaN epilayers bombarded at 300 K with 200 MeV 197Au16+ ions are studied by a combination of transmission electron microscopy (TEM) and Rutherford backscattering/channeling spectrometry (RBS/C). Results reveal the formation of near-continuous tracks propagating throughout the entire ∼1.5-μm-thick GaN film. These tracks, ∼100 Å in diameter, exhibit a large degree of structural disordering but do not appear to be amorphous. Throughout the bombarded epilayer, high-resolution TEM reveals planar defects which are parallel to the basal plane of the GaN film. The gross level of lattice disorder, as measured by RBS/C, gradually increases with increasing ion fluence up to ∼1013cm-2. For larger fluences, delamination of the nitride film from the sapphire substrate occurs. Based on these results, physical mechanisms of the formation of lattice disorder in GaN in such a high electronic stopping power regime are discussed. © 2004 American Institute of Physics. View full abstract»

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  • In situ micro Raman investigation of the laser crystallization in Si thin films plasma enhanced chemical vapor deposition-grown from He-diluted SiH4

    Page(s): 5366 - 5372
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    A cw Ar+ laser crystallization has been performed locally (on a 2 μm sized spot), using a Raman microscope, on plasma enhanced chemical vapor deposition-grown Si films. The deposition has been carried out from differently He-diluted SiH4 so that no high temperature dehydrogenation has been required before the laser treatment. X-ray diffraction patterns and Raman spectra of the deposited films reveal their amorphous nature whereas infrared spectra would indicate a larger degree of local order in the high dilution (HD) material (SiH4/He=0.02) if compared to the low dilution (LD) one (SiH4/He≈3). Atomic force microscopy and scanning electron microscopy images show large, well defined outgrowths, few hundreds of nanometers-sized, on the surface of the HD film whereas these are few tens of nanometers-sized in the case of the LD film. The threshold laser power densities (LPDs) required to attain the crystallization of the HD and the LD materials (in the range of times of irradiation investigated) are 1.2×105 and 2.0×105W cm-2, respectively. The relative ease to crystallize the HD material possibly originates from the fact that the heavy dilution of the reacting gas implies a lower rate of growth and so a larger degree of order. Large crystalline fractions (∼0.8) have been observed for the laser-treated HD material. Using a phenomenological model, the diameters of the nanocrystallites from the Raman shift of the crystalline peaks have been estimated. The size of the small crystals increases with the time of irradiation (up to a certain time). The smallest nanocrystals would have been fabricated irradiating the LD material at the th- reshold LPD for the shortest time of irradiation considered in this work. This low temperature process is of great technological interest (e.g., optoelectronics, microelectronics) because it allows the patterning down to a micrometric scale of (amorphous) a-Si:H films deposited onto glass and/or plastic substrates. © 2004 American Institute of Physics. View full abstract»

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  • Influence of H on the composition and atomic concentrations of “N-rich” plasma deposited SiOxNyHz films

    Page(s): 5373 - 5382
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    The influence of H on the composition and atomic concentrations of Si, O, and N of plasma deposited SiOxNyHz films was investigated. The bonding scheme of H was analyzed by Fourier-transform infrared spectroscopy. The composition and absolute concentrations of all the species present in the SiOxNyHz, including H, was measured by heavy-ion elastic recoil detection analysis (HI–ERDA). Samples were deposited from SiH4, O2, and N2 gas mixtures, with different gas flow ratios in order to obtain compositions ranging from SiNyHz to SiO2. Those samples deposited at higher SiH4 partial pressures show both Si–H and N–H bonds, while those deposited at lower SiH4 partial pressures show N–H bonds only. The Si–H and N–H bond concentrations were found to be proportional to the N concentration. The concentration of H was evaluated from the Si–H and N–H stretching absorption bands and compared to the HI–ERDA results, finding good agreement between both measurements. The deviation from H-free stoichiometric SiOxNy composition due to the presence of N–H bonds results in an effective coordination number of N to produce Si–N bonds lower than 3. By fitting the experimental composition data to a theoretical model taking into account the influence of N–H bonds, the actual concentration of N–H - bonds was obtained, making evident the presence of nonbonded H. The presence of Si–H and Si–Si bonds was found to partially compensate the effect of N–H bonds, from the point of view of the relative N and Si contents. Finally, the presence of N–H bonds results in a lower Si atom concentration with respect to the stoichiometric film, due to a replacement of Si atoms by H atoms. This decrease of the Si concentration is lower in those films containing Si–H and Si–Si bonds. A model was developed to calculate the Si, O, and N atom concentrations taking into account the influence of N–H, Si–H, and Si–Si bonds, and was found to be in perfect agreement with the experimental data measured by HI–ERDA. © 2004 American Institute of Physics. View full abstract»

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  • Raman and absorption spectra and thermal conductance of Er:Yb:GdCa4O(BO3)3 crystals

    Page(s): 5383 - 5387
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    Raman data and thermal expansion of Er:Yb:GdCa4O(BO3)3 (EYGCOB) crystals reveal that the crystal thermal conductance and thermomechanical properties are outstanding especially along the b direction. The Z-direction polarized absorbance of the b-direction wafer exhibits that the Yb3+ ion is very effectual as a sensitizer. These indicate that the EYGCOB crystals are suitable as an infrared radiation laser at about 1500 nm by using a pump wavelength of about 1000 nm from an InGaAs diode laser. © 2004 American Institute of Physics. View full abstract»

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  • Cluster size and composition variations in yellow and red light-emitting InGaN thin films upon thermal annealing

    Page(s): 5388 - 5396
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    We study thermal annealing effects on the size and composition variations of indium-aggregated clusters in two InGaN thin films with photoluminescence (PL) in the yellow and red ranges. The methods of investigation include optical measurement, nanoscale material analysis, and theoretical calculation. Such a study is important for determining the relation between the band gap and the average indium content of InGaN. In one of the samples, the major part of the PL spectrum is shifted from the yellow band into the blue range upon thermal annealing. In the other sample, after thermal annealing, a broad spectrum covering the whole visible range is observed. Cathodo-luminescence (CL) spectra show that the spectral changes occur essentially in the photons emitted from the shallow layers of the InGaN films. Photon emission spectra from the deeper layers are essentially unaffected by thermal annealing. The spectral changes upon thermal annealing are mainly attributed to the general trend of cluster size reduction. This interpretation is supported by the CL, x-ray diffraction, and high-resolution transmission electron microscopy results. To obtain a basic physics picture behind the spectral blue shift upon thermal annealing in the yellow emission sample, we theoretically study the quantum-confinement effects of InGaN clusters based on a quantum box model. The theoretical results can generally explain the large blue shift of PL spectral peak position. © 2004 American Institute of Physics. View full abstract»

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  • Impact of the metal cathode and CsF buffer layer on the performance of organic light-emitting devices

    Page(s): 5397 - 5402
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    The influences of different metal cathodes on the performance of organic light-emitting devices were systematically studied. In addition to the well-known effects of metal work function, the effects of reflectivity and reactivity of the metal cathode on the device efficiency and operational stability were explored. The interplays of different metal cathodes and a CsF buffer layer were also studied in standard α-napthylphenylbiphenyl diamine/tris-(8-hydroxyquinoline) aluminum (NPB/Alq3) devices. It was found that when the metal cathode is directly deposited on the organic layer, the device performance improves as the metal work function decreases. This effect is modulated by the metal reflectivity such that rare-earth metal cathodes, which typically have a lower reflectance, have a lower efficiency than alkaline-earth metal cathodes. Device operational stability is found to be related to the reactivity between Alq3 and the metal cathode. Devices with metal cathodes that react detrimentally with Alq3, such as Al and Ca, have a much lower lifetime than devices with other cathodes. On the other hand, when a thin CsF buffer layer was inserted at the organic/metal interface, I-V characteristics and efficiency improve considerably and become almost independent of the metal work function. Device lifetime also increases, and its dependence on the reactivity between the Alq3 and the metal cathode remains. © 2004 American Institute of Physics. View full abstract»

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  • Raman identification of the in-plane axes of zincblende (100) surfaces: Basic principles and application to II–VI/III–V heterostructures

    Page(s): 5403 - 5407
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    We use the interference of deformation-potential- and Fröhlich-induced Raman scattering from LO phonons in zincblende materials to identify the in-plane axes of zincblende (100) surfaces and interfaces. This procedure, which allows e.g. to distinguish between the [011] and the [0–11] direction, is demonstrated experimentally for n- and p-type GaAs(100). The main potential of the method is its application to heterostructures. Here it allows the unambiguous assignment of polarized Raman scattering features from surfaces and interfaces to their characteristic symmetry directions. Two examples are presented: (i) localized vibrations of CdSe monolayers, embedded in BeTe stacks, and (ii) vibration modes of Te dimers on clean (2×1) reconstructed BeTe(100) surfaces. © 2004 American Institute of Physics. View full abstract»

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  • Fractal topography of surfaces exposed to gas-cluster ion beams and modeling simulations

    Page(s): 5408 - 5418
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    Surface topography measured by atomic force microscope is reported before and after various gas-cluster ion beam (GCIB) treatments along with modeling simulations of topography changes. Height correlation and spectral distributions of these surfaces show characteristics of random fractals with Hurst exponent H typically 0.5≪H≪1.0 and correlation lengths from ∼10 to over 500 nm. The roughness increases or decreases depending on the initial surface and the nature of the GCIB. The power spectral density distributions observed have a broad power-law roll off from a low-frequency plateau to a high-frequency one. This occurs over an approximate range of spatial frequencies from 5×10-3 to 5×10-1nm-1. Data from several example surfaces are given. Roughening is shown to be a statistical accumulation of individual cluster impacts and the process is modeled by Monte Carlo simulations resulting in fractal surfaces. A continuum model that incorporates surface mobility is used to simulate the smoothing, and methods to combine this with the Monte Carlo model are presented. The behavior of surfaces under exposure to GCIB is satisfactorily simulated by this combined model. Accurate simulation of the surface smoothing requires that the surface-mobility model be independent of the spatial frequency over the bandwidth of observation, unlike Fick’s law of diffusion. The nonphysical prediction of previous simulations that the topography trends toward the complete absence of roughness is also corrected. © 2004 American Institute of Physics. View full abstract»

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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