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15 Sep 2001

Volume 90, Issue 6, pp. 2635-3127

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Lighting up erbium with water: Observation of substantial crystalline matrix element enhancements

G. A. Thomas, D. M. Bubb, T.-Y. Koo, D. J. Werder, S.-W. Cheong, and J. F. Federici

J. Appl. Phys. 90, 2678 (2001); http://dx.doi.org/10.1063/1.1390311 (5 pages) | Cited 2 times

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We have found substantial enhancements of the optical matrix elements of Er atoms when water molecules augment the symmetry-breaking electric fields in their crystalline environment. We measure enhancement factors of order 5 for the set of Er energy levels with wavelengths near 1550 nm. These transitions are technologically important because they are used in optical amplifiers for communications. © 2001 American Institute of Physics.
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78.40.Ha Other nonmetallic inorganics
42.70.-a Optical materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Atomic structures at a Si–nitride/Si(001) interface

Nobuyuki Ikarashi, Koji Watanabe, and Yoshiyuki Miyamoto

J. Appl. Phys. 90, 2683 (2001); http://dx.doi.org/10.1063/1.1389759 (6 pages) | Cited 4 times

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We used high-resolution transmission electron microscopy to show that the atomic structures at a Si3N4/Si interface are clearly different from those at a SiO2/Si interface. Using first-principles calculations, we also found that, in one of the observed N-induced interfacial geometries, a dangling bond was produced on a Si atom adjacent to a N atom. We thus argue that such N-induced interfacial dangling bonds can cause degradation in the performance of metal–oxide–semiconductor transistors with Si–oxynitride (SiON) gate dielectrics when the N concentration is increased at the SiON/Si interfaces. We also argue that the difference in flatness between Si3N4 and SiON/Si interfaces and SiO2/Si interfaces is the result of the difference between their atomic structures. © 2001 American Institute of Physics.
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68.35.Ct Interface structure and roughness
68.37.Lp Transmission electron microscopy (TEM)
85.30.Tv Field effect devices

Deformation behavior of coherently strained InAs/GaAs(111)A heteroepitaxial systems: Theoretical calculations and experimental measurements

Luis A. Zepeda-Ruiz, Rodney I. Pelzel, Brett Z. Nosho, W. Henry Weinberg, and Dimitrios Maroudas

J. Appl. Phys. 90, 2689 (2001); http://dx.doi.org/10.1063/1.1392966 (10 pages) | Cited 2 times

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A comprehensive, quantitative analysis is presented of the deformation behavior of coherently strained InAs/GaAs(111)A heteroepitaxial systems. The analysis combines a hierarchical theoretical approach with experimental measurements. Continuum linear elasticity theory is linked with atomic-scale calculations of structural relaxation for detailed theoretical studies of deformation in systems consisting of InAs thin films on thin GaAs(111)A substrates that are mechanically unconstrained at their bases. Molecular-beam epitaxy is used to grow very thin InAs films on both thick and thin GaAs buffer layers on epi-ready GaAs(111)A substrates. The deformation state of these samples is characterized by x-ray diffraction (XRD). The interplanar distances of thin GaAs buffer layers along the [220] and [111] crystallographic directions obtained from the corresponding XRD spectra indicate clearly that thin buffer layers deform parallel to the InAs/GaAs(111)A interfacial plane, thus aiding in the accommodation of the strain induced by lattice mismatch. The experimental measurements are in excellent agreement with the calculated lattice interplanar distances and the corresponding strain fields in the thin mechanically unconstrained substrates considered in the theoretical analysis. Therefore, this work contributes direct evidence in support of our earlier proposal that thin buffer layers in layer-by-layer semiconductor heteroepitaxy exhibit mechanical behavior similar to that of compliant substrates [see, e.g., B. Z. Nosho, L. A. Zepeda-Ruiz, R. I. Pelzel, W. H. Weinberg, and D. Maroudas, Appl. Phys. Lett. 75, 829 (1999)]. © 2001 American Institute of Physics.
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68.35.Gy Mechanical properties; surface strains
68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
68.35.Ct Interface structure and roughness
81.40.Jj Elasticity and anelasticity, stress-strain relations
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Ultraviolet-infrared optical properties of highly (100)-oriented LaNiO3 thin films on Pt–Ti–SiO2–Si wafer

J. Yu, J. L. Sun, X. J. Meng, Z. M. Huang, J. H. Chu, D. Y. Tang, C. Y. Jin, G. Li, W. Y. Li, and Q. Liang

J. Appl. Phys. 90, 2699 (2001); http://dx.doi.org/10.1063/1.1394903 (4 pages) | Cited 7 times

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The optical constants of highly (100)-oriented LaNiO3 thin films on Pt(111)-Ti–SiO2–Si substrate derived by metalorganic deposition have been obtained using spectroscopic ellipsometry techniques in the wide wavelength range from ultraviolet to far infrared. In fitting the dielectric functions of LaNiO3, two harmonic oscillators are observed, one is believed to come from the valence–conduction interband transition and the other is attributed to the transition from a donor band to the conduction. Simultaneously the frequency of plasmon is also obtained, which results from the strong electron–electron interaction. Based on these optical and electrical properties, a promising application of LaNiO3 thin films in infrared microsensors has been proposed. © 2001 American Institute of Physics.
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78.66.Nk Insulators
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
78.30.Hv Other nonmetallic inorganics
78.40.Ha Other nonmetallic inorganics
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.60.Gz Photodetectors (including infrared and CCD detectors)
71.20.Ps Other inorganic compounds

Highly oriented lead zirconium titanate thin films: Growth, control of texture, and its effect on dielectric properties

S. Kalpat and K. Uchino

J. Appl. Phys. 90, 2703 (2001); http://dx.doi.org/10.1063/1.1385580 (8 pages) | Cited 32 times

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Highly oriented lead–zirconium–titanate (PZT) thin films have been grown by reactive rf-magnetron sputtering using multielemental metallic targets. The effects of deposition parameters on the film composition and texture evolution have been established. The partial pressure of oxygen (O2) and the heating rates during postdeposition anneal have been identified as critical parameters for the growth of highly oriented (111) and (100) PZT films. In order to control the growth of (111) and (100) orientation it was important to understand the interplay between these two parameters. Texture evolution mechanisms for the growth of oriented films have been proposed based on the effect of O2/argon flow and heating rates on the crystallization kinetics. The effects of crystal orientation on the dielectric and ferroelectric properties of PZT films have also been investigated. © 2001 American Institute of Physics.
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81.15.Cd Deposition by sputtering
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.-e Ferroelectricity and antiferroelectricity
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
68.55.A- Nucleation and growth
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology
61.72.Cc Kinetics of defect formation and annealing

Insulator issues in alternating-current thin-film electroluminescent devices

J. C. Hitt and J. F. Wager

J. Appl. Phys. 90, 2711 (2001); http://dx.doi.org/10.1063/1.1388598 (7 pages) | Cited 5 times

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An n-sheet, state-space model is employed for the assessment of insulator issues of relevance to the operation of alternating-current thin-film electroluminescent (ACTFEL) devices. The model presented herein has been refined by the inclusion of luminance, which is modeled as arising from impact excitation of luminescent impurities. Simulation demonstrates that ACTFEL devices which have large insulator capacitances and no space charge present in the phosphor are optimal in terms of providing maximum luminance and efficiency. A method for estimating the phosphor space charge density from a single transferred charge curve is presented. Simulation indicates that the use of a leaky insulator in an ACTFEL device can result in an increase in luminance, but a decrease in efficiency and that measured charge–voltage and internal charge–phosphor field curves are misleading when one or more of the constituent insulator or phosphor layers is leaky. © 2001 American Institute of Physics.
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85.60.Jb Light-emitting devices
73.61.Ng Insulators
78.60.Fi Electroluminescence
77.22.Jp Dielectric breakdown and space-charge effects

Structural study of a thermally diffused Al/Ni bilayer via x-ray absorption spectroscopy and x-ray photoelectron spectroscopy

France Chevrier, Anne Delobbe, Agnés Traverse, and Didier Zanghi

J. Appl. Phys. 90, 2718 (2001); http://dx.doi.org/10.1063/1.1392961 (7 pages) | Cited 9 times

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Ni thin films deposited on (111) Al thick samples have been submitted to annealing treatment. The goal is to identify the phases formed in the early stage of mixing between Ni and Al. Combining complementary techniques such as x-ray absorption spectroscopy and x-ray photoelectron spectroscopy, we characterized two different systems depending on the temperature conditions. For a thermal treatment at 110 °C, a system formed of small AlNi3 clusters embedded in the Al matrix was identified. This was interpreted as due to the existence of a spontaneous Al/Ni interface mixed layer acting as a seed for the AlNi3 cluster formation. After annealing at 300 °C, the Al3Ni intermetallic compound was detected, in agreement with results in the literature. © 2001 American Institute of Physics.
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68.35.Fx Diffusion; interface formation
81.40.Gh Other heat and thermomechanical treatments
78.70.Dm X-ray absorption spectra
79.60.Jv Interfaces; heterostructures; nanostructures

Extracting composition and alloying information of coherent Ge(Si)/Si(001) islands from [001] on-zone bright-field diffraction contrast images

X. Z. Liao, J. Zou, D. J. H. Cockayne, Z. M. Jiang, and X. Wang

J. Appl. Phys. 90, 2725 (2001); http://dx.doi.org/10.1063/1.1394900 (5 pages) | Cited 15 times

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Ge(Si)/Si(001) coherent islands grown at 700 °C by molecular beam epitaxy were investigated using transmission electron microscopy. [001] on-zone bright-field diffraction contrast imaging and image simulation techniques were used to investigate the structure of these coherent islands. Comparison of simulated and experimental images indicates nonuniform composition distribution within the coherent islands when the islands were grown at high temperatures (700 °C), but uniform composition for growth at lower temperatures (600 °C). © 2001 American Institute of Physics.
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68.65.Hb Quantum dots (patterned in quantum wells)
68.37.Lp Transmission electron microscopy (TEM)
68.55.-a Thin film structure and morphology
81.05.Cy Elemental semiconductors

Dislocation glide and blocking kinetics in compositionally graded SiGe/Si

C. W. Leitz, M. T. Currie, A. Y. Kim, J. Lai, E. Robbins, E. A. Fitzgerald, and M. T. Bulsara

J. Appl. Phys. 90, 2730 (2001); http://dx.doi.org/10.1063/1.1389333 (7 pages) | Cited 40 times

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The effects of growth temperature, substrate offcut, and dislocation pileup formation on threading dislocation density (TDD) in compositionally graded SiGe buffers are explored. To investigate dislocation glide kinetics in these structures, a series of identical samples graded to 30% Ge were grown at temperatures between 650 and 900 °C on (001)-, (001) offcut 6° towards an in-plane 〈110〉-, and (001) offcut 6° towards an in-plane 〈100〉-oriented Si substrates. The field threading dislocation density (field TDD) in the on-axis samples varied exponentially with temperature, from 3.7×106 cm−2 at 650 °C to 9.3×104 cm−2 at 900 °C. The activation energy for dislocation glide in this series, calculated from the evolution of field TDD with growth temperature, was 1.38 eV, much lower than the expected value for this composition. This deviation indicates that strain accumulating during the grading process at low growth temperatures is forcing further dislocation nucleation, resulting in a deviation from pure glide-limited relaxation. The TDD of samples grown on offcut substrates exhibited a more complicated temperature dependence, likely because films grown on offcut substrates have an increased tendency towards saturation in dislocation reduction reactions at high temperature. Dislocation reduction processes were further explored by initiating compositional grading up to 15% Ge at 650 °C and continuing the grade to 30% Ge at 900 °C. The low temperature portion of this growth provided an excess concentration of threading dislocations which could subsequently be annihilated during the high temperature portion of the growth, enabling a comparison of reduction rates for different substrate offcuts. Combining these results with threading dislocation densities in a variety of other samples, a complete picture of strain relaxation kinetics in compositionally graded SiGe/Si emerges. Generally, strain relaxation in these structures is limited by dislocation glide, and threading dislocation densities are independent of final Ge content. However, we theorize that dislocation pileup formation inhibits the strain relaxation process and is therefore accompanied by a rise in field threading dislocation density. Based on these results, we now have a predictive model for TDD in compositionally graded SiGe/Si over a wide range of growth conditions. © 2001 American Institute of Physics.
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61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
81.05.Hd Other semiconductors
68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology
81.05.Cy Elemental semiconductors
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
68.35.Ct Interface structure and roughness
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
62.20.F- Deformation and plasticity

Optical and electronic properties of TiCxNy films

G. G. Fuentes, E. Elizalde, and J. M. Sanz

J. Appl. Phys. 90, 2737 (2001); http://dx.doi.org/10.1063/1.1394157 (7 pages) | Cited 10 times

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The optical and electronic properties of TiCxNy(x+y∼1,0<y<1) thin films have been investigated by spectroscopic ellipsometry in the 1.5–4.5 eV energy range and by valence band x-ray photoemission spectroscopy as a function of the composition. The dielectric functions measured in the energy range of intraband transitions are analyzed in terms of a Drude-like approximation. Both the free plasma energy and the damping constant are observed to depend on the nitrogen content of the samples, suggesting a certain tunability of the optical and electronic properties of these films. Analysis of the valence band reveals that the C 2p band shifts toward higher binding energies upon an increase of the nitrogen content, in good agreement with the shift observed in the minimum of the optical reflectivity associated with the threshold of the interband transitions. The enhancement of the metallic character of the films as the nitrogen content increases is also evidenced by x-ray photoemission spectroscopy as a continuous intensity growth of the conduction band at the Fermi level. © 2001 American Institute of Physics.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.-w Optical properties of specific thin films
73.20.At Surface states, band structure, electron density of states
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Iron–acceptor pairs in silicon: Structure and formation processes

Song Zhao, L. V. C. Assali, J. F. Justo, G. H. Gilmer, and L. C. Kimerling

J. Appl. Phys. 90, 2744 (2001); http://dx.doi.org/10.1063/1.1389763 (11 pages) | Cited 12 times

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We performed a theoretical investigation on the properties of iron–acceptor impurity pairs (Fe–A, with A=B, Al, Ga, and In) in silicon. The calculations were performed within the framework of an ionic model, including elastic and electrostatic interactions. In contrast to the conventional point charge ionic model, our model includes a correction to the electrostatic interaction that takes into account the valence electronic cloud polarization, which adds a short range, attractive interaction to Fe–A pair bonding, and includes the silicon lattice relaxation due to the atomic size difference between the acceptor and the lattice atoms. Our results are in good agreement with the experimental trends among the Fe–A pairs, describing the increase in the pair donor energy level with increasing A principal quantum number and decreasing pair separation distance, and the pair configurational symmetries. © 2001 American Institute of Physics.
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71.55.Cn Elemental semiconductors
61.72.S- Impurities in crystals
61.72.Yx Interaction between different crystal defects; gettering effect
61.72.uf Ge and Si

Multichannel detection x-ray absorption near edge structures study on the structural characteristics of dendrimer-stabilized CdS quantum dots

P. Zhang, S. J. Naftel, and T. K. Sham

J. Appl. Phys. 90, 2755 (2001); http://dx.doi.org/10.1063/1.1394899 (5 pages) | Cited 9 times

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Starburst poly-(amidoamine) dendrimers were used to obtain dendrimer stabilized CdS nanoparticles, or quantum dots (QDs). The average particle size of the QDs was examined by UV-vis absorption spectra and powder x-ray diffraction measurements. The technique of x-ray absorption near edge structure (XANES) near the S K-edge was employed to study the structural characteristics of a series of QDs. The use of a multichannel detection scheme in XANES, monitoring total electron yield, x-ray fluorescence yield, and photoluminescence yield simultaneously, was demonstrated to be a powerful tool to evaluate the structure of the QDs from a sulfur perspective. The relationship between the luminescence property and the local structure of sulfur in the QDs was also discussed on the basis of the results of x-ray excited optical luminescence and XANES studies. © 2001 American Institute of Physics.
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68.65.Hb Quantum dots (patterned in quantum wells)
78.67.Hc Quantum dots
78.40.Fy Semiconductors
78.70.Dm X-ray absorption spectra
78.55.Et II-VI semiconductors
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods

Excimer laser annealing of Er-implanted GaN

Seuk Joo Rhee, Sangsig Kim, Christopher W. Sterner, Jeffrey O. White, and Stephen G. Bishop

J. Appl. Phys. 90, 2760 (2001); http://dx.doi.org/10.1063/1.1391217 (4 pages) | Cited 10 times

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Thin films of Er-implanted GaN are annealed with pulses of 31 ns duration from a KrF excimer laser. The degree of annealing is evaluated by measuring the Er photoluminescence at 1540 nm. The implantation dose is 4×1013–4×1015 cm−2. The laser fluence is 0.15–0.88 J/cm2. The number of laser pulses is 102–5×104. A total heating time on the order of 1 ms is long enough to produce good structural reordering, and short enough to avoid decomposition. The results are compared with a numerical simulation of the heating as a function of time and depth in the sample. © 2001 American Institute of Physics.
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61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
61.72.uj III-V and II-VI semiconductors
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
61.72.Cc Kinetics of defect formation and annealing
68.55.-a Thin film structure and morphology

Models for quantitative charge imaging by atomic force microscopy

Elizabeth A. Boer, L. D. Bell, Mark L. Brongersma, and Harry A. Atwater

J. Appl. Phys. 90, 2764 (2001); http://dx.doi.org/10.1063/1.1394896 (9 pages) | Cited 9 times

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Two models are presented for quantitative charge imaging with an atomic-force microscope. The first is appropriate for noncontact mode and the second for intermittent contact (tapping) mode imaging. Different forms for the contact force are used to demonstrate that quantitative charge imaging is possible without precise knowledge of the contact interaction. From the models, estimates of the best charge sensitivity of an unbiased standard atomic-force microscope cantilever are found to be on the order of a few electrons. © 2001 American Institute of Physics.
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07.79.Lh Atomic force microscopes
68.37.Ps Atomic force microscopy (AFM)

Microscopic nature of the Er3+ emission in mixed amorphous-nanocrystalline Si:H films

S. B. Aldabergenova, H. P. Strunk, P. C. Taylor, and A. A. Andreev

J. Appl. Phys. 90, 2773 (2001); http://dx.doi.org/10.1063/1.1388564 (8 pages) | Cited 3 times

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ErO6 complexes, where every Er3+ ion is surrounded by six oxygen atoms forming an octahedron with C3v point symmetry, are found to best describe the strong Stark splitting of the characteristic Er3+ emission in the 1460–1610 nm range. An a-Si:H matrix serves as an ideal semiconductor host to permit codoped O atoms to form an optimal octahedral ligand field around the Er3+ ions. The observation of sharp intense Stark peaks for temperatures between 153 and 300 °C and of strong enhancement of the Er3+ emission after 350 °C annealing can be understood first by diffusion and then outdiffusion of weakly bound hydrogen atoms in the a-Si matrix. © 2001 American Institute of Physics.
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78.55.Ap Elemental semiconductors
81.05.Cy Elemental semiconductors
81.05.Gc Amorphous semiconductors
78.20.Jq Electro-optical effects
71.55.Cn Elemental semiconductors
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect

Exciton linewidth in semiconducting cylindrical quantum wire structures due to scattering by polar optical phonons: Finite potential well model

Heon Ham and Harold N. Spector

J. Appl. Phys. 90, 2781 (2001); http://dx.doi.org/10.1063/1.1390492 (5 pages) | Cited 2 times

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In our previous work [H. Ham and H. N. Spector, Phys. Rev. B 62, 13599 (2000)], the contribution to the exciton linewidth due to scattering by polar optical phonons was calculated in semiconducting cylindrical quantum wire structures using the infinite confining potential well model. This model showed the linewidth steadily increasing as the wire radius decreased for both elastic and inelastic scattering of the exciton. The same calculation is repeated here using the finite confining potential well model which is more appropriate for small wire radii in quantum wires. We find in this case, that this contribution to the exciton linewidth initially increases with decreasing wire radius until a critical radius is reached, which depends upon the height of the confining potential barrier, and for smaller wire radii, the linewidth decreases. This is due to the fact that in narrow wires, the exciton is no longer completely confined. © 2001 American Institute of Physics.
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73.21.Hb Quantum wires
68.65.La Quantum wires (patterned in quantum wells)
63.20.kk Phonon interactions with other quasiparticles
71.35.Gg Exciton-mediated interactions
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

Variation of spin densities and the solid-phase crystallization of amorphous Si1−xGex:H films

O. H. Roh, W. J. Yun, and J.-K. Lee

J. Appl. Phys. 90, 2786 (2001); http://dx.doi.org/10.1063/1.1394897 (6 pages) | Cited 2 times

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We have investigated the solid-phase crystallization (SPC) of hydrogenated amorphous silicon–germanium (a-Si1−xGex:H) alloy films by using x-ray diffraction and electron spin resonance measurements. The films were deposited on glass in a plasma-enhanced chemical vapor deposition system by using SiH4 and GeH4 gases. The deposited films were then annealed at 600 °C, which resulted in crystallization. The variation of the spin densities with annealing time was found to be strongly correlated with the structural changes in the SPC process, and the Ge dangling bonds were the dominant defects involved in the SPC process for Si1−xGex:H films (for x>0.05). The incubation time and the final grain size of the recrystallized films depended on the Ge composition and were closely related to the variations of the Si–H and the Ge–H dissociation energies. The SPC process is thought to be influenced by the initial structural disorder of the a-Si1−xGex:H films, and by the Ge composition. © 2001 American Institute of Physics.
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61.43.Dq Amorphous semiconductors, metals, and alloys
81.05.Gc Amorphous semiconductors
76.30.-v Electron paramagnetic resonance and relaxation

Microscopic observation of Cu damascene interconnect grains using x-ray microbeam

Masaki Hasegawa and Yasuharu Hirai

J. Appl. Phys. 90, 2792 (2001); http://dx.doi.org/10.1063/1.1398074 (4 pages) | Cited 4 times

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Microscopic observation and imaging of Cu damascene interconnect grains were carried out using the x-ray microbeam of the BL-16XU at SPring-8. The x-ray focusing system of the beamline consists of a bent-cylindrical prefocusing mirror and elliptical mirrors with a Kirkpatric–Baez configuration. Diffraction spots from the microscopic area irradiated by the intense x-ray microbeam (7×6 μm full width at half maximum) at the boundary between the metal line and the dielectric were observed. The diffraction spots observed show that Cu(111) grains grow normally on the sidewall and Cu(200) grain orientation distribution is quite broad, suggesting that crystallographic texture near the trench is quite disordered. Two-dimensional images of grains with a specific orientation angle were also obtained. Grains as large as about 10 μm caused by self-annealing were observed. © 2001 American Institute of Physics.
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85.40.Ls Metallization, contacts, interconnects; device isolation
68.37.Yz X-ray microscopy
07.85.Tt X-ray microscopes
81.40.Gh Other heat and thermomechanical treatments

Low-dose aluminum and boron implants in 4H and 6H silicon carbide

N. S. Saks, A. K. Agarwal, S-H. Ryu, and J. W. Palmour

J. Appl. Phys. 90, 2796 (2001); http://dx.doi.org/10.1063/1.1392958 (10 pages) | Cited 18 times

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Aluminum and boron p-type low-dose implants have been characterized in 4H- and 6H-SiC for anneals from 1300 °C to 1600 °C. In contrast to previous studies of heavily doped p-type layers, here we study more lightly doped layers for use as active regions in high-voltage power devices. Activation rates of the implanted ions, depth profiles from secondary mass ion spectroscopy, and surface roughness data using atomic force microscopy are presented as a function of anneal temperature. The temperature dependence of the free hole density and hole mobility are characterized with Hall effect measurements. For 1600 °C anneals, usable device quality p-type layers are obtained for both SiC polytypes and implant species. For anneals at or below ∼1500 °C, the implanted layers have much higher sheet resistivity due to the presence of unannealed compensating defects. These layers are not device quality. B-implanted layers have higher mobility, while activation of implanted Al is much higher and more uniform. Therefore, boron and aluminum have different advantages and disadvantages as p-type implants in SiC. © 2001 American Institute of Physics.
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61.72.up Other materials
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
68.37.Ps Atomic force microscopy (AFM)
61.72.Cc Kinetics of defect formation and annealing
72.20.Fr Low-field transport and mobility; piezoresistance
72.20.My Galvanomagnetic and other magnetotransport effects
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
84.32.Tt Capacitors

Trapping of gold by nanocavities induced by H+ or He++ implantation in float zone and Czochralski grown silicon wafers

I. Périchaud, E. Yakimov, S. Martinuzzi, and C. Dubois

J. Appl. Phys. 90, 2806 (2001); http://dx.doi.org/10.1063/1.1394917 (7 pages) | Cited 6 times

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In silicon, implantation of He++ or H+ ions and subsequent annealing can lead to the formation of nanocavities below the implanted surface of the wafers. These nanocavities, which behave as trapping sites for metallic impurities, can be located near the devices in integrated circuits in order to induce a proximity gettering. In this article, we investigate, in float zone (FZ) and Czochralski (Cz) wafers, the trapping of gold by nanocavities formed by implantation of He++ or H+ ions at 250 keV and at a dose of 3×1016 cm−2 followed by subsequent annealing(s) at 750  °C for 1 h. Deep level transient spectroscopy profiles show that substitutional gold concentration decreases near the cavity band in FZ and Cz samples. Gold profiles obtained by secondary ion mass spectroscopy show that there is a strong trapping of gold in the cavity band in all samples. In the case of He++ implanted wafers, this trapping also occurs in the region between the implanted surface and the cavities, and the higher the oxygen concentration, the higher this trapping is. This could be explained by a higher density of implantation induced defects in He++ implanted samples and by the formation of oxygen-vacancy complexes in this region. In H+ implanted samples, the hydrogen passivation of such defects reduces their efficiency as trapping sites. The results suggest that gold trapping is related to gold precipitation which could inject self-interstitials in the bulk and then decreases the substitutional gold concentration near the cavity band even though there is a constant source of gold atoms in our experiments. © 2001 American Institute of Physics.
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61.72.Yx Interaction between different crystal defects; gettering effect
81.05.Cy Elemental semiconductors
61.72.Qq Microscopic defects (voids, inclusions, etc.)
61.72.uf Ge and Si
61.80.Jh Ion radiation effects
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
81.65.Tx Gettering
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
71.55.Cn Elemental semiconductors

Low temperature photoluminescence of Ga0.84In0.16As0.22Sb0.78 solid solutions lattice matched to InAs

K. D. Moiseev, M. P. Mikhailova, Yu. P. Yakovlev, T. Šimeček, E. Hulicius, and J. Oswald

J. Appl. Phys. 90, 2813 (2001); http://dx.doi.org/10.1063/1.1388570 (5 pages) | Cited 7 times

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Low-temperature photoluminescence (PL) study of liquid phase epitaxy grown undoped and Sn doped GaIn0.16As0.22Sb layers lattice matched to InAs is reported. The quaternary solid solutions Ga1−xInxAsySb1−y are promising materials for the fabrication of optoelectronics devices operating in the spectral range 3–5 μm because these alloys can form type II heterojunctions both with staggered and broken-gap alignment. The band structure engineering of these devices requires the knowledge of energy gaps and mechanism of radiative recombination transitions in the forbidden gap of cladding layers. The high quality quaternary GaIn0.16As0.22Sb epitaxial layers with low native defect concentration were grown lattice matched to InAs and their photoluminescence was studied at low temperatures. The emission band related to bound exciton was dominant. While the emission bands associated with the first ionization state of VGaGaSb vacancy-antisite defect with activation energy ΔEA=22 meV and unknown deep defect with ΔEB=46 meV were found besides the main PL peak ΔEBE=16 meV. It was established that Sn as an amphoteric impurity can form shallow donor levels. © 2001 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
71.55.Eq III-V semiconductors
64.75.-g Phase equilibria
71.20.Nr Semiconductor compounds
68.55.-a Thin film structure and morphology

Optical and photovoltaic properties of indium selenide thin films prepared by van der Waals epitaxy

J. F. Sánchez-Royo, A. Segura, O. Lang, E. Schaar, C. Pettenkofer, W. Jaegermann, L. Roa, and A. Chevy

J. Appl. Phys. 90, 2818 (2001); http://dx.doi.org/10.1063/1.1389479 (6 pages) | Cited 15 times

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Indium selenide thin films have been grown on p-type gallium selenide single crystal substrates by van der Waals epitaxy. The use of two crucibles in the growth process has resulted in indium selenide films with physical properties closer to these of bulk indium selenide than those prepared by other techniques. The optical properties of the films have been studied by electroabsorption measurements. The band gap and its temperature dependence are very close to those of indium selenide single crystals. The width of the fundamental transition, even if larger than that of the pure single crystal material, decreases monotonously with temperature. Exciton peaks are not observed even at low temperature, which reveals that these layers still contain a large defect concentration. The current–voltage characteristic of indium selenide thin film devices was measured under simulated AM2 conditions. The solar conversion efficiency of these devices is lower than 0.6%. The high concentration of defects reduces the diffusion length of minority carriers down to values round to 0.2 μm. © 2001 American Institute of Physics.
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78.66.Li Other semiconductors
73.61.Le Other inorganic semiconductors
78.20.Jq Electro-optical effects
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Ion channeling, high resolution x-ray diffraction and Raman spectroscopy in strained quantum wells

Azher M. Siddiqui, S. V. S. Nageswara Rao, Anand P. Pathak, V. N. Kulkarni, R. Keshav Murthy, Eric Williams, Daryush Ila, Claudiu Muntele, K. S. Chandrasekaran, and B. M. Arora

J. Appl. Phys. 90, 2824 (2001); http://dx.doi.org/10.1063/1.1390301 (7 pages)

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InGaAs strained epitaxial layers on GaAs are of considerable interest in semiconductor devices. An important feature is the critical thickness of the epitaxial layer beyond which relaxation occurs, affecting the device performance. With this in view, a series of such structures have been grown by organometallic vapor phase epitaxy and characterized by ion channeling, high resolution x-ray diffraction and Raman spectroscopy. The results of these three techniques are compared for the samples in this study which are fully strained, nominally and by experimental measurements. Beam steering effect that occurs at low energy channeling is also addressed. © 2001 American Institute of Physics.
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68.65.Fg Quantum wells
78.67.De Quantum wells
81.07.St Quantum wells
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
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