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16 Jul 2001

Volume 79, Issue 3, pp. 281-445

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Optical metastability of subband gap (2.2 eV) yellow luminescence in GaN

Y. C. Chang, A. E. Oberhofer, J. F. Muth, R. M. Kolbas, and R. F. Davis

Appl. Phys. Lett. 79, 281 (2001); http://dx.doi.org/10.1063/1.1381417 (3 pages) | Cited 11 times

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Optical metastability has been studied in undoped GaN films grown on SiC substrates having a previously deposited AlN buffer layer. Brief exposures to a higher intensity ultraviolet light resulted in temporary changes in the optical properties of the GaN layer. The photoinduced changes created high contrast patterns on samples that could be observed under an optical microscope with lower intensity ultraviolet excitation. The subband gap yellow photoluminescence peak at 2.2 eV increased significantly after the patterns were created. This change slowly returned (hours) to its initial value at room temperature. The retention time decreased to a few seconds at temperatures above 100 °C. The data showed that a 1.34 eV thermal activation energy exists, which suggests that the cause of these metastable properties is related to the subband gap yellow luminescence. © 2001 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
73.20.At Surface states, band structure, electron density of states

Indium tin oxide thin films grown on flexible plastic substrates by pulsed-laser deposition for organic light-emitting diodes

H. Kim, J. S. Horwitz, G. P. Kushto, Z. H. Kafafi, and D. B. Chrisey

Appl. Phys. Lett. 79, 284 (2001); http://dx.doi.org/10.1063/1.1383568 (3 pages) | Cited 57 times

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Transparent conducting indium tin oxide (ITO) thin films were grown by pulsed laser deposition (PLD) on flexible polyethylene terephthalate (PET) substrates. The structural, electrical, and optical properties of these films were investigated as a function of substrate deposition temperature and background gas pressure. ITO films (200 nm thick), deposited by PLD on PET at 25 °C and 45 mTorr of oxygen, exhibit high optical transparency (∼87%) in the visible (400–700 nm) with a low electrical resistivity of 7×10−4 Ω cm. ITO films grown by PLD on PET were used as the anode contact in organic light-emitting devices. A luminous power efficiency of ∼1.6 lm/W was achieved at 100 cd/m2, slightly higher than that (∼1.5 lm/W) measured for the control device based on a sputter-deposited ITO on glass. © 2001 American Institute of Physics.
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73.61.Le Other inorganic semiconductors
78.66.Li Other semiconductors
81.15.Fg Pulsed laser ablation deposition
68.55.-a Thin film structure and morphology
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
85.60.Jb Light-emitting devices

Er3+ photoluminescence properties of erbium-doped Si/SiO2 superlattices with subnanometer thin Si layers

Yong Ho Ha, Sehun Kim, Dae Won Moon, Ji-Hong Jhe, and Jung H. Shin

Appl. Phys. Lett. 79, 287 (2001); http://dx.doi.org/10.1063/1.1383802 (3 pages) | Cited 9 times

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The effect of the Si layer thickness on the Er3+ photoluminescence properties of the Er-doped Si/SiO2 superlattice is investigated. We find that the Er3+ luminescence intensity increases by over an order of magnitude as the Si layer thickness is reduced from 3.6 nm down to a monolayer of Si. Temperature dependence of the Er3+ luminescence intensity and time-resolved measurement of Er3+ luminescence intensity identify the increase in the excitation rate as the likely cause for such an increase, and underscore the importance of the Si/SiO2 interface in determining the Er3+ luminescence properties. © 2001 American Institute of Physics.
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78.55.Ap Elemental semiconductors
71.55.Cn Elemental semiconductors
81.05.Cy Elemental semiconductors
78.66.Db Elemental semiconductors and insulators
73.21.Cd Superlattices
61.46.-w Structure of nanoscale materials
81.07.Bc Nanocrystalline materials
78.47.-p Spectroscopy of solid state dynamics

Modified Mach–Zender laser interferometer for probing bulk acoustic waves

G. G. Fattinger and P. T. Tikka

Appl. Phys. Lett. 79, 290 (2001); http://dx.doi.org/10.1063/1.1385340 (3 pages) | Cited 12 times

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This letter reports the usage of a modified Mach–Zehnder interferometer for visualization of the mechanical vibrations of high-frequency, bulk-mode, thin-film resonators. The setup is capable of detecting frequencies from 30 kHz up to 12 GHz with an amplitude down to less than 10 pm, which means a dynamic range above 80 dB. The achieved lateral resolution of the measured field image is more than 300 nm. Due to a new phase stabilizing system phase sensitive measurements are possible, additionally bringing up the possibility of establishing a tremendous measurement speed of up to 5 million points/h. This setup can be applied to bulk acoustic wave development in order to provide information such as material parameters, to verify theoretical models and to learn about device behavior which cannot be done using only electrical measurement tools. © 2001 American Institute of Physics.
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07.10.-h Mechanical instruments and equipment
43.58.-e Acoustical measurements and instrumentation

Continuous-wave self-pumped optical parametric oscillator based on Yb3+-doped bulk periodically poled LiNbO3 (MgO)

J. Capmany, D. Callejo, V. Bermúdez, E. Diéguez, D. Artigas, and L. Torner

Appl. Phys. Lett. 79, 293 (2001); http://dx.doi.org/10.1063/1.1383567 (3 pages) | Cited 11 times

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We present experimental evidence of continuous-wave self-pumped parametric oscillation in Yb3+-doped periodically poled lithium niobate co-doped with MgO. A single bulk crystal of periodically poled lithium niobate containing Yb3+ laser-active ions performs as a singly resonant parametric oscillator generating a signal wave at 1360 nm. The optical parametric oscillator is intracavity pumped by the laser emission at 1063 nm produced by the Yb3+ ions in the crystal. The whole system is end pumped at 980 nm. © 2001 American Institute of Physics.
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42.65.Yj Optical parametric oscillators and amplifiers
77.80.-e Ferroelectricity and antiferroelectricity

Formation dynamics of diffraction gratings in reactive liquid crystals

P. A. Kossyrev and G. P. Crawford

Appl. Phys. Lett. 79, 296 (2001); http://dx.doi.org/10.1063/1.1385343 (3 pages) | Cited 6 times

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Using in situ diffraction measurements of diffraction grating formation in a single component reactive mesogen system, the anisotropy in the diffusion constants is determined. The data are well explained by a diffusion model, which accounts for the density modulation due to shrinkage upon photopolymerization with interfering laser beams. © 2001 American Institute of Physics.
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42.79.Dj Gratings
42.70.Df Liquid crystals
82.35.Ej Nonlinear optics with polymers
82.50.Nd Control of photochemical reactions
82.50.Hp Processes caused by visible and UV light

Modulation of light radiation during input into waveguide by resonance excitation of surface plasmons

N. A. Janunts and Kh. V. Nerkararyan

Appl. Phys. Lett. 79, 299 (2001); http://dx.doi.org/10.1063/1.1385798 (3 pages) | Cited 9 times

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The process of transfer of energy of a surface plasmon polariton between modes located on two surfaces of a metal layer is studied. It is shown that this process strongly depends on the refractive indices of dielectrics surrounding the metal layer. The possibilities of high-speed optical signal modulation, based on this phenomenon, are discussed. © 2001 American Institute of Physics.
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42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
42.79.Hp Optical processors, correlators, and modulators
78.68.+m Optical properties of surfaces
42.82.Bq Design and performance testing of integrated-optical systems
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)

Optically pumped integrated absorber 3.4 μm laser with InAs-to-InGaAsSb type-II transition

R. Kaspi, A. Ongstad, C. Moeller, G. C. Dente, J. Chavez, M. L. Tilton, and D. Gianardi

Appl. Phys. Lett. 79, 302 (2001); http://dx.doi.org/10.1063/1.1385581 (3 pages) | Cited 12 times

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We report optically pumped lasing at λ∼3.4 μm from an integrated absorber structure in which the electrons confined in the InAs quantum wells recombine with holes in adjacent InGaAsSb layers to provide the gain. This type-II laser exhibits an estimated photon-to-photon conversion rate of ∼24% at 85 K. The self-consistent empirical pseudopotential method calculations suggest that Coulomb attraction can lead to a strong enhancement in carrier overlap, and the resulting small shift in transition energy is consistent with that observed. © 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Efficient and stable dye laser action from modified dipyrromethene BF2 complexes

A. Costela, I. García-Moreno, C. Gómez, F. Amat-Guerri, and R. Sastre

Appl. Phys. Lett. 79, 305 (2001); http://dx.doi.org/10.1063/1.1385185 (3 pages) | Cited 13 times

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We report on the lasing action of modified dipyrromethene BF2 complexes in air-equilibrated liquid solutions. All recent dyes share a common chromophore core and were dissolved in apolar, polar nonprotic, and polar protic solvents. When pumped transversely at 534 nm, nearly solvent-independent laser emission was obtained with efficiencies well over 40% in most cases. Highest lasing efficiency was 59%. Under continuous ultraviolet irradiation some of these dyes demonstrated improved photostability as compared with commercial dye pyrromethene 567. © 2001 American Institute of Physics.
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42.55.Mv Dye lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

White-light electroluminescence from soluble oxadiazole-containing phenylene vinylene ether-linkage copolymer

Yuh-Zheng Lee, Xiwen Chen, Ming-Chih Chen, Show-An Chen, Jui-Hung Hsu, and Wunshain Fann

Appl. Phys. Lett. 79, 308 (2001); http://dx.doi.org/10.1063/1.1385586 (3 pages) | Cited 65 times

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We report a promising oxadiazole-containing phenylene vinylene ether-linkage copolymer, which can emit nearly white light from a single-layer light-emitting diode. The emission spectrum is composed of a red component originating from the new excited dimer in addition to the blue-green component from an individual lumophore and excimer. This excited dimer is formed under a strong electric field inside the diode and cannot be produced by photoexcitation, which is different from the excimer or exciplex that is often found both in photoluminescence and electroluminescence, and it is termed the “electromer.” © 2001 American Institute of Physics.
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42.70.Jk Polymers and organics
78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices

Speed enhancement in a photorefractive multiple-quantum-well modulator by pulsed illumination

A. K. Abeeluck, P. Heinz, and E. Garmire

Appl. Phys. Lett. 79, 311 (2001); http://dx.doi.org/10.1063/1.1385797 (3 pages)

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A factor-of-four increase in the operating speed of a high-resolution low-temperature-grown photorefractive multiple-quantum-well (PRMQW) spatial light modulator is reported. This is achieved by shining a spatially uniform erasing pulse from a light-emitting diode (LED) on the device that is driven by a single-sided applied voltage. The erasing pulse is turned on briefly during the off-voltage cycle while a grating is written during the on-voltage cycle using a continuous-wave laser diode. The dependence of the change in diffraction efficiency on the frequency of the applied voltage, on the timing and duration of the LED pulse, and on the intensities of the LED and of the pump beams has been investigated. Our results are relevant to applications of PRMQW modulators where both high spatial resolution and fast operating speed are required. © 2001 American Institute of Physics.
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42.79.Hp Optical processors, correlators, and modulators
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.25.Fx Diffraction and scattering
42.79.Dj Gratings

All-optical diode in a periodically poled lithium niobate waveguide

Katia Gallo, Gaetano Assanto, Krishnan R. Parameswaran, and Martin M. Fejer

Appl. Phys. Lett. 79, 314 (2001); http://dx.doi.org/10.1063/1.1386407 (3 pages) | Cited 75 times

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We have demonstrated a guided-wave all-optical diode based on engineered quasiphase Matching in a LiNbO3 channel waveguide. For input peak powers beyond 1.5 W at 1.55 μm, the device exhibited a spatially nonreciprocal response, leading to optical isolation with contrasts as high as 90% at 3.1 W, in agreement with theoretical predictions. © 2001 American Institute of Physics.
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42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers
42.70.-a Optical materials
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Spatial charge effects in retarding field analyzer ion measurements in a cathodic vacuum arc

D. Grondona, H. Kelly, and A. Márquez

Appl. Phys. Lett. 79, 317 (2001); http://dx.doi.org/10.1063/1.1380402 (3 pages) | Cited 3 times

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The ion energy distribution generated in a pulsed vacuum arc operated with a Ti cathode and N2 filling gas is reported. A retarding field analyzer system is employed, for which the usual derivation of the ion energy spectrum has been modified to take into account spatial charge effects in the grid-collector region of the analyzer. It allows one to interpret the decrease in the collector current at collector bias voltages unusually low (even negatives) observed in this experiment, as well as in others. It is found that spatial charge effects are more marked when the arc operates with gas filling because of the creation (by charge-exchange processes) of low energy gaseous ions which are easily stopped by the potential hump created by the positive charge in the grid-collector region of the analyzer. © 2001 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.80.Vp Discharge in vacuum
52.70.Nc Particle measurements
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Infrared properties of room-temperature-deposited ZrO2

L. Koltunski and R. A. B. Devine

Appl. Phys. Lett. 79, 320 (2001); http://dx.doi.org/10.1063/1.1384476 (3 pages) | Cited 11 times

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ZrO2 films have been deposited at room temperature using Zr(OC4H9)4 and O2 source gases in a low-pressure electron-cyclotron-resonance-excited plasma reactor. The deposited films were, in general, mixed (amorphous and polycrystalline; monoclinic or tetragonal), the crystallinity depending upon the substrate polarization during deposition and the postdeposition annealing. Infrared vibrational modes of the films have been characterized. In as-deposited films, the dielectric constants were ∼12–18, dependent upon sample bias during deposition, and the refractive indices were ∼1.85–1.92. © 2001 American Institute of Physics.
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78.66.Nk Insulators
78.30.Hv Other nonmetallic inorganics
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.77.Dq Plasma-based ion implantation and deposition
77.55.-g Dielectric thin films
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
77.22.Ch Permittivity (dielectric function)
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
63.20.-e Phonons in crystal lattices

Physical properties of N2O and NO-nitrided gate oxides grown on 4H SiC

P. Jamet and S. Dimitrijev

Appl. Phys. Lett. 79, 323 (2001); http://dx.doi.org/10.1063/1.1385181 (3 pages) | Cited 45 times

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N2O and NO nitridation by either annealing or direct growth of gate oxides on 4H SiC is analyzed in this letter. The analysis is based on x-ray photoelectron spectroscopy binding energies and secondary ion mass spectroscopy depth profiles of nitrogen at the SiO2–SiC interface. A clean SiO2–SiC interface is found in both NO and N2O annealed/grown samples, as opposed to the interface annealed in Ar which exhibits complex suboxides and oxide–carbon compounds. The results demonstrate that nitridation in the industry-preferred N2O ambient could be as effective as nitridation in NO, provided appropriate process optimization is performed. © 2001 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
61.72.Cc Kinetics of defect formation and annealing
79.60.Jv Interfaces; heterostructures; nanostructures

Room temperature persistent spectral hole burning in x-ray irradiated Eu3+-doped borate glasses

Woon Jin Chung and Jong Heo

Appl. Phys. Lett. 79, 326 (2001); http://dx.doi.org/10.1063/1.1385346 (3 pages) | Cited 9 times

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Irradiation of x-rays has induced room-temperature persistent spectral hole burning (PSHB) in Eu3+-doped borate glasses melted under an inert atmosphere. Defects were formed by x-ray irradiation and these defects, especially electron trapping centers near rare-earth ions in glasses, were responsible for the PSHB. Electrons were released from these defects upon irradiation of a burning light. Photoreduction of Eu3+ to Eu2+ by trapping these electrons resulted in the formation of persistent spectral holes. © 2001 American Institute of Physics.
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42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
61.43.Fs Glasses
61.80.Cb X-ray effects
61.82.Ms Insulators
82.50.-m Photochemistry

Friction and wear characteristics of ceramic nanocomposite coatings: Titanium carbide/amorphous hydrocarbon

D. M. Cao, B. Feng, W. J. Meng, L. E. Rehn, P. M. Baldo, and M. M. Khonsari

Appl. Phys. Lett. 79, 329 (2001); http://dx.doi.org/10.1063/1.1384477 (3 pages) | Cited 24 times

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Friction and wear characteristics of titanium-containing amorphous hydrocarbon (Ti–C:H) coatings were measured during unlubricated sliding against WC–Co. These Ti–C:H coatings consist of nanocrystalline TiC clusters embedded in an amorphous hydrocarbon (a-C:H) matrix, i.e., they are TiC/a-C:H nanocomposites. The elastic modulus and hardness of the coatings exhibit smooth variations with increasing Ti composition. In contrast, a relatively abrupt transition occurs in the friction coefficient and wear rate of the coatings over a relatively narrow (20–30 at. %) Ti composition range. Our results reveal bimodal friction and wear behaviors for the TiC/a-C:H nanocomposites, a-C:H like at Ti compositions below 20%, and TiC like at Ti compositions above 30%. The two different wear mechanisms that operate as the volume fraction of nanocrystalline TiC clusters changes are discussed. © 2001 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
62.20.Qp Friction, tribology, and hardness
81.40.Pq Friction, lubrication, and wear
61.46.-w Structure of nanoscale materials
62.20.D- Elasticity

Thermal diffusivity in amorphous silicon carbon nitride thin films by the traveling wave technique

S. Chattopadhyay, L. C. Chen, C. T. Wu, K. H. Chen, J. S. Wu, Y. F. Chen, G. Lehmann, and P. Hess

Appl. Phys. Lett. 79, 332 (2001); http://dx.doi.org/10.1063/1.1386619 (3 pages) | Cited 8 times

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Thermal diffusivity (α) of amorphous silicon carbon nitride (a-SiCxNy) thin films on crystalline silicon, prepared by ion beam sputtering, has been studied using the traveling wave technique. The variation of thermal diffusivity with carbon content in amorphous silicon carbon nitride samples are reported. Thermal diffusivity decreased from ∼ 0.35 cm2/s for samples with carbon contents of less than 30 at. %, to about 0.15 cm2/s for a-SiCxNy films with a carbon content of ∼ 70 at. %. A similar variation was found for the film density as measured by surface acoustic wave spectroscopy as a function of the carbon content. The results on a-SiCxNy, elucidate the relation between thermal diffusivity and the bonding configuration, density and microstructure of the network. © 2001 American Institute of Physics.
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66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
68.55.A- Nucleation and growth
61.43.Dq Amorphous semiconductors, metals, and alloys
68.60.Dv Thermal stability; thermal effects

Enhancement of dislocation velocities by stress-assisted kink nucleation at the native oxide/SiGe interface

E. A. Stach and R. Hull

Appl. Phys. Lett. 79, 335 (2001); http://dx.doi.org/10.1063/1.1384904 (3 pages) | Cited 4 times

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Experiments have shown that a native oxide layer on the surface of a strained SiGe epilayer causes an order of magnitude increase in dislocation velocities during annealing over those observed in atomically clean samples and during crystal growth [E. A. Stach, R. Hull, R. M. Tromp, M. C. Reuter, M. Copel, F. K. LeGoues, and J. C. Bean, J. Appl. Phys. 83, 1931 (1998)]. This behavior is explained herein by stress-assisted dislocation kink nucleation at the oxide/epilayer interface. Finite element models are used to estimate the stress local to steps at this interface due to both intrinsic and thermal expansion stresses, and dislocation theory is used to determine the resulting increase in single kink nucleation. © 2001 American Institute of Physics.
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68.35.Ct Interface structure and roughness
65.40.De Thermal expansion; thermomechanical effects
02.70.Dh Finite-element and Galerkin methods
61.72.Cc Kinetics of defect formation and annealing
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Bb Theories and models of crystal defects
61.72.Lk Linear defects: dislocations, disclinations

Local structure of implanted B in amorphous Si

F. Mai, B. Ittermann, M. Füllgrabe, M. Heemeier, F. Kroll, K. Marbach, P. Meier, H. Mell, D. Peters, H. Thieß, H. Ackermann, and H.-J. Stöckmann

Appl. Phys. Lett. 79, 338 (2001); http://dx.doi.org/10.1063/1.1384482 (3 pages) | Cited 1 time

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12B probe nuclei are implanted in amorphous Si and monitored by β-radiation-detected nuclear magnetic resonance (β-NMR). Independently of growth conditions and impurity content, we find the same frequency distribution in a variety of samples. This is interpreted as an intrinsic signature of the amorphous environment while preferential B–H pairing is not observed. Comparing our data with earlier 11B-NMR work, we find the local B configuration to be completely controlled by the incorporation process. In our low-dose implantation experiment, all B is fourfold coordinated and electrically active. This is in contrast to gas-phase doping or high-dose implantation where the threefold coordination prevails. © 2001 American Institute of Physics.
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61.43.Dq Amorphous semiconductors, metals, and alloys
81.05.Gc Amorphous semiconductors
61.05.Qr Magnetic resonance techniques; Mössbauer spectroscopy (for structure determination only)
76.60.-k Nuclear magnetic resonance and relaxation
81.05.Cy Elemental semiconductors

Localized excitons in an In0.06Ga0.94N multiple-quantum-well laser diode lased at 400 nm

Shigefusa F. Chichibu, Takashi Azuhata, Takayuki Sota, and Takashi Mukai

Appl. Phys. Lett. 79, 341 (2001); http://dx.doi.org/10.1063/1.1385583 (3 pages) | Cited 11 times

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An InGaN multiple-quantum-well laser diode wafer that lased at 400 nm was shown to have InN mole fraction x of only 6% and 2% in the wells and barriers, respectively. The Stokes-like shift (SS) and localization depth E0 were estimated to be 49 and 35 meV at 300 K although the compositional fluctuation in the well was as small as 1% or less. Since the well thickness fluctuation is insufficient to reproduce the SS or E0, the quantum-well exciton localization is considered to be an intrinsic phenomenon in InGaN, which is due to the large band-gap bowing and In clustering. The spontaneous emission was thus assigned as being due to the recombination of excitons localized at the exponential tail-type potential minima in the density of states. However, shallow and low-density localized states are leveled by injecting high-density carriers under the lasing conditions. © 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.35.-y Excitons and related phenomena
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Fabrication of strain-balanced Si/Si1−xGex multiple quantum wells on Si1−yGey virtual substrates and their optical properties

K. Kawaguchi, Y. Shiraki, N. Usami, J. Zhang, N. J. Woods, G. Breton, and G. Parry

Appl. Phys. Lett. 79, 344 (2001); http://dx.doi.org/10.1063/1.1387263 (3 pages) | Cited 2 times

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Strain-balanced Si/SiGe multiple quantum wells (MQWs), which are designed to overcome the limitation of the number of wells coming from the strain accumulation, were fabricated, and their optical properties were investigated. X-ray diffraction spectra and cross-sectional transmission-electron-microscope images showed a high-crystalline quality of samples and excellent uniformity of the well width. Well-resolved no-phonon and TO-phonon-assisted transitions from strain-balanced MQWs were observed by low-temperature photoluminescence spectroscopy, and both their temperature and excitation power dependence showed blueshifts due to the delocalization of excitons, the band bending, and/or the band-filling effect. © 2001 American Institute of Physics.
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81.07.St Quantum wells
78.67.De Quantum wells
73.21.Fg Quantum wells
68.65.Fg Quantum wells
78.55.Hx Other solid inorganic materials
71.35.Gg Exciton-mediated interactions
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Micromechanical properties of silicon-carbide thin films deposited using single-source chemical-vapor deposition

C. R. Stoldt, M. C. Fritz, C. Carraro, and R. Maboudian

Appl. Phys. Lett. 79, 347 (2001); http://dx.doi.org/10.1063/1.1383277 (3 pages) | Cited 17 times

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1,3-Disilabutane is used as a single-source precursor to deposit conformal silicon-carbide films on silicon atomic-force-microscopy cantilevers. By measuring the resonance frequency of the cantilever as a function of silicon-carbide film thickness and developing an appropriate model, the value of the film’s elastic modulus is determined. This value is in good agreement with those reported for silicon-carbide films deposited using conventional dual-source chemical-vapor deposition. Additionally, we comment on the feasibility of integrating this process into the fabrication technology for microelectromechanical systems. © 2001 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.60.Bs Mechanical and acoustical properties
68.55.A- Nucleation and growth
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations

Magnetochromatics of the magnetic fluid film under a dynamic magnetic field

Herng-Er Horng, S. Y. Yang, S. L. Lee, Chin-Yih Hong, and H. C. Yang

Appl. Phys. Lett. 79, 350 (2001); http://dx.doi.org/10.1063/1.1385796 (3 pages) | Cited 33 times

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The structure and the corresponding magnetochromatics of homogeneous magnetic fluid films under dynamic magnetic fields perpendicular to the film surfaces are investigated in this letter. During the application of a magnetic field from 0 up to 200 Oe, the structure in the magnetic fluid film evolves from a monodispersed state to a disordered-column state, and then to an ordered hexagonal structure. The column spacing for the instant hexagonal structure during the dynamic process was measured and found to vary from 2.41 to 1.83 μm when the field strength was raised from 60 to 200 Oe. Within this range, the hexagonal structure diffracts the visible light like an optical grating. Due to the dynamic variation of the column spacing with the increasing field strength, the color of the diffracted light changed unceasingly from red to blue when observed from a fixed point above the film. The results strongly suggest the possibility that optical devices may be developed by utilizing the magnetochromatics of magnetic fluid films under dynamic magnetic fields. © 2001 American Institute of Physics.
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78.20.Ls Magneto-optical effects
75.50.Mm Magnetic liquids
78.66.-w Optical properties of specific thin films
68.15.+e Liquid thin films
75.70.Ak Magnetic properties of monolayers and thin films
61.25.-f Studies of specific liquid structures
42.25.Fx Diffraction and scattering
42.79.Dj Gratings
42.79.Wc Optical coatings

On the mechanism of the cubic phase formation in the boron nitride thin-film systems

Sakhrat Khizroev and Dmitri Litvinov

Appl. Phys. Lett. 79, 353 (2001); http://dx.doi.org/10.1063/1.1386403 (3 pages) | Cited 5 times

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This work addresses the issue of cubic phase formation in boron nitride thin-film systems. The presented data suggest strain-induced formation of cubic phase. The compliant nature of the turbostratic boron nitride buffer layer is shown to be an essential factor for cubic phase nucleation. Two distinct regimes of cubic phase formation are observed. First, a cubic boron nitride seed layer is formed on top of the turbostratic boron nitride buffer layer under nitrogen ion irradiation of the growth surface. This is followed by the growth mode of the cubic phase, which requires a different set of growth conditions. The role of nitrogen ion irradiation in two deposition regimes is discussed. © 2001 American Institute of Physics.
Show PACS
68.55.A- Nucleation and growth
81.05.Ea III-V semiconductors
81.15.Cd Deposition by sputtering
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