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14 Jun 1999

Volume 74, Issue 24, pp. 3595-3737

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Modal expansion analysis of strained photonic lattices based on vertical cavity surface emitting laser arrays

Tal Fishman, Eli Kapon, Harald Pier, and Amos Hardy

Appl. Phys. Lett. 74, 3595 (1999); http://dx.doi.org/10.1063/1.123192 (3 pages) | Cited 5 times

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The optical modes of lasing photonic lattices incorporating alternating-shear strain were analyzed using a background-resonator mode expansion model. The model correctly explains the observed locking of the photon mode near fields to square or hexagonal-like lattice patterns for subcritical strain values, as well as the abrupt switching between the two mode patterns. Control of the optical mode switching point by adjusting the lattice reflectivity is proposed and analyzed. © 1999 American Institute of Physics.
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42.60.Fc Modulation, tuning, and mode locking
42.55.Sa Microcavity and microdisk lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.50.-p Quantum optics
42.70.Qs Photonic bandgap materials
42.55.Px Semiconductor lasers; laser diodes

Temperature dependence of InGaAs/GaAs quantum well microcavity light-emitting diodes

T. Takamori, A. R. Pratt, and T. Kamijoh

Appl. Phys. Lett. 74, 3598 (1999); http://dx.doi.org/10.1063/1.123193 (3 pages) | Cited 5 times

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We report a systematic investigation of the emission properties of semiconductor microcavity light-emitting diodes (MC-LEDs) with different cavity detuning. Evidence that varying the cavity detuning leads to temperature insensitive output characteristics is provided by changes in the temperature dependence of the slope efficiency extracted from the light output versus current characteristics. For resonantly tuned devices the slope efficiency decreases monotonically with increasing temperature. However when the cavity peak is detuned to long wavelength with respect to the room temperature quantum well (QW) emission, temperature insensitive characteristics are achieved. Compared to a noncavity type LED, enhanced efficiency and narrow spectral linewidth have been observed for the MC-LEDs with the highest output efficiency achieved when the QW emission and cavity peak are exact resonant. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.66.Fd III-V semiconductors

Wavelength shifting of optical pulses in a polydiacetylene waveguide

Daniela Grando, Stefano Sottini, Gian Piero Banfi, Davide Fortusini, and Monica LoPapa

Appl. Phys. Lett. 74, 3601 (1999); http://dx.doi.org/10.1063/1.123194 (3 pages) | Cited 2 times

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We characterize the process of wavelength shifting (generation of a pulse at the wavelength λp−Δ from a signal at λp+Δ under the action of a pump at λp) in a planar waveguide of poly (3BCMU) for short. With a propagation length of 4.5 mm, pulses of 20 ps time duration, and λ′ s around 1.3 μm, we observe wavelength conversion with 1% efficiency when the energy of the pump pulse per unit width is about 10−5 J/m. © 1999 American Institute of Physics.
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42.65.Wi Nonlinear waveguides
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.70.Jk Polymers and organics
42.79.Nv Optical frequency converters
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Gn Optical waveguides and couplers

Noncontact continuous wavefront/diffractive acoustic elements for Rayleigh wave control

M. Clark, S. D. Sharples, and M. G. Somekh

Appl. Phys. Lett. 74, 3604 (1999); http://dx.doi.org/10.1063/1.123195 (3 pages) | Cited 3 times

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A laser is used to excite Rayleigh waves on a sample. The optical distribution of the laser energy as it strikes the sample is controlled using a computer generated hologram—this optical distribution determines the initial acoustic wavefront and hence the acoustic amplitude distribution. In this letter, we present two designs of acoustic elements which use diffraction of the Rayleigh waves as a means of controlling the acoustic amplitude distribution. © 1999 American Institute of Physics.
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43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect
68.35.Gy Mechanical properties; surface strains
43.20.El Reflection, refraction, diffraction of acoustic waves
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography

Thermally induced threefold upconversion emission enhancement in nonresonant excited Er3+/Yb3+-codoped chalcogenide glass

P. V. dos Santos, E. A. Gouveia, M. T. de Araujo, A. S. Gouveia-Neto, A. S. B. Sombra, and J. A. Medeiros Neto

Appl. Phys. Lett. 74, 3607 (1999); http://dx.doi.org/10.1063/1.123196 (3 pages) | Cited 36 times

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Thermally induced threefold infrared-to-visible upconversion emission enhancement in Er3+/Yb3+-codoped Ga2S3:La2O3 chalcogenide glasses excited at 1.064 μm is reported. The times three upconversion efficiency enhancement was achieved by heating the sample in the temperature range of 23–155 °C, and is assigned to the temperature-dependent multiphonon-assisted anti-Stokes sideband excitation process of the ytterbium sensitizer. A theoretical analysis based upon rate equations considering the sensitizer absorption cross section as a function of the phonon occupation number in the host material exhibited very good agreement with experimental data. © 1999 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Ce Glasses, quartz
63.50.-x Vibrational states in disordered systems

High-reflectivity GaN/GaAlN Bragg mirrors at blue/green wavelengths grown by molecular beam epitaxy

R. Langer, A. Barski, J. Simon, N. T. Pelekanos, O. Konovalov, R. André, and Le Si Dang

Appl. Phys. Lett. 74, 3610 (1999); http://dx.doi.org/10.1063/1.123197 (3 pages) | Cited 35 times

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Highly-reflective GaN/GaAlN quarter-wave Bragg mirrors, designed to be centered at blue/green wavelengths, have been grown by molecular beam epitaxy. The reflectivity for a mirror centered at 473 nm was as high as 93% and the bandwidth reached 22 nm. Detailed x-ray diffraction measurements allowed us to characterize the structural parameters of the Bragg mirrors. We show that, in spite of substantial strain relaxation occurring in our samples, high reflectivity is still possible. In addition, we show that growth interruption at the heterointerfaces is crucial for achieving high reflectivities. © 1999 American Institute of Physics.
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42.79.Bh Lenses, prisms and mirrors
42.55.Px Semiconductor lasers; laser diodes
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Ea III-V semiconductors

Multicolor multilayer light-emitting devices based on pyridine-containing conjugated polymers and para-sexiphenyl oligomer

Y. Z. Wang, R. G. Sun, F. Meghdadi, G. Leising, and A. J. Epstein

Appl. Phys. Lett. 74, 3613 (1999); http://dx.doi.org/10.1063/1.123198 (3 pages) | Cited 43 times

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There is increased interest in developing multicolor light-emitting devices. We report here the fabrication and study of multilayer color-variable/white light-emitting devices based on pyridine-containing conjugated polymers and para-sexiphenyl (6P) oligomer. Voltage-dependent multicolor emission was observed in both bilayer and trilayer configurations. The emission colors of single devices cover a wide range of visible spectra whose Commission International de I’Eclairage (CIE) color coordinates vary from blue to white to green with increasing voltages. The color coordinate traverses along a straight line in the CIE chromaticity diagram. The role of interfaces in the operation of devices is discussed. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices

GaInN/GaN multiple-quantum-well light-emitting diodes grown by molecular beam epitaxy

N. Grandjean, J. Massies, S. Dalmasso, P. Vennéguès, L. Siozade, and L. Hirsch

Appl. Phys. Lett. 74, 3616 (1999); http://dx.doi.org/10.1063/1.123199 (3 pages) | Cited 21 times

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GaInN and GaN were grown by molecular beam epitaxy on c-plane sapphire using NH3. 9 K photoluminescence performed on both GaInN thin layers and GaInN/GaN multiple-quantum wells (MQWs) exhibits narrow emission (∼50 meV linewidths). Transmission electron microscopy images show sharp GaInN/GaN interfaces and homogeneous GaInN layers. Strong indium surface segregation is also evidenced. Light-emitting diodes were fabricated from 5×GaInN (25 Å)/GaN (35 Å) MQW heterostructures. The 300 K electroluminescence yields blue light at 440 nm. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.66.Fd III-V semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.60.Fi Electroluminescence

Passive Q-switching of fiber lasers using a broadband liquefying gallium mirror

P. Petropoulos, H. L. Offerhaus, D. J. Richardson, S. Dhanjal, and N. I. Zheludev

Appl. Phys. Lett. 74, 3619 (1999); http://dx.doi.org/10.1063/1.123200 (3 pages) | Cited 20 times

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Using a nonlinear cavity element, a liquefying gallium mirror, we demonstrate stable, self-starting, passive Q-switching of both erbium and ytterbium fiber laser cavities operating at wavelengths of 1550 and 1030 nm, respectively. The performance at 1550 nm is shown to be equivalent to that achieved with a state of the art semiconductor saturable absorber designed to work at this wavelength. The results highlight the suitability of this tremendously broadband, inexpensive nonlinear medium for a wide range of passive Q-switch applications. © 1999 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Rz Doped-insulator lasers and other solid state lasers
42.55.Wd Fiber lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.79.Bh Lenses, prisms and mirrors

High-repetition-rate, high-average-power, mode-locked Ti:sapphire laser with an intracavity continuous-wave amplification scheme

Zhenlin Liu, Shinji Izumida, Shingo Ono, Hideyuki Ohtake, and Nobuhiko Sarukura

Appl. Phys. Lett. 74, 3622 (1999); http://dx.doi.org/10.1063/1.123201 (2 pages) | Cited 5 times

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We have demonstrated a high-average-power, mode-locked Ti:sapphire laser with an intracavity continuous-wave amplification scheme. The laser generated 150 fs pulses with 3.4 W average power at a repetition rate of 79 MHz. This simple amplification scheme can be applied for the power scaling of other lasers. © 1999 American Institute of Physics.
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42.60.By Design of specific laser systems
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Fc Modulation, tuning, and mode locking
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
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Multiwire screw-pinch loads for generation of terawatt x-ray radiation

T. A. Golub, N. B. Volkov, R. B. Spielman, and N. A. Gondarenko

Appl. Phys. Lett. 74, 3624 (1999); http://dx.doi.org/10.1063/1.123202 (3 pages) | Cited 3 times

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A multiwire screw pinch (a variant of a Z pinch) for high-current 100 ns pulsed power generators used for terawatt x-ray radiation is proposed and discussed. Wires, twisted along a curved load surface, are suggested to be an effective way to create the initial axial magnetic field, to begin the rotation of the plasma, and to mitigate the growth of Rayleigh–Taylor instabilities. A screw-pinch design is predicted by a zero-dimensional model to provide more efficient energy transfer from the pulse power generator to the load compared with a straight, cylindrical wire array. © 1999 American Institute of Physics.
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52.55.Ez Theta pinch
52.35.Py Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
52.30.-q Plasma dynamics and flow
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Fast optical switching by a laser-manipulated microdroplet of liquid crystal

Saulius Juodkazis, Masaya Shikata, Toshimasa Takahashi, Shigeki Matsuo, and Hiroaki Misawa

Appl. Phys. Lett. 74, 3627 (1999); http://dx.doi.org/10.1063/1.123203 (3 pages) | Cited 28 times

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We demonstrate the feasibility of an all-optical liquid-crystal (LC) switch with submillisecond switching time. This switch is realized by optical manipulation of a three-dimensionally trapped microscopic nematic LC droplet using an “optical tweezers.” Transmission of a polarizer/LC droplet/analyzer system can be modulated at frequencies as high as 103 Hz, a faster response than that of a nematic LC demonstrated so far. The response corresponds to a submillisecond switching time when the LC droplet is rotated by an angle of π/4. The alignment of the LC droplet to the plane of the incident plane-polarized beam is also demonstrated. © 1999 American Institute of Physics.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Kr Display devices, liquid-crystal devices
42.70.Df Liquid crystals
37.10.Vz Mechanical effects of light on atoms, molecules, and ions

Field-enhanced Stokes shifts in tensilely strained carbon-based quantum wells

Y. Sugawara, S. Fukatsu, K. Brunner, and K. Eberl

Appl. Phys. Lett. 74, 3630 (1999); http://dx.doi.org/10.1063/1.123204 (3 pages) | Cited 1 time

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A large, rigid downward shift of excitonic luminescence peak energies was observed with increasing transverse electric field in tensilely strained Si1−yCy/Si(001) symmetric quantum wells, as opposed to theoretical calculations predicting a blueshift due to exciton weakening, which more than balances the redshift due to quantum-confined Stark effects. The observed anomalies are interpreted in terms of field-enhanced Stokes shifts which occur due to carrier relaxation in an inhomogeneously distributed potential of the grown-in Si1−yCy/Si interfaces. © 1999 American Institute of Physics.
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78.66.Li Other semiconductors
78.55.Hx Other solid inorganic materials
78.20.Jq Electro-optical effects
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Syntactic coalescence of WS2 nanotubes

M. Remškar, Z. Škraba, R. Sanjinés, and F. Lévy

Appl. Phys. Lett. 74, 3633 (1999); http://dx.doi.org/10.1063/1.123205 (3 pages) | Cited 12 times

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WS2 nanoropes merged from nanotube coalescence present a new case of inorganic fiber composites with several nanotubes grown side by side up to a few millimeters in length. The extremities of external and inner spirally rolled-up molecular layer building the tubes are at the origin of the nanotube nucleation leading to the syntactic growth of nanotubes. The model of undulation of thin crystal flakes based on stacking mismatch is discussed. The nanoropes grow also by self-assembly or by coalescence of single tubes at low angles of incidence. An attractive long-range force leading to the nanotube approach is proposed. © 1999 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
61.46.-w Structure of nanoscale materials

Strain effects and microstructure of epitaxial manganite thin films and heterostructures

B. Wiedenhorst, C. Höfener, Yafeng Lu, J. Klein, L. Alff, R. Gross, B. H. Freitag, and W. Mader

Appl. Phys. Lett. 74, 3636 (1999); http://dx.doi.org/10.1063/1.123206 (3 pages) | Cited 44 times

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We have grown epitaxial La2/3Sr1/3MnO3 (LSMO) and La2/3Ba1/3MnO3 (LBMO) thin films as well as La2/3Ba1/3MnO3/SrTiO3 heterostructures by pulsed-laser deposition. The microstructure of the films was analyzed by x-ray diffraction and transmission electron microscopy. A significant effect of strain due to lattice mismatch was found. Whereas the thick LBMO films show perfect epitaxy and grow coherently strained over the full film thickness, the LSMO films were found to be composed of two layers separated by an intrinsic interface region containing a high density of defects. The approximately 60 nm thick bottom layer grows coherently on the SrTiO3 (STO) substrate and is highly strained, whereas the top layer is almost strain free. The LBMO/STO heterostructures are coherently strained and show a very low density of defects and sharp interfaces. © 1999 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.72.-y Defects and impurities in crystals; microstructure
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Fg Pulsed laser ablation deposition
68.35.Ct Interface structure and roughness

Improved thermal stability of nonpolymeric organic glasses by doping with fullerene C60

T. Krieg, A. Petr, G. Barkleit, and L. Dunsch

Appl. Phys. Lett. 74, 3639 (1999); http://dx.doi.org/10.1063/1.123207 (3 pages) | Cited 3 times

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The doping of nonpolymeric organic glasses with C60 is found to improve their thermal stability. Films of triphenylamine dimer (TPD) N,N′-diphenyl-N,N′-(3-methyl-phenyl)-1,1′-biphenyl-4,4′-diamine, doped with fullerene C60 and 7,7,8,8-tetracyano-quinodimethane (TCNQ) on a level between 10 and 20 mol %, were prepared using vacuum codeposition techniques. While undoped and TCNQ-doped TPD films tend to crystallize under ambient conditions, no crystallization occurs on C60-doped TPD films on minimum doping level of 15 mol %. The crystallization can be suppressed even at temperatures about 333 K, the glass transition temperature of pure TPD, if the doping level of the C60-doped TPD films reaches 20 mol %. © 1999 American Institute of Physics.
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61.43.Er Other amorphous solids
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
68.60.Dv Thermal stability; thermal effects
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
68.55.-a Thin film structure and morphology

Dense arrays of well-aligned carbon nanotubes completely filled with single crystalline titanium carbide wires on titanium substrates

Y. Gao, J. Liu, M. Shi, S. H. Elder, and J. W. Virden

Appl. Phys. Lett. 74, 3642 (1999); http://dx.doi.org/10.1063/1.123208 (3 pages) | Cited 19 times

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We report the synthesis of dense and uniform arrays of well-aligned carbon nanotubes on titanium substrates over large areas, in which all the tubes are simultaneously and completely filled with single crystals of titanium carbide. The carbon nanotubes were synthesized by thermal chemical vapor deposition of ethylene on iron-coated substrates, while the titanium carbide was simultaneously formed inside the nanotubes through a simultaneous solid state reaction. We propose a base dissolution and precipitation mechanism for the growth of titanium carbide filled carbon nanotubes. The same method can be used to fabricate oriented nanotube arrays filled with other carbides on a variety of substrates over large scale. Such well-aligned and densely packed uniform carbon nanotubes, completely filled with nanowires on conducting substrates, will have great potential in many applications. © 1999 American Institute of Physics.
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81.05.ub Fullerenes and related materials
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
64.75.-g Phase equilibria
81.07.-b Nanoscale materials and structures: fabrication and characterization

Polyaniline and poly(N-vinylcarbazole) blends as anode for blue light-emitting diodes

Jinkoo Chung, Beomrak Choi, and Hong H. Lee

Appl. Phys. Lett. 74, 3645 (1999); http://dx.doi.org/10.1063/1.123209 (3 pages) | Cited 15 times

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Polyaniline and poly(N-vinylcarbazole) (PANI:PVK) blends are introduced as an anode, and the advantages are demonstrated for organic light-emitting diodes (LEDs). Compared to the usual PANI network electrodes, use of the blend allows for simpler fabrication and provides a better planarized surface, especially for the device with vapor-deposited emitting layer. PANI is not usually used for blue LEDs because of its strong light absorption in the deep-blue spectral region. This problem is practically solved by the use of the blend. © 1999 American Institute of Physics.
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42.70.Jk Polymers and organics
85.60.Jb Light-emitting devices
78.40.Me Organic compounds and polymers

Oxygen diffusion in heavily antimony-, arsenic-, and boron-doped Czochralski silicon wafers

Toshiaki Ono, George A. Rozgonyi, Eiichi Asayama, Hiroshi Horie, Hideki Tsuya, and Koji Sueoka

Appl. Phys. Lett. 74, 3648 (1999); http://dx.doi.org/10.1063/1.123210 (3 pages) | Cited 9 times

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The effect of dopant-type, antimony (Sb), arsenic (As), and boron (B), on the outdiffusion of oxygen in heavily doped Czochralski (Cz) silicon wafers has been investigated using secondary ion mass spectroscopy. The results indicate that, although oxygen diffusion in Cz silicon is retarded in heavily B- and As-doped wafers during low temperature annealing (800 °C), it is not influenced by heavy Sb doping. This indicates that charge effects and atom size effects have negligible influence on the diffusion of oxygen. The B and As diffusion retardation effect is attributed to the existence of dopant-oxygen complexes. The oxygen solubility was largest in the most heavily B-doped samples annealed at low temperature. © 1999 American Institute of Physics.
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66.30.J- Diffusion of impurities
81.05.Cy Elemental semiconductors
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
64.75.-g Phase equilibria

Graphitization of nanodiamond powder annealed in argon ambient

Jian Chen, S. Z. Deng, Jun Chen, Z. X. Yu, and N. S. Xu

Appl. Phys. Lett. 74, 3651 (1999); http://dx.doi.org/10.1063/1.123211 (3 pages) | Cited 50 times

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Nanodiamond powder was annealed at each of the following temperatures: 300, 600, 800, 1000, and 1150 °C, for an hour in flowing argon ambient. The variations of x-ray diffraction patterns and Raman spectra of the powder with different annealing temperatures were studied. While being annealed at temperatures higher than 800 °C, the powder can undergo a phase-transition process from cubic diamond to graphite. In addition, the size of nanodiamond crystallites decreased from ∼50 to ∼25 Å. The physical mechanism responsible for the variation in Raman spectra is discussed using a phonon-confinement model. © 1999 American Institute of Physics.
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81.05.ub Fullerenes and related materials
61.46.-w Structure of nanoscale materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
78.30.Na Fullerenes and related materials
81.40.Gh Other heat and thermomechanical treatments
61.43.Gt Powders, porous materials
64.70.K- Solid-solid transitions
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

Supersoft elastic parameters and low melting temperature of the C49 phase in TiSi2 by Brillouin scattering and molecular dynamics

Leo Miglio, M. Iannuzzi, M. Celino, R. Pastorelli, C. Bottani, A. Sabbadini, and G. Pavia

Appl. Phys. Lett. 74, 3654 (1999); http://dx.doi.org/10.1063/1.123212 (3 pages) | Cited 11 times

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In this letter, we show that the polymorphic C49 form of TiSi2 has much smaller elastic constants than those of the C54 bulk-stable structure and that its melting temperature is about 300 °C lower. These issues supply intriguing hints in explaining the kinetic advantage of the C49 over the C54 phase and in understanding the role of the elastic energy in the phase transformation from C49 to C54. © 1999 American Institute of Physics.
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62.20.D- Elasticity
64.70.D- Solid-liquid transitions
78.35.+c Brillouin and Rayleigh scattering; other light scattering
64.70.K- Solid-solid transitions
43.35.Pt Surface waves in solids and liquids
81.40.Jj Elasticity and anelasticity, stress-strain relations
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B cluster formation and dissolution in Si: A scenario based on atomistic modeling

Lourdes Pelaz, G. H. Gilmer, H.-J. Gossmann, C. S. Rafferty, M. Jaraiz, and J. Barbolla

Appl. Phys. Lett. 74, 3657 (1999); http://dx.doi.org/10.1063/1.123213 (3 pages) | Cited 84 times

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A comprehensive model of the nucleation, growth, and dissolution of B clusters in Si is presented. We analyze the activation of B in implanted Si on the basis of detailed interactions between B and defects in Si. In the model, the nucleation of B clusters requires a high interstitial supersaturation, which occurs in the damaged region during implantation and at the early stages of the postimplant anneal. B clusters grow by adding interstitial B to preexisting B clusters, resulting in B complexes with a high interstitial content. As the annealing proceeds and the Si interstitial supersaturation decreases, the B clusters emit Si interstitials, leaving small stable B complexes with low interstitial content. The total dissolution of B clusters involves thermally generated Si interstitials, and it is only achieved at very high temperatures or long anneal times. © 1999 American Institute of Physics.
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64.75.-g Phase equilibria
61.72.Yx Interaction between different crystal defects; gettering effect
61.72.uf Ge and Si
61.72.J- Point defects and defect clusters
61.72.Cc Kinetics of defect formation and annealing

Influence of AlN nucleation layers on growth mode and strain relief of GaN grown on 6H–SiC(0001)

P. Waltereit, O. Brandt, A. Trampert, M. Ramsteiner, M. Reiche, M. Qi, and K. H. Ploog

Appl. Phys. Lett. 74, 3660 (1999); http://dx.doi.org/10.1063/1.123214 (3 pages) | Cited 42 times

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We study the growth mode and strain state of GaN layers grown either directly on 6H–SiC(0001) or on thin (5 nm), coherently strained AlN nucleation layers. Using a combination of structural, optical, and vibrational characterization methods, we show that the 3.4% compressive lattice mismatch strain is fully relieved in the former case, whereas in the latter case a significant amount (0.3%) remains even after 1 μm of growth. This finding is clarified by in situ reflection high-energy electron diffraction and transmission electron microscopy. We demonstrate that the strain state of the GaN layer is determined by its growth mode, which in turn is governed by the degree of wetting of the underlayer rather than by lattice mismatch. © 1999 American Institute of Physics.
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68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
78.66.Fd III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
78.55.Cr III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Ea III-V semiconductors

ZnSe/GaAs interface state probed by time-resolved reflectance difference spectroscopy

K. S. Wong, H. Wang, Z. Yang, I. K. Sou, and G. K. L. Wong

Appl. Phys. Lett. 74, 3663 (1999); http://dx.doi.org/10.1063/1.123215 (3 pages) | Cited 2 times

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Time-resolved reflectance difference spectroscopy (TRDS) has been applied to study the dynamics and relaxation processes of the 2.7 eV ZnSe/GaAs interface state associated with Zn–As bonds. The instantaneous screening due to the photoexcited carriers and ∼18 ps recovery time of the 2.7 eV interface state is observed in the TRDS spectra. The rapid cooling of the hot carrier in the spectral region above the ZnSe band edge is also observed. © 1999 American Institute of Physics.
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73.20.At Surface states, band structure, electron density of states
78.47.-p Spectroscopy of solid state dynamics
78.66.Hf II-VI semiconductors
78.40.Fy Semiconductors
78.66.Fd III-V semiconductors

Prediction of room-temperature high-thermoelectric performance in n-type La(Ru1−xRhx)4Sb12

Marco Fornari and David J. Singh

Appl. Phys. Lett. 74, 3666 (1999); http://dx.doi.org/10.1063/1.124220 (3 pages) | Cited 7 times

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First-principles calculations are used to investigate the band structure and the transport-related properties of unfilled and filled 4d skutterudite antimonides. The calculations show that, while RhSb3 and p-type La(Rh,Ru)4Sb12 are unfavorable for thermoelectric application, n-type La(Rh,Ru)4Sb12 is very likely a high figure-of-merit thermoelectric material in the important temperature range 150–300 K. © 1999 American Institute of Physics.
Show PACS
72.15.Jf Thermoelectric and thermomagnetic effects
71.20.Eh Rare earth metals and alloys
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