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14 Mar 2005

Volume 86, Issue 11, Articles (11xxxx)

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Appl. Phys. Lett. 86, 113104 (2005); http://dx.doi.org/10.1063/1.1883725 (3 pages)

S. Bhattacharyya, C. Sinturel, J. P. Salvetat, and M.-L. Saboungi
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Polarization anisotropy in the electroluminescence of m-plane InGaN–GaN multiple-quantum-well light-emitting diodes

N. F. Gardner, J. C. Kim, J. J. Wierer, Y. C. Shen, and M. R. Krames

Appl. Phys. Lett. 86, 111101 (2005); http://dx.doi.org/10.1063/1.1875765 (3 pages) | Cited 95 times

Online Publication Date: 7 March 2005

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InGaN–GaN multiple-quantum-well light-emitting diodes were fabricated on (10math0) m plane GaN films grown on (10math0) m plane 4H–SiC substrates. The [0001] axis of the epitaxial film is parallel to the [0001] axis of the substrate. The surface is striated, with features running perpendicular to the c axis and a maximum surface height difference of 45 nm. Electroluminescence shows strong polarization anisotropy, with 7× more light emitted with polarization perpendicular to the c axis compared to parallel to the c axis. An Ahrrenius fit of the polarization ratio indicates that there is a 49 meV difference in the energy gap between the two polarization states. This suggests that a high polarization ratio can be maintained at the high temperatures (>150°C) and drive current densities required for high-power light-emitting diode applications.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.60.Fi Electroluminescence
78.67.De Quantum wells

Experimental demonstration of the slow group velocity of light in two-dimensional coupled photonic crystal microcavity arrays

Hatice Altug and Jelena Vučković

Appl. Phys. Lett. 86, 111102 (2005); http://dx.doi.org/10.1063/1.1882755 (3 pages) | Cited 52 times

Online Publication Date: 7 March 2005

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We recently proposed two-dimensional coupled photonic crystal microcavity arrays as a route to achieve a slow-group velocity of light (flat band) in all crystal directions. In this letter we present the experimental demonstration of such structures with a measured group velocity below 0.008c and discuss the feasibility of applications such as low-threshold photonic crystal lasers with increased output powers, optical delay components, and sensors.
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42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers
42.70.Qs Photonic bandgap materials

Quantum cascade lasers with lateral double-sided distributed feedback grating

S. Golka, C. Pflügl, W. Schrenk, and G. Strasser

Appl. Phys. Lett. 86, 111103 (2005); http://dx.doi.org/10.1063/1.1883332 (3 pages) | Cited 16 times

Online Publication Date: 7 March 2005

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Midinfrared single mode emission, up to 20 °C, for a distributed feedback structure consisting of lateral index variation on both sides of a rib waveguide is achieved on a quantum cascade laser. Fabrication was made possible by a high density plasma process developed for high aspect ratio etching of GaAlAs/GaAs structures. A lateral grating considerably enhances design freedom by decoupling the vertical waveguide structure from the grating strength. The grating coupling, now being mainly determined by waveguide width, can then be exploited for device applications.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.79.Dj Gratings
42.79.Gn Optical waveguides and couplers
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.82.Et Waveguides, couplers, and arrays
81.65.Cf Surface cleaning, etching, patterning

Continuous-wave laser oscillation on the 1315 nm transition of atomic iodine pumped by O2(a1Δ) produced in an electric discharge

David L. Carroll, Joseph T. Verdeyen, Darren M. King, Joseph W. Zimmerman, Julia K. Laystrom, Brian S. Woodard, Gabriel F. Benavides, Kirk Kittell, D. Shane Stafford, Mark J. Kushner, and Wayne C. Solomon

Appl. Phys. Lett. 86, 111104 (2005); http://dx.doi.org/10.1063/1.1883317 (3 pages) | Cited 55 times

Online Publication Date: 7 March 2005

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Laser action at 1315 nm on the I(math)→I(math) transition of atomic iodine is conventionally obtained by a near-resonant energy transfer from O2(a1Δ) which is produced using wet-solution chemistry. The difficulties in chemically producing O2(a1Δ) has motivated investigations into purely gas phase methods to produce O2(a1Δ) using low-pressure electric discharges. In this letter, we report on the demonstration of a continuous-wave laser on the 1315 nm transition of atomic iodine where the O2(a1Δ) used to pump the iodine was produced by a radio-frequency-excited electric discharge. The electric discharge was sustained in a He/O2 gas mixture upstream of a supersonic cavity which is employed to lower the temperature of the continuous gas flow and shift the equilibrium of atomic iodine in favor of the I(math) state. The laser output power was 220 mW in a stable cavity composed of two 99.99% reflective mirrors.
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42.55.Ks Chemical lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
82.40.-g Chemical kinetics and reactions: special regimes and techniques
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Semiconductor quantum dot microcavity pillars with high-quality factors and enlarged dot dimensions

A. Löffler, J. P. Reithmaier, G. Sęk, C. Hofmann, S. Reitzenstein, M. Kamp, and A. Forchel

Appl. Phys. Lett. 86, 111105 (2005); http://dx.doi.org/10.1063/1.1880446 (3 pages) | Cited 7 times

Online Publication Date: 7 March 2005

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Vertical-emitting AlAs/GaAs microcavity pillars with a type of GaInAs quantum dots within a one λ cavity have been realized based on high reflectivity distributed Bragg reflectors. High-quality factors were achieved due to an improved fabrication technology with a maximum quality factor of 27 700 for a micropillar with a diameter of 4 μm. The dot dimensions could be enlarged by one order of magnitude using a low strain Ga0.7In0.3As nucleation layer.
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42.79.Bh Lenses, prisms and mirrors
42.82.Cr Fabrication techniques; lithography, pattern transfer
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Obtaining super resolution light spot using surface plasmon assisted sharp ridge nanoaperture

Eric X. Jin and Xianfan Xu

Appl. Phys. Lett. 86, 111106 (2005); http://dx.doi.org/10.1063/1.1875747 (3 pages) | Cited 56 times

Online Publication Date: 8 March 2005

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Finite difference time domain computations is used to study surface plasmon (SP) excitation around C- and H-shaped ridge nanoapertures made in silver film. The SP enhances optical transmission, in addition to the transmission mechanism of the waveguide propagation mode and Fabry-Pérot-like resonance. However, the near-field collimation of ridge aperture is found completely destroyed. On the other hand, using a bowtie-shaped aperture with sharp ridges made in silver, the loss of near-field collimation can be recovered. A super resolution optical spot with full width half magnitude as small as 12 nm×16 nm is achieved due to the resonant SP excitation localized at the tips of bowtie. Much higher field enhancement is also obtained compared to the bowtie aperture made in chromium.
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84.40.Az Waveguides, transmission lines, striplines
42.79.Gn Optical waveguides and couplers
42.79.Ag Apertures, collimators

Dynamic behaviors in coupled self-electro-optic effect devices

Y. Ohkawa, T. Yamamoto, T. Nagaya, and S. Nara

Appl. Phys. Lett. 86, 111107 (2005); http://dx.doi.org/10.1063/1.1875760 (3 pages)

Online Publication Date: 8 March 2005

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Dynamic behaviors of two coupled bistable elements optically connected in a series are theoretically predicted and discussed based on a phenomenological model with respect to photocarrier densities, where each bistable element is a self-electro-optic effect device (SEED). Feedback from one of the two SEEDs to the power of an incident light beam was introduced, which resulted in various types of oscillatory solutions and bifurcation structures depending on incident light power and choices of parameter values included in our model.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.-e Optical elements, devices, and systems
42.65.Sf Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Enhanced performance of bipolar cascade light-emitting diodes by doping the aluminum oxide apertures

W. J. Siskaninetz, J. E. Ehret, J. A. Lott, J. C. Griffith, and T. R. Nelson

Appl. Phys. Lett. 86, 111108 (2005); http://dx.doi.org/10.1063/1.1885168 (3 pages) | Cited 1 time

Online Publication Date: 8 March 2005

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Performance improvements in multiple-stage, single-cavity bipolar cascade light-emitting diodes including reduced operating voltages, enhanced light generation, and reduced device heating are obtained by doping intracavity aluminum oxide apertures with silicon. This doping results in a reduced electron energy barrier and, therefore, a reduced series resistance which leads to better power and heating characteristics. Nearly 50% reductions in operating voltages, 200% increases in light power, and increased operating range are demonstrated. We discuss the direct implications of these results for the design of bipolar cascade vertical-cavity surface-emitting lasers.
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85.60.Jb Light-emitting devices
85.30.Kk Junction diodes
61.72.up Other materials
73.40.Ty Semiconductor-insulator-semiconductor structures
42.55.Px Semiconductor lasers; laser diodes

Evidence for charge-carrier mediated magnetic-field modulation of electroluminescence in organic light-emitting diodes

John Wilkinson, A. H. Davis, K. Bussmann, and J. P. Long

Appl. Phys. Lett. 86, 111109 (2005); http://dx.doi.org/10.1063/1.1883322 (3 pages) | Cited 16 times

Online Publication Date: 8 March 2005

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Electroluminescence (EL) from organic light-emitting diodes can be surprisingly sensitive ( ∼ 20%) to modest magnetic fields B (0–2 T). The origin of this magnetic-field effect has not been clearly identified, although the magnetic-field effect in some devices resembles that of delayed fluorescence in anthracene, which originates from magnetic-field-dependent singlet-exciton production via triplet-triplet annihilation (TTA). Here, we test the role of TTA at low magnetic fields ( ∼ 80 mT) by measuring transient EL and by employing dc drive levels so low that the bimolecular rate of TTA is unimportant. Under these conditions, we find enhancements of EL exceeding 14% at the lowest drives, which excludes TTA-mediated magnetic-field effects and indicates a role for charge-carrier pair states.
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85.60.Jb Light-emitting devices
78.60.Fi Electroluminescence
78.20.Ls Magneto-optical effects
78.55.Kz Solid organic materials
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Excitation and direct imaging of surface plasmon polariton modes in a two-dimensional grating

Kevin A. Tetz, Rostislav Rokitski, Maziar Nezhad, and Yeshaiahu Fainman

Appl. Phys. Lett. 86, 111110 (2005); http://dx.doi.org/10.1063/1.1883334 (3 pages) | Cited 20 times

Online Publication Date: 8 March 2005

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We describe the simultaneous excitation and direct far-field imaging of the scattering from surface plasmon polariton modes in a two-dimensional metallic hole array grating. Conditions for the coupling and imaging are discussed, where the coupling is shown to be consistent with both measured and calculated dispersion relations. Excitation is accomplished at several different wavelengths (from 1.31 to 1.57 μm), incidence angles, and grating periods, enabling the observation of a number of distinct modes with various in-plane wave vectors.
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42.79.Dj Gratings
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
42.82.Et Waveguides, couplers, and arrays
78.68.+m Optical properties of surfaces

Propagation loss measurements and Fabry–Pérot mode analysis using out-of-plane light scattering in photonic crystal waveguides

B. Lombardet, R. Ferrini, L. A. Dunbar, R. Houdré, C. Cuisin, O. Drisse, F. Lelarge, F. Pommereau, F. Poingt, and G.-H. Duan

Appl. Phys. Lett. 86, 111111 (2005); http://dx.doi.org/10.1063/1.1880447 (3 pages) | Cited 3 times

Online Publication Date: 8 March 2005

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An experimental technique is presented for the measurements of propagation losses in planar photonic crystal waveguides (PhC-WGs). When the guided light interacts with the air holes, it is partially scattered out of the propagation plane. The intensity of this diffracted light is measured along the PhC-WG and the propagation losses are deduced from its attenuation. To illustrate this, the Fabry–Pérot-type mode of a single-line defect PhC-WG is investigated. The propagation loss values obtained experimentally agree well with theoretical predictions. Finally, a study of single-line defect 60° bends shows that this technique also provides an efficient method to obtain modal information along PhC structures.
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42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
42.70.Qs Photonic bandgap materials

External-cavity tunable mid-infrared laser using off-band surface-emitting Bragg grating coupler

H. L. Zhang, C. Peng, A. Seetharaman, G. P. Luo, Han Q. Le, C. Gmachl, D. L. Sivco, and A. Y. Cho

Appl. Phys. Lett. 86, 111112 (2005); http://dx.doi.org/10.1063/1.1885188 (3 pages) | Cited 6 times

Online Publication Date: 9 March 2005

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An external-cavity laser using an integrated two-segment design allows broad and continuous wavelength tuning with independent control of power and wavelength. The laser has a gain segment and a surface-emitting Bragg grating segment that was designed to be off-band for zero reflection inside the cavity, and with a strong free-space coupling to an external mirror to form a linear cavity. Wavelength control was achieved with a combination of coarse and broad wavelength tuning (140 nm) with the external mirror, and continuous, fine wavelength tuning via current-induced phase shift in the Bragg grating. Separate controls of the two segments allowed wavelength fine tuning without power variation and vice versa. The concept was applied to a 7 μm laser, and is applicable to other wavelength.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Fc Modulation, tuning, and mode locking
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.82.Et Waveguides, couplers, and arrays
42.79.Dj Gratings

Phase-shift effect on a two-dimensional surface-emitting photonic-crystal laser

Eiji Miyai and Susumu Noda

Appl. Phys. Lett. 86, 111113 (2005); http://dx.doi.org/10.1063/1.1885182 (3 pages) | Cited 8 times

Online Publication Date: 9 March 2005

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Theoretical analysis was performed by means of the finite-difference time-domain method to examine the mode properties of two-dimensional surface-emitting photonic-crystal lasers with elliptical air holes. It was found that a single-lobed beam pattern could be obtained from the device surface by introducing a phase shift to the center of the crystal. The effects of the shift on the polarization mode and on two-dimensional optical coupling (which is needed for single-mode lasing over a large area) were also investigated. It was shown that the phase shift emphasized the linear polarization of the emitted beam due to symmetry reversal. On the other hand, it was also found that the shift did not spoil the two-dimensional optical coupling.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Fc Modulation, tuning, and mode locking
42.55.Tv Photonic crystal lasers and coherent effects
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Topology optimization of a photonic crystal waveguide termination to maximize directional emission

W. R. Frei, D. A. Tortorelli, and H. T. Johnson

Appl. Phys. Lett. 86, 111114 (2005); http://dx.doi.org/10.1063/1.1885170 (3 pages) | Cited 30 times

Online Publication Date: 10 March 2005

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Topology optimization based on nonlinear programming techniques and design sensitivity analysis are used to maximize directional emission from a waveguide termination in a two-dimensional square lattice rods-in-air photonic crystal. Maximizing directional emission from a photonic crystal waveguide termination is desirable since a horn antenna style termination of comparable functionality is very large, while small simple terminations show strong angular spread. The optimized waveguide termination designed here is compact and exhibits a fivefold increase in power incident upon the target area over the simple termination. This improvement is achieved by creating surface modes that interfere to produce highly directional emission.
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42.65.Wi Nonlinear waveguides
42.70.Qs Photonic bandgap materials

Measurement of subband electronic temperatures and population inversion in THz quantum-cascade lasers

Miriam S. Vitiello, Gaetano Scamarcio, Vincenzo Spagnolo, Benjamin S. Williams, Sushil Kumar, Qing Hu, and John L. Reno

Appl. Phys. Lett. 86, 111115 (2005); http://dx.doi.org/10.1063/1.1886266 (3 pages) | Cited 55 times

Online Publication Date: 10 March 2005

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We compare the electronic temperatures and the population inversion both below and above the lasing threshold in three quantum-cascade lasers (QCLs) operating at 2.8 THz, 3.2 THz, and 3.8 THz using microprobe band-to-band photoluminescence. In the lasing range, while the ground-state temperature remains close to the lattice one (90 K–100 K), the upper radiative state heats up to ∼ 200 K. From the measured thermal resistance and the power dependence of the ground-state electronic temperature, we get a value of the electron-lattice energy relaxation rate comparable with that typical of midinfrared QCLs.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Generation of sub-10-fs, 5-mJ-optical pulses using a hollow fiber with a pressure gradient

Akira Suda, Masatoshi Hatayama, Keigo Nagasaka, and Katsumi Midorikawa

Appl. Phys. Lett. 86, 111116 (2005); http://dx.doi.org/10.1063/1.1883706 (3 pages) | Cited 65 times

Online Publication Date: 10 March 2005

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We propose and demonstrate a pulse compression technique using a hollow fiber with a pressure gradient. This technique improves the spatial and spectral qualities of femtosecond laser pulses spectrally broadened by self-phase modulation, and allows an increase of the pulse energy for pulse compression. Using chirped mirrors for dispersion compensation, we have successfully compressed the pulse to less than 10 fs with an energy as high as 5 mJ.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.81.Dp Propagation, scattering, and losses; solitons
42.60.Fc Modulation, tuning, and mode locking
42.62.Fi Laser spectroscopy

Efficient coupling of Er-doped silicon-rich oxide to microdisk whispering gallery modes

J. Verbert, F. Mazen, T. Charvolin, E. Picard, V. Calvo, P. Noé, J.-M. Gérard, and E. Hadji

Appl. Phys. Lett. 86, 111117 (2005); http://dx.doi.org/10.1063/1.1883331 (3 pages) | Cited 5 times

Online Publication Date: 11 March 2005

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We report room-temperature light emission from erbium-doped silicon-rich oxide integrated in a silica microdisk. Silica disks are fabricated by standard optical lithography and etching techniques. Erbium-doped silicon-rich oxide is then deposited by coevaporation of silicon and erbium under oxygen flux. A spatially resolved photoluminescence experiment highlights the efficient coupling of the signal to whispering gallery modes when the excitation beam is focused near the edge of the disk. Quality factors as high as 3000 are measured, limited by the setup’s spectral resolution.
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42.82.Ds Interconnects, including holographic interconnects
42.82.Cr Fabrication techniques; lithography, pattern transfer
78.55.Hx Other solid inorganic materials
81.65.Cf Surface cleaning, etching, patterning

Transparent Nd and (Nd, Yb)-doped Sc2O3 ceramics as potential new laser materials

V. Lupei, A. Lupei, and A. Ikesue

Appl. Phys. Lett. 86, 111118 (2005); http://dx.doi.org/10.1063/1.1886897 (3 pages) | Cited 26 times

Online Publication Date: 11 March 2005

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Highly transparent Sc2O3 ceramics with uniform doping up to 0.5 at. % Nd and with (Nd, Yb) codoping are reported. The spectroscopic and emission decay properties of Nd:Sc2O3 ceramics are similar to those of single crystals. Highly efficient Nd-to-Yb energy transfer is observed in the codoped ceramics. It is inferred that these materials have potential for construction of Nd or Nd-sensitised-Yb lasers.
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42.70.Hj Laser materials
78.55.Hx Other solid inorganic materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
61.72.up Other materials
42.55.Rz Doped-insulator lasers and other solid state lasers

Multiphoton discrimination at telecom wavelength with charge integration photon detector

Mikio Fujiwara and Masahide Sasaki

Appl. Phys. Lett. 86, 111119 (2005); http://dx.doi.org/10.1063/1.1886903 (3 pages) | Cited 14 times

Online Publication Date: 11 March 2005

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We present a charge integration photon detector (CIPD) that enables the efficient measurement of photon number states at the telecom-fiber wavelengths with a quantum efficiency of 80% and a resolution less than 0.5 electrons at 1 Hz sampling. The CIPD consists of an InGaAs pin photodiode and a GaAs JFET in a charge integration amplifier, which is cooled to 4.2 K to reduce thermal noise and leakage current. The charge integration amplifier exhibits a low noise level of 470 nV/Hz1/2. The dark count is as low as 500 electrons/h.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.50.Ar Photon statistics and coherence theory
85.60.Dw Photodiodes; phototransistors; photoresistors
85.30.Tv Field effect devices

Large-area traveling-wave photonic mixers for increased continuous terahertz power

E. A. Michael, B. Vowinkel, R. Schieder, M. Mikulics, M. Marso, and P. Kordoš

Appl. Phys. Lett. 86, 111120 (2005); http://dx.doi.org/10.1063/1.1884262 (3 pages) | Cited 19 times

Online Publication Date: 11 March 2005

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A large-aperture design for terahertz traveling-wave photomixers, continuously pumped free space by two detuned diode lasers, is proposed and experimentally verified for devices based on low-temperature-grown GaAs (LT-GaAs). It combines the advantages of conventional interdigitated small-area structures and traveling-wave devices. An output power of 1 μW at the mixing frequency of 1 THz was measured in initial testing, which meets local oscillator power requirements for superconducting heterodyne mixer devices.
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84.30.Qi Modulators and demodulators; discriminators, comparators, mixers, limiters, and compressors
84.40.-x Radiowave and microwave (including millimeter wave) technology
85.25.-j Superconducting devices

Cluster effects in high-order harmonics generated by ultrashort light pulses

C. Vozzi, M. Nisoli, J-P. Caumes, G. Sansone, S. Stagira, S. De Silvestri, M. Vecchiocattivi, D. Bassi, M. Pascolini, L. Poletto, P. Villoresi, and G. Tondello

Appl. Phys. Lett. 86, 111121 (2005); http://dx.doi.org/10.1063/1.1888053 (3 pages) | Cited 31 times

Online Publication Date: 11 March 2005

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High-order harmonic generation in argon driven by 25-fs-light pulses is investigated from the gaseous to the cluster regime. The harmonic cutoff observed in presence of clusters shows a considerable extension with respect to the gaseous phase. Harmonic spectra are investigated as a function of cluster size, showing the existence of an optimal cluster dimension, which maximizes the harmonic photon yield.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
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40 000 pixel arrays of ac-excited silicon microcavity plasma devices

S.-J. Park, K.-F. Chen, N. P. Ostrom, and J. G. Eden

Appl. Phys. Lett. 86, 111501 (2005); http://dx.doi.org/10.1063/1.1880441 (3 pages) | Cited 16 times

Online Publication Date: 8 March 2005

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Arrays of (50 μm)2 Si microcavity plasma devices, as large as 40 000 pixels (200×200) with a packing density of 104 pixels cm−2, have been operated continuously in 500–900 Torr of Ne with ac excitation (5–20 kHz). More than two orders of magnitude larger than previously reported microplasma device arrays, 200×200 pixel structures produce uniform glow discharges in each pixel, have a power consumption of ∼ 0.85 W cm−2 for pNe = 700 Torr and an excitation frequency of 5 kHz, and exhibit maximum radiative efficiency for a Ne pressure of pNe ≅ 700 Torr and an excitation frequency of 10–15 kHz. All arrays examined (10×10→200×200) are characterized by pixel-to-pixel emission intensities constant over the entire array to within ±10%, and no barriers to the successful operation of much larger arrays are apparent.
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52.75.-d Plasma devices
85.60.Pg Display systems
42.79.Kr Display devices, liquid-crystal devices
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Low-dislocation-density, nonplanar GaN templates for buried heterostructure lasers grown by lateral epitaxial overgrowth

Dawei Ren, Wei Zhou, and P. Daniel Dapkus

Appl. Phys. Lett. 86, 111901 (2005); http://dx.doi.org/10.1063/1.1866502 (3 pages) | Cited 2 times

Online Publication Date: 7 March 2005

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We report here the formation of nonplanar GaN templates, which consist of low-dislocation-density, naturally grown GaN ridge mesas, as a mean to facilitate the fabrication of buried heterostructure lasers. Defect reduction is realized by introducing a two-step lateral epitaxial overgrowth procedure that utilizes dislocation bending in the formation of pyramidal mesas to eradicate the threading dislocations that originate from a planar buffer layer. Transmission electron microscopy and atomic force microscopy indicate a mesa top facet having low defect density ( ∼ 8×107 cm−2), atomic flatness ( ∼ 0.29 nm mean roughness). Our demonstration has opened the possibility of forming buried heterostructure lasers on nonplanar GaN templates.
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81.05.Ea III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Kk Vapor phase epitaxy; growth from vapor phase
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.37.Lp Transmission electron microscopy (TEM)
68.37.Ps Atomic force microscopy (AFM)
42.55.Px Semiconductor lasers; laser diodes
68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology
78.66.Fd III-V semiconductors

Unusual stress behavior in W-incorporated hydrogenated amorphous carbon films

Ai-Ying Wang, Hyo-Shin Ahn, Kwang-Ryeol Lee, and Jae-Pyoung Ahn

Appl. Phys. Lett. 86, 111902 (2005); http://dx.doi.org/10.1063/1.1883328 (3 pages) | Cited 18 times

Online Publication Date: 7 March 2005

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Unusual stress behavior was observed in W-incorporated hydrogenated amorphous carbon films prepared by a hybrid process composed of ion-beam deposition and magnetron sputtering. As the tungsten concentration increased from 0 to 2.8 at.%, the residual compressive stress decreased by 50%, without significant deterioration in the mechanical properties. This was followed by a rapid increase and a gradual decrease in the residual stress with increasing W concentration. High-resolution transmission electron microscopy analysis and first-principle calculations show that the reduced directionality of the W–C bonds in the W-incorporated amorphous carbon matrix relaxes the stress caused by the distorted bonds.
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81.05.U- Carbon/carbon-based materials
68.60.Bs Mechanical and acoustical properties
81.40.Jj Elasticity and anelasticity, stress-strain relations
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.43.Er Other amorphous solids
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
68.55.-a Thin film structure and morphology
68.37.Lp Transmission electron microscopy (TEM)

Carrier dynamics of low-temperature-grown In0.53Ga0.47As on GaAs using an InGaAlAs metamorphic buffer

Seong June Jo, Soo-Ghang Ihn, Jong-In Song, Ki-Ju Yee, and Dong-Han Lee

Appl. Phys. Lett. 86, 111903 (2005); http://dx.doi.org/10.1063/1.1872207 (3 pages) | Cited 2 times

Online Publication Date: 7 March 2005

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Show Abstract
Structural and carrier dynamic properties of low-temperature-grown In0.53Ga0.47As (LT-InGaAs) on GaAs using an InGaAlAs metamorphic buffer were studied. Investigation of dependence of the structural and carrier dynamic properties of the LT-InGaAs on annealing temperature showed that they were closely related. The use of the metamorphic buffer was effective in reducing the carrier lifetime in the LT-InGaAs. A carrier lifetime as short as 2.14 ps, comparable to that of Be-doped LT-InGaAs was achieved.
Show PACS
73.61.Ey III-V semiconductors
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
61.72.uj III-V and II-VI semiconductors
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
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