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6 Sep 1999

Volume 75, Issue 10, pp. 1345-1481

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GaAs/AlGaAs superlattice quantum cascade lasers at λ ≈ 13 μm

G. Strasser, S. Gianordoli, L. Hvozdara, W. Schrenk, K. Unterrainer, and E. Gornik

Appl. Phys. Lett. 75, 1345 (1999); http://dx.doi.org/10.1063/1.124688 (3 pages) | Cited 35 times

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We report the realization of an injection laser based on intraband transitions in a finite AlGaAs/GaAs superlattice. The active material is a 30 period sequence of injectors/active regions made from AlGaAs/GaAs quantum wells. By an applied electric field, electrons are injected into the second miniband of a chirped superlattice and relax radiative to the lowest miniband. At a heat-sink temperature of 10 K, the laser emission wavelength is 12.9 μm with peak optical powers exceeding 100 mW and a threshold current density of 9.8 kA/cm2. The maximum operating temperature is 50 K. For this device, a waveguide consisting of heavily doped GaAs cladding and low doped core layers has been used as a plasma-enhanced confinement. © 1999 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Nonlinearly induced escape from a defect state in waveguide arrays

U. Peschel, R. Morandotti, J. S. Aitchison, H. S. Eisenberg, and Y. Silberberg

Appl. Phys. Lett. 75, 1348 (1999); http://dx.doi.org/10.1063/1.124689 (3 pages) | Cited 40 times

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We experimentally investigate the linear and nonlinear optical properties of a nonuniform waveguide array. By reducing the width of a single waveguide, we decrease its effective index and induce waveguiding along the defect. Due to the positive nonlinearity, the index difference is reduced for increasing power levels with the result that the field escapes. Waveguiding is suppressed by the action of the nonlinearity. © 1999 American Institute of Physics.
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42.65.Wi Nonlinear waveguides
42.82.Et Waveguides, couplers, and arrays
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
71.55.Eq III-V semiconductors
78.66.Fd III-V semiconductors

Wavelength-dependent optical degradation of green II–VI laser diodes

R. Vogelgesang, J. J. Liang, V. Wagner, H. J. Lugauer, J. Geurts, A. Waag, and G. Landwehr

Appl. Phys. Lett. 75, 1351 (1999); http://dx.doi.org/10.1063/1.124690 (3 pages) | Cited 2 times

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In this letter we report on optical degradation studies on BeMgZnSe separate confinement quantum well laser structures for the blue-green spectral region. The wavelength of the incident light has been tuned from 3.81 down to 2.10 eV, corresponding to an energy range from above the band gap of the cladding layers down to below the band gap of the quantum well. The dominant degradation mechanism is initiated when electron hole pairs are created in the quantum well. Absorption of light in deep defect bands, e.g., of the p-type cladding material is negligible in these structures. The strain state of the quantum well is one possible driving force for the degradation. In this context, point defect propagation as well as a structural phase transition of the ZnCdSe quantum well are discussed. © 1999 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
78.66.Hf II-VI semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.55.Et II-VI semiconductors
71.55.Gs II-VI semiconductors

Piezoelectric effects on many-body optical gain of zinc-blende and wurtzite GaN/AlGaN quantum-well lasers

Seoung-Hwan Park, Shun-Lien Chuang, and Doyeol Ahn

Appl. Phys. Lett. 75, 1354 (1999); http://dx.doi.org/10.1063/1.124691 (3 pages) | Cited 12 times

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Electronic and optical properties for (001)-, (111)-oriented zinc-blende (ZB), and (0001)-oriented wurtzite (WZ) structures are investigated taking into account the piezoelectric (PZ) effects. Self-consistent (SC) calculation of electronic structure is also considered within Hartree approximation. Using the SC model with the PZ field, we show that the many-body optical gain of (111)-oriented ZB and (0001)-oriented WZ quantum well (QW) lasers is reduced compared to results using the flat-band (FB) model. This is caused by the separation between the electron and hole wave functions in the presence of PZ electric field. However, when the optical gain is plotted as a function of the radiative current density Jrad, it is found that there is no significant difference between the results of the FB and SC models. We believe that this is due to the fact that the peak gain and the radiative recombination current are reduced simultaneously with increasing PZ field. For the same threshold gain level, the ZB and WZ quantum well structures are expected to have nearly the same threshold current density Jth within 10%. © 1999 American Institute of Physics.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
77.65.Ly Strain-induced piezoelectric fields
78.66.Fd III-V semiconductors

Photoemission study of the interface between phenyl diamine and treated indium–tin–oxide

Quoc Toan Le, F. Nüesch, L. J. Rothberg, E. W. Forsythe, and Yongli Gao

Appl. Phys. Lett. 75, 1357 (1999); http://dx.doi.org/10.1063/1.124692 (3 pages) | Cited 35 times

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The interface formation between indium–tin–oxide (ITO) having various work functions and N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) was investigated using x-ray and ultraviolet photoelectron spectroscopy. Phosphoric acid and tetrabutylammonium hydroxide were used to modify the ITO work function. The energy difference between the highest occupied molecular orbital (HOMO) position of NPB and the ITO Fermi level can be varied substantially by surface treatment. The work function of acid-treated ITO dramatically decreases after deposition of a thin NPB layer. We attribute this to the reaction between the NPB nitrogen and the proton of the adsorbed dipole layer. No significant reaction was observed for NPB deposited on standard ITO. © 1999 American Institute of Physics.
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79.60.Jv Interfaces; heterostructures; nanostructures
73.30.+y Surface double layers, Schottky barriers, and work functions
81.65.-b Surface treatments
73.20.At Surface states, band structure, electron density of states

Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson

Appl. Phys. Lett. 75, 1360 (1999); http://dx.doi.org/10.1063/1.124693 (3 pages) | Cited 93 times

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Indium–gallium nitride (InGaN) multiple-quantum-well (MQW) light-emitting diode (LED) membranes, prefabricated on sapphire growth substrates, were created using pulsed-excimer laser processing. The thin-film InGaN MQW LED structures, grown on sapphire substrates, were first bonded onto a Si support substrate with an ethyl cyanoacrylate-based adhesive. A single 600 mJ/cm2, 38 ns KrF (248 nm) excimer laser pulse was directed through the transparent sapphire, followed by a low-temperature heat treatment to remove the substrate. Free-standing InGaN LED membranes were then fabricated by immersing the InGaN LED/adhesive/Si structure in acetone to release the device from the supporting Si substrate. The current–voltage characteristics and room-temperature emission spectrum of the LEDs before and after laser lift-off were unchanged. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices
85.60.Bt Optoelectronic device characterization, design, and modeling
42.62.-b Laser applications
78.66.Fd III-V semiconductors
78.60.Fi Electroluminescence

Short-coherence photorefractive holography in multiple-quantum-well devices using light-emitting diodes

M. Tziraki, R. Jones, P. M. W. French, D. D. Nolte, and M. R. Melloch

Appl. Phys. Lett. 75, 1363 (1999); http://dx.doi.org/10.1063/1.124694 (3 pages) | Cited 10 times

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We demonstrate an application of light-emitting diodes to photorefractive holography with multiple-quantum-well devices. Holograms corresponding to three-dimensional images with a depth resolution of less than 10 μm were recorded, with image acquisition times as short as 5 ms. © 1999 American Institute of Physics.
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42.40.Ht Hologram recording and readout methods
42.70.Ln Holographic recording materials; optical storage media
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
85.60.Jb Light-emitting devices
78.66.Fd III-V semiconductors

Ultrafast low-temperature grown AlGaAs/GaAs photorefractive quantum wells using point defects as capture centers

M. H. Zhang, Q. Huang, Y. F. Zhang, J. M. Zhou, Q. Li, and Z. Y. Xu

Appl. Phys. Lett. 75, 1366 (1999); http://dx.doi.org/10.1063/1.124695 (3 pages) | Cited 1 time

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At a medium substrate temperature of 400 °C and a lower As flux, we have grown an ultrafast AlGaAs/GaAs photorefractive multiple quantum well (MQW) structure by molecular beam epitaxy. The as-grown sample exhibits strong photorefractive effect under the transverse Frantz–Keldysh geometry. A peak electroabsorption of 2100 cm−1 is measured in the as-grown sample in an 11 kV/cm dc electric field, and the peak photorefractive diffraction efficiency can be 1.2%. After postgrowth annealing, the photorefractive effect becomes weak and disappears in samples annealed above 700 °C. Using optical transient current spectroscopy, deep levels are measured in these samples. It is found that deep levels are stable against annealing until 700 °C. Using a pump-probe technique, carrier lifetimes are measured at room temperature. We find that the as-grown sample has a lifetime of 20 ps, while the 700 °C annealed sample has a lifetime of more than 200 ps. The ultrafast lifetime in the as-grown sample is caused by point defects, not by As clusters. Our result show that AlGaAs/GaAs MQW structure grown around 400 °C has better performance of the photorefractive effect. © 1999 American Institute of Physics.
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42.70.Ln Holographic recording materials; optical storage media
78.47.-p Spectroscopy of solid state dynamics
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.66.Fd III-V semiconductors
71.55.Eq III-V semiconductors
73.61.Ey III-V semiconductors
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.20.Jq Electro-optical effects
61.72.Cc Kinetics of defect formation and annealing
61.72.J- Point defects and defect clusters
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Radio frequency discharge excited diffusively cooled kilowatt carbon monoxide slab waveguide laser with a three mirror resonator

Jianguo Xin, Wang Zhang, and Wentao Jiao

Appl. Phys. Lett. 75, 1369 (1999); http://dx.doi.org/10.1063/1.124696 (2 pages) | Cited 6 times

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In this letter, we describe a kilowatt radio frequency discharge excited diffusively cooled slab waveguide carbon monoxide laser, in which the top and bottom electrodes were cooled with liquid nitrogen and which utilized a modified resonator. With this design we obtained a maximum laser power output of 1020 W, which was 10% higher than the same device employing a conventional unstable resonator. © 1999 American Institute of Physics.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Fabrication of a substrate-independent aluminum oxide-GaAs distributed Bragg reflector

D. E. Wohlert, H. C. Lin, K. L. Chang, G. W. Pickrell, J. H. Epple, K. C. Hsieh, and K. Y. Cheng

Appl. Phys. Lett. 75, 1371 (1999); http://dx.doi.org/10.1063/1.124697 (3 pages) | Cited 7 times

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We propose a method for forming a top distributed Bragg reflector (DBR) during very-low temperature (VLT) molecular-beam epitaxy (MBE) growth that is independent of the substrate being used. By varying the arsenic overpressure during VLT MBE, it was determined by Auger electron spectroscopy and cross-section transmission electron microscopy that alternating layers of polycrystalline GaAs and amorphous (Al,As) can be deposited. Because these layers are not single crystal, they can be grown on any host lattice. After lateral wet oxidation, the polycrystalline GaAs does not undergo any significant changes; whereas the amorphous (Al,As) becomes an amorphous aluminum oxide. An index step of Δn = 1.88 is realized between these two layers which makes it possible to fabricate a high efficiency DBR with very few polycrystal-GaAs/amorphous-Al-oxide pairs on GaAs-, GaP-, or InP-based materials. Using reflectivity measurements, we demonstrate a five pair GaAs/AlAs-based DBR grown on an InP substrate that reflects wavelengths between 1.4 and 2.3 μm up to 95%. © 1999 American Institute of Physics.
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42.82.Cr Fabrication techniques; lithography, pattern transfer
42.60.By Design of specific laser systems
42.79.Bh Lenses, prisms and mirrors
81.65.Mq Oxidation
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Displacement measurement and surface profiling using semi-insulating photoconductive semiconductors and linearly frequency-ramped lasers

Feng Jin, Jacob B. Khurgin, Suhdir Trivedi, Chen-Chia Wang, and Esam Gad

Appl. Phys. Lett. 75, 1374 (1999); http://dx.doi.org/10.1063/1.124698 (3 pages) | Cited 1 time

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Target displacement measurement and surface profiling are demonstrated experimentally using coherence frequency domain reflectometry and the photo-emf optical difference frequency sensor that was recently shown to generate steady state dc photocurrents linearly proportional to the optical frequency differences between two laser beams interfering inside semi-insulating photoconductive semiconductors. The simplicity and spatial adaptivity of photo-emf optical frequency sensors eliminate the stringent requirements of optical alignment and calculation-intensive signal processing found in conventional coherence frequency domain reflectometry systems. © 1999 American Institute of Physics.
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06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
07.60.Hv Refractometers and reflectometers
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
72.40.+w Photoconduction and photovoltaic effects
42.79.Nv Optical frequency converters
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