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16 Jun 1997

Volume 70, Issue 24, pp. 3185-3313

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Guided-wave acousto-optic Bragg diffraction in indium gallium arsenide phosphide waveguides

C. S. Tsai, B. Sun, and A. Kar-Roy

Appl. Phys. Lett. 70, 3185 (1997); http://dx.doi.org/10.1063/1.119153 (3 pages) | Cited 6 times

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Theoretical and experimental studies on guided-wave acousto-optic (AO) Bragg diffraction in a composite indium gallium arsenide phosphide (InGaAsP) planar waveguide were carried out. In this letter, the experimental results of the excitation and propagation of a 〈110〉-directed surface acoustic wave (SAW) at the center frequency of 167 MHz, and the AO Bragg diffraction at a 1.31 micron wavelength in In0.22Ga0.78As0.47P0.53 waveguide are reported. An AO Bragg diffraction efficiency as high as 14% was achieved at an acoustic drive power of 8.5 mW with an interaction length (transducer aperture) of only 1.0 mm. Two orders of magnitude improvement in the Bragg diffraction efficiency versus rf drive power should be achievable by the optimization of the SAW transducer and the optical waveguide parameters. © 1997 American Institute of Physics.
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42.82.Et Waveguides, couplers, and arrays
42.79.Jq Acousto-optical devices

Midinfrared lasers and light-emitting diodes with InAsSb/InAsP strained-layer superlattice active regions

S. R. Kurtz, A. A. Allerman, and R. M. Biefeld

Appl. Phys. Lett. 70, 3188 (1997); http://dx.doi.org/10.1063/1.119154 (3 pages) | Cited 21 times

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The properties of InAsSb/InAsP strained-layer superlattice (SLS), midwave infrared materials, and devices are reported. SLSs were grown by metal-organic chemical vapor deposition and characterized by magnetophotoluminescence and x-ray diffraction. Excellent performance was observed for an SLS light emitting diode (LED) and an optically pumped SLS laser. The semimetal injected, broadband LED emitted at 4 μm with 80 μW of power at 300 K and 200 mA average current. The laser displayed 3.86 μm emission at 240 K, the maximum operating temperature of the laser, and a characteristic temperature of 33 K. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.60.Jb Light-emitting devices
78.66.Fd III-V semiconductors

“Plastic” lasers: Comparison of gain narrowing with a soluble semiconducting polymer in waveguides and microcavities

María A. Díaz-García, Fumitomo Hide, Benjamin J. Schwartz, Michael D. McGehee, Mats R. Andersson, and Alan J. Heeger

Appl. Phys. Lett. 70, 3191 (1997); http://dx.doi.org/10.1063/1.119156 (3 pages) | Cited 68 times

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Gain narrowing and lasing from a soluble, highly photoluminescent conjugated polymer, poly(2-butyl,5-(2′-ethyl-hexyl)-1,4-phenylenevinylene) (BuEH-PPV), are compared using two resonant structures: planar waveguides and microcavities. The gain narrowing and lasing thresholds are comparable, 0.05–0.1 μJ (10 ns pulse focused to ∼ 1.5 mm). Gain narrowing is not observed in films on indium tin oxide (ITO) unless a cladding layer is placed between the BuEH-PPV and ITO. Single-mode microcavity lasers are obtained when a cavity resonance occurs at the wavelength where the gain of the polymer is maximum. © 1997 American Institute of Physics.
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42.55.-f Lasers
42.70.Hj Laser materials
42.70.Jk Polymers and organics

Voltage tunable SiGe photodetector: A novel tool for crypted optical communications through wavelength mixing

G. Masini, L. Colace, F. Galluzzi, G. Assanto, T. P. Pearsall, and H. Presting

Appl. Phys. Lett. 70, 3194 (1997); http://dx.doi.org/10.1063/1.119155 (3 pages) | Cited 3 times

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A novel tandem SiGe–Si device is demonstrated which, based on different photoresponses in two back-to-back diodes, exhibits a voltage tunable spectral responsivity. This feature, in conjunction with a wavelength dependence in the current direction, allows the efficient decryption of a signal when substantial noise is added to distinct carrier frequencies. Time dependent encryption schemes are also possible via a modulated voltage bias. © 1997 American Institute of Physics.
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42.79.Sz Optical communication systems, multiplexers, and demultiplexers
85.60.Gz Photodetectors (including infrared and CCD detectors)

Intersubband stimulated emission in GaAs/AlGaAs quantum wells: Pump-probe experiments using a two-color free-electron laser

O. Gauthier-Lafaye, S. Sauvage, P. Boucaud, F. H. Julien, R. Prazeres, F. Glotin, J.-M. Ortega, V. Thierry-Mieg, R. Planel, J.-P. Leburton, and V. Berger

Appl. Phys. Lett. 70, 3197 (1997); http://dx.doi.org/10.1063/1.119125 (3 pages) | Cited 13 times

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Intersubband stimulated emission under optical pumping has been observed in the conduction band of GaAs–AlGaAs quantum wells. The asymmetric coupled quantum wells which exhibit three conduction bound levels are designed to exhibit population inversion under optical pumping. An optical excitation at λ = 9.2 μm is used to bleach the absorption between the ground and second excited subband. The population inversion between excited subbands is pumped and probed on a picosecond time scale by a tunable two-color free-electron laser. The stimulated amplification is studied at low temperature in infrared waveguides as a function of the waveguide length and of the probe wavelength. A stimulated gain ≈ 80 cm−1 is measured at 12.5 μm in agreement with calculations. © 1997 American Institute of Physics.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
78.45.+h Stimulated emission
78.66.Fd III-V semiconductors

Ultraviolet and blue discretely tunable double-pass fiber Raman laser

Ilko K. Ilev, Hiroshi Kumagai, and Koichi Toyoda

Appl. Phys. Lett. 70, 3200 (1997); http://dx.doi.org/10.1063/1.119126 (3 pages) | Cited 3 times

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The experimental realization of a new ultraviolet and blue tunable fiber Raman laser, based on a simple double-pass fiber laser arrangement with Littrow-prism-tuned emission, is demonstrated. The third harmonic of a Q-switched Nd:YAG laser (λp = 355 nm) is used to pump a 100-μm-core-diam multimode silica UV optical fiber. As a result of a single pass of the pump laser emission through the fiber, an initial multicascade Raman Stokes spectrum that contains up to 21 Stokes orders in the spectral range 360–527 nm at 1.9 GW/cm2 input pump intensity is generated. By using the double-pass regime of the fiber Raman laser and multimode fibers with different lengths, a discretely tunable generation corresponding to the various Stokes orders over the multicascade Stokes spectrum in the ultraviolet and blue regions (360–493 nm) is obtained. © 1997 American Institute of Physics.
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42.55.Wd Fiber lasers
42.55.Ye Raman lasers

Determination of the interfacial magneto-optical effects in Co/Pt multilayer structures

Xiang Gao, Daniel W. Thompson, and John A. Woollam

Appl. Phys. Lett. 70, 3203 (1997); http://dx.doi.org/10.1063/1.119152 (3 pages) | Cited 6 times

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In this letter, we present results of a study of the magneto-optical Kerr response in Co/Pt superlattices by solving for optical constants and Voigt parameters of constituent layers in the structure. The absolute values of the Voigt parameters of Co/Pt interfaces were found to be about twice as large as for the Co layer in the superlattice. Furthermore, using the determined optical constants and Voigt parameters, we can generate the Kerr rotations and ellipticities for Co/Pt superlattices or sandwich structures with continuously changed layer thicknesses and different repeat numbers. Comparison of these theoretical results to the experimental magneto-optical responses for selected structures exhibits strong consistency. © 1997 American Institute of Physics.
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78.20.Ls Magneto-optical effects
85.70.Sq Magnetooptical devices

Dispersion properties of aluminum nitride as measured by an optical waveguide technique

Xiao Tang, Yifang Yuan, Kobchat Wongchotigul, and Michael G. Spencer

Appl. Phys. Lett. 70, 3206 (1997); http://dx.doi.org/10.1063/1.119127 (3 pages) | Cited 27 times

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An aluminum nitride thin film on sapphire substrate was prepared by metal–organic chemical-vapor deposition for optical waveguide study. A rutile prism coupler was employed to display the waveguide modes (N lines) with wavelengths of 632.8, 532.1, 514.5, and 488.0 nm. The refractive index and thickness of the waveguide material were obtained by prism–coupler measurement. The parameters in the dispersion equation were determined by curve fitting. The attenuation in the waveguide was evaluated by scattering loss measurements using a fiber probe. The attenuation coefficient α is in the range of 1.5–2.1 cm−1 (5.4–7.6 dB cm−1), depending on the surface roughness of the sample and different orders of waveguide modes. © 1997 American Institute of Physics.
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42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.82.Et Waveguides, couplers, and arrays
78.66.Fd III-V semiconductors

Optical properties of wurtzite structure GaN on sapphire around fundamental absorption edge (0.78–4.77 eV) by spectroscopic ellipsometry and the optical transmission method

G. Yu, G. Wang, H. Ishikawa, M. Umeno, T. Soga, T. Egawa, J. Watanabe, and T. Jimbo

Appl. Phys. Lett. 70, 3209 (1997); http://dx.doi.org/10.1063/1.119157 (3 pages) | Cited 93 times

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Spectroscopic ellipsometry (SE) together with the optical transmission method is successfully used to determine the refractive index n and absorption coefficient α of undoped gallium nitride film over the spectral range of 0.78–4.77 eV of photon energy. The SE measurement is carried out at angle of incidence of 60° over the 1.5–4.77 eV energy range and optical transmission measurement over the 0.78–3.55 eV energy range. The refractive index n and absorption coefficient α obtained by both methods show unique results in the overlap wavelength region. Refractive index n is found to follow the Sellmeir dispersion relationship n2(λ) = 2.272+304.72/(λ2−294.02) below the fundamental band edge. A free excitonic structure at the band is clearly observed at room temperature, with the transmission energy of free exciton at 3.44 eV, which is in reasonable agreement with the reported results. © 1997 American Institute of Physics.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
07.60.Fs Polarimeters and ellipsometers

Theoretical performance of mid-infrared broken-gap multilayer superlattice lasers

Michael E. Flatté, J. T. Olesberg, S. A. Anson, Thomas F. Boggess, T. C. Hasenberg, R. H. Miles, and C. H. Grein

Appl. Phys. Lett. 70, 3212 (1997); http://dx.doi.org/10.1063/1.119128 (3 pages) | Cited 23 times

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See Also: Erratum

Show Abstract
We present calculations of the differential gain and threshold current densities for a 3.7 μm multiple quantum well structure consisting of a “well” composed of several periods of an InAs/InGaSb superlattice alternating with a quinternary alloy “barrier.” We find serious limitations to the optical properties of active regions composed of these multiple quantum wells, and propose a four-layer superlattice structure which corrects these problems. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes

Color variable bipolar/ac light-emitting devices based on conjugated polymers

Y. Z. Wang, D. D. Gebler, D. K. Fu, T. M. Swager, and A. J. Epstein

Appl. Phys. Lett. 70, 3215 (1997); http://dx.doi.org/10.1063/1.119129 (3 pages) | Cited 27 times

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There is increased interest in developing color variable light emitting devices. We report here the fabrication of color variable bipolar/ac light-emitting devices based on conjugated polymers. The devices consist of blends of pyridine-phenylene and thiophene-phenylene based copolymers sandwiched between the emeraldine base form and the sulfonated form of polyaniline. ITO and Al are used as electrodes. The devices operate under either polarity of driving voltage with different colors of light being emitted, red under forward bias, and green under reverse bias. The relative fast time response allows the rapid switching of colors and ac operation. © 1997 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.66.Qn Polymers; organic compounds
42.70.Jk Polymers and organics

Stop-bands for periodic metallic rods: Sculptures that can filter the noise

Manvir S. Kushwaha

Appl. Phys. Lett. 70, 3218 (1997); http://dx.doi.org/10.1063/1.119130 (3 pages) | Cited 102 times

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We perform extensive band structure computation for two-dimensional (2D) periodic arrays of rigid stainless steel cylinders in air, with Bloch vector being perpendicular to the cylinders. For cylinders 2.9 cm in diameter and period of 10 cm (i.e., filling fraction f = 0.066) there is no acoustic gap for frequencies below 6.4 kHz. However, the density of states reveals prominent minima at 1.7 and 2.4 kHz. These frequencies do agree with those of the first two attenuation maxima observed in the experiment [Nature 378, 241 (1995)] and are indeed related to diffraction from the [100] and [110] planes. Thus, even with idealization, Sempere’s sculpture exhibits pseudogaps—not full gaps. We stress that, for any value of the period, there is no acoustic gap for f ⩽ 30%; magnitude of the gap, for f>30%, is inversely proportional to the period of the system. Moreover, if the filling fraction exceeds 40%, a second gap, higher in frequency, opens up. In addition, we propose the fabrication of a multiperiodic system in tandem that could create a huge hole in sound within the human audible range of frequencies. © 1997 American Institute of Physics.
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43.40.-r Structural acoustics and vibration
62.65.+k Acoustical properties of solids

Room temperature crystal structure and relaxor ferroelectric behavior of Pb0.5Ca0.5TiO3

Rajeev Ranjan, Neelam Singh, Dhananjai Pandey, V. Siruguri, P. S. R. Krishna, S. K. Paranjpe, and Alok Banerjee

Appl. Phys. Lett. 70, 3221 (1997); http://dx.doi.org/10.1063/1.119131 (3 pages) | Cited 29 times

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Superlattice reflections observed for the first time in the room temperature powder neutron diffraction patterns of (Pb0.5Ca0.5)TiO3 (PCT50) are shown to arise due to an orthorhombic distortion (space group Pbnm) resulting from tilted TiO6 octahedra and off-center location of Pb2+/Ca2+. From a study of the temperature dependence of the real and imaginary parts of the dielectric constant at various frequencies, PCT50 is found to be a relaxor ferroelectric. It is proposed that the structural frustration introduced by the tilted octahedra may be responsible for the relaxor behavior.© 1997 American Institute of Physics.
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61.05.fm Neutron diffraction
61.66.Fn Inorganic compounds
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

Reduction of dislocation density in mismatched SiGe/Si using a low-temperature Si buffer layer

K. K. Linder, F. C. Zhang, J.-S. Rieh, P. Bhattacharya, and D. Houghton

Appl. Phys. Lett. 70, 3224 (1997); http://dx.doi.org/10.1063/1.119132 (3 pages) | Cited 52 times

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The reduction of the dislocation density in relaxed SiGe/Si heterostructures using a low-temperature Si(LT-Si) buffer has been investigated. We have shown that a 0.1 μm LT-Si buffer reduces the threading dislocation density in mismatched Si0.85Ge0.15/Si epitaxial layers as low as ∼ 104 cm−2. Samples were grown by both gas-source molecular beam epitaxy and ultrahigh vacuum chemical vapor deposition. © 1997 American Institute of Physics.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Metallization induced band bending of SrTiO3(100) and Ba0.7Sr0.3TiO3

M. Copel, P. R. Duncombe, D. A. Neumayer, T. M. Shaw, and R. M. Tromp

Appl. Phys. Lett. 70, 3227 (1997); http://dx.doi.org/10.1063/1.119148 (3 pages) | Cited 64 times

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We have investigated the interaction of Pt with single-crystal SrTiO3(001) and polycrystalline Ba0.7Sr0.3TiO3 thin films using photoemission spectroscopies. Significant band bending is caused by interface formation, determining the Schottky barrier height. We have depth profiled the band bending for Ba0.7Sr0.3TiO3 thin films, giving a direct measurement of the depletion depth and built-in potential. © 1997 American Institute of Physics.
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73.30.+y Surface double layers, Schottky barriers, and work functions
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

A stable Ti-based quasicrystal

K. F. Kelton, W. J. Kim, and R. M. Stroud

Appl. Phys. Lett. 70, 3230 (1997); http://dx.doi.org/10.1063/1.119133 (3 pages) | Cited 86 times

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The thermal stability of the icosahedral phase (i phase) in Ti45Zr38Ni17 alloys is demonstrated. As-cast alloys containing initially only the C14 hexagonal Laves and α-solid-solution phases transformed primarily to the icosahedral phase upon annealing in vacuum for 64 h at 570 °C. This confirms previous evidence for i-phase stability and firmly establishes this quasicrystal as the first nonaluminum stable icosahedral phase. Diffraction data show that this stable i phase is primitive; energy dispersive x-ray spectroscopy measurements place its composition near Ti41.5Zr41.5Ni17. These and other results suggest that the structure of this i phase is similar to that of i(AlLiCu). © 1997 American Institute of Physics.  
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61.44.Br Quasicrystals
61.05.cp X-ray diffraction

Fullerene and nanoparticle formation in carbon cathodic arc deposition

M. Chhowalla, A. I. Munindradasa, and G. A. J. Amaratunga

Appl. Phys. Lett. 70, 3233 (1997); http://dx.doi.org/10.1063/1.119134 (3 pages) | Cited 4 times

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We report on a method for detecting C60 and other C2n molecules in the vapor phase during their initial growth stage. The technique, which utilizes a Langmuir probe, was originally proposed by Fukuzawa et al. [T. Fukuzawa, M. Shiratani, and Y. Watanabe, Appl. Phys. Lett. 64, 3098 (1994)] for the detection of dust particles in silane plasmas. By measuring the positive and negative saturation currents in the afterglow plasma, the mass ratio of negative and positive ions can be determined. We found that a M−/M+ = 56±10 occurs only for discharge times greater than 0.5 s. As most of the positively charged species are expected to be singly charged carbon, a mass ratio of 56 is close enough to be attributed to the C60 molecule, in agreement with mass spectroscopy results. © 1997 American Institute of Physics.
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61.48.-c Structure of fullerenes and related hollow and planar molecular structures
61.46.-w Structure of nanoscale materials
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
52.80.Mg Arcs; sparks; lightning; atmospheric electricity

Stability of far fields in double heterostructure and multiple quantum well InAsSb/InPAsSb/InAs midinfrared lasers

H. Yi, A. Rybaltowski, J. Diaz, D. Wu, B. Lane, Y. Xiao, and M. Razeghi

Appl. Phys. Lett. 70, 3236 (1997); http://dx.doi.org/10.1063/1.119135 (3 pages) | Cited 3 times

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Far fields in perpendicular direction to the junction are investigated in double heterostructure (DH) and multiple quantum well (MQW) midwave-infrared InAsSb/InPAsSb/InAs lasers (λ = 3.2–3.6 μm). Strong broadening of the far fields in the DH lasers was observed with increases in temperature and/or current. On the contrary, MQW lasers with otherwise identical structure exhibit very stable far fields as narrow as 23° for all the operating conditions investigated. Our experiment and theoretical modeling suggest that these different behaviors of far fields in DH and MQW lasers are attributed to the refractive index fluctuation in the InAsSb laser active region. © 1997 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Optical phonons in laser-deposited CdSxTe1−x films

A. Fischer, Z. Feng, E. Bykov, G. Contreras-Puente, A. Compaan, Fray de Landa Castillo-Alvarado, Jaime Avendaño, and Alice Mason

Appl. Phys. Lett. 70, 3239 (1997); http://dx.doi.org/10.1063/1.119136 (3 pages) | Cited 11 times

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We report the longitudinal optical (LO) phonon frequencies for thin films of the ternary alloy CdSxTe1−x and their composition dependence for the full range of x values from pure CdTe to pure CdS. Pulsed laser deposition was used to prepare the polycrystalline thin films including compositions well inside the miscibility gap. We find that this ternary system exhibits a “two-mode” behavior with CdS- and CdTe-like longitudinal optic phonon modes. The modified random-element isodisplacement model yields a good description of the composition dependence of the LO phonon frequencies. © 1997 American Institute of Physics.
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63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
78.30.Fs III-V and II-VI semiconductors
81.15.Fg Pulsed laser ablation deposition

Growth of single phase GaAs1−xNx with high nitrogen concentration by metal–organic molecular beam epitaxy

Y. Qiu, S. A. Nikishin, H. Temkin, N. N. Faleev, and Yu. A. Kudriavtsev

Appl. Phys. Lett. 70, 3242 (1997); http://dx.doi.org/10.1063/1.119137 (3 pages) | Cited 39 times

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High quality layers of GaAs1−xNx were grown on (001)GaAs by metal–organic molecular beam epitaxy. The growth conditions, and especially the nitrogen to arsenic flux ratio, were carefully explored to assure epitaxial crystal growth. We show well behaved and reproducible growth of single phase GaAs1−xNx with the GaN mole fraction as high as x = 0.10. The nitrogen content of epitaxial layers was determined directly by secondary ion mass spectroscopy and high resolution x-ray diffraction. © 1997 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Ea III-V semiconductors
68.55.Nq Composition and phase identification

High-carrier-density electron dynamics in low-temperature-grown GaAs

T. S. Sosnowski, T. B. Norris, H. H. Wang, P. Grenier, J. F. Whitaker, and C. Y. Sung

Appl. Phys. Lett. 70, 3245 (1997); http://dx.doi.org/10.1063/1.119138 (3 pages) | Cited 34 times

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Pump-probe differential transmission measurements examine high-carrier-density phenomena in as-grown and annealed GaAs samples grown at temperatures from 210 to 270 °C. We observe trap saturation and Auger recombination, and accurately model the measurements on annealed samples with a simple two level rate equation, allowing us to extract the trapped-electron lifetimes. © 1997 American Institute of Physics.
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73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.Ey III-V semiconductors

Spatial correlations across n+n semiconductor junctions

O. M. Bulashenko, G. Gomila, J. M. Rubí, and V. A. Kochelap

Appl. Phys. Lett. 70, 3248 (1997); http://dx.doi.org/10.1063/1.119151 (3 pages) | Cited 9 times

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An analytical model for the spatial correlations and noise across an abrupt n+n junction is presented. The model is able to treat the junction as a whole in strongly inhomogeneous conditions self-consistently, by taking into account both the drift and diffusion contributions to the current. It is shown that within the analytical approach, the voltage noise across the junction can be decomposed into the sample and the contact contributions and the term representing sample-contact cross correlation. It is argued that the proposed analytical method is quite universal and could be effectively applied to different devices, operating under strongly inhomogeneous distributions of the electric field and charge concentration. © 1997 American Institute of Physics.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.70.+m Noise processes and phenomena
85.30.Hi Surface barrier, boundary, and point contact devices

Parallel quantum-point-contacts as high-frequency-mixers

A. G. C. Haubrich, D. A. Wharam, H. Kriegelstein, S. Manus, A. Lorke, J. P. Kotthaus, and A. C. Gossard

Appl. Phys. Lett. 70, 3251 (1997); http://dx.doi.org/10.1063/1.119139 (3 pages) | Cited 6 times

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The results of high-frequency mixing experiments performed upon parallel quantum point contacts defined in the two-dimensional electron gas of an AlxGa1−xAs/GaAs heterostructure are presented. The parallel geometry, fabricated using a novel double-resist technology, enables the point-contact device to be impedance matched over a wide frequency range and, in addition, increases the power levels of the mixing signal while simultaneously reducing the parasitic source-drain capacitance. Here, we consider two parallel quantum point-contact devices with 155 and 110 point contacts, respectively; both devices operated successfully at liquid helium and liquid nitrogen temperatures with a minimal conversion loss of 13 dB. © 1997 American Institute of Physics.
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85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
84.40.Lj Microwave integrated electronics
73.23.Ad Ballistic transport

Temperature dependent tunnelling current at metal/polymer interfaces—potential barrier height determination

M. Koehler and I. A. Hümmelgen

Appl. Phys. Lett. 70, 3254 (1997); http://dx.doi.org/10.1063/1.119149 (3 pages) | Cited 23 times

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It has been demonstrated that the expression for the temperature dependent tunneling current through a triangular potential barrier at metal/polymer interfaces fits experimental data including the deviation from a straight line observed in Fowler–Nordheim plots. The fitting parameters can be used to calculate the potential barrier height at the metal/polymer interface, which is of crucial importance for the control of charge injection in organic light emitting diodes. The tunneling current density expression reproduces the observed dependence of the current with temperature. © 1997 American Institute of Physics.
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73.61.Ph Polymers; organic compounds
73.40.Ns Metal-nonmetal contacts
73.40.Gk Tunneling

Type II recombination and band offset determination in a tensile strained InGaAs quantum well

C. Lugand, T. Benyattou, G. Guillot, T. Venet, M. Gendry, G. Hollinger, and B. Sermage

Appl. Phys. Lett. 70, 3257 (1997); http://dx.doi.org/10.1063/1.119140 (3 pages) | Cited 5 times

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Photoluminescence measurements under different excitation powers and time-resolved photoluminescence experiments were carried out at low temperature on tensile strained In0.3Ga0.7As quantum wells with InGaAs barriers lattice matched to InP. Evidence of a type II recombination is found between carriers confined in the tensile strained layer and in the lattice matched one. This study allows us to propose a precise determination of the light holes band offset in the In0.3Ga0.7As/In0.53Ga0.47As system. © 1997 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
71.70.Fk Strain-induced splitting
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