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17 Dec 2001

Volume 79, Issue 25, pp. 4073-4251

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Current crowding in InAsSb light-emitting diodes

V. K. Malyutenko, O. Yu. Malyutenko, A. D. Podoltsev, I. N. Kucheryavaya, B. A. Matveev, M. A. Remennyi, and N. M. Stus’

Appl. Phys. Lett. 79, 4228 (2001); http://dx.doi.org/10.1063/1.1424065 (3 pages) | Cited 16 times

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High-resolution two-dimensional infrared (IR) imaging of dynamic electronic processes in the surface-emitting p-InAsSb/n-InAsSbP light-emitting diodes (LEDs) (λ = 4.3 μm, T>300 K) showed that forward current crowding drastically decreases efficiency of LEDs with point contacts. Current flows and IR emittance “forget” the emitting area size and geometry, whereas extended areas far off the point contacts become even “darker” with the current increase. Contrary to this, the reverse bias causes remarkable current spreading and uniform “negative emittance” distribution. Therefore the negative luminescence mode is more favorable for IR LEDs operating at higher temperatures. © 2001 American Institute of Physics.
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85.60.Jb Light-emitting devices

Quantum coherent transport versus diode-like effect in semiconductor-free metal/insulator structure

C. Tiusan, M. Chshiev, A. Iovan, V. da Costa, D. Stoeffler, T. Dimopoulos, and K. Ounadjela

Appl. Phys. Lett. 79, 4231 (2001); http://dx.doi.org/10.1063/1.1426685 (3 pages) | Cited 10 times

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Quantum coherent transport in double barrier tunnel junctions has been exploited for building micrometric-size semiconductor-free diodes. At room temperature, we observe strongly asymmetric current–voltage characteristics with an asymmetry ratio increasing with the bias voltage, reaching a maximum of 20 at 1 V. Our experimental data can be perfectly explained using a theoretical model involving resonance-assisted tunneling. The coherent/resonant tunneling regime is achieved using metallic 3 nm diameter monodisperse Cu clusters, sandwiched between two Al2O3 barriers. © 2001 American Institute of Physics.
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73.40.Ns Metal-nonmetal contacts
73.23.-b Electronic transport in mesoscopic systems
81.07.Bc Nanocrystalline materials
81.05.Bx Metals, semimetals, and alloys
73.22.-f Electronic structure of nanoscale materials and related systems
73.63.Bd Nanocrystalline materials

Bright white organic light-emitting diode

C. W. Ko and Y. T. Tao

Appl. Phys. Lett. 79, 4234 (2001); http://dx.doi.org/10.1063/1.1425454 (3 pages) | Cited 92 times

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A very bright white organic light-emitting diode (OLED) was realized by using a bright blue-emitting layer, 1,7-diphenyl-4-biphenyl-3,5-dimethyl-1,7-dihydrodipyrazolo[3,4-b;4′,3′-e]pyridine (PAP-Ph), together with a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyry)-4H-pyran (DCM)-doped Alq [tris(8-hydroxyquinolinato) aluminum (III)] layer to provide blue, red, and green emission for color mixing. By appropriately controlling the layer thickness, the white light OLED achieved good performance of 24 700cd/m2 at 15 V, 1.93 lm/W at 6.5 V, and >300cd/m2 at 7.7 mA/cm2. The Commission Internationale de l’Eclairage coordinates of the emitted light are quite stable at voltages from 6 to 12 V, ranging from (0.35, 0.34) to (0.34, 0.35). © 2001 American Institute of Physics.
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85.60.Jb Light-emitting devices

High absorption (>90%) quantum-well infrared photodetectors

H. C. Liu, R. Dudek, A. Shen, E. Dupont, C. Y. Song, Z. R. Wasilewski, and M. Buchanan

Appl. Phys. Lett. 79, 4237 (2001); http://dx.doi.org/10.1063/1.1425066 (3 pages) | Cited 28 times

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The intrinsic short carrier lifetime ( ∼ 5 ps) makes the quantum-well infrared photodetector (QWIP) well suited for high speed and high frequency applications. In such cases, since lasers are commonly used, a high dark current can be tolerated. The most important parameter is then the absorption efficiency. For system simplicity and potential wide use, room temperature operation is desirable. Using GaAs/AlGaAs QWIPs, high absorption ( ∼ 100%) and up to room temperature operation are achieved in devices having high doping densities and 100 quantum wells. © 2001 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Ultraviolet light-emitting diodes at 340 nm using quaternary AlInGaN multiple quantum wells

V. Adivarahan, A. Chitnis, J. P. Zhang, M. Shatalov, J. W. Yang, G. Simin, M. Asif Khan, R. Gaska, and M. S. Shur

Appl. Phys. Lett. 79, 4240 (2001); http://dx.doi.org/10.1063/1.1425453 (3 pages) | Cited 41 times

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An ultraviolet light-emitting diode with peak emission wavelength at 340 nm is reported. The active layers of the device were comprised of quaternary AlInGaN/AlInGaN multiple quantum wells, which were deposited over sapphire substrates using a pulsed atomic-layer epitaxy process that allows precise control of the composition and thickness. A comparative study of devices over sapphire and SiC substrates was done to determine the influence of the epilayer design on the performance parameters and the role of substrate absorption. © 2001 American Institute of Physics.
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78.67.De Quantum wells
81.07.St Quantum wells
85.60.Jb Light-emitting devices
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
78.66.Fd III-V semiconductors
73.21.Fg Quantum wells
68.65.Fg Quantum wells
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Local lattice strain distribution around a transistor channel in metal–oxide–semiconductor devices

Akio Toda, Nobuyuki Ikarashi, Haruhiko Ono, Shinya Ito, Takeshi Toda, and Kiyotaka Imai

Appl. Phys. Lett. 79, 4243 (2001); http://dx.doi.org/10.1063/1.1427440 (3 pages) | Cited 11 times

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The local lattice strain around the channel in metal–oxide–semiconductor (MOS) field-effect transistors of 0.1 μm gate length was measured by using convergent-beam electron diffraction. It was found that the normal strain along the gate-length direction is compressive beneath the gate and is larger for devices having smaller diffusion sizes in the gate length direction L′. The drive current Ion decreased for an n-channel MOS and increased for a p-channel MOS as L′ decreased. These results are consistent with those of a previous study. However, our results also revealed that the strain distribution around the channel region was strongly affected not only by the stress from the shallow trench isolation but also by the device structures around the gate. © 2001 American Institute of Physics.
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85.30.Tv Field effect devices
85.30.De Semiconductor-device characterization, design, and modeling
85.40.Ls Metallization, contacts, interconnects; device isolation
68.60.Bs Mechanical and acoustical properties

Hole mobility enhancements in strained Si/Si1−yGey p-type metal-oxide-semiconductor field-effect transistors grown on relaxed Si1−xGex (x<y) virtual substrates

C. W. Leitz, M. T. Currie, M. L. Lee, Z.-Y. Cheng, D. A. Antoniadis, and E. A. Fitzgerald

Appl. Phys. Lett. 79, 4246 (2001); http://dx.doi.org/10.1063/1.1423774 (3 pages) | Cited 54 times

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We have achieved peak hole mobility enhancement factors of 5.15 over bulk Si in metal-oxide-semiconductor field-effect transistors (MOSFETs) by combining tensile strained Si surface channels and compressively strained 80% Ge buried channels grown on relaxed 50% Ge virtual substrates. To further investigate hole transport in these dual channel structures, we study the effects of strain, alloy scattering, and layer thickness on hole mobility enhancements in MOSFETs based upon these layers. We show that significant performance boosts can be obtained despite the effects of alloy scattering and that the best hole mobility enhancements are obtained for structures with thin Si surface layers. © 2001 American Institute of Physics.
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85.30.Tv Field effect devices
73.50.Dn Low-field transport and mobility; piezoresistance
68.60.Bs Mechanical and acoustical properties
85.40.Sz Deposition technology
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
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