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25 Oct 1999

Volume 75, Issue 17, pp. 2521-2692

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Optimized random/ordered grating for an n-type quantum well infrared photodetector

Shmuel I. Borenstain, U. Arad, I. Lyubina, A. Segal, and Y. Warschawer

Appl. Phys. Lett. 75, 2659 (1999); http://dx.doi.org/10.1063/1.125110 (3 pages) | Cited 2 times

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Coupling efficiency of infrared radiation to electron intersubband transition in quantum well infrared photodetector by a two-dimensional (2D) grooved grating is examined. A resonant enhancement of the coupling efficiency at a certain optimal groove depth is predicted and confirmed experimentally. It is argued that a detector with a properly designed ordered cross grating performs better than a detector with optimized 2D random grating. In a detector with ordered grating a quantum efficiency of 75% is obtained with a doping level of only 3.5×1017 cm−3 in each quantum well and dark current density of 0.34 mA/cm2 at 78 K. © 1999 American Institute of Physics.
Show PACS
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.79.Dj Gratings

Supercapacitors based on nanostructured carbon electrodes grown by cluster-beam deposition

L. Diederich, E. Barborini, P. Piseri, A. Podestà, P. Milani, A. Schneuwly, and R. Gallay

Appl. Phys. Lett. 75, 2662 (1999); http://dx.doi.org/10.1063/1.125111 (3 pages) | Cited 63 times

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Nanostructured carbon films have been grown at room temperature by supersonic cluster beam deposition. Due to a structure based on nanotube embryos and a porosity with grain sizes of a few tens of nanometers, these films have a highly accessible surface area needed for electrochemical applications such as supercapacitors. Films with a density of 1 g/cm3 show, in the dc regime, a specific capacitance per electrode of 75 F/g on a single-cell device with polycarbonate as the organic electrolyte. The resulting energy and power densities of cluster-assembled carbon electrodes are 76 Wh/kg and 506 kW/kg. The possibility of depositing nanostructured films over a large area on a variety of substrates makes cluster-beam deposition very interesting for the realization of supercapacitors. © 1999 American Institute of Physics.
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82.47.-a Applied electrochemistry
82.45.-h Electrochemistry and electrophoresis
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Storage capabilities of a four-junction single-electron trap with an on-chip resistor

S. V. Lotkhov, H. Zangerle, A. B. Zorin, and J. Niemeyer

Appl. Phys. Lett. 75, 2665 (1999); http://dx.doi.org/10.1063/1.125112 (3 pages) | Cited 13 times

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We report on the operation of a single-electron trap comprising a chain of four Al/AlOx/Al tunnel junctions attached, at one side, to a memory island and, at the other side, to a miniature on-chip Cr resistor (R ≈ 50 kΩ), which served to reduce cotunneling. At appropriate voltage bias, the bistable states of the trap, with the charges differing by the elementary charge e, were realized. At low temperature, spontaneous switching between these states was found to be very infrequent. For instance, at T = 70 mK the system was capable of holding an electron for more than 2 h, this time being limited by the time of the measurement. © 1999 American Institute of Physics.
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73.23.Hk Coulomb blockade; single-electron tunneling
85.35.Gv Single electron devices
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Application of an AlGaAs/GaAs/InGaAs heterostructure emitter for a resonant-tunneling transistor

Jung-Hui Tsai

Appl. Phys. Lett. 75, 2668 (1999); http://dx.doi.org/10.1063/1.125113 (3 pages) | Cited 5 times

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An AlGaAs/GaAs/InGaAs resonant-tunneling heterostructure-emitter bipolar transistor with negative-differential-resistance (NDR) behavior has been fabricated and demonstrated. Typical device performances with current gain of 140 incorporating an N-shaped NDR with a peak-to-valley current ratio of 5.3 are obtained at room temperature. The NDR behavior is believed to mainly result from a double-barrier-like resonant-tunneling effect. In other words, the on and off electron resonant tunneling from a depleted GaAs emitter through an InGaAs quantum well and ultrathin base toward a collector layer yield the interesting NDR behavior. Consequently, the proposed device provides a good potential for applications in amplifiers, low-power consumption, and logic currents. © 1999 American Institute of Physics.
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85.30.Pq Bipolar transistors
73.50.Fq High-field and nonlinear effects
85.30.De Semiconductor-device characterization, design, and modeling
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