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19 Mar 2001

Volume 78, Issue 12, pp. 1649-1795

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Effects of sulfur treatment on electrical and optical performance of InGaN/GaN multiple-quantum-well blue light-emitting diodes

Chul Huh, Sang-Woo Kim, Hyun-Soo Kim, Hyun-Min Kim, Hyunsang Hwang, and Seong-Ju Park

Appl. Phys. Lett. 78, 1766 (2001); http://dx.doi.org/10.1063/1.1355990 (3 pages) | Cited 15 times

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The results of the sulfur treatment of multiple-quantum-well (MQW) light-emitting diodes (LEDs) with (NH4)2S and (NH4)2S+t-C4H9OH solutions prior to the deposition of a light-transmitting p-electrode metal are presented. The room-temperature I–V curves showed that the forward voltages of MQW LEDs treated with the two sulfur solutions decrease by 0.12 and 0.35 V at 20 mA, respectively, compared to the untreated MQW LED, as the result of an improvement in p-Ohmic contact characteristics. The relative light-output power and external quantum efficiency of MQW LEDs increased by a factor of 1.28 for the (NH4)2S treated sample and 2.23 for the (NH4)2S+t-C4H9OH treated sample compared to the untreated sample. In addition, the reverse leakage current characteristic of MQW LEDs was reduced as a result of sulfur treatment. This can be attributed to the passivation of surface and sidewall damages formed after the dry-etching process for a reliable pattern transfer. The present results indicate that the sulfur treatment greatly improves the electrical and optical performance of MQW LEDs. © 2001 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.63.Hs Quantum wells
78.67.De Quantum wells
78.60.Fi Electroluminescence
81.65.Rv Passivation

Role of the buildup oscillations on the speed of resonant tunneling diodes

Roberto Romo and Jorge Villavicencio

Appl. Phys. Lett. 78, 1769 (2001); http://dx.doi.org/10.1063/1.1354164 (3 pages) | Cited 7 times

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The fastest tunneling response in double barrier resonant structures is investigated by considering explicit analytic solutions of the time-dependent Schrödinger equation. For cutoff initial plane waves, we find that the earliest tunneling events consist of the emission of a series of propagating pulses of the probability density governed by the buildup oscillations in the quantum well. We show that the fastest tunneling response comes from the contribution of incident carriers at energies different from resonance, and that its relevant time scale is given by τr = πℏ/∣E−ε∣, where ε is the resonance energy and E is the incidence energy. © 2001 American Institute of Physics.
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85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
85.30.De Semiconductor-device characterization, design, and modeling
73.23.Hk Coulomb blockade; single-electron tunneling

Reflectionless tunneling in planar Nb/GaAs hybrid junctions

Francesco Giazotto, Marco Cecchini, Pasqualantonio Pingue, Fabio Beltram, Marco Lazzarino, Daniela Orani, Silvia Rubini, and Alfonso Franciosi

Appl. Phys. Lett. 78, 1772 (2001); http://dx.doi.org/10.1063/1.1357211 (3 pages) | Cited 5 times

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Reflectionless tunneling was observed in Nb/GaAs superconductor/semiconductor junctions fabricated by a two-step procedure. First, periodic δ-doped layers were grown by molecular-beam epitaxy near the GaAs surface, followed by an As cap layer to protect the surface during ex situ transfer. Second, Nb was deposited by dc-magnetron sputtering onto a GaAs(001) 2×4 surface in situ after thermal desorption of the cap layer. The magnetotransport behavior of the resulting hybrid junctions was successfully analyzed within the random matrix theory of phase-coherent Andreev transport. The impact of junction morphology on reflectionless tunneling and the applicability of the fabrication technique to the realization of complex superconductor/semiconductor mesoscopic systems are discussed. © 2001 American Institute of Physics.
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74.50.+r Tunneling phenomena; Josephson effects
73.23.-b Electronic transport in mesoscopic systems
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.78.Fk Multilayers, superlattices, heterostructures
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