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Proceedings Paper

High-efficiency blue LEDs with thin AlGaN interlayers in InGaN/GaN MQWs grown on Si (111) substrates
Author(s): Shigeya Kimura; Hisashi Yoshida; Toshihide Ito; Aoi Okada; Kenjiro Uesugi; Shinya Nunoue
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Paper Abstract

We demonstrate high-efficiency blue light-emitting diodes (LEDs) with thin AlGaN interlayers in InGaN/GaN multiquantum wells (MQWs) grown on Si (111) substrates. The peak external quantum efficiency (EQE) ηEQE of 82% at room temperature and the hot/cold factor (HCF) of 94% have been obtained by using the functional thin AlGaN interlayers in the MQWs in addition to reducing threading dislocation densities (TDDs) in the blue LEDs. An HCF is defined as ηEQE(85°C)/ηEQE(25°C). The blue LED structures were grown by metal-organic chemical vapor deposition on Si (111) substrates. The MQWs applied as an active layer have 8- pairs of InGaN/AlyGa1-yN/GaN (0≤y≤1) heterostructures. Thinfilm LEDs were fabricated by removing the Si (111) substrates from the grown layers. It is observed by high-resolution transmission electron microscopy and three-dimensional atom probe analysis that the 1 nm-thick AlyGa1-yN interlayers, whose Al content is y=0.3 or less, are continuously formed. EQE and the HCFs of the LEDs with thin Al0.15Ga0.85N interlayers are enhanced compared with those of the samples without the interlayers in the low-current-density region. We consider that the enhancement is due to both the reduction of the nonradiative recombination centers and the increase of the radiative recombination rate mediated by the strain-induced hole carriers indicated by the simulation of the energy band diagram.

Paper Details

Date Published: 26 February 2016
PDF: 7 pages
Proc. SPIE 9748, Gallium Nitride Materials and Devices XI, 97481U (26 February 2016); doi: 10.1117/12.2211880
Show Author Affiliations
Shigeya Kimura, Toshiba Corp. (Japan)
Hisashi Yoshida, Toshiba Corp. (Japan)
Toshihide Ito, Toshiba Corp. (Japan)
Aoi Okada, Toshiba Corp. (Japan)
Kenjiro Uesugi, Toshiba Corp. (Japan)
Shinya Nunoue, Toshiba Corp. (Japan)

Published in SPIE Proceedings Vol. 9748:
Gallium Nitride Materials and Devices XI
Jen-Inn Chyi; Hiroshi Fujioka; Hadis Morkoç; Yasushi Nanishi; Ulrich T. Schwarz; Jong-In Shim, Editor(s)

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