Improved wall-plug efficiency of III-nitride tunnel junction micro-light-emitting diodes with AlGaN/GaN polarization charges

Matthew S. Wong; Aditya Raj; Hsun-Ming Chang; Vincent Rienzi; Feng Wu; Jacob J. Ewing; Emily S. Trageser; Stephen Gee; Nathan C. Palmquist; Philip Chan; Ji Hun Kang; James S. Speck; Umesh K. Mishra; Shuji Nakamura; Steven P. DenBaars

doi:10.1063/5.0131142

AIP Advances (Jan 2023)

Improved wall-plug efficiency of III-nitride tunnel junction micro-light-emitting diodes with AlGaN/GaN polarization charges

Matthew S. Wong,
Aditya Raj,
Hsun-Ming Chang,
Vincent Rienzi,
Feng Wu,
Jacob J. Ewing,
Emily S. Trageser,
Stephen Gee,
Nathan C. Palmquist,
Philip Chan,
Ji Hun Kang,
James S. Speck,
Umesh K. Mishra,
Shuji Nakamura,
Steven P. DenBaars

Affiliations

Matthew S. Wong: Materials Department, University of California, Santa Barbara, California 93106, USA
Aditya Raj: Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA
Hsun-Ming Chang: Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA
Vincent Rienzi: Materials Department, University of California, Santa Barbara, California 93106, USA
Feng Wu: Materials Department, University of California, Santa Barbara, California 93106, USA
Jacob J. Ewing: Materials Department, University of California, Santa Barbara, California 93106, USA
Emily S. Trageser: Materials Department, University of California, Santa Barbara, California 93106, USA
Stephen Gee: Materials Department, University of California, Santa Barbara, California 93106, USA
Nathan C. Palmquist: Materials Department, University of California, Santa Barbara, California 93106, USA
Philip Chan: Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA
Ji Hun Kang: Seoul Viosys, 97-11, Sandan-ro 163beon-gil, Danwon-gu, Ansan-si, Gyeonggi-do 15429, South Korea
James S. Speck: Materials Department, University of California, Santa Barbara, California 93106, USA
Umesh K. Mishra: Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA
Shuji Nakamura: Materials Department, University of California, Santa Barbara, California 93106, USA
Steven P. DenBaars: Materials Department, University of California, Santa Barbara, California 93106, USA

DOI: https://doi.org/10.1063/5.0131142
Journal volume & issue: Vol. 13, no. 1
pp. 015107 – 015107-5

Abstract

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The electrical performances of III-nitride blue micro-light-emitting diodes (µLEDs) with different tunnel junction (TJ) epitaxial architectures grown by metalorganic chemical vapor deposition are investigated. A new TJ structure that employs AlGaN is introduced. The current density–voltage characteristic is improved by incorporating AlGaN layer above the n-side of the TJ layer, and the effects of the AlGaN/GaN superlattices is examined. Based upon the data from band diagram simulation, net positive polarization charge is formed at the AlGaN/GaN interface, which results in a reduction in tunneling distance and increase in tunneling probability. Moreover, similar electrical improvement is observed in various device dimensions and is independent of operating current density, suggesting that AlGaN/GaN biaxial tensile strain or current spreading is not the main contribution for the improvement. Finally, the effects on the efficiency performances are determined. While the maximum external quantum efficiency of the TJ devices remains identical, the wall-plug efficiency of µLEDs is enhanced significantly by the proposed AlGaN-enhanced TJ design. This work reveals the possibility of energy efficient TJ contact with high transparency in the visible wavelength range.

Published in AIP Advances

ISSN: 2158-3226 (Online)
Publisher: AIP Publishing LLC
Country of publisher: United States
LCC subjects: Science: Physics
Website: http://aipadvances.aip.org/

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