Improved External Efficiency InGaN-Based Light-Emitting Diodes with Transparent Conductive Ga-Doped ZnO as p-Electrodes

Ken Nakahara; Kentaro Tamura; Mitsuhiko Sakai; Daisuke Nakagawa; Norikazu Ito; Masayuki Sonobe; Hidemi Takasu; Hitoshi Tampo; Paul Fons; Koji Matsubara; Kakuya Iwata; Akimasa Yamada; Shigeru Niki

doi:10.1143/jjap.43.l180

Improved External Efficiency InGaN-Based Light-Emitting Diodes with Transparent Conductive Ga-Doped ZnO as p-Electrodes

Ken Nakahara, Kentaro Tamura, Mitsuhiko Sakai, Daisuke Nakagawa, Norikazu Ito, Masayuki Sonobe, Hidemi Takasu, Hitoshi Tampo, Paul Fons, Koji Matsubara, Kakuya Iwata, Akimasa Yamada, Shigeru Niki

Research output: Contribution to journal › Article › peer-review

65 Citations (Scopus)

Abstract

Transparent conductive Ga-doped ZnO (ZnO:Ga) was fabricated to serve as p-contacts of InGaN-based light-emitting diodes (LEDs) using molecular-beam epitaxy. As-grown ZnO:Ga films typically have resistivities of ρ = 2 - 4 × 10^-4 Ω-cm, and over 80% transparency in the near UV and visible wavelength ranges. The current-voltage characteristics between as-grown ZnO:Ga contacts and p-GaN layers were ohmic. The brightness of LEDs fabricated with ZnO:Ga p-contacts was nearly double compared to LEDs with conventional Ni/Au p-contacts. We obtained the external efficiency as high as 20.8% in the case of the near UV LED. The forward voltage at 20mA was found not to increase even after the lamp LED with ZnO:Ga were kept for 80h in high humidity and high temperature environments.

Original language	English
Pages (from-to)	L180-L182
Journal	Japanese Journal of Applied Physics, Part 2: Letters
Volume	43
Issue number	2 A
DOIs	https://doi.org/10.1143/jjap.43.l180
Publication status	Published - 2004 Feb 1
Externally published	Yes

Keywords

External efficiency
GaN
InGaN
LED
MBE
Ohmic contact
Reliability
Transparent
ZnO

ASJC Scopus subject areas

Engineering(all)
Physics and Astronomy(all)

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10.1143/jjap.43.l180

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Nakahara, K., Tamura, K., Sakai, M., Nakagawa, D., Ito, N., Sonobe, M., Takasu, H., Tampo, H., Fons, P., Matsubara, K., Iwata, K., Yamada, A., & Niki, S. (2004). Improved External Efficiency InGaN-Based Light-Emitting Diodes with Transparent Conductive Ga-Doped ZnO as p-Electrodes. Japanese Journal of Applied Physics, Part 2: Letters, 43(2 A), L180-L182. https://doi.org/10.1143/jjap.43.l180

Nakahara, K, Tamura, K, Sakai, M, Nakagawa, D, Ito, N, Sonobe, M, Takasu, H, Tampo, H, Fons, P, Matsubara, K, Iwata, K, Yamada, A & Niki, S 2004, 'Improved External Efficiency InGaN-Based Light-Emitting Diodes with Transparent Conductive Ga-Doped ZnO as p-Electrodes', Japanese Journal of Applied Physics, Part 2: Letters, vol. 43, no. 2 A, pp. L180-L182. https://doi.org/10.1143/jjap.43.l180

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abstract = "Transparent conductive Ga-doped ZnO (ZnO:Ga) was fabricated to serve as p-contacts of InGaN-based light-emitting diodes (LEDs) using molecular-beam epitaxy. As-grown ZnO:Ga films typically have resistivities of ρ = 2 - 4 × 10-4 Ω-cm, and over 80% transparency in the near UV and visible wavelength ranges. The current-voltage characteristics between as-grown ZnO:Ga contacts and p-GaN layers were ohmic. The brightness of LEDs fabricated with ZnO:Ga p-contacts was nearly double compared to LEDs with conventional Ni/Au p-contacts. We obtained the external efficiency as high as 20.8% in the case of the near UV LED. The forward voltage at 20mA was found not to increase even after the lamp LED with ZnO:Ga were kept for 80h in high humidity and high temperature environments.",

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author = "Ken Nakahara and Kentaro Tamura and Mitsuhiko Sakai and Daisuke Nakagawa and Norikazu Ito and Masayuki Sonobe and Hidemi Takasu and Hitoshi Tampo and Paul Fons and Koji Matsubara and Kakuya Iwata and Akimasa Yamada and Shigeru Niki",

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AU - Nakahara, Ken

AU - Tamura, Kentaro

AU - Sakai, Mitsuhiko

AU - Nakagawa, Daisuke

AU - Ito, Norikazu

AU - Sonobe, Masayuki

AU - Takasu, Hidemi

AU - Tampo, Hitoshi

AU - Fons, Paul

AU - Matsubara, Koji

AU - Iwata, Kakuya

AU - Yamada, Akimasa

AU - Niki, Shigeru

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N2 - Transparent conductive Ga-doped ZnO (ZnO:Ga) was fabricated to serve as p-contacts of InGaN-based light-emitting diodes (LEDs) using molecular-beam epitaxy. As-grown ZnO:Ga films typically have resistivities of ρ = 2 - 4 × 10-4 Ω-cm, and over 80% transparency in the near UV and visible wavelength ranges. The current-voltage characteristics between as-grown ZnO:Ga contacts and p-GaN layers were ohmic. The brightness of LEDs fabricated with ZnO:Ga p-contacts was nearly double compared to LEDs with conventional Ni/Au p-contacts. We obtained the external efficiency as high as 20.8% in the case of the near UV LED. The forward voltage at 20mA was found not to increase even after the lamp LED with ZnO:Ga were kept for 80h in high humidity and high temperature environments.

AB - Transparent conductive Ga-doped ZnO (ZnO:Ga) was fabricated to serve as p-contacts of InGaN-based light-emitting diodes (LEDs) using molecular-beam epitaxy. As-grown ZnO:Ga films typically have resistivities of ρ = 2 - 4 × 10-4 Ω-cm, and over 80% transparency in the near UV and visible wavelength ranges. The current-voltage characteristics between as-grown ZnO:Ga contacts and p-GaN layers were ohmic. The brightness of LEDs fabricated with ZnO:Ga p-contacts was nearly double compared to LEDs with conventional Ni/Au p-contacts. We obtained the external efficiency as high as 20.8% in the case of the near UV LED. The forward voltage at 20mA was found not to increase even after the lamp LED with ZnO:Ga were kept for 80h in high humidity and high temperature environments.

KW - External efficiency

KW - GaN

KW - InGaN

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KW - MBE

KW - Ohmic contact

KW - Reliability

KW - Transparent

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Improved External Efficiency InGaN-Based Light-Emitting Diodes with Transparent Conductive Ga-Doped ZnO as p-Electrodes

Abstract

Keywords

ASJC Scopus subject areas

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