Presentation 2017-12-15
[Invited Talk] Recent progress of AlGaN deep-UV LEDs
Hideki Hirayama, Masafumi Jo, Noritoshi Maeda, Yukio Kashima,
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Abstract(in Japanese) (See Japanese page)
Abstract(in English) AlGaN deep ultraviolet light-emitting diodes (DUV-LEDs) are attracting a great deal of attention, since they have the potential to be used in a wide variety of applications, such as for sterilization, water purification, UV curing, and in the medical and biochemistry fields, and so on. As a result of recent developments in AlGaN DUV LEDs, high internal quantum efficiencies (IQE) of more than 60-70 % have been achieved by reducing the threading dislocation density (TDD) of the AlN, by improving the crystal growth technique and/or by the introduction of AlN single crystal wafers. However, the wall-plug efficiency (WPE) of AlGaN DUV-LEDs still remains at several percent. The first target for the efficiency of AlGaN DUV-LEDs is to go beyond an efficiency of 20%, which would make them comparable to mercury lamps. A significant problem is that the light-extraction efficiency (LEE) of AlGaN DUV-LEDs is still quite low because of heavy UV absorption through the p-GaN contact-layer. Clearly, improving the LEE is a major topic in the development of AlGaN DUV-LEDs. Transparent contact layers and highly reflective electrodes are considered to be necessary in order to obtain sufficiently high LEEs in DUV LEDs. In this work, we demonstrate a record EQE ever reported of over 20% in an AlGaN DUV-LED by using a transparent p-AlGaN contact layer and a highly reflective p-type electrode to improve the LEE. We also demonstrated a record WPE of 10.8% in a DUV LED by suppressing the applying voltage reducing the contact resistance of p-AlGaN/reflective electrode.
Keyword(in Japanese) (See Japanese page)
Keyword(in English) deep-UV LEDAlNAlGaNMOCVDthreading dislocation densitywall plug efficiency
Paper # LQE2017-91
Date of Issue 2017-12-08 (LQE)

Conference Information
Committee LQE
Conference Date 2017/12/15(1days)
Place (in Japanese) (See Japanese page)
Place (in English)
Topics (in Japanese) (See Japanese page)
Topics (in English)
Chair Tsuyoshi Yamamoto(Fujitsu Labs.)
Vice Chair Kiichi Hamamoto(Kyusyu Univ.)
Secretary Kiichi Hamamoto(Tohoku Univ.)
Assistant Yasumasa Kawakita(Furukawa Electric Industries) / Naoki Fujiwara(NTT)

Paper Information
Registration To Technical Committee on Lasers and Quantum Electronics
Language ENG
Title (in Japanese) (See Japanese page)
Sub Title (in Japanese) (See Japanese page)
Title (in English) [Invited Talk] Recent progress of AlGaN deep-UV LEDs
Sub Title (in English)
Keyword(1) deep-UV LEDAlNAlGaNMOCVDthreading dislocation densitywall plug efficiency
1st Author's Name Hideki Hirayama
1st Author's Affiliation RIKEN(RIKEN)
2nd Author's Name Masafumi Jo
2nd Author's Affiliation RIKEN(RIKEN)
3rd Author's Name Noritoshi Maeda
3rd Author's Affiliation RIKEN(RIKEN)
4th Author's Name Yukio Kashima
4th Author's Affiliation Marubun(Marubun)
Date 2017-12-15
Paper # LQE2017-91
Volume (vol) vol.117
Number (no) LQE-358
Page pp.pp.21-26(LQE),
#Pages 6
Date of Issue 2017-12-08 (LQE)