2004 Fiscal Year Final Research Report Summary
Development of ultraviolet bright light-emitting diodes using quaternary InAlGaN
| Project/Area Number |
14205006
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | RIKEN |
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Principal Investigator |
HIRAYAMA Hideki RIKEN, Advanced Devices Laboratory, Senior Research Scientist, 石橋極微デバイス工学研究室, 先任研究員 (70270593)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Quaternary InAlGaN / Wide bandgap / MOCVD / In segregation / UV-LEDs / Threading dislocation density / Optical properties / Photoluminescence |
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| Research Abstract |
The demands for high-intensity ultraviolet(UV) laser diodes(LDs) and light-emitting diodes(LEDs) are increasing in the fields of high-density optical storage or high-efficiency lighting or biochemical and medical fields. GaN and III-nitride compound semiconductors are attracting considerable attention as candidate materials for the realization of UV-LDs and LEDs. The purpose of our work is to develop high-intensity UV-LEDs or LDs operating in the 250-350 nm wavelength range.
We have demonstrated high-efficiency UV emission from quaternary InAlGaN-based quantum wells(QWs) in the wavelength range between 290-375 nm at room temperature(RT) using the In-segregation effect. Emission fluctuations in the submicron region due to In-segregation were clearly observed for quaternary InAlGaN epitaxial layers. An internal quantum efficiency as high as 15% was estimated for a quaternary InAlGaN-based single quantum well(SQW) at RT. Such high efficiency UV emission can even be obtained on high threading-dislocation density buffers. We fabricated 310 nm-band deep UV light-emitting diodes(LEDs) with quaternary InAlGaN active regions. We achieved sub-milliwatt output power under RT pulsed operation for 308-314 nm LEDs. We also demonstrated a high output power of 7.4 mW from a 352 nm quaternary InAlGaN-based LED fabricated on a GaN substrate under RT CW operation. The maximum external quantum efficiency(EQE) of the 352 nm InAlGaN-based LED was 1.1%, which is the highest EQE ever obtained for 350 nm-band UV LEDs with top-emission geometry. From these results, the advantages of the use of quaternary InAlGaN for 300-350nm-band UV emitters was revealed.
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[Journal Article] Surprisingly low built-in electric fields in quaternary AlInGaN heterostructures2004
Author(s)
S.Anceau, P.Lefebvre, T.Suski, S.P.Lepkowski, H.Teisseyre, L.H.Dmowski, L.Konczewicz, A.Kaminska, A.Suchocki, H.Hirayama, Y.Aoyagi
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Journal Title
Phys.Stat.Sol.(a) vol.201, no.2
Pages: 190-194
Description
「研究成果報告書概要(欧文)」より
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