| 학회 |
한국재료학회 |
| 학술대회 |
2013년 가을 (11/06 ~ 11/08, 제주롯데호텔) |
| 권호 |
19권 2호 |
| 발표분야 |
A. 전자/반도체 재료(Electronic and Semiconductor Materials) |
| 제목 |
Improvement of Light Emission Efficiency of Green InGaN/GaN Multi-Quantum-Well Light-Emitting Diodes with Applying External Tensile Stress |
| 초록 |
Improvement of the light emission efficiency in green InGaN/GaN multi-quantum-well (MQW) light-emitting diodes (LEDs) has been achieved using external tensile stress. These improvements are achieved by reducing the quantum-confined Stark effect by attenuating piezoelectric polarization that results from compressive stress developed in the InGaN active layer. It was found that applying external tensile stress effectively compensates for the strong compressive stress. As a result, the peak wavelength of electroluminescence spectra was blue-shifted by approximately 4nm. The light emission efficiency was improved by ~35% when the LEDs were subjected to an external tensile stress of 1.33GPa without changing the operating voltage at an injection current of 20mA. Moreover, when the compressive strain developed in InGaN/GaN MQW active region is relaxed, the efficiency droop at high injection current is deteriorated due to the carrier overflow. In contrast, when the LEDs were exposed to an external compressive stress, the light emission efficiency was decreased by ~7% under the same injection current of 20mA and the efficiency droop was slightly reduced. The results confirmed that the reduction in piezoelectric field due to strain relaxation in the InGaN/GaN MQWs caused an enlargement of the effective band gap, an increase in electron-hole wave function overlap, and a corresponding increase in IQE. |
| 저자 |
Wael Z. Tawfik, Seo-Jung Bae, Hyo-Won Seo, June Key Lee
|
| 소속 |
Chonnam National Univ. |
| 키워드 |
Green-LED; Strain relaxation; Optical power; Electroluminescence
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| E-Mail |
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