Improvement of light output power of InGaN/GaN light-emitting diode by lateral epitaxial overgrowth using pyramidal-shaped SiO2

Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea.
Optics Express (Impact Factor: 3.49). 01/2010; 18(2):1462-8. DOI: 10.1364/OE.18.001462
Source: PubMed


We report on the improvement of light output power of InGaN/GaN blue light-emitting diodes (LEDs) by lateral epitaxial overgrowth (LEO) of GaN using a pyramidal-shaped SiO(2) mask. The light output power was increased by 80% at 20 mA of injection current compared with that of conventional LEDs without LEO structures. This improvement is attributed to an increased internal quantum efficiency by a significant reduction in threading dislocation and by an enhancement of light extraction efficiency by pyramidal-shaped SiO(2) LEO mask.

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Available from: Chu-Young Cho, Jan 23, 2014
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    • "It is well known that one of the methods to reduce TDs and enhance the internal quantum efficiency of GaN-based LEDs is epitaxial lateral overgrowth (ELO). Light output enhancement of GaN-based LEDs through microscale or nanoscale ELO (NELO) have been reported for sapphire substrates [5], [6]. However, there are few reported device results for LEDs on Si substrates through the NELO method [7], especially for Manuscript received March 26, 2013; accepted April 20, 2013. "
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    ABSTRACT: High-performance GaN-based green and yellow light-emitting diodes (LEDs) are grown on SiO2 nanorod patterned GaN/Si templates by metalorganic chemical vapor deposition. The high-density SiO2 nanorods are prepared by nonlithographic HCl-treated indium tin oxide and dry etching. The dislocation density of GaN is significantly reduced by nanoscale epitaxial lateral overgrowth. In addition to the much improved green LED (505 and 530 nm) results, the fabricated yellow (565 nm) InGaN/GaN-based multiquantum well (MQW) LEDs on Si substrates are demonstrated for the first time. High-quality GaN buffer and localized states in MQWs are correlated to obtaining high-efficiency long-wavelength emission in our devices.
    IEEE Electron Device Letters 07/2013; 34(7):903-905. DOI:10.1109/LED.2013.2260126 · 2.75 Impact Factor
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    • "Since 1999, InGaN-based LED's have gained great attention and provide the impressive results due to their highest external quantum efficiencies of 18% and 20% at low currents of 0.6mA and 0.1 mA, respectively (Mukai et al, 1999). Although InGaN-based LEDs are already commercially available for visible light emission such as in display and automotive lighting applications, further improvement of the light output power and the external quantum efficiency are required (Chu et al., 2010). To find out the efficiency of LEDs, it would require the study of electrical characteristics in advance. "

    04/2012; 4(2). DOI:10.5539/apr.v4n2p98
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    ABSTRACT: Multi-quantum wells (MQWs) InGaN/GaN LEDs, 300 microm x 300 microm chip size, were fabricated with Ta(2)O(5) / SiO(2) dielectric multi-layer micro-mirror array (MMA) embedded in the epitaxiallateral- overgrowth (ELOG) gallium nitride (GaN) on the c-plane sapphire substrate. MQWs InGaN/GaN LEDs with ELOG embedded patterned SiO(2) array (P-SiO(2)) of the same dimension as the MMA were also fabricated for comparison. Dislocation density was reduced for the ELOG samples. 75.2% light extraction enhancement for P-SiO(2)-LED and 102.6% light extraction enhancement for MMA-LED were obtained over the standard LED. We showed that multiple-diffraction with high intensity from the MMA redirected the trap lights to escape from the LED causing the light extraction enhancement.
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