Controlling the defect density to improve the output power of InGaN/GaN-based vertical light-emitting diodes by using substrates patterned with SiO2 lenses
- Authors
- Kang, Daesung; Kim, Da-Som; Kim, Sun-Kyung; Song, Kiyoung; Jung, Myunghoon; Jeong, Hwanhee; Song, June-O; Seong, Tae-Yeon
- Issue Date
- 2016
- Publisher
- TAYLOR & FRANCIS LTD
- Keywords
- GaN; light emitting diode; line defects; patterned substrate; external quantum efficiency; structural analysis
- Citation
- PHILOSOPHICAL MAGAZINE, v.96, no.27, pp.2919 - 2929
- Indexed
- SCIE
SCOPUS
- Journal Title
- PHILOSOPHICAL MAGAZINE
- Volume
- 96
- Number
- 27
- Start Page
- 2919
- End Page
- 2929
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/90358
- DOI
- 10.1080/14786435.2016.1219784
- ISSN
- 1478-6435
- Abstract
- In this study, we investigated the effect of SiO2 lenses on the output power of InGaN/GaN-based vertical light-emitting diodes (VLEDs; wavelength=445nm) and compared the results to those of reference VLEDs without the SiO2 lenses (planar samples). Arrays of SiO2 lenses (pitch=3m, width=2.5m, height=1.0m) were formed on c-plane sapphire substrates. The external quantum efficiency (EQE) of the packaged VLEDs with planar and patterned substrates was characterised. At 5mA, the EQE of the patterned samples was 150% higher than that of the planar samples. A patterned, N-polar, n-GaN sample contained far fewer nanopipes (approximately 2.2 x 10(5)cm(-2)) than a planar n-GaN sample (approximately 2.4 x 10(6)cm(-2)). Furthermore, the patterned samples contained far fewer threading dislocations (approximately 1.0 x 10(8)cm(-2)) than the planar samples (approximately 5.0 x 10(8)cm(-2)). Scanning electron microscopy (SEM) images showed that the photoelectrochemical (PEC)-etched patterned samples contained cones that were 150% larger than that of the PEC-etched planar samples. In addition, SEM images, cathode luminescence measurements and finite-difference time-domain simulations were used to characterise the improved light output of the patterned samples.
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Collections - College of Engineering > Department of Materials Science and Engineering > 1. Journal Articles
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