High efficiency ultraviolet GaN-based vertical light emitting diodes on 6-inch sapphire substrate using ex-situ sputtered AlN nucleation layer

Jeong Tak Oh, Yong Tae Moon, Dae Sung Kang, Chan Keun Park, Jae Woong Han, Myung Hoon Jung, Youn Joon Sung, Hwan Hee Jeong, June O. Song, Tae Yeon Seong

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

We demonstrated the growth of crack-free high-quality GaN-based UV vertical LEDs (VLEDs) (λ = 365 nm) on 6-inch sapphire substrates by using an ex-situ sputtered AlN nucleation layer (NL) and compared their performance with that of UV VLEDs with an in situ low temperature (LT) AlGaN NL. The X-ray diffraction (XRD) results showed that the ex-situ AlN sample contained lower densities of screw-type and edge-type threading dislocations than the in situ AlGaN NL sample. The micro-Raman results revealed that the ex-situ AlN sample was under more compressive stress than the in situ AlGaN sample. As the current was increased, the electroluminescence peaks of both of the samples blue-shifted, reached a minimum wavelength at 1000 mA, and then slightly red-shifted. Packaged VLEDs with the ex-situ AlN NL yielded 6.5% higher light output power at 500 mA than that with the in situ AlGaN NL. The maximum EQEs of the VLED with the in situ AlGaN and ex-situ AlN NLs were 43.7% and 48.2%, respectively. Based on the XRD and Raman results, the improved light output power of the ex-situ AlN sample is attributed to the lower density of TDs.

Original languageEnglish
Pages (from-to)5111-5117
Number of pages7
JournalOptics Express
Volume26
Issue number5
DOIs
Publication statusPublished - 2018 Mar 5

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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