AlGaN-Based Deep Ultraviolet Light-Emitting Diodes with Thermally Oxidized AlxGa2- xO3Sidewalls

Tien Yu Wang, Wei Chih Lai*, Syuan Yu Sie, Sheng Po Chang, Cheng Huang Kuo, Jinn Kong Sheu, Jong Shing Bow

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

AlGaN and GaN sidewalls were turned into AlxGa2-xO3and Ga2O3, respectively, by thermal oxidation to improve the optoelectrical characteristics of deep ultraviolet (DUV) light-emitting diodes (LEDs). The thermally oxidized Ga2O3is a single crystal with nanosized voids homogenously distributed inside the layer. Two oxidized AlxGa2-xO3layers were observed on the sidewall of the AlGaN layer in transmission electron microscopy images. The first oxidized AlxGa2-xO3layer is a single crystal, while the second oxidized AlxGa2-xO3layer is a single crystal with numerous nanosized voids inside. The composition of Al in the first oxidized AlxGa2-xO3layer is higher than that in the second one. The thermal oxidation at high temperature degrades the quality of the p-GaN layer and increases the forward voltage from 8.18 to 11.36 V. The thermally oxidized AlxGa2-xO3sidewall greatly enhances the light extraction efficiency of the lateral light of the DUV LEDs by combined mechanisms of holey structure, graded refractive index, high transparency, and tensile stress. Consequently, the light output power of the DUV LEDs increases from 0.69 to 0.88 mW by introducing a 420 nm thick AlxGa2-xO3sidewall oxidized at 900 °C, in which the enhancement of light output power can reach 27.5%.

Original languageEnglish
Pages (from-to)15027-15036
Number of pages10
JournalACS Omega
Volume7
Issue number17
DOIs
StatePublished - 3 May 2022

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