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N-face GaN substrate roughening for improved performance GaN-on-GaN LED

Ezzah Azimah Alias (Institute of Nano Optoelectronics Research and Technology (INOR), Universiti Sains Malaysia, Penang, Malaysia)
Muhammad Esmed Alif Samsudin (Institute of Nano Optoelectronics Research and Technology (INOR), Universiti Sains Malaysia, Penang, Malaysia)
Steven DenBaars (Materials Department, University of California, Santa Barbara, California, USA and Department of Electrical and Computer Engineering, University of California, Santa Barbara, California, USA)
James Speck (Materials Department, University of California, Santa Barbara, California, USA)
Shuji Nakamura (Materials Department, University of California, Santa Barbara, California, USA and Department of Electrical and Computer Engineering, University of California, Santa Barbara, California, USA)
Norzaini Zainal (Institute of Nano Optoelectronics Research and Technology (INOR), Universiti Sains Malaysia, Penang, Malaysia)

Microelectronics International

ISSN: 1356-5362

Article publication date: 23 August 2021

Issue publication date: 2 September 2021

238

Abstract

Purpose

This study aims to focus on roughening N-face (backside) GaN substrate prior to GaN-on-GaN light-emitting diode (LED) growth as an attempt to improve the LED performance.

Design/methodology/approach

The N-face of GaN substrate was roughened by three different etchants; ammonium hydroxide (NH4OH), a mixture of NH4OH and H2O2 (NH4OH: H2O2) and potassium hydroxide (KOH). Hexagonal pyramids were successfully formed on the surface when the substrate was subjected to the etching in all cases.

Findings

Under 30 min of etching, the highest density of pyramids was obtained by NH4OH: H2O2 etching, which was 5 × 109 cm–2. The density by KOH and NH4OH etchings was 3.6 × 109 and 5 × 108 cm–2, respectively. At standard operation of current density at 20 A/cm2, the optical power and external quantum efficiency of the LED on the roughened GaN substrate by NH4OH: H2O2 were 12.3 mW and 22%, respectively, which are higher than its counterparts.

Originality/value

This study demonstrated NH4OH: H2O2 is a new etchant for roughening the N-face GaN substrate. The results showed that such etchant increased the density of the pyramids on the N-face GaN substrate, which subsequently resulted in higher optical power and external quantum efficiency to the LED as compared to KOH and NH4OH.

Keywords

Acknowledgements

This work was funded by Research University-Individual (RUI) under account number 1001/CINOR/8014033 and Fundamental Research Grant Scheme (FRGS) under account number 203/CINOR/6711718. The authors would like to thank the Collaborative Research in Engineering, Science and Technology Center (CREST) for their continuous support in this research and the NOR Lab School of Physics staff for technical supports.

Citation

Alias, E.A., Samsudin, M.E.A., DenBaars, S., Speck, J., Nakamura, S. and Zainal, N. (2021), "N-face GaN substrate roughening for improved performance GaN-on-GaN LED", Microelectronics International, Vol. 38 No. 3, pp. 93-98. https://doi.org/10.1108/MI-02-2021-0011

Publisher

:

Emerald Publishing Limited

Copyright © 2021, Emerald Publishing Limited

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