1. N-face GaN substrate roughening for improved performance GaN-on-GaN LED.
- Author
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Alias, Ezzah Azimah, Samsudin, Muhammad Esmed Alif, DenBaars, Steven, Speck, James, Nakamura, Shuji, and Zainal, Norzaini
- Subjects
GALLIUM nitride ,QUANTUM efficiency ,POTASSIUM hydroxide ,LIGHT emitting diodes ,ETCHING reagents ,AMMONIUM hydroxide - 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 NH
4 OH and H2 O2 (NH4 OH: H2 O2 ) 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: H2 O2 etching, which was 5 × 109 cm–2 . The density by KOH and NH4 OH 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 NH4 OH: H2 O2 were 12.3 mW and 22%, respectively, which are higher than its counterparts. Originality/value: This study demonstrated NH4 OH: H2 O2 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 NH4 OH. [ABSTRACT FROM AUTHOR]- Published
- 2021
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