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.

中文翻译：

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N 面 GaN 衬底粗糙化以提高性能 GaN-on-GaN LED

目的

本研究的重点是在 GaN-on-GaN 发光二极管 (LED) 生长之前粗糙化 N 面（背面）GaN 衬底，以尝试提高 LED 性能。

设计/方法/方法

GaN 衬底的 N 面被三种不同的蚀刻剂粗糙化；氢氧化铵 (NH4OH)、NH ₄ OH 和 H ₂ O ₂ (NH ₄ OH: H ₂ O ₂ ) 和氢氧化钾 (KOH)的混合物。在所有情况下，当基板经受蚀刻时，在表面上成功地形成六棱锥。

发现

在蚀刻 30 分钟后，通过 NH4OH:H ₂ O ₂蚀刻获得最高密度的金字塔，为 5 × 10 ⁹  cm ^–2。KOH 和 NH ₄ OH 蚀刻的密度分别为 3.6 × 10 ⁹和 5 × 10 ⁸  cm ^–2。在电流密度为 20 A/cm ^{2 的}标准操作下，NH ₄ OH: H ₂ O ₂粗糙化 GaN 衬底上的 LED 的光功率和外量子效率分别为 12.3 mW 和 22%，高于它的同行。

原创性/价值

该研究表明，NH ₄ OH: H ₂ O ₂是一种用于粗糙化 N 面 GaN 衬底的新型蚀刻剂。结果表明，与 KOH 和 NH ₄ OH相比，这种蚀刻剂增加了 N 面 GaN 衬底上金字塔的密度，随后导致 LED 的光功率和外部量子效率更高。