This work attempted to improve roughening on backside (N-face) of GaN substrate by increasing the density of hexagonal pyramids for enhanced GaN-on-GaN LED performance. Prior to the roughening by ammonium hydroxide-based etching, the substrate was annealed in two different ambiences; air and oxygen. After the roughening, the hexagonal pyramids with a density of 4.3 × 10¹⁰ cm⁻² were formed on the substrate with oxygen pre-annealing. For the substrate with air pre-annealing, the hexagonal pyramids density was 2.0 × 10¹⁰ cm⁻². Meanwhile, the pyramids density for the roughened GaN substrate without pre-annealing was 0.5 × 10¹⁰ cm⁻². The oxygen pre-annealing introduced more Ga–O compound on the surface. This increased the density of hexagonal pyramids, which resulted after the etching. The GaN-on-GaN LEDs grown on the roughened GaN substrates with pre-annealing (air and oxygen) emitted at 488 nm, while the LED on the roughened GaN substrate without pre-annealing at 510 nm. The optical power increased significantly when the LED grown on the roughened GaN substrate with the oxygen pre-annealing. Overall, this work revealed that the backside GaN roughening can be improved by oxygen pre-annealing, leading to enhance the GaN-on-GaN LED performance.

这项工作试图通过增加六棱锥的密度来改善 GaN 衬底背面（N 面）的粗糙化，以增强 GaN-on-GaN LED 的性能。在通过基于氢氧化铵的蚀刻粗化之前，基板在两种不同的环境中退火；空气和氧气。粗化后，通过氧预退火在基板上形成密度为4.3×10 ¹⁰  cm ^-2的六棱锥。对于空气预退火的基板，六棱锥密度为2.0×10 ¹⁰  cm ^-2。同时，未经预退火的粗糙化 GaN 衬底的金字塔密度为 0.5 × 10 ¹⁰  cm ^-2. 氧预退火在表面引入了更多的 Ga-O 化合物。这增加了蚀刻后产生的六棱锥的密度。GaN-on-GaN LED 生长在经过预退火（空气和氧气）的粗糙化 GaN 衬底上，发射波长为 488 nm，而粗糙化 GaN 衬底上的 LED 未经过 510 nm 预退火。当 LED 在经过氧预退火的粗糙 GaN 衬底上生长时，光功率显着增加。总的来说，这项工作表明，通过氧预退火可以改善背面 GaN 粗糙化，从而提高 GaN-on-GaN LED 的性能。