Evolution of Bottomc-Plane on Wet-Etched Patterned Sapphire Substrate

Abstract

Wet-etched pattern sapphire substrate (PSS) has been employed to improve the epitaxy of GaN-based LEDs. It was found that the crystal quality and performance of LEDs improved with decrease in c-plane areas of PSS. However, further decrease in bottom c-plane areas makes epitaxy of GaN film very difficult. In this research, the evolution of bottom c-plane was investigated through a systematic study. It was found that epitaxy difficulty might be due to the appearance of 6C facets {41318} and the disappearance of bottom c-plane.

Study on the morphology and shape control of volcano-shaped patterned sapphire substrates fabricated by imprinting and wet etching

“…Many etching facets are reported on different crystallographic planes under different etching conditions, including the R-plane and R-like planes, 3,9,13 the N-plane and N-like planes 4,5,9 and some other planes. [14][15][16] The higher Miller-Bravais indices of the etching facets obtained in the above research indicate the complications of the wet etching and crystal plane calibration. These complications make it difficult to control the shape of the VPSS.…”

Crystal Quality and Light Output Power of GaN-Based LEDs Grown on Concave Patterned Sapphire Substrate

“…However, when the pattern space decreased to 0.41 μm, the crystallinity of S0.41-GaN dropped. We believe this drop is because further decrease in c-plane area makes epitaxy of GaN film on PSS very difficult [ 18 ].…”

Suppressing the Initial Growth of Sidewall GaN by Modifying Micron-Sized Patterned Sapphire Substrate with H3PO4-Based Etchant

“…Compared with RPSS, B3 fraction of PSSE reduced from 18% to 12%, while B2 fraction reduced from 3% to 0 %. This reduction of bottom c-plane made epitaxy of GaN film on PSSE very difficult [29]. Consequently, it appeared that the K BAlN of AlNE was much less than that of AlNR.…”