Evolution of the crystallographic planes of cone-shaped patterned sapphire substrate treated by wet etching

Abstract

A series of wet etching experiments were performed to investigate the evolution of crystallographic planes of cone-shaped patterned sapphire substrate. During the etching process, three kinds of etching zones were found. Two etching zones appeared first and vanished with increasing etching time. The other one exposed later and expanded gradually. Finally, the cone-shaped pattern with an arcuate slope transformed to a hexagonal pyramid. The calculated orientation of the crystallographic planes in the two etching zones was {1 1¯ 0 3} and {4 3¯1¯ 27}, which were different from the previous reports.