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) over bar 0 3} and {4 (3) over bar (1) over bar 27}, which were different from the previous reports. (C) 2014 Elsevier B. V. All rights reserved.