Wet etching of semi-polar (11–22) GaN on m-sapphire by different methods

Abstract Wet etching methods with conventional alkali solution, molten alkali and photo-assisted alkali solution were performed on semi-polar (11–22) GaN separately to study the wet etching characteristics of it. Different corrosion morphologies were compared and the causes were analyzed. The results show that, contrary to the general view of chemical corrosion resistance of GaN, the semi-polar GaN is easy to be corroded even at room temperature. Prism structures with different sizes are formed after etching, and the size diversity increases with prolonging etching time, which could attribute to the extension of dislocations. Molten KOH corrosion could form a layer like structure and strip corrosion pits reflecting dislocations along c-direction. Moreover, a more uniform morphology could be obtained and the density of threading dislocations could be revealed by photo-assisted etching.