Straight and Smooth Etching of GaN (1100) Plane by Combination of Reactive Ion Etching and KOH Wet Etching Techniques

GaN striped structures along the and directions were fabricated by a combination etching technique, consisting of reactive ion etching followed by KOH wet etching. After wet etching, the sidewalls of the striped structures along the direction became very smooth and straight, compared with normal wet etching and dry etching. From the differences of the etching along the direction, it was found that etching mainly occurs in the (1 100) plane. This phenomenon can be explained by the action of OH - ions, which are repelled by N dangling bonds on the surface and which attack Ga back bonds as well as the mechanism of (000 1) polar GaN etching.