Photoassisted anodic etching of gallium nitride

The first study of photo-assisted anodic etching of unintentionally doped n-GaN at room temperature is reported here. The electrolyte used is a mixture of buffered aqueous solution of tartaric acid and ethylene glycol. The etching rate varies from similar to 20 Angstrom/min to as high as 1600 Angstrom/min. A systematic study shows that (i) the etch rate, as well as the surface roughness, increases with the current density, (ii) the etching rate is the highest when the pH of the electrolyte is similar to 7; and (iii) the etching is faster when there is more ethylene glycol in the electrolyte solution.