Electrochemical etching of highly conductive GaN single crystals

It is shown that the (0 0 0 1) Ga-polar surface of highly doped GaN single crystals can be etched anodically in the dark in dilute aqueous KOH solution. Two etching regimes involving electron tunneling and avalanche breakdown are defined. The electrochemistry and surface morphology encountered in each regime are described. Possible applications of anodic etching are considered. (C) 2001 Elsevier Science B.V. All rights reserved.