Inductively coupled plasma etching of metallized GaN Schottky diodes in Cl-2/Ar discharges produces reductions in both reverse breakdown voltage and Schottky barrier height. The extent of these reductions is a function of both ion energy and ion flux. Two different postetch treatments were performed in an attempt to remove the ion-damaged GaN surface layer, namely, annealing in N-2 or W-ozone oxidation followed by dissolution of the oxide. Both treatments provide only partial restoration of the diode properties.