The effects of H-2 or N-2 plasma exposure on the current-voltage characteristics of GaN Schottky diodes were examined as a function of source power and rf chuck power. Under all conditions there was a strong reduction in diode reverse breakdown voltage and an increase in forward and reverse currents, The results are consistent with creation of a thin (less than or equal to 600 Angstrom) n-type conducting surface region after ion bombardment of the GaN surface. Much of the degradation in diode quality can be recovered by annealing in N-2 at 750 degrees C.