The effect of annealing on the behavior of GaN Schottky diodes was investigated. Rapid thermal annealing experiments were performed in N-2 ambients for 30 s at temperatures of 500-900 degrees C. After annealing, each sample was chemically treated using ozone/HCl to remove the thermally damaged layer prior to deposition of the metal. Samples were examined by current-voltage measurements and scanning electron microscopy or atomic force microscopy to monitor electrical and structural property changes. Only annealing at temperatures greater than or equal to 900 degrees C significantly degraded the Schottky diode characteristics. This degradation is believed to be due to the preferential loss of surface nitrogen. Ozone/HCl surface chemical treatments were only partially successful in repairing the thermal damage. (C) 1000 Elsevier Science Ltd, All rights reserved.