Wet etching of GaN damaged by heavy ion irradiation

Defects in GaN films can be revealed by wet etching in hot H3PO4 and molten potassium hydroxide or by photoelectrochemical (PEC) etching. GaN film was irradiated by 500 keV Au ions with ion fluences in the range from 1 × 109/cm2 to 5 × 1015/cm2. Afterwards, AZ-400 K photoresist developer and aqueous KOH were used for wet etching of GaN at a relatively low temperature of 80 °C. With this method, defects in GaN films, after being irradiated by heavy ions, can be revealed with an etch pit density of 106–108/cm2, the same magnitude with that in as-grown GaN films. Additionally, the etched pits present different features at different ion fluences. Our experimental results indicate that heavy ion irradiation can enhance the wet etching of GaN films at the sites having original defects. The related mechanism was also discussed in this paper.