Abstract Nitrogen-ion-implantation damage on GaN has been clearly visualized using scanning internal photoemission microscopy. Ni Schottky contacts were formed on selectively N-ion-implanted n-GaN surfaces at 80 keV with an ion dose of 1 × 10¹⁴ or 1 × 10¹⁵ cm⁻², and a photocurrent was detected by focusing and scanning a laser beam over the contacts. We found that the photocurrent decreased in the implanted regions due to an increase in the Schottky barrier and carrier depletion. Photocurrent maps showed that the induced damage did not spread from the implanted regions within the spatial resolution of the equipment. We confirmed that this method is a powerful tool for mapping implanted highly resistive regions.