Porous p-type GaN films were obtained after photo-electrochemical (PEC) etching in a mixed sulfuric acid and methanol solution under ultraviolet illumination for 90 min with the assistance of 50 Hz alternating current (AC) current (40, 60, 80, and 100 mA). Porous film obtained by etching at 60 mA has demonstrated the highest photoluminescence intensity and bandgap (3.42 eV) value, owing to the generation of the highest amount of point defects and the lowest total dislocation density, which have respectively served as the radiative and non-radiative defects. In addition, the highest root-mean-square surface roughness was obtained for this film, which could be corroborated through the detection of A(1)(TO) phonon mode that indicated an increased scattering effect off the sidewalls of the pores as well as the acquisition of a high in-plane biaxial stress relaxation. A simple mechanism on AC-assisted PEC etching of the films was also proposed and described. (C) 2016 The Electrochemical Society. All rights reserved.