Characteristics of porous GaN prepared by KOH photoelectrochemical etching

This paper presents the structural and optical studies of porous GaN prepared by photoelectrochemical etching in diluted KOH under different etching durations. Such etching technique is a cheaper and simpler way of fabricating porous structure. The as-grown and porous GaN samples were investigated by field emission scanning electron microscopy, high resolution X-ray diffraction and Raman spectroscopy. Field emission scanning electron microscopy measurement allowed us to observe the morphology of the porous samples, and we found that the pore density increased with etching duration. From high resolution X-ray diffraction characterisation, the width at half maximum value of the rocking curve at (0002) and (10 (1) over bar 12) plane decrease for all porous samples because of the reduction in dislocation density. Furthermore, as compared to the as-grown sample, the porous samples exhibit a significant enhancement of Raman peak intensity because of multiple scattering of light from the GaN crystallite sidewalls. Overall, this study shows that the surface nanostructure could improve the structural and optical properties of GaN. This is an initial demonstration to show the prospect of the porous GaN structure in optical and sensor applications.