Fabrication of layer-ordered porous GaN for photocatalytic water splitting

Ordered nanoporous structures are promising for multifunctional devices and systems. Here, we demonstrate the controllable layer-ordered porous GaN structures using selective electrochemical etching of the n-GaN layers from n-GaN/u-GaN multilayers. The shape of layer-ordered porous structures can be modulated to dome-shaped or triangular by changing the electrochemical etching solution. Compared with the corresponding planar GaN, the photocurrent of the porous GaN increases by ~2.7 times in photocatalytic water splitting process. The enhanced photocatalytic performance is mainly attributed to the increased specific surface area and the modulation of the electric fields of incident light in the porous structures as simulated using finite-difference time-domain method. This approach can help to design and diversify highly ordered nanostructures for the III-nitride semiconductor, which lays a foundation for photocatalytic or other optoelectronic applications.