Photoelectrochemical response of GaN, InGaN, and GaNP nanowire ensembles

Abstract

The photoelectrochemical responses of GaN, GaNP, and InGaN nanowire ensembles are investigated by the electrical bias dependent photoluminescence, photocurrent, and spin trapping experiments. The results are explained in the frame of the surface band bending model. The model is sufficient for InGaN nanowires, but for GaN nanowires the electrochemical etching processes in the anodic regime have to be considered additionally. These processes lead to oxygen rich surface (GaxOy) conditions as evident from energy dispersive X-ray fluorescence. For the GaNP nanowires, a bias dependence of the carrier transfer to the electrolyte is not reflected in the photoluminescence response, which is tentatively ascribed to a different origin of radiative recombination in this material as compared to (In)GaN. The corresponding consequences for the applications of the materials for water splitting or pH-sensing will be discussed.