Axial p-n Junctions in GaN Microrods

GaN microrods with an axial p-n junction are grown by metal-organic vapor phase epitaxy (MOVPE). Scanning electron microscopy in combination with cathodoluminescence measurements have been performed to visualize the microrod sections consisting of n- and p-type GaN and the p-n junction. Current-voltage measurements are carried out between different microrod sections to prove the successful formation of a p-n junction. Photovoltaic and photodetecting properties have been determined by illumination of the p-n junction with a UV laser. The shorter p-type sections in axial microrods and the presence of large diameter rods suggest a growth mode change from vertical to lateral growth during p-type deposition.