Abstract
We developed a technique for fabricating photonic crystal (PhC) voids embedded in GaN by dry etching, mass transport, and annealing. We report the annealing conditions and shape of the embedded PhC voids. After dry etching to pattern PhC air holes, they are fully capped with a flat GaN layer (34 nm thick) by annealing at 1025 °C. Inner void walls exhibit GaN crystallographic facets. Upon annealing at 900 °C, the air holes are not capped and instead become narrower with increasing annealing duration. Hence, both the shape and diameter can be controlled in the fabrication of PhC structures in GaN.