Synthesis and optical properties of GaN micro/nanocone bundles on copper wafers

GaN micro/nanocone bundles with controllable size and density have been synthesized on Cu or Cu95In5 alloy wafers using a modified thermal-evaporation process. The size and density of GaN cone bundles could be efficiently controlled by adjusting growth temperatures and the components of metal substrates. The structure and morphology of the as-synthesized GaN cones were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The as-synthesized micro/nanocones are single crystals with a hexagonal wurtzite structure, growing along the [ 1   0   1 ¯   1 ] direction. The growth process follows a vapor–liquid–solid mechanism. The dependence of photoluminescence property on the size and density of GaN cone bundles at room temperature was also investigated.