GaN nanowire fabricated by selective wet-etching of GaN micro truncated-pyramid

•Well-controlled GaN nanowires were fabricated by selective etching of GaN micro truncated-pyramids in KOH solution.•GaN nanowire is hexagonal prism structure, which consists of a (0 0 0 1) top surface and six {1 -1 0 0} sidewalls.•Geometry of GaN nanowire is determined by the diameter of (0 0 0 1) facet and the height of GaN micro truncated-pyramid.•Wet-etching of GaN micro truncated-pyramid is influenced by the surface polarity and surface energy of its crystal planes.

We demonstrated the fabrication of GaN nanowire (NW) by selective etching of the GaN micro truncated-pyramid (μ-TP) in KOH solution. The GaN μ-TP, which consists of a (0 0 0 1) Ga-polar top surface and six {1 1¯ 0 1} N-polar sidewalls, were grown on the patterned AlN/Si template in metal organic chemical vapor deposition (MOCVD) system. KOH solution can selectively etch the N-polar sidewalls while leave the Ga-polar top surface intact. Hexagonal-prism-structured GaN NW with (0 0 0 1) top surface and {1 1¯ 0 0} sidewalls was obtained after adequate chemical etching. It was found that the three-dimensional geometry of the GaN NW is determined by the diameter of the (0 0 0 1) top surface and the height of the GaN μ-TP. And the chemical etching mechanism of GaN μ-TP towards GaN NW in hydroxide solution was explained.