Previously different morphologies of GaN have been studied such
as nanowires, prismatic rods and cone nanowires, patterned nanowires,
needle-like bicrystalline nanowires and well aligned nanocolumns
etc. [4–8] which are very supportive to FE due to high aspect
ratio. For synthesizing such different morphologies of GaN, numerous
methods such as sol–gel method, simple thermal evaporation method,
templates method and Chemical vapor deposition (CVD) method
have been used.