Morphology control of gallium nitride grown on silicon nanoporous pillar array: From cone-strings to nanowires

Fascicle arrays of gallium nitride (GaN) nanostructures were grown on silicon nanoporous pillar array (Si-NPA) by a reactive chemical vapor deposition method. Through adjusting the distance between the gallium source and Si-NPA substrate, the morphology of GaN nanostructures was tuned from cone-strings, cone-strings plus nanowires to nanowires, accompanied with the average diameter changed from ∼800 nm to ∼13 nm. Both the cone-strings and the nanowires were found growing along [0001] direction. These results indicate that Ga concentration is a key factor in determining both the morphology and the average diameter of GaN nanostructures. The growing process of the GaN nanostructures was explained under the frame of vapor–liquid–solid deposition mechanism. Our method might be expanded to the growth of other compound semiconductor nanostructures on patterned silicon substrates for constructing functional nanodevices.

► GaN nanostructure fascicle arrays were grown on silicon nanoporous pillar array.
► Chemical vapor deposition method was employed.
► Only the distance between the gallium source and substrate was changed.
► The morphology changed from cone-strings, cone-strings plus nanowires to nanowires.