Self-formation of GaN hollow nanocolumns by inductively coupled plasma etching

GaN hollow nanocolumns were formed by ICP etching. It was found that tops of these nanocolumns were hexagonal with the c-axis perpendicular to substrate surface. It was also found that the density of the GaN nanocolumns depends strongly on etching parameters which suggests that the formation of these GaN nanocolumns was not related to the dislocation density in the original GaN epitaxial layers. With an Ar concentration of 42.86%, it was found that the diameter of the whole nanocolumns was around 80 nm, the diameter of the nanocavities inside these nanocolumns was around 40 nm while the density of the nanocolumns was around 4.4×10⁹ cm^-2.