1 research outputs found
Role of Surface Polarity in Self-Catalyzed Nucleation and Evolution of GaN Nanostructures
Self-catalytic growth of GaN nanotips and nanoparticles,
grown
by chemical vapor deposition technique, are investigated. Three important
parameters, comprised of incubation time, anisotropy of diffusion,
and rate-limiting factors of Ga and N adatoms migration over polar
and nonpolar surfaces, are found to play significant roles in determining
the final morphology of these nanostructures. Nucleation of GaN nanotips
takes place under Ga-rich conditions. As the reaction proceeds, the
stochiometry changes occur as a result of a shift in Ga-rich to N-rich
conditions on the surface. In all of these cases, the growth continues
to be in vapor–solid mode. The conical shape of the nanotips
is explained in terms of differential growth in the reduced surface
diffusion of Ga under N-rich conditions on polar surfaces (0001) relative
to nonpolar surfaces (101̅0). Nanoparticles are grown initially
in N-rich conditions with significantly shorter incubation times.
A mechanistic approach that expounds evolution of nanotips and nanoparticles
is elucidated in details using crystallographic and electronic structural
studies