Formation of nickel nanodats on GaN

We examine the annealing-induced formation of nickel nanodots on GaN substrates. The initial Ni layer thickness is 2 nm. Annealing temperatures range from 550 to 930 °C. The islands are well defined at the highest temperatures. Island formation kinetics provide an activation energy of 0.34±0.07 eV. Time dependence of the nanodot island areas, annealed at 750 °C, is consistent with a t2/3. These observations are indicative of diffusion-limited ripening as the primary formation mechanism. X-ray diffraction results show that nickel gallides form at anneal temperatures 750 °C and above.