Formation and transformation of embedded GaN nanocrystals

We have investigated the nucleation, growth and transformation of nitride nanostructures synthesized by nitrogen ion implantation into GaAs, followed by thermal annealing. High energy implantation into GaAs thin films results in the formation of a nitrogen-rich amorphous layer, with crystalline remnants. Subsequent annealing leads to the formation of polycrystalline zincblende and/or wurtzite GaN nanocrystals. We discuss the role of annealing time and temperature on nanocrystal nucleation and growth and present a time-temperature-transformation diagram that describes the nucleation of zincblende GaN and its subsequent transformation to wurtzite GaN.