Formation of GaN quantum dots by molecular beam epitaxy using NH3 as nitrogen source

Self-assembled GaN quantum dots (QDs) in AlxGa1-xN (0.3 <= x <= 1) were grown on c-plane sapphire and Si (111) substrates by molecular beam epitaxy using ammonia as nitrogen source. The QD formation temperature was varied from 650 degrees C to 800 degrees C. Surprisingly, the density and size of QDs formed in this temperature range are very similar. This has been explained by considering together experimental results obtained from reflection high-energy electron diffraction, atomic force microscopy, and photoluminescence to discuss the interplay between thermodynamics and kinetics in the QD formation mechanisms. Finally, possible ways to better control the QD optical properties are proposed. (c) 2015 AIP Publishing LLC.