Gallium droplet formation during MOVPE and thermal annealing of GaN

Conditions favorable for liquid droplet appearance on the surface of GaN can be predicted for metal–organic vapor phase epitaxy and for thermal annealing of the crystal in a nitrogen or hydrogen atmosphere. A critical issue of the model is accounting for the specific kinetics of N2 and NH3 adsorption/desorption on a nitride surface. H2 is found to lower considerably GaN thermal stability, in good agreement with experimental observations. The theoretical results are compared with available experimental data.