Tóm tắt:

We present features in the incorporation of Nitrogen-related species on the Ga-rich GaN (0001) surface based on firstprinciples total energy calculations. We find that the N adatom spontaneously substitutes for the Ga adatom upon adsorption and forms 4-fold N structure. Surprisingly, this substitutional adsorption does not have any activation energy. Also, we find that NH2 and NH units intervene in the Ga-Ga weak bonds and form - Ga - (NHx) - Ga - structure during the adsorption. This finding gives an insight into the fate of ammonia species during adsorption on the Ga-rich GaN (0001) surface.