Improved ambient stability of thermally annealed zinc nitride thin films

Zinc nitride films are known to readily oxidize in an ambient atmosphere, forming a ZnO/Zn(OH)2 medium. We report that post-growth thermal annealing significantly improves the stability of zinc nitride with a three-order magnitude increase in degradation time from a few days in un-annealed films to several years after annealing. A degradation study was performed on samples annealed under a flow of nitrogen at 200–400 °C, which showed that the stability of the films depends strongly on the annealing temperature. We propose a mechanism for this improvement, which involves a stabilization of the native oxide layer that forms on the surface of zinc nitride films after exposure to ambient conditions. The result holds significant promise for the use of zinc nitride in devices where operational stability is a critical factor in applications.