Thermal stability of GaN thin films grown on (0001) Al2O3, (011̄2) Al2O3 and (0001)Si 6H-SiC substrates

Abstract

Single crystals of GaN were grown on (0001), (011̄2) Al₂O₃ and (0001)_Si 6H‐SiC substrates using an atmospheric pressure metalorganic chemical‐vapor‐deposition reactor. The relationship has been studied between the thermal stability of the GaN films and the substrate’s surface polarity. It appeared that the N‐terminated (0001) GaN surface grown on (0001)_Si 6H‐SiC has the most stable surface, followed by the nonpolar (112̄0) GaN surface grown on (011̄2) Al₂O₃, while the Ga‐terminated (0001) GaN surface grown on (0001) Al₂O₃ has the least stable surface. This is explained with the difference in the atomic configuration of each of these surfaces which induces a difference in their thermal decomposition.