Post-Growth Enhancement of Hexagonal Boron Nitride Films Grown on C-Sapphire Substrates by Chemical Vapor Deposition

This study shows the effect of post-growth annealing on hexagonal boron nitride (hBN) films grown on c-sapphire substrates by chemical vapor deposition. hBN films are grown at 1100 and are annealed at 1300 under a nitrogen atmosphere. The annealed hBN films are more continuous and have a pronounced granular structure as compared to the as-grown hBN films. The annealed BN films retain the 1:1 B:N stoichiometry and the hexagonal phase as observed in the as-grown hBN films. The optical bandgap of the hBN films is augmented from 5.70 eV to 5.82 eV after annealing.