Effect of Annealing on the Optical Properties of GaN Films Grown by Pulsed Laser Deposition

In the present study, gallium nitride thin films were grown by using pulsed laser deposition. After the growth samples were annealed at 400 and 600 °C in the nitrogen atmosphere. Surface morphology of the as-grown and annealed samples was observed by atomic force microscopy. Post-growth annealing results in an improved surface roughness of the films. Chemical analysis of the samples was performed by X-ray photoelectron spectroscopy. Stoichiometric gallium nitride thin films were obtained for the samples annealed at 600 °C. Optical measurements of the samples were performed to measure the band gap and optical constants of the films. Effect of annealing on the band gap and optical constants of the films was studied.