One embodiment of depositing a gallium nitride (GaN) film on a substrate comprises providing a source of indium (In) and gallium (Ga) and depositing a monolayer of indium (In) on the surface of the gallium nitride (GaN) film. The monolayer of indium (In) acts as a surfactant to modify the surface energy and facilitate the epitaxial growth of the film by suppressing three dimensional growth and enhancing or facilitating two dimensional growth. The deposition temperature is kept sufficiently high to enable the indium (In) to undergo absorption and desorption on the gallium nitride (GaN) film without being incorporated into the solid phase gallium nitride (GaN) film. The gallium (Ga) and indium (In) can be provided by a single source or separate sources.