Growth dynamics of pulsed-laser-deposited AlN films

Films of AlN with different thicknesses are synthesized by pulsed laser deposition in a nitrogen gas ambient. The study of the structure and surface morphology is focused on the different mechanisms governing the film growth. Film crystalline properties, growth rate, lattice mismatch induces strain and strain relaxation process is considered. The films start growing in a 2D mode, resulting in a smooth surface and a predominantly amorphous structure with a small amount of crystalline AlN. The change in the surface energy with the number of laser pulses applied is the reason for the formation of a 3D structure and 3D island growth at the later stages, resulting in a rough surface and a dense polycrystalline film structure with a cubic phase. These conclusions conform to results from structural and optical analyses.