AlN thin films prepared by optical emission spectroscopy-controlled reactive sputtering

AlN films have been deposited by direct current reactive magnetron sputtering using optical emission spectroscopy to control reactive gas (nitrogen) flow. For nitrogen to argon flow ratio between 1:2.5 and 1:2, we have deposited transparent films of aluminium nitride with relatively high deposition rates in the range of 0.3-0.7 nm/s. At the highest deposition rate, we observed the influence of metallic aluminium admixture on the optical properties of films. Free aluminium fraction decreases with increasing substrate temperature during deposition.