Optical and dielectric properties of dc magnetron sputtered AlN thin films correlated with deposition conditions

Thin films of AlN were grown on glass and aluminium foil substrates by reactive dc magnetron sputtering. The films exhibit a columnar growth with surface roughness in the order of 8.8–5.2 nm. The optical and dielectric properties of the films were studied as a function of the nitrogen concentration in the reactive gas mixture. The refractive index and extinction coefficient were found to be in the range of 1.93 to 2.3 and 10−4–10−3 at λ=520 nm. The real part of dielectric constant and dielectric losses were measured to be about 7.0 and 0.006–0.085, respectively, using metal–insulator–metal (MIM) structures.