Microscopic investigations of aluminum nitride thin films grown by low-temperature reactive sputtering

Aluminum nitride (AlN) films were grown on sapphire substrates by radio frequency magnetron sputtering in plasma containing a mixture of argon and nitrogen, using a pure aluminum target. Surface morphology dependence of the AlN films on growth conditions such as substrate temperature and nitrogen concentration was investigated. c-axis preferred wurtzite AlN film with surface roughness as small as 2.9 nm was obtained at substrate temperature of 100 °C and nitrogen concentration of 20%. The surface roughness of the AlN films increased with increasing substrate temperature and nitrogen concentration. The correlation between the growth conditions and the film morphology was discussed.