Characterization of aluminium nitride thin film structure using second-harmonic generation

Second-harmonic generation measurements are carried out on aluminium nitride thin films deposited by dc magnetron sputtering. Second-order nonlinear susceptibility components are found to be around 6 pmV-1 for d33 and 0.15 pmV-1 for d31. The crystallographic structure of the films is related to the variations of the second-harmonic power as a function of the optical axis orientation. Theoretical calculations are confirmed by experimental results obtained on several samples grown under various deposition conditions.