Impact of Growth Temperature During Pulsed Magnetron Sputtering on the Structure and Defects of Aluminum Nitride Films

Structural features of aluminum nitride thin films, which are important for applications as a piezoelectric material, are studied. The films are grown by pulsed magnetron sputtering at deposition temperatures from 60 °C to 300 °C and a magnetron power of 300 W. The powder XRD analysis indicates textured growth of films along the c axis and a microstrain decrease with increasing deposition temperatures. The growth rate also decreases and the refractive index increases with increasing deposition temperature. The obtained patterns are explained by the ordering of the microstructure of the films with increasing deposition temperature due to increased mobility of atoms adsorbed on the substrate. It is shown by transmission electron microscopy and electron diffraction that the sample prepared at 200 °C is characterized by a lower disorientation of crystallites relative to the c axis than the samples deposited at 100 °C and 300 °C. For the sample prepared at 200 °C, the highest piezoresponse is qualitatively detected by piezoresponse force microscopy. The films exhibit two photoluminescence bands, the position and intensity of which do not depend on the growth temperature. The nature of defects corresponding to these bands is discussed.