Magnetic and structural properties of AlN-Co-Fe thin films prepared by two-facing-target type DC sputtering (TFTS) system

AlN is a wide band gap promising material for applications due to its large thermal conductivity, negative electron affinity, and for its insulating and passivating behavior. Nanocrystalline Co and Fe particles in the AlN matrix could lead to the development of a material for the above applications. In this study, we investigated anneal-induced magnetic and electric properties with respect to changes in microstructure as well as Fe content in the AlN-Co and AlN-Fe thin films. AlN-Co and AlN-Fe thin films were reactively deposited with two different combinations of targets, such as Al-Co50Fe50 (Case-I) and Al-Co20Fe80 (Case-II) targets, in a two-facing-target type dc sputtering (TFTS) system and their structural changes were investigated together with magnetic and electrical property changes. The saturation magnetization increases with increasing annealing temperature on account of the formation of magnetic phases after annealing. The films prepared with Al-Co50Fe50 target combination show a higher magnetization and a smaller coercivity than the films prepared with Al-Co20Fe80 target combination. The resistivity decreases with increasing annealing time and temperature for Case-I film but increases with annealing time and temperature for Case-II film attributed to the difference of the conducting component in the respective films. All the films show a semiconducting conduction mechanism except the annealed films prepared with Al-Co50Fe50 target combination, which shows an ohmic conduction mechanism.