Preparation of c-axis-oriented barium ferrite thin films with small crystallite size

BaM thin films were deposited on thermally oxidized silicon wafer substrates at temperatures near 580 degrees C by using a dc facing-target sputtering system. The crystallite size of films 200 nm thick was greater than 200 nm, and it decreased monotonically with decreasing film thickness, reaching a value below 30 nm in films 30 nm thick. Further decreases in film thickness led to a degradation of the crystallinity of the film, causing the saturation magnetization and coercive force of the film to decrease significantly. Growth of BaM crystallites in films deposited on a SiO2/Si substrate was significantly suppressed when the films were deposited on a thin initial layer deposited beforehand under a substrate bias of -50 V. (C) 1997 American Institute of Physics.