Surface roughness and magnetic properties of in situ heated and postannealed thin films of perpendicular barium ferrite

Abstract

The surface roughness and magnetic properties of thin films of hexagonal barium ferrite (BaFe) deposited on SiO2/Si and Si substrates by facing target sputtering were studied using in situ heating during deposition and postannealing after deposition. The perpendicular coercivity of the BaFe films varied between 775 and 1430 Oe with substrate temperature for both in situ heated (560–620 °C) and postannealed (800–1200 °C) films. The effect of temperature on the surface roughness of BaFe/Si was greater than that of BaFe/SiO2/Si. The results of this study indicate that the mean surface roughness (Ra=11.4–27 nm) of BaFe films on Si substrates was greater than the roughness (Ra=3.9–17 nm) of BaFe films on amorphous SiO2/Si substrates. This increase of surface roughness with increasing substrate temperature is due to the evolution of grain boundaries and step formation during deposition and annealing.