PREFERRED CRYSTAL ORIENTATION OF COBALT FERRITE THIN-FILMS INDUCED BY ION-BOMBARDMENT DURING DEPOSITION

Thin films of CoxFe3-xO4-y (x=0.8, 1.0, 1.15, 1.25, 1.5, 1.8) were prepared under 100-500 eV Ar+ -ion bombardment during film deposition. Strong crystallization enhancement and preferred crystallographic orientation were observed as the effects of ion bombardment. Crystal orientation normal to the substrate depended on the composition x; [110]-axis orientation was obtained for x=0.8 and 1.0 and [111] orientation for x=1.15, 1.25, 1.5, and 1.8. The orientation was not affected significantly by the incident angle of the ions and did not vary with ion energy in the range 100-500 eV. The mechanism of crystal orientation is thought to have a close relationship with the preferential sputtering of oxygen by Ar+-ion impact.