Fabrication and in situ X-ray photoelectron spectroscopy of granular metal thin films

A series of Fex(SiO2)1−x, Co0.5(SiO2)0.5, and Ni0.5(SiO2)0.5 transition metal based granular films were prepared by r.f. sputter deposition. Owing to their novel magnetic properties, and possible application as magnetic storage media, the iron based granular films were studied over a range of compositions from x = 0.3 to x = 0.9 atomic fraction. X-ray diffraction and transmission electron microscopy measurements indicated that these films consist of small metal particles embedded in an amorphous SiO2 matrix. In the case of the Fex(SiO2)1−x films, mean particle sizes from several nanometers to about 10 nm could be obtained by varying the relative metal composition. The mean particle size was also observed to decrease, and the particle size distribution to become more uniform, with decreasing metal composition. In situ X-ray photoelectron spectroscopy measurements were carried out to determine the kind and relative composition of metal oxides associated with the metal particles. The metal oxides FeO, Fe2O3, Fe3O4, CoO, NiO, and Ni2O3 were identified in the case of the iron, cobalt and nickel particles respectively.