Investigation of the properties of BiFeO$_3$/intermediate-layer structures fabricated by magnetron sputtering

The properties of BiFeO$_3$/intermediate layer/substrate structures fabricated by radio-frequency magnetron sputtering at low temperatures (450$^\circ$C) and by deposition on substrates and intermediate layers between the substrate and the BiFeO$_3$ film have been investigated. In the structures, glass substrates or commercial Pt/Ti/SiO$_2$/Si(001) substrates have been used, and intermediate layers have been prepared from $L1_0$ FePt or Pt films. Intermediate layers of Pt and $L1_0$ FePt have the (111) and (001) textures, respectively, induced by rapid thermal annealing. It has been revealed that the deposition on the commercial substrates leads to the formation of BiFeO$_3$ isotropic films that have a large surface roughness and consist of grains $\sim$ 200 nm in size with the BiFeO$_3$ perovskite structure. In the case of the deposition of a BiFeO$_3$ film on a Pt(111) intermediate layer, the BiFeO$_3$ phase is suppressed. The deposition on an intermediate layer of the $L1_0$ FePt film with the (001) texture results in the formation of a single-phase BiFeO$_3$ film with the (001) texture and the perovskite structure, which (as compared to the BiFeO$_3$ films grown on the commercial substrate) has a less pronounced roughness, smaller grain sizes, and significantly better ferroelectric properties.