Structural properties of films grown by magnetron sputtering of a BiFeO3 target

Thin films have been prepared on silicon substrates by pulsed DC magnetron sputtering of a BiFeO3 target under an Ar/O2 mixture with various oxygen flow (0–50 sccm) at room temperature. Due to the low deposition-temperature, the as-grown films are amorphous. As a consequence, we have investigated the effect of the annealing temperature (400–900 °C) and atmosphere (100% N2 or 90% N2/10% O2) on the crystallisation. Microstructural investigations (XRD, HREM, Raman and FTIR spectroscopy) have been performed in order to determine the structural properties of the films and to establish the experimental parameters leading to BiFeO3 films. A temperature-dependent Raman study points to a spin-phonon coupling around the Néel temperature.