Properties of iron boride films prepared by magnetron sputtering

Iron boride coatings have been deposited on glass and steel substrates by sputtering of a FeB target. Whatever the deposition conditions are, no crystallised compound is detected by X-ray diffraction. In order to obtain further information on the chemical environment of sputtered atoms, X-ray photoemission spectroscopy and conversion electron Mössbauer spectrometry have been performed. The atomic ratio Fe/B in the films has been estimated from XPS results. It is ranging between 1.3 and 1.4, explaining the amorphous structure of the deposited films. The Mössbauer analyses show that the sputtered atoms are homogeneously distributed in the films. The crystallisation of the deposited films has been realised by vacuum annealing at 600 °C. Then, FeB and Fe2B diffraction peaks are detected after this thermal treatment. Mechanical properties and electrical resistivity of sputtered iron boride films have been investigated in connection with the argon flow rate injected in the deposition reactor. The films are hard (approx. 20 GPa) and their electrical resistivity is low (approx. 200 μΩ cm). Moreover, their deposition rate is higher than that of others borides synthesised in the same reactor with similar deposition conditions.