Development and characterization of Fe ultrathin films on the SrTiO3(100) surface

The adsorption of Fe on the SrTiO3(100) surface at room temperature has been studied in ultrahigh vacuum by means of Auger electron spectroscopy, low energy electron diffraction, electron energy loss spectroscopy, thermal desorption spectroscopy and work function measurements. The results show that iron probably grows in the mode of successive incomplete layers. For coverages >= 1.5 ML, a short range 1 x 1 order appears and the deposited Fe overlayer develops in body-centred cubic structure with Fe(100) parallel to SrTiO3(100) and crystallographic orientation Fe[110] parallel to SrTiO3[100]. The results of the electron spectroscopies do not indicate any iron oxidation at the metal-oxide interface. Instead, an interaction between the Fe adatoms gradually leads to the metallization of the Fe overlayer. Thus, the Fe/SrTiO3(100) interface seems to be a rather abrupt metal-oxide interface, which presents a good thermal stability for annealing up to similar to 800 K. In conclusion, this adsorption system looks ideal for free-standing ultrathin Fe films and low-dimensional structures, useful for technological applications.