New optoelectronic materials: Effects of annealing upon the formation of epitaxial iron silicide nanostructures on Si(001)

Iron silicide nanostructures were grown on Si(001) by a strain-induced, self-assembly method. 1 nm iron was deposited by electron gun evaporation and subsequently annealed at 850 °C for different times, between 10 and 50 min. The formation of nanostructures was traced by reflection high energy electron diffraction, and the formed nanoobjects were characterized by scanning electron microscopy and atomic force microscopy. The electrical features were measured by I–V, C–V, deep level transient spectroscopy and conductive atomic force microscopy. As a function of the annealing time the size and the shape of the iron silicide nanoobjects varied, while they were orientated in normal directions. With the rising duration of annealing time the height of the nanostructures emerged, with moderate lateral size enhancement. The electrical characterization shows that the Fe-related defects dominated in all samples in a depth below the surface depending on the time of annealing. These defects are closer to the conduction band at the beginning of the annealing, and after 30 min their concentration is much reduced and they are closer to the valence band.