Microstructure and interdiffusion behaviour of β-FeSi2 flat islands grown on Si(111) surfaces

beta-FeSi2 flat islands have been fabricated on ultra- thin oxidized Si(111) surfaces by Fe deposition on Si nanodots. The microstructure and interdiffusion behaviour of the beta-FeSi2/Si(111) system at the atomic level were studied by using spherical aberration- corrected high- angle annular dark- field scanning transmission electron microscopy and energy dispersive X- ray spectroscopy. The formed beta-FeSi2 flat islands had a disc shape with an average size of 30- 150 nm width and 10- 20 nm height, and were epitaxically grown on high- quality singlephase Si with a crystallographic relationship (110) beta-FeSi2/(111) Si and [ 001] beta-FeSi2/[1 (1) over bar0] Si. Moreover, the heterojunction between the beta-FeSi2(110) flat islands and the Si(111) substrate was an atomically and chemically abrupt interface without any irregularities. It is believed that these results are caused by the use of ultra- thin SiO2 films in our fabrication method, which is likely to be beneficial particularly for fabricating practical nanoscaled devices.