Analytical UHV transmission electron microscopy studies of electronic structure changes between as-deposited Mn and Mn silicide on Si(1 1 1) surface

Mn was deposited on Si(1 1 1) 7×7 surface at room temperature in an ultrahigh vacuum (UHV) chamber and then transferred to a UHV transmission electron microscope through a UHV transportation system, followed by investigation of changes in crystallographic structure and electronic structure of the deposited Mn layer before and after annealing at about 400 °C. Transmission electron microscopy observation showed that the as-deposited Mn layer had microcrystalline particles composed of pure Mn but the annealed one exhibited the round shaped MnSi islands with the size of several tens nanometers growing epitaxially on the Si(1 1 1) surface. In situ electron energy loss spectroscopy indicated the change of white lines Mn L2,3 edges between the as-deposited Mn and MnSi. From intensity calculation of the white lines, it was estimated that 3d occupancies of Mn increased by 2.5±0.06 electron/atom for MnSi formation.