Imaging defect formation in the template growth of NiSi2/Si(111): An application of quantum size microscopy.

The tunneling microscope is used to study the solid phase reaction of thin nickel films on silicon substrates to form epitaxial nickel disilicide. The initially flat Si(111)-7×7substrate develops defects in the form of surface and interface steps as the silicide reaction proceeds, with the steps corresponding to domains of NiSi 2 (111) of varying thicknesses. For low-temperature growth, the nickel disilicide terraces are atomically flat, whereas below the surface there is substantial inhomogeneity. Annealing this surface to higher temperature reduces the subsurface inhomogeneity by diffusing residual silicon to the surface to form adatom islands, trading of volume defects for surface defects