A SCANNING-TUNNELING-MICROSCOPY STUDY OF THE (2X2) P4G NITROGEN-INDUCED SURFACE RECONSTRUCTION ON NI(100)

Scanning tunneling microscopy (STM) and low-energy-electron diffraction (LEED) were used to study N adsorbed via ion bombardment on the (100) face of Ni. LEED patterns indicate a (2 x 2) p4g structure formed on the surface. Bias dependent atomic resolution images enable the selective imaging of the N and Ni atoms. Images indicate that the N atoms sit in four-fold hollow sites with the positions of the Ni atoms in qualitative agreement with a model previously proposed on the basis of LEED. Large area images show a variety of defect structures. Out-of-phase domain boundaries occur along the [001] and [010] directions. One atomic layer deep depressions shaped like polygons and troughs occur on the surface. These depression structures are most likely artifacts of the method of nitrogen deposition.