Titanium-induced charge of Si(0Â 0Â 1) surface dependent on local configuration

High-resolution X-ray photoemission spectroscopy (XPS) was applied to Ti-deposited Si(0 0 1) surfaces, which were structurally characterized by means of scanning tunneling microscopy (STM). Negative chemical shift of Si due to Ti deposition was assigned to the distorted TiSi bonds formed on the surface. The shift was reduced when a Ti sank beneath a Si dimer. Silicidation resulted in a positive shift to the TiSi bonding. The charge on the Si atoms near Ti was estimated through preliminary natural bonding orbital (NBO) calculation. We show that the shifts can be explained in terms of the sensitivity of charges of Si near Ti to the local structure near the dimer.