A surface exafs study of the Vanadium/Si(111) interface

Surface EXAFS spectra recorded above the K-absorption edge of the refractory metal vanadium for submonolayer coverages on the Si(111)7 × 7 surface are presented. Analysis of spectra recorded after depositions at 300 K. gives a VSi bond length of 2.57 ± 0.03 Å. By comparison with possible sites on an unreconstructed Si(111) surface the data most favour the six-fold interstitial site between the first and second Si layers. No evidence was found for V cluster formation at submonolayer coverages. The results therefore indicate some degree of reactivity/ intermixing at the room temperature V Si interface, unlike previous reports. SEXAFS spectra recorded for a ∼ 2 monolayer V overlayer following annealing at 825 K for 5 min indicated the formation of the disilicide, VSi 2, as previously reported.