Journal of Vacuum Science & Technology A
Several recent structural studies of the Si(111)–B ((3)1/2×(3)1/2) surface have established that the boron atoms occupy substitutional sites in the second full Si layer and have Si adatoms directly above them. High‐resolution (∼80–100 meV) Si(2p) core‐level photoemission was used to determine the B‐induced perturbation of the surface Si atoms. The samples were prepared by surface segregation from Si(111) wafers (∼1.5 at. % B) after thermally removing the thin protective oxide layer on the surface. Photoemission spectra for photon energies from 110 to 140 eV show three peaks, indicative of at least two well‐separated spin‐orbit doublet components. Attempts to fit the data with only two components were unsatisfactory unless a Doniach–Šunjić line shape was used for the B‐induced component. This suggests that the surface region influenced by the B impurities is metallic, i.e., the Fermi level lies within the B‐modified valence band. The intensity of the bulk component goes through a minimum at a photon energy of 130 eV corresponding to a kinetic energy of 26 eV and is 0.19 of the total intensity. This leads to an escape depth of ∼3 Å if the B‐influenced region includes three layers below the adatom layer. Improved fits were obtained by using three distinct surface components. These are identified with the Si adatoms, the three B‐influenced surface layers, and the Si in the third layer which directly bonded to B.
Silicon (2p) surface core-level line shape of Si(111)--B J. E. Rowe, G. K. Wertheim, and D. M. Riffe, J. Vac. Sci. Technol. A 9, 1020 (1991), DOI:10.1116/1.577569