Initial stage of the Bi surfactant-mediated growth of Ge on Si(111): a structural study

Abstract We have used Bi as a surfactant in Ge growth on Si(111) and present a detailed analysis of the adsorption site geometry of Bi on bare Si(111) as well as on ultrathin Ge films (1–2 monolayers, ML) grown on Bi-terminated Si(111). X-ray standing waves (XSWs) have been employed to show that at a growth temperature of 485°C, Bi occupies T 1 adsorption sites on Si(111). After Ge deposition, a site exchange of Ge and Bi is observed, and Bi is found to reside on T 1 sites on top of the pseudomorphically strained Ge. The SiBi and the GeBi bond lengths have been determined to be very close to the sum of the respective covalent radii.