Publication
Surface Science
Paper

Influence of ion bombardment on the interaction of Sb with the Si(100) surface

View publication

Abstract

One monolayer (ML) of Sb, which is the saturation coverage at the substrate temperature Ts = 425 °C used in these experiments, was adsorbed on clean Si(100) surfaces and subsequently bombarded with 2 keV Ar+ ions incident at an angle of 21° and a flux JAr = 1.7 ×1014 cm-2 s-2. Thermally-stimulated desorption (TSD) was then used to measure the remaining Sb coverage θ as a function of ion dose D (0 to 2.3 × 1016 cm-2) and to determine the effect of ion irradiation on the Sb surface binding energy. In the absence of ion bombardment, only one TSD peak was observed which, at a heating rate of 10 °C s-1, occurred at T1 = 890°C. In agreement with previous results, the peak was fit with a binding energy E1 = 2.33 eV. Ion irradiation resulted in the formation of an additional, higher temperature, TSD peak at T2 = 1005°C which was fit with E2 = 2.6 eV. The Sb coverage θ2 at the T2 site increased with increasing ion dose, reached a maximum of θ = 0.08 ML at D {all equal to} 8.5 ×1015 cm-2, and then gradually decreased. A simple model, which includes terms for ion-bombardment-induced sputtering and trapping processes, was used to calculate Sb coverages on both the T1 and T2 sites as a function of D and shown to be in good agreement with experimental results. The sputtering yield S from the two sites was found to be ~ 0.08 atoms/ion and the trapping yield α2 of Sb adatoms from the T1 into the T2 site was 0.015 atoms/ion. The low value of S was due primarily to the poor mass matches between Ar/Sb and Si/Sb. Ion bombardment carried out during Sb deposition on Si(100) with JSb4 = 1.5 ×1013 cm-2 s-1 and the same value of JAr resulted in an increase in the saturation coverage from 1 to 1.6 ML. TSD peaks were observed at both the T1 and T2 positions and an additional broad low-energy TSD peak was obtained at T3 {all equal to} 710 °C. The coverage of Sb bound at the T3 site was ~ 0.25 ML. © 1987.

Date

Publication

Surface Science

Authors

Topics

Share