Atomic layer control by electromigration on semiconductor surfaces

Abstract

It is proposed that the novel electromigration on semiconductor surfaces can be applied to the control of adatom overlayer on semiconductor surfaces when adatoms grow in the Stranski-Krastanov (island-on-layer) or Frank-van der Merwe (layer-by-layer) modes. By virtue of the nature of the electromigration, the overlayer formed by the electromigration is homogeneous in coverage and structure, well-ordered, defect-free and eventually of a single domain. The nature of the driving force of the electromigration which possesses a great significance for the atomic layer control is investigated for Ag/Ge(111)c(2 × 8) and Ag/Si(111) 7 × 7. The effective charge number Z * is derived from the analysis of the spread of a patch of deposit to be + (15 ± 2) for the Ag adatom on Ge(111)/Ag√3 × √3and+ 1 ∼ + 4 for the Ag adatom on Si(111)/Ag√ × √3. The force is proven to be directly proportional to the electric field available on the surface for Ag/Si(111). As an application of the electromigration to the surface modification, an electron-beam drawing of the Ag atomic layer on Si(111) is tentatively demonstrated. The behavior of the drawing is consistent with the above-described dependence of the electromigration on the electric field.