Scanning tunneling microscopy studies of the formation and coarsening of manganese silicides on Si(111)

Solid-phase epitaxial growth of manganese silicides on a Si(111)-7×7 surface at temperatures between room temperature and ∼750 °C has been studied using scanning tunneling microscopy. The as-deposited Mn film of ∼0.6–1 ML shows an ordered honeycomb structure with each Mn cluster occupying a half of the 7×7 unit cell. The Mn clusters begin to react with the Si substrate to form silicides at ∼250 °C. Two types of silicides, the three-dimensional (3D) and tabular islands, which correspond to Mn-rich silicides and monosilicide MnSi, respectively, coexist on the Si(111) surface at annealing temperatures between 250 and 500 °C. At 500 °C annealing, all 3D islands convert into tabular islands and MnSi is the only Mn silicide phase. Above 600 °C, the tabular islands convert into large 3D islands that are likely to be Si-rich manganese silicides. With increasing annealing temperature and time, the number density of silicide islands decreases, while the average size (area) of the remaining islands increases. The gr...