Annealing effect on an amorphous Si film deposited on a 7×7 superlattice surface of Si(111) studied with low-energy electron diffraction

Abstract

The intensity profile of low-energy electron diffraction (LEED) was observed for a Si film grown on a Si(111)–7×7 substrate under low-temperature epitaxial growth conditions. The epitaxial relation for Si(111) holds for each film with its thickness region below a certain value (dC) from the substrate, and an amorphous phase is formed above it. The values of dC were 0.5, 6.5, 17, and 100 nm at substrate temperatures (TS) of 35, 170, 200, and 250 °C, respectively. The annealing effect on the films grown at Ts=35 and 170 °C was studied. The LEED intensity (IS) is proportional to the surface area occupied by the 7×7 and 5×5 superlattices such that (1) IS depends sensitively on the film thickness (d) and TS, and (2) the dependence of IS on the annealing temperature is independent of TS and d. This is discussed from the viewpoint of the change in structural hierarchy formed in the as-grown film due to the annealing.