RHEED studies of vicinal Si(111) surfaces and Ag films grown on Si(111)

摘要

Reflection high energy electron diffraction (RHEED) was used to study the growth of silver films and the evolution of step structures on the silicon (111) surface. Silver films were deposited by molecular beam epitaxy onto the Si(111) 7 x 7 surface. Films deposited below room temperature showed RHEED intensity oscillation whose quality improved with decreasing temperature. RHEED oscillations were also improved by the application of an initial burst in the deposition flux. Such improvement and the temperature dependence of the oscillations is attributed to an increase in the island nucleation density. Vicinal silicon samples miscut from the (111) plane by 1.2 deg, 2.5 deg, and 4.5 deg towards the (2(bar 1)(bar 1)) direction were studied. If the samples were cooled slowly through the 1 x 1 to 7 x 7 phase transition, a step bunching transformation would occur that produced large (111) terraces. During this transition, the diffraction spot splitting would vanish while maintaining a constant splitting width. This suggest that the transition occurs by the growth of a few terraces incorporating the others with the widths of the other terraces remaining fixed until incorporation.