Types of surface modulation in a Ge–Si(111) heterosystem

Abstract

Three types of elastic modulation in atomic layers of epitaxial Ge films on the surface of Si(111) observed in scanning tunnel microscopy are discussed. Two types of modulation are associated with misfit dislocations accumulating at the interface. Modulation of the third type arises on the surfaces of dislocation-free pseudomorphic films and could be due to the presence on a Si substrate surface of two-dimensional silicon islands with a height of three atomic bilayers and lateral dimensions of 15–20 nm. Measured bending values Δh for the third type of modulation (Δh ≤ 0.1 nm) agree with data calculated within the theory of elasticity