Mechanical stresses in (sub)monolayer epitaxial films

Abstract

We have studied stresses in thin Ge growing on Si(001), in situ and in real time, with submonolayer sensitivity. As a result of the 4.3% lattice mismatch, Ge films develop a compressive stress in the 2D growth regime, which saturates when 3D growth sets in. These measurements give new insight in the interatomic forces that play a dominant role in establishing growth mode and the generation of defects, and provide a new test for state-of-the-art total-energy calculations.