Real-time stress analysis of low-temperature Ge nanodot growth on H-terminated Si(1 1 1) 1 × 1 and Si(1 1 1) 7 × 7 surfaces

We have focused on the stress evolution during initial growth stage of Ge nanodots on H-terminated Si(1 1 1) 1 × 1 and Si(1 1 1) 7 × 7 surfaces by using simultaneous measurements of substrate curvature and surface morphology. A clear bend in the stress curve is observed corresponding to a Stranski-Krastanow growth mode, when the wetting layer thickness approaches the critical value for three-dimensional nucleation. In case of the deposition on H-terminated Si(1 1 1) 1 × 1 surface, the first Ge sub-bilayer shows tensile stress followed by compressive stress. The unique behavior demonstrates the important role of one atomic layer of H termination to control the intrinsic stress for nanodot fabrication.