Elastic relaxation of dry-etched Si/SiGe quantum dots

Elastic relaxation of the compressive strain due to the lattice mismatch between SiGe and Si has been studied with both x-ray diffraction and Raman scattering in small (30-100 nm) dry-etched Si/SiGe quantum dots fabricated from high-quality multilayers grown on (001)-oriented Si. The Raman spectroscopic investigations showed that the dot alloy layers have relaxed by approximately 65% from their fully strained value and that a compensating tensile strain has been induced in the Si layers. The relaxation is essentially independent of the dot size and the values derived experimentally compare well with analytical and numerical model calculations.