Quantitative local strain measurements in compressive strained Ge/tensile strained Si bi-layers grown on top of relaxed Si0.5Ge0.5 virtual substrates

This paper reports on quantitative measurements of strain in a 7.5 nm compressive strained Ge/5.1 nm tensile strained Si bi-layer grown by reduced pressure chemical vapour deposition on top of a relaxed Si0.5Ge0.5 virtual substrate. Geometric phase analysis of high resolution transmission electron microscopy images acquired using the SACTEM-Toulouse, an aberration-corrected transmission electron microscope, is used to quantify the strain within s-Ge and s-Si layers. Finite element simulations are carried out to estimate the impact of strain relaxation in thin areas of a TEM specimen. Experimental results are compared with the predictions of elasticity theory and finite element simulations.