Dark field electron holography for quantitative strain measurements with nanometer-scale spatial resolution

Strain measurements on strained SiGe specimens have been performed using dark field electron holography. By combining the excellent stability of state-of-the-art electron microscopes with careful specimen preparation we have been able to acquire two-dimensional strain maps of the layers with a spatial resolution of 5 nm, a background noise of 2×10−4, an interference width of 1500 nm, and a field of view of more than 500×500 nm2. We also show that the strain measurements are quantitative to within experimental error.