Mapping stress and strain in nanostructures by high-resolution transmission electron microscopy

We present the current state-of-the-art of geometric phase analysis (GPA), a technique for measuring stress and strain at the nanoscale by high-resolution transmission electron microscopy (HRTEM). The method will be illustrated with an experimental study of SiGe strained layers using the SACTEM-Toulouse, an aberration-corrected transmission electron microscope. This latest generation machine improves signal-to-noise allowing deformations to be measured to an accuracy of 0.1% at nanometre scale resolution. The relation between strain and deformation will be discussed in the light of thin film relaxation and chemical interdiffusion.