Dark field electron holography for strain measurement

Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity.

Research Highlights► Step by step explanation of the dark field electron holography technique. ► Presentation of the theoretical equations to obtain quantitative strain map. ► Description of experimental parameters influencing dark field holography results. ► Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.