Electron Microscopy and Nanoengineering

The electron microscope is a versatile tool used to obtain structural, magnetic and electronic information. Different imaging, reciprocal space as well as spectroscopic techniques are applied to retrieve these materials properties with a spatial resolution down to 1 Ångström. Focussed ion and electron beams are used to nano-structure matter.

Electron microscopy proactively contributes to the search of novel materials both in applied and basic studies. In most modern hard and biological materials the study of structural and electronic properties on the atomic scale is key for the understanding of mesoscopic and macroscopic properties. Several techniques in electron microscopy shade light in materials properties on this length scale. Structural imaging enables us to detect atomic configurations at interfaces or in nanoparticles. Nanoparticles, first used to colorize medieval church windows, nowadays have a broad range of applications. Using high resolution electron microscopy, we contribute to the understanding the fundamental interplay between particle structure and physical properties. Thus these particles can be engineered for use in applications ranging from catalysers over light emitters to cancer therapy. The distribution of elements in a material or in a tissue can often not be derived from a study of the crystal structure alone. Spectroscopic methods in the electron microscope are not only used to identify the local position of chemical elements with subnanometer resolution but also to study their electronic properties. The electron beam in the microscope also interacts with magnetic fields in the sample. In fact, by using the techniques of Lorentz microscopy and electron holography, we can visualise magnetic field lines and domains.

The use of focussed electron and ion beams allows us to structure matter on a length scale of 10nm to some 100nm. Particle assisted structuring contains several approaches such as sputtering, etching, deposition as well as materials transformations. Using these instruments, nanopillars can be grown that are inserted into magnetic force microscopes. The development of ion beam assisted deposition enables us to contact device elements or nanowires. By focussed ion beam sputtering, structures such as electrodes, trenches and fresnel lenses can be created. The intimate link between electron microscopy and advanced focussed ion beam techniques (FIB) is the capacity of the FIB to prepare electron transparent samples on well defined sites, i.e. in a device.