As part of the Physics Colloquium, Dr. Carsten Richter from the Leibniz Institute for Crystal Growth (IKZ) in Berlin, Experimental Characterisation Section, gave a lecture entitled ‘X-ray diffraction imaging of lattice defects and strain’. He was following an invitation from Tilmann Leisegang. In his lecture, he presented the latest developments and techniques in X-ray microscopy with synchrotron radiation for characterising crystal lattice defects and strain in crystalline materials.
Fittingly, Carsten Richter's lecture coincided with the birthday of the theoretical physicist and 1965 Nobel Prize winner Julian Seymour Schwinger (12 February 1918 – 16 July 1994). His work laid the foundations for scattering theory, the well-known Lippmann-Schwinger equation, and for the precise prediction of the properties of sychrotron radiation.
High-resolution insights into crystalline structures
While conventional X-ray diffraction provides precisely averaged information on strain and defect density, its spatial resolution and selectivity are limited. Advances in synchrotron radiation sources, X-ray optics and instrumentation now enable high-resolution X-ray microscopy techniques that overcome these limitations. Carsten Richter presented the latest concepts and potential of X-ray diffraction imaging, which allow non-destructive investigation of crystal lattice defects and mechanical stresses down to the nanometre scale.
Significance for materials science and semiconductor technology
Defects and strains have a significant influence on the properties of crystalline materials and are therefore of central importance for material science and material development. In so-called strain engineering, the stress state is specifically influenced in order to adapt material properties for specific applications, for example in electronics, lighting technology or photovoltaics. At the same time, lattice defects can lead to localised strain fluctuations that impair the performance of semiconductor components. Using aluminium nitride single crystals, indium gallium arsenide epitaxial layers and germanium semiconductor components, Dr. Richter impressively illustrated the influence of these defects and their analysis using X-ray microscopy.
Outlook and future prospects
A particular advantage of X-ray diffraction is the ability to analyse buried layers, in-operando components or samples in complex environments in detail. Against the background of the latest upgrades to synchrotron radiation sources, Carsten Richter also gave an outlook on the future prospects of X-ray microscopy. When asked about semiconductor materials with a promising future, he revealed aluminium nitride and gallium oxide in particular as promising semiconductor materials.
The Leibniz Institute for Crystal Growth in Berlin-Adlershof is an internationally renowned centre of excellence for science, technology and the transfer of knowledge in the field of crystalline materials. The institute's research and development spectrum ranges from basic research to application-orientated and pre-industrial research tasks.
We would like to thank Dr. Carsten Richter for his visit.