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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 9: Microscopy and Tomography with X-ray Photons, Electrons, Ions and Positron

KFM 9.6: Vortrag

Mittwoch, 29. März 2023, 10:40–11:00, POT 106

Electron tomography analysis of Ge/SiGe asymmetrically coupled quantum wells — •Ekaterina Paysen¹, Giovanni Capellini^2,3, and Achim Trampert¹ — ¹Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Berlin, Germany — ²IHP - Leibniz-Institut für innovative Mikroelektronik, Frankfurt (Oder), Germany — ³Dipartimento di Scienze, Università degli Studi Roma Tre, Roma, Italy

We present a method for the three-dimensional (3D) characterisation of the morphology and chemical intermixing of buried interfaces in a Ge/SiGe asymmetrically coupled quantum well structure applying electron tomography method based on high-angle annular dark-field (HAADF) scanning transmission electron microscopy. For this purpose, a needle-shaped specimen with a diameter of a few 100 nanometres is prepared with a focused ion beam, from which a tilt series of HAADF projections is recorded. Subsequently, the series is used to calculate a complete 3D image or tomogram of the specimen with the simultaneous iterative reconstruction technique. The analysis of iso-concentration surfaces enables a quantitative determination of morphological quantities such as the root mean square roughness and lateral correlation length individually for each interface. Subnanometre-thin cross-sections from the tomogram are used to measure the chemical interface width with the highest spatial resolution. An advantage of this method is thus the investigation of the interfaces as 3D entities in their buried state on a length scale of a few 100 nanometres without the projection problem.