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Rolled-up tubes and cantilevers by releasing SrRuO 3-Pr 0.7Ca 0.3MnO 3 nanomembranes
2011, Deneke, C., Wild, E., Boldyreva, K., Baunack, S., Cendula, P., Mönch, I., Simon, M., Malachias, A., Dörr, K., Schmidt, O.G.
Three-dimensional micro-objects are fabricated by the controlled release of inherently strained SrRuO 3/Pr 0.7Ca 0.3MnO 3/SrRuO 3 nanometer-sized trilayers from SrTiO 3 (001) substrates. Freestanding cantilevers and rolled-up microtubes with a diameter of 6 to 8 μm are demonstrated. The etching behavior of the SrRuO3 film is investigated, and a selectivity of 1:9,100 with respect to the SrTiO3 substrate is found. The initial and final strain states of the rolled-up oxide layers are studied by X-ray diffraction on an ensemble of tubes. Relaxation of the sandwiched Pr0.7Ca0.3MnO3 layer towards its bulk lattice parameter is observed as the major driving force for the roll-up of the trilayers. Finally, μ-diffraction experiments reveal that a single object can represent the ensemble proving a good homogeneity of the rolled-up tubes.
Characterization of encapsulated graphene layers using extreme ultraviolet coherence tomography
2022, Wiesner, Felix, Skruszewicz, Slawomir, Rödel, Christian, Abel, Johann Jakob, Reinhard, Julius, Wünsche, Martin, Nathanael, Jan, Grünewald, Marco, Hübner, Uwe, Paulus, Gerhard G., Fuchs, Silvio
Many applications of two-dimensional materials such as graphene require the encapsulation in bulk material. While a variety of methods exist for the structural and functional characterization of uncovered 2D materials, there is a need for methods that image encapsulated 2D materials as well as the surrounding matter. In this work, we use extreme ultraviolet coherence tomography to image graphene flakes buried beneath 200 nm of silicon. We show that we can identify mono-, bi-, and trilayers of graphene and quantify the thickness of the silicon bulk on top by measuring the depth-resolved reflectivity. Furthermore, we estimate the quality of the graphene interface by incorporating a model that includes the interface roughness. These results are verified by atomic force microscopy and prove that extreme ultraviolet coherence tomography is a suitable tool for imaging 2D materials embedded in bulk materials.