Micro-Raman and Photoluminescence Spectrometer

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In this proposal, the funding of a confocal micro-Raman and photoluminescence spectrometer is requested. This system will be used for the comprehensive investigation of crystalline and hybrid quantum and nanomaterials, in particular two-dimensional (2D) materials. A major focus is on the characterization of the crystal quality and the interfacial properties of 2D materials and related van der Waals (vdW) heterostacks and hybrid structures. Those structures are mostly prepared by micromechanical exfoliation and vdW assembly. Examples of the materials to be studied include semiconducting transition metal dichalcogenides (TMDC), graphene, hexagonal boron nitride, defect-based quantum emitters in 2D membranes, magnetic and multiferroic 2D materials, 2D polar metals with crystal phase transitions, twisted homo- and heterobilayers partially embedded in field-effect circuits, as well as hybrid structures consisting, for example, of Mie-Voids combined with 2D materials with strong excitonic light-matter interaction. A special focus is on the investigation of twisted bilayers for the experimental realization and study of Mott-Hubbard simulators. Since the start of intensive worldwide research on 2D materials, the so-called phonon fingerprint, which is experimentally accessible using Raman spectroscopy, has proven to be a very important tool to access the properties of 2D materials and related hetero- and hybrid structures. The phonon modes are sensitive to type of material and crystal structure, number of layers, strains, defects, charge carrier density, temperature, interlayer coupling, and in the case of twisted layers also to the angle between two layers. The proposed confocal µ-Raman microscope is used to study and characterize those properties non-destructively and with diffraction-limited lateral resolution with high throughput using non-resonant Raman spectroscopy. The combined micro-Raman and Micro-photoluminescence spectroscopy is established as a very powerful method to comprehensively assess the quality and homogeneity of crystalline solids and in particular of 2D structures and vdW assemblies. Comprehensive and easy access to this methodology has a direct effect on the quality of the generated structures. The sensitivity of the analytical methods as wells as the number of samples that can be analyzed per time limits the quality and the quantity of structures that can be prepared. The number of high-quality samples that can be produced is therefore limited by the throughput of the characterization. The requested mirco-Raman and photoluminescence system will make this high-quality and high throughput analysis accessible even to users who are not experienced in optical setups without an extensive training period.