High-resolution Raman microscope in combination with thermal stage and electrical probes

• Subject Area: Electrical Engineering and Information Technology
• Term: Funded in 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 581482776

Raman spectroscopy is a non-destructive technique for the characterization of ultrathin crystalline materials, especially two-dimensional (2D) materials. Hence, Raman microscopes belong to the most important instrumentation for research on crystalline thin-film materials and devices. They enable the monitoring of material properties after synthesis and after process steps during device fabrication including micron-scale spatial mapping. For instance, properties of 2D materials such as crystalline quality, defects, material thicknesses, strain, doping, and layer orientation can be identified with Raman spectroscopy. Similarly, other crystalline materials can be analyzed, e.g., group IV materials (Si, Ge, etc.), compound semiconductors, and phase-change materials. Advantages of Raman spectroscopy constitute extreme surface sensitivity and fast verification of material properties. This enables fast close-loop 2D material growth optimization which is one of the activities at the Institute of Semiconductor Engineering (IHT), University of Stuttgart (USTUTT). Other methods either lack in sensitivity for atomically thin-films (X-ray diffraction), or come with more complicated experimental effort, time, and the potential of material altering (destructive) effects (e.g., scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy). While these methods are also important to obtain a complete picture of material properties, the rich information provided by Raman spectroscopy, instantly after material synthesis or processing steps, makes it the most important technique to study 2D materials. IHT works on material synthesis, device fabrication, and characterization using semiconductor materials such as 2D materials, group IV materials, oxide semiconductors and chalcogenide compounds (e.g., phase-change materials). Raman microscopy is important for the characterization of all these materials. The planned Raman microscope has 3D mapping functionality and will be equipped with a thermal stage including electrical probes for the in-situ study of temperature and electrical biasing effects. This enables studying phase-transitions in phase-change materials or self-heating in transistors. Thus, the combination of Raman signal, photoluminescence (a built-in feature of the Raman microscope), and effect of temperature and electrical biasing provides unique insights into functional mechanisms of materials and devices. This is important to address timely research questions on transistors, memory, and optoelectronic devices down to a fundamental and in-depth materials level. In this context, the tool needs high spatial (sub-micron) and spectral (smaller than 0.3 wavenumbers) resolutions for detailed material analysis. Combined with the multifunctionality (temperature, electrical), this will be a unique characterization system highly valuable to the research landscape at USTUTT and currently not available with any other tool.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Hochauflösendes Raman-Mikroskop in Kombination mit thermischer Platte und elektrischen Prüfspitzen
• Instrumentation Group: 1840 Raman-Spektrometer
• Applicant Institution: Universität Stuttgart
• Leader: Professor Dr. Alwin Stefan Daus