Cryogenic Scanning Electron Microscope for Quantum-Sensitive Measurements

• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: Funded in 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 535573191

Electron microscopy has recently established itself as an important tool to characterize the optical excitations at the nanoscale. Particularly, additional developments in cathodoluminescence and electron energy-loss spectroscopy allow for exploring collective excitations such as polaritons with a high spatial resolution. Merging electron microscopes with radiation sources allow for not only spectroscopically imaging the optical excitations, but also exploring their dynamics. Here, we aim at exploring the dynamics of exciton-polaritons, exciton-plasmon-polaritons, and quantum emitters in organic/inorganic semiconductors and hybrid systems, using electron microscopes merged with internal radiation sources. For this purpose, a cryostat or cryostage; herein referred to as cryo-system, is requested to be installed in an already installed scanning electron microscope in our group. The existing scanning electron microscope is equipped with a cathodoluminescence spectroscopy and angle-resolved mapping unit to probe the optical responses of materials. The cryo-system should be able to decrease the temperature to below 5 K and it has to be integrated with a liquid Helium Dewar. The vibrations caused by the cryo-system – if any – on the sample, should be maintained to be less than 1 nm in its maximum range. The cryo-system should be modular, in the sense that it should be retractable by the operator and/or replaceable by the already installed sample stage of the scanning electron microscope. The cryostage should allow for manipulating the position of the sample with respect to the electron optics and the installed parabolic mirrors inside the vacuum chamber of the electron microscope for cathodoluminescence detection. This cryo-system will be accompanied by a high-temporal-resolution hybrid direct electron detector to be installed in the same scanning electron microscope. The detector should provide us with a fast acquisition time to enable imaging of beam-sensitive materials, as well as a platform to perform correlative electron and photon detection mechanisms. In this sense, the electrons inelastically scattered from the sample will be correlated with the emitted cathodoluminescence photons. The cryo-system and the electron detector, hold a single piece of equipment together with the scanning electron microscope and its cathodoluminescence detector, to enable us to explore the optical responses of quantum materials and sensitive organic semiconductors and molecules with electron beams. The entire system will be used to investigate (i) the emission from single-photon emitters that appear as defect centers in van der Waals materials and operate at cryogenic temperatures, (ii) exciton polariton dynamics in organic and inorganic semiconductors coupled to plasmonic and photonic cavities, and (iii) Bose-Einstein condensation of exciton polaritons.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Kryogenes Rasterelektronenmikroskop für quantenempfindliche Messungen
• Instrumentation Group: 5120 Rasterelektronenmikroskope (REM)
• Applicant Institution: Christian-Albrechts-Universität zu Kiel
• Leader: Professorin Nahid Talebi, Ph.D.