Atomic Spatiotemporal Characterization of Light-Emitting 2D Materials by Cathodoluminescence and Femtosecond Photoluminescence Spectroscopies

The emerging realm of two-dimensional (2D) materials has introduced remarkable advancements in the fields of optoelectronics and photonics. To harness the full potential of these materials, a comprehensive understanding of their light-emitting characteristics at atomic spatiotemporal scales is indispensable. Cathodoluminescence (CL) integrated within a scanning electron microscope (CL-SEM) or scanning transmission electron microscope (CL-STEM) is capable of conferring material properties with sub-nanometer spatial and spectral resolutions, surpassing the limitations of traditional photoluminescence (PL) techniques imposed by the Abbe diffraction limit. Furthermore, time-resolved photoluminescence (TrPL) spectroscopy enables the characterization of ultrafast electron-hole recombination dynamics through the up-conversion technique, employing ultrashort excitation and gating laser pulses. In this context, our specifically designed sample holder and spectrometer, integrated with the high-resolution Hitachi S5500 SEM and equipped with sample loading chips featuring ultrathin windows, are aimed to develop an atomic-resolution hyperspectral CL-SEM/STEM imaging system. Additionally, in conjunction with our homemade ultrafast TrPL setup, the ultimate goal is to investigate the electronic and optical characteristics of 2D materials at the atomic scale, encompassing both spatial and temporal dimensions.