Xuejian Ma, UT-Austin

"Spatio-Temporal-Spectral Imaging of Photo-carrier Dynamics in Perovskites and Two-dimensional Semiconductors"

Abstract: Laser-illuminated microwave impedance microscopy (iMIM) is a scanning probe microscopy technique that measures the spatiotemporal and spectral responses of photo-carriers in materials under laser illumination. In this dissertation, we use iMIM to study the photo-carrier dynamics in perovskites and two-dimensional (2D) semicon- ductors, which are promising materials for optoelectronic applications. We investigate the effects of laser power, wavelength, and sample temperature on the iMIM signals, and we reveal the underlying mechanisms of photo-carrier generation, transport, and recombination in these materials. We also demonstrate the potential of iMIM for imaging the spatial distribution of defects, grain boundaries, and heterostructures in perovskites and 2D semiconductors. Our results provide new insights into the photo-physical properties of these materials and pave the way for their optimization and integration in future devices.