4D Electron Microscopy


Mapping carrier dynamics in space and time using 4D electron microscopy

We have established and developed the second generation of four-dimensional (4D) scanning ultrafast electron microscopy (S-UEM) and demonstrate the ability to record time-resolved images (snapshots) of material surfaces with 650 fs and ~ 5 nm temporal and spatial resolutions, respectively.

Mapping charge carrier dynamics on the surface of InGaN nanowires

Using S-UEM, we spatially and temporally visualize the charge carrier dynamics on the surface of InGaN NW arrays before and after surface passivation with octadecylthiol (ODT).

Mapping charge carrier dynamics on the surface of CIGSe nanocrystals

​Here, we precisely map the surface charge carrier dynamics of the CIGS before and after surface passivation in space and time. 

Real-space imaging of carrier trapping on surface of CdSe single crystals

​By visualizing different surface of CdSe single crystals, we show that the morphology, grains and nanostructure features of the material surface can impact the overall carrier relaxation processes.

Real-space Visualization of SE energy loss and carrier diffusion on material surfaces

​Using our S-UEM with a 650 fs and ~5 nm temporal and spatial resolutions, respectively, we show that time resolved imaging of the energy loss dynamics and carrier spreading on the surfaces of a densely packed array of InGaN nanowires (NWs) as a model system can be achieved now in real space.