Picosecond behaviors probed with ultrafast electron beam-induced current microscopy
DOI: 10.1063/10.0041782
Picosecond behaviors probed with ultrafast electron beam-induced current microscopy lead image
Improving and miniaturizing semiconductors to keep up with the ever-increasing demand for faster processing requires detailed characterization of semiconductor devices on small scales. Electron beam-induced current (EBIC) microscopy is commonly used to measure defects in semiconductor devices, but with its microsecond timescale, it has long been considered too slow to allow observations in ultrafast electronics.
By combining EBIC with an ultrafast scanning electron microscope, Rehmann et al. dramatically improved time resolution while maintaining high spatial resolution observations of electric field dynamics down to the micro- and nanometer scales.
“It was believed that electron beam-induced current microscopy could not be used to study fast processes,” said author Yves Acremann. “In our paper, we extend this technique to the picosecond time domain.”
The method employs a pump-probe technique to create a pulse of high-energy electrons that generate electron-hole pairs. These pairs act like test charges as they travel to the contacts of the device under study, allowing the investigation of transport processes inside the device. When tested with an avalanche photodiode with the charge multiplication process acting as a contrast mechanism, the results showed the voltage-dependent capacitance of the device governs gain dynamics. Furthermore, they showed the method could resolve spatial variations in carrier dynamics.
The ultrafast EBIC enables the observation of other transport processes in semiconductor devices, such as charges moving across a field-effect transistor. The authors plan to use their method to study carrier transport in these transistors as well as power semiconductors and solar cells.
Source: “Introducing ultrafast EBIC: Spatially resolved transient analysis of an avalanche photodiode,” by J. Rehmann, M. Röllin, A. Vaterlaus, and Y. Acremann, Applied Physics Letters (2025). The article can be accessed at https://doi.org/10.1063/5.0293783 .
