Photodiode for low energy electron detection in a SEM
Agata Sakic developed photodiodes for electron microscopes.
They can detect back-scattered and secondary electrons, both with high efficiency. They are very small and CMOS compatible – meaning they can be fabricated with existing technology. But their most important quality is their high sensitivity.
"Our photodiodes are able to detect energies as low as 50 electron volts - which is a world record, as far as we know. As a result, the SEM-images have an increased depth of field and a higher resolution. The secret behind our success is a two-nanometers-thick boron layer that allows even very low-energy electrons to reach the photosensitive surface. It’s fascinating that we are able to deposit such an ultrathin layer, with amazing electric properties, in a reliable and reproducible way."
The devices are now used in the latest SEMs of the FEI company.
|Complete detector with etched centre hole||Position of the detector in the SEM||Cross section schematic|