Electron Detector for 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