Scintillator-Free Electron Detection and Counting Using Single-Photon Avalanche Diodes

In-vacuum single electrons counting has been demonstrated with single-photon avalanche diodes without scintillation. An electron detection probability (EDP) of ~70% at 10-keV electron energy has been achieved, corresponding to the lowest measureable electrical current of ~0.9 aA. A parameter-free method for EDP simulation has been developed and used to compare with the experimental results. This work presents an unprecedented quantitative study on energetic electron counting and shows the potential of SPADs for high-speed and ultralow-current electron microscopy imaging.