Response of windowless silicon avalanche photo-diodes to electrons in the 90–900 eV range

We report on the characterization of the response of windowless silicon avalanche photodiodes to electrons in the 90-900 eV energy range. The electrons were provided by a monoenergetic electron gun present in the LASEC laboratories of University of Roma Tre. We find that the avalanche photo-diode generates a current proportional to the current of electrons hitting its active surface. The gain is found to depend on the electron energy , and varies from 2.147+-0.027 (for = 90 eV) to 385.8+-3.3 (for = 900 eV), when operating the diode at a bias of apd = 350V. This is the first time silicon avalanche photo-diodes are employed to measure electrons with <1 keV.