Response of 100% internal quantum efficiency silicon photodiodes to low energy electrons and ions

Silicon photodiodes with only a 60 {angstrom} SiO{sub 2} front window are used in fusion and space research for detection of XUV photons with high quantum efficiency. In these environments, plasma ions and electrons can deposit energy in the active layer of the photodiode and influence the XUV measurement. Here, we characterize the response of these photodiodes to bombardment of 1-20 keV electrons and 30 keV H, H{sub 2}, Ne, and Ar. For electrons, the responsivity is 0.24 A/W, inferring an electron-hole pair creation energy of 4.2 eV. The measured responsivity to 30 keV H{sub 2}{sup +} is approximately 0.2 A/W, corresponding to an electron- hole pair creation energy of 5 eV. Photodiode damage due to ion bombardment is observed though an exponential decrease of the responsivity with ion dose. The decrease in responsivity is more rapid with increasing ion mass. Annealing of damage induced by heavy ions is observed by subsequent bombardment with protons.