Silicon Photodiode Vacuum Ultraviolet Detector

The photosensitivity of silicon surface-barrier photodiodes has been measured over the photon energy range from 4.9 to 21.2 eV (2537 to 584 Å). The photodiodes are operated in the reverse-bias mode at room temperature. The sensitivity of a typical photodiode with approximately 100 Å of gold on the sensitive surface is 0.16 electron per photon at 2537 Å and 1.1 electrons per photon at 584 Å. Photosensitivity did not vary more than a few percent over the sensitive area. The operating characteristics of these devices are reported and the use of the silicon photodiode directly, or in combination with sodium salicylate, as a vacuum ultraviolet detector is discussed.