Stable silicon photodiodes for absolute intensity measurements in the VUV and soft x-ray regions

Stable silicon photodiodes with 100% internal quantum efficiency have been developed for the vacuum ultraviolet and soft x-ray regions. It is demonstrated that the response of these detectors can be reasonably well represented by a simple model for photon energies above 40 eV. The measured efficiency is consistent with a constant electron-hole pair creation energy for Si above 40 eV. Radiation damage is demonstrated to result in loss of carriers to recombination at the front surface. The uniformity of the diodes is shown to be better than 0.1% RMS at 110 eV.