Semiconductor Electron Detectors

The properties of p-n junctions made by phosphorus diffusion in 12 000 ¿ cm p-type silicon have been examined using the Chalk River ¿ ¿2 ß -ray spectrometer as a source of monoenergetic electrons. With 200 V reverse bias the depletion layer is thick enough to absorb totally 350 keV electrons. Up to 1200 keV some of the electrons are scattered sufficiently to deposit all their energy in the junction. This results in a total absorption peak up to electron energies of 1.2 MeV. However, at this energy most of the electrons act like minimum ionizing particles and deposit 180 keV of energy in the junction.