DAMAGE INDUCED IN SILICON BY BACKSCATTERED ELECTRONS

Thin wafers of crystalline silicon supported on graphite, aluminium, copper and silver mounts were irradiated with 1 MeV electrons to three fluences, 1. 14, 2.28 and 4 X 10(14) e/cm2 and the damage induced in each sample was estimated by measuring the lifetime of minority carriers with a pulsed electron beam. For a given electron fluence, the level of induced damage was found to depend on the atomic number of the mount element - relatively minimum for graphite and maximum for silver. The results indicate that a fraction of the backscattered electrons possess energies above threshold to induce damage in silicon and their number depends on the mount element.