Introduction Rates of Electrically Active Defects in n- and p-Type Silicon by Electron and Neutron Irradiation

Abstract

Carrier-removal rates produced in n- and p-type silicon by 1.7 MeV electron and reactor neutron irradiations were measured at 270°K on samples with resistivities between 0.1 and 50 Ω·cm. The measurements were performed under well-defined conditions on test samples selected from float-zone, quartz-crucible, Dash, and Lopex silicon crystals, and from epitaxial silicon slices. Most of the carrier-removal rates were determined from the initial 10% decrease in conductivity. Carrier-removal rates also were determined in heavily irradiated samples of float-zone and crucible-grown silicon. The electron-produced carrier-removed rate is strongly crystal growth dependent in n-type silicon, and the smallest removal rate is observed in quartz-crucible-grown material. The hole removal rate in p-type silicon under electron irradiation exhibits only weak crystal-growth dependence which becomes more pronounced during subsequent isochronal annealing. After 370°K annealing of both n- and p-type 10 Ω·cm materials, the smallest carrier-removal rate is observed in p-type Lopex silicon. Carrier-removal rates decrease with increasing electron fluence in both n- and p-type silicon. Neutron-produced carrier removal at 270°K is only weakly dependent upon crystal-growth method and conductivity type. Crystal-growth and conductivity-type dependence become significant, however, during subsequent isochronal annealing. After annealing to 370°K, the carrier removal remaining in n-type silicon is smallest for the crucible grown material, and the hole removal remaining in p-type silicon is smallest for the Lopex material. Carrier-removal rates increase with increasing carrier concentration and decrease with increasing neutron fluence in both n- and p-type silicon.