Electron-irradiated p+-n−-n+ diodes produced from low-doped high-purity Si wafers were found, by deep-level transient spectroscopy, to have a prominent defect, labelled E4, with an energy level 0.37eV below the conduction-band edge and a concentration of about 25% relative to the divacancy. The samples were kept at room temperature, and the E4 concentration was seen to reduce to half during five weeks. Annealing data revealed a similar peak E5 overlapping that of the single-negatively charged divacancy and showing a one-to-one proportionality with E4. E4 and E5 arise most likely from a vacancy-type defect and a tentative assignment to a planar tetravacancy was proposed.

Room-Temperature Annealing of Vacancy-Type Defect in High-Purity n-Type Si. J.H.Bleka, E.V.Monakhov, B.G.Svensson, B.S.Avset: Physical Review B, 2007, 76[23], 233204 (3pp)