Room-temperature annealing of vacancy-type defect in high-purity n-type Si

Electron-irradiated p+-n--n+ diodes produced from low-doped high-purity Si wafers were found, by deep-level transient spectroscopy (DLTS), to have a prominent defect, labeled E4, with an energy level 0.37 eV below the conduction-band edge and a concentration of ∼(1/4) 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 is put forward