The annealing kinetics of the so-called E4/E5 center or E4a/E4b center in electron-irradiated Si particle detectors were studied at four different temperatures from 23 to 65C using deep-level transient spectroscopy. The center gave rise to 2 energy levels at 0.37 and 0.45eV below the conduction-band edge, and the annealing process was found to be of dissociative nature with an energy barrier of 1.1–1.2eV. A striking similarity of the annealing rates (and kinetics) was revealed with that obtained for the 936/cm infra-red absorption band, studied by Fourier-transform infrared spectroscopy using identical type of Si material as in the deep-level transient spectroscopy study but irradiated with neutrons. The result strongly suggested that the E4/E5 levels and the 936/cm band originated from the same defect, and the latter was attributed to a di-interstitial-oxygen (I2O) complex. The E4/E5 center played a crucial role for the detrimental leakage current in irradiated Si particle detectors, and an assignment of E4/E5 to I2O implied that O-lean Si material (<1014/cm3) should be advantageous in enhancing detector performance.

On the Identity of a Crucial Defect Contributing to Leakage Current in Silicon Particle Detectors. J.H.Bleka, L.Murin, E.V.Monakhov, B.S.Avset, B.G.Svensson: Applied Physics Letters, 2008, 92[13], 132102