Structure, Electronic Properties and Annealing Behavior of Di-Interstitial-Oxygen Center in Silicon

Abstract

It is argued in this work that a DLTS signal associated with hole emission from a radiation-induced defect with an energy level at Ev + 0.09 eV is related to a complex of silicon di-interstitial with an oxygen atom (I2O). This signal has been observed in the DLTS spectra of p-type Si:O samples irradiated with either 4-6 MeV electrons or alpha particles. Isochronal and isothermal annealing studies of the samples have shown that the defect responsible for the DLTS signal from the Ev + 0.09 eV level disappears upon heat-treatments in the temperature range 75-100 °C and its formation and annealing behavior is similar to that of a center giving rise to the infrared absorption band at 936 cm-1 previously assigned to a local vibrational mode (LVM) due to the I2O complex. Possible configurations of the I2O complex have been found by ab-initio modeling and analyzed. Formation and binding energies, energy levels and LVMs for different configurations have been determined. It has been found that the minimum energy configuration of the I2O complex consists of the compact I2 to which a divalent interstitial oxygen atom is attached. Calculated values of the strongest LVM (ν = 971 см-1 ) and position of the donor level {Ev + (0.11-0.13) eV} for the minimum energy configuration are very close to those assigned to the I2O defect in the infrared absorption and DLTS experiments.