Metastable VO_2 complexes in silicon: experimental and theoretical modeling studies

摘要

We report on a combined experimental and theoretical study of the metastable form of the vacancy-dioxygen defect in Si labeled VO_2~*. Important new experimental observations are the detection of mixed local vibrational modes of VO_2~* in ~(16)O, ~(18)O co-doped samples, the determination of the position of LVM bands for the negatively charged defect, and an assignment of an acceptor level at about E_c - 0.05 eV. Defect energetics, electrical levels and LVM frequencies of the VO_2~* complex are also investigated by ab-initio density-functional modeling. We find it to be a bistable defect which accounts well for the experimental data. The metastable form produces an acceptor state at ～0.05 eV below E_c, and can be thought of as a VO defect perturbed by interstitial oxygen.