Electronic structure calculations of defect states in Ti-doped LiF.

This work investigates, using density functional theory (DFT), the localization of electrons and holes produced by irradiation in LiF crystals doped with Ti. We show that the Ti can act either as an electron trap, when located at an interstitial position of the LiF lattice, or as a trap for holes by substituting a Li atom. We also observe that an excess electron is localized in a Ti p-state while a hole localizes in a Ti d-state. The localization of the hole in this state when the Ti substitutes a Li is supported by results reported in the literature where it was assumed that the Ti substitute is a hole trap. The defect energy levels obtained in this work agree quite well with those reported in experiments. • Electronic structure calculations of Ti-doped LiF are performed from first principles. • Ti impurity shows a dual character behaving as an electron trap when interstitial and a hole trap when substitutional. • Excess electron is localized in a Ti p-state while a hole localizes in a Ti d-state. [ABSTRACT FROM AUTHOR]