Versatile electrical behavior of1T−TiS2elucidated from a theoretical study

Herein we report the formation energies of native point defects in $1T\text{\ensuremath{-}}{\mathrm{TiS}}₂$ material. In the present study we used one of the most refined models, e.g., a global hybrid density functional with dispersion corrections for all the calculations. The stability domain of $1T\text{\ensuremath{-}}{\mathrm{TiS}}₂$ was thoroughly investigated. We demonstrate unambiguously that the most stable defect is titanium interstitial in octahedral site in the van der Waals gap. Indeed, this simple defect can explain the distinguishable electric behavior of ${\mathrm{TiS}}₂$ reported in the litterature, i.e., nondegenerated semiconductor (SC) or semimetal (SM) depending on the synthesis conditions. Simulated defect concentrations vs synthesis temperature are also provided and the SC-SM transition is discussed.