First-principles study of the native defects with charge states in ZrSe2

Study of the native defects in transition metal dichalcogenides (TMDCs) is of fundamental interest and potential technological importance. The atomic and electronic structures of native defects with charge states in ZrSe2 are systematically investigated for the first time based on first-principles calculations with the optB86R-vdW and HSE06 functionals. We identify the configurations of relatively stable defects including Zr interstitial (Zrint), Se vacancy (VSe) and Zr antisite (ZrSe). The positive charged Zr interstitial defect (Zr2+int) has the lowest formation energy and thus is most commonly seen in ZrSe2, which is in good agreement with experimental observation. The ZrSe defect is found to form a DX-like configuration. Moreover, the non-interacting Zr Frenkel pairs are the most favorable form of intrinsic defects. The electronic structure analyses of these defects reveal that the extra Zr atoms adjacent to the defects act as donors, which are responsible for the native n-type conductivity of as-grown ZrSe2. Our study can provide an insight into understanding the properties of native defects in ZrSe2.