  Nickel ditelluride (NiTe2), a new discovered type-II Dirac semimetal whose
Dirac node lies close to its Fermi level, is expected to exhibit exotic
phenomena including Lifshitz transition and superconductivity. As we know,
defects are inevitable for transition metal dichalcogenides and have
significant impacts on the optical and electronic properties. However, the
systematic study of defects in NiTe2 is still lack. Here, by using
high-resolution scanning tunneling microscopy combined with first-principles
calculations, the point defects including the vacancy, intercalation and
antisite defects in NiTe2 are systematically investigated. We identified five
main types native defects and revealed that the growth condition could affect
the type of native defects. By controlling the ratio of ingredient during
synthesis, the types of point defects are expected to be manipulated,
especially antisite defects. Additionally, we find native defects could
slightly dope the topological surface states. Our results provide a facile way
to manipulate defects for future optimizing the electronic properties of NiTe2
and other related materials.
