Electronic properties of defects induced by hydrogen and helium radiation on semimetal MoTe2

The orthorhombic phase of molybdenum ditelluride(Td-MoTe2) is regarded as a topological Weyl semimetal, which have generated considerable interest. It is an important system both from a fundamental physical point of view and for potential applications. In this paper, several defects in hydrogen (H) and helium (He) ions irradiated Td-MoTe2 are investigated in detail by using density functional theory (DFT). We study the electronic properties of the defects by analyzing the electron dispersion curves and density of states. In addition, the formation energy for different defects is evaluated and compared. It is found that various defects have different effects on the topological properties. Low concentrations of interstitial defects IH and IHe do not affect the topological properties of MoTe2, while vacancy and substitution defects destroy part of the Weyl nodes, and the Fermi level shifts and partial band separations of these defects. Comparison of formation energies indicates that H interstitial defects are the most easily formed defects among all defects and the most stable defect structure.