Synthesis of two-dimensional Dirac semi-metallic NiTe as high-performance contacts for MoS₂ transistors

Two-dimensional Dirac semi-metals have attracted extensive attention for their potential applications in next-generation electronics, optoelectronics and quantum technologies. However, numerous topological semi-metals predicted by theory have not yet been experimentally confirmed. Here, we report the controlled synthesis of high-quality NiTe nanosheets via the chemical vapor deposition method. Theoretical analysis confirms the semi-metallic nature of centrosymmetric NiTe and elucidates that its unusual second harmonic generation response originates from the electron transitions between linear dispersed bands near Dirac cone. Furthermore, NiTe nanosheets exhibit an ultra-high conductivity exceeding 10⁶ ​S ​m⁻¹, rivaling noble metal-based Dirac semi-metals. Dirac semi-metallic NiTe serves as a contact electrode for MoS₂ field-effect transistors, showing a remarkable apparent carrier mobility of 22.45 cm² V⁻¹ s⁻¹, which is 6.43 times higher than that of the Au-MoS₂ device. These findings establish NiTe as an ideal platform for exploring topological quantum states and advancing high-performance electronic devices.