Evaluating low-resistance Ohmic-contact electrodes for bilayer WSe ₂ : A first-principles study

Two-dimensional tungsten diselenide (2D WSe 2 ) has emerged as a leading candidate for post-silicon nanoelectronics. A critical determinant of high-performance WSe 2 -based devices is the realization of ideal electrodes that form low-resistivity Ohmic contacts. To address this challenge, we conduct a comprehensive first-principles study to evaluate the interfacial characteristics between bilayer (BL) WSe 2 and various monolayer (ML) metallic candidates. By applying work function alignment and lattice compatibility as initial screening criteria, six promising electrode materials—Zr 2 NF 2 , Sc 2 NF 2 , Hf 2 NF 2 , Sc 2 NO 2 , 2H-TaSe 2 , and 2H-NbSe 2 —are identified. Among these, Zr 2 NF 2 , Sc 2 NF 2 , and Hf 2 NF 2 form n-type Ohmic contacts with BL WSe 2 , with the Hf 2 NF 2 /BL WSe 2 interface exhibiting optimal performance with moderate lattice mismatch of 4.18%, a stable negative binding energy of −22.79 meV/Å 2 , the highest electron tunneling probability of 29.91%, and the lowest tunneling-specific resistivity of 3.83×10 −11 Ω·cm 2 . ML Sc 2 NO 2 , 2H-TaSe 2 , and 2H-NbSe 2 form p-type Ohmic contacts, among which the 2H-TaSe 2 /BL WSe 2 interface demonstrates the most favorable overall characteristics, including an exceptionally low lattice mismatch of −0.94%, a stable binding energy of −53.72 meV/Å 2 , and balanced transport properties with moderate tunneling probability (12.57%) and tunneling-specific resistivity (3.99×10 −9 Ω·cm 2 ). This systematic investigation provides essential theoretical guidance for the rational design of high-performance nanoelectronic devices incorporating low-resistance Ohmic interfaces.