First-principles study on the electronic properties and Schottky barrier of WC/ WS2 and WC/ WSe2 heterostructures

Within the realm of two-dimensional materials, monolayer transition metal dichalcogenide semiconductors boasting intrinsic band gaps of 1--2 eV are regarded as promising candidates for channel materials in next-generation transistors. The judicious choice of electrodes is paramount to achieving low-resistance contacts, thereby enhancing the performance of nanoelectronic devices. Therefore, the exploration of novel metal-semiconductor combinations and a comprehensive grasp of the atomistic nature of interfaces are indispensable. In this work, we present a systematic examination of vertical Moir\'e pattern contacts between WC and $\mathrm{W}{\mathrm{S}}_{2}$ or $\mathrm{WS}{\mathrm{e}}_{2}$, with the termination atoms (tungsten or carbon termination) being investigated through density-functional theory calculations. The Moir\'e pattern heterostructure is found to exhibit greater energetic favorability when compared to coherent epitaxial strain heterostructures. Our analyses encompass an in-depth exploration of the interface structure, effective potential, electron localization function, Bader charge, energy bands, and density of states within these heterostructures. These investigations reveal the formation of Schottky barriers within these systems, with the dominant carrier type and height of the Schottky barriers being under the control of the termination atoms. Metal-induced gap states formed in the interfaces give rise to a strong Fermi-level pinning. We conclude that the WC/$\mathrm{WS}{\mathrm{e}}_{2}$ heterostructure with carbon terminations in WC have the smallest $p$-type Schottky-barrier height of 0.08 eV among all other heterostructures considered. Transport properties are assessed using the Simmons tunneling injection model. These findings yield valuable insights that can be leveraged in the design of high-performance nanoelectronic d built upon two-dimensional materials.