Improved electrical contact to multilayer MoS₂-based field-effect transistor by tunable tellurium substitutional doping via MOCVD

Electrical metal contacts with two-dimensional transition metal dichalcogenides (2D TMDs)-based field-effect transistors (FETs) remain a critical challenge because of their high contact resistance, which primarily results from the Schottky barrier, poor interface quality, and Fermi level pinning. Enhancing the contact properties of 2D TMDs using controllable doping techniques is vital for next-generation nanoscale devices. In this study, we fabricated quantitatively controllable substitutional tellurium-doped molybdenum disulfide (Te-MoS₂) via metal-organic chemical vapor deposition. The fabricated Te-MoS₂ FET exhibits a contact resistance (R_C) of 89.3 kΩ∙μm and Schottky barrier height (SBH) values of 38.35 meV. This significant reduction in R_C is attributed to the high hole carrier density, which leads to enhanced charge-screening effects and a notable reduction in Schottky barrier width. The top-gate structure of Te-MoS₂ FET using an ion–gel dielectric exhibited ambipolar behavior, with increased p-type conductivity when compared to n-type characteristic of pristine MoS₂. Te-MoS₂ FET showed tunable channel currents and threshold voltage (V_th) shifts. Furthermore, the responsivity of the Te-MoS₂-based photodetector device recorded 1.5 A/mW, an 11-fold improvement over pristine MoS₂. This doping strategy effectively addresses contact issues between metal electrodes and 2D TMDs and offers potential applications in 2D TMD-based nanoelectronic and optoelectronic devices.