Room Temperature Negative Differential Resistance with High Peak Current in MoS₂/WSe₂ Heterostructures

Two-dimensional transition metal dichalcogenide (2D TMD) semiconductors allow facile integration of p- and n-type materials without a lattice mismatch. Here, we demonstrate gate-tunable n- and p-type junctions based on vertical heterostructures of MoS₂ and WSe₂ using van der Waals (vdW) contacts. The p-n junction shows negative differential resistance (NDR) due to Fowler-Nordheim (F-N) tunneling through the triangular barrier formed by applying a global back-gate bias (V_GS). We also show that the integration of hexagonal boron nitride (h-BN) as an insulating tunnel barrier between MoS₂ and WSe₂ leads to the formation of sharp band edges and unintentional inelastic tunnelling current. The devices based on vdW contacts, global V_GS, and h-BN tunnel barriers exhibit NDR with a peak current (I_peak) of 315 μA, suggesting that the approach may be useful for applications.