<p>The development of nanoscale diodes with controllable charge transport and negative differential resistance (NDR) characteristics remains a key challenge in future electronics. In planar superlattices based on two-dimensional materials such as monolayer transition metal dichalcogenides (ML-TMDCs), precise structural parameter control for optimized device performance has not yet to be fully explored. In this study, using an extended transfer matrix method and the Landauer–Büttiker formalism, we analyze the carrier transport behavior and NDR features of a planar superlattice diode composed of WSe₂ and MoS₂ monolayers, which offers a promising platform for next-generation nanoelectronic devices. Our results indicate that the observed NDR behavior is primarily driven by resonant tunneling phenomena and strongly depends on structural parameters such as layer widths, unitcell size, and applied bias voltage. Furthermore, increasing the number of unitcells modifies the carrier transmission probability due to quantum interference effects, which in turn influences the current–voltage response. The ability to engineer the band structure through precise control of layer dimensions opens new opportunities for tunable nanoelectronic applications.</p>