Thickness-Driven Modification of Interface States and Polarization Switching in MoTe₂/BaTiO₃ Heterostructures

Van der Waals (vdW) ferroelectric heterostructures provide a versatile platform for exploring interfacial interactions and advanced functionalities. Here, we report a thickness-engineered strategy to modulate the interfacial states and polarization switching in 2H-MoTe₂/BaTiO₃ (BTO) heterostructures. The interplay among band-alignment-induced charge transfer, polarization field, and defect-related traps governs the interfacial electronic structure. Remarkably, a two-unit-cell (u.c.) thickness variation (from 18 to 20 u.c.) in MoTe₂ induces a 0.44 eV work function shift, reversing the band alignments and interfacial doping polarity. This transition triggers a reversal of BTO polarization from P_up to P_down state, enabling deterministic and nondestructive polarization control. Electrical transport evolves from trap-assisted space-charge-limited conduction and thermionic emission to Fowler-Nordheim tunneling under strong polarization field, yielding robust multilevel nonvolatile memory characteristics. These results highlight thickness-controlled interfacial states as an effective route to tailor ferroelectric switching dynamics for nonvolatile memory and neuromorphic computing applications.