Optical Modulation of MoTe₂/Ferroelectric Heterostructure via Interface Doping

Optical modulation through interface doping offers a convenient and efficient way to control ferroelectric polarization, thereby advancing the utilization of ferroelectric heterostructures in nanoelectronic and optoelectronic devices. In this work, we fabricated heterostructures of MoTe₂/BaTiO₃/La_0.7Sr_0.3MnO₃ (MoTe₂/BTO/LSMO) and demonstrated opposite ultraviolet (UV) light-induced polarization switching behaviors depending on the varied thicknesses of MoTe₂. The thickness-dependent band structure of MoTe₂ film results in interface doping with opposite polarity in the respective heterostructures. The polarization field of BTO interacts with the interface charges, and an enhanced effective built-in field (E_bi) can trigger the transfer of massive UV light-induced carriers in both MoTe₂ and BTO films. As a result, the interplay among the contact field of MoTe₂/BTO, the polarization field, and the optically excited carriers determines the UV light-induced polarization switching behavior of the heterostructures. In addition, the electric transport characteristics of MoTe₂/BTO/LSMO heterostructures reveal the interface barrier height and E_bi under opposite polarization states, as well as the presence of inherent in-gap trap states in MoTe₂ and BTO films. These findings represent a further step toward achieving multifield modulation of the ferroelectric polarization and promote the potential applications in optoelectronic, logic, memory, and synaptic ferroelectric devices.