Adjustable embedded selectors in a ferroelectric LiNbO3 domain-wall memory

The interfacial layers appearing in low-dimensional ferroelectric devices due to polarization fluctuations near electrodes could destabilize spontaneous polarizations and reduce dielectric permittivity significantly. But they can conversely work as embedded selectors in high-density ferroelectric LiNbO3 crossbar memories when the interfacial domains are volatile. In contrast, the digital data stored in the nearby intrinsic domains are nonvolatile. The stored data can be nondestructively read out through on/off currents following through erasable conducting domain walls between two antiparallel/parallel domains. However, the intrinsic physics how to adjust the onset voltage of the selector is still unclear. Here, we fabricated the mesa-like cell in contact with two side electrodes at the surface of a monodomain LiNbO3 single crystal and found the selection functionality of the interfacial layer near the head of the pristine domain. The onset voltage of the selector proportional to the interfacial-layer thickness can be continuously modulated by the tilted angle of the electrode projected along the domain orientation, unlike the electrode in the tail that cannot change the onset voltage. It is believed that the volatile domain within the interfacial layer arises from an imprint field built up by trapped electrons in compensation of the opposite domain boundary charge near the head. The designed electrode geometry provides guidance to integrate the high-density LiNbO3 crossbar memory.