Giant electroresistive ferroelectric diode on 2DEG

Manipulation of electrons in a solid through transmitting, storing, and switching is the fundamental basis for the microelectronic devices. Recently, the electroresistance effect in the ferroelectric capacitors has provided a novel way to modulate the electron transport by polarization reversal. Here, we demonstrate a giant electroresistive ferroelectric diode integrating a ferroelectric capacitor into two-dimensional electron gas (2DEG) at oxide interface. As a model system, we fabricate an epitaxial Au/Pb(Zr_0.2Ti_0.8)O₃/LaAlO₃/SrTiO₃ heterostructure, where 2DEG is formed at LaAlO₃/SrTiO₃ interface. This device functions as a two-terminal, non-volatile memory of 1 diode-1 resistor with a large I₊/I_- ratio (>10⁸ at ±6 V) and I_on/I_off ratio (>10⁷). This is attributed to not only Schottky barrier modulation at metal/ferroelectric interface by polarization reversal but also the field-effect metalinsulator transition of 2DEG. Moreover, using this heterostructure, we can demonstrate a memristive behavior for an artificial synapse memory, where the resistance can be continuously tuned by partial polarization switching, and the electrons are only unidirectionally transmitted. Beyond non-volatile memory and logic devices, our results will provide new opportunities to emerging electronic devices such as multifunctional nanoelectronics and neuromorphic electronics.