Effect of Electric Field on the Hysteresis and Switching Behavior of the MoS ₂ /Au(111) Heterojunction

It can be said that the interface is the device. A holistic understanding of interfacial interactions and electronic structure of 2D materials with electrodes is far from complete but is necessary for tailored electronic devices, including in memristors for neuromorphic computing. Here, we develop a computational protocol to study the hysteretic behavior and charge carrier transport mechanisms of the MoS₂/Au(111) junction under applied electric fields using first-principles calculations. We show that even in the absence of defects, formation of conducting bridges, or significant atomic reconstruction, the pristine MoS₂/Au(111) junction shows hysteresis in the induced polarization, the electron barrier heights, and the carrier transport. A primary finding from our calculations is the modulation of the Schottky barrier and electron tunneling barrier as a mechanism behind the resistive switching mechanism of the pristine MoS₂/Au(111) junction. We also show that changes of interfacial dipole moments with an external electric field contribute to the memory effect by lowering the electron barriers. Our results indicate that in the absence of defects, electric-field-induced relaxation of the interlayer spacing provides the means for spontaneous polarization. Based on this understanding of the MoS₂/Au(111) junction, we propose that a back-to-back double Schottky barrier ferroelectric tunnel junction diode can be used to phenomenologically model the characteristics of the MoS₂/Au(111) heterojunction. Our study has implications for revealing the physical origins of the onset of hysteretic properties of heterostructures based on low-dimensional materials, providing a more complete understanding of the mechanisms in resistive switching.