Resistance Switching of Janus MoSSe-Bilayer-Based Ferroelectric Tunnel Junctions by Lateral Sliding versus Vertical Displacement

The two-dimensional (2D) Janus van der Waals (vdW) materials possess ferroelectricity due to inborn out-of-plane symmetry breaking such as 2D Janus transition-metal dichalcogenides (TMDs). Furthermore, "slidetronics" also shows us that the lateral sliding of two parallel-stacked 2D vdW layers can realize out-of-plane electric polarization. The Janus MoSSe monolayer was stacked in three modes to generate MoSSe bilayers referring to its parent MoS2, and their sliding ferroelectricity was systematically studied by using the first-principles calculations. Our calculations also reveal that vertical displacement can consume similar energies to realize out-of-plane polarizations for MoSSe bilayers. The current density–voltage curves of two-terminal MoS2/MoSSe-bilayer-based ferroelectric tunnel junctions were estimated by using the nonequilibrium Green's function method to judge their resistance switching capability. The 2D Janus vdW materials behave excellently like their nonferroelectric parents to fabricate low-power-consumption and high-speed data-reading-and-writing ferroelectric tunnel junctions.