Atomic Threshold Switch Based on All‐2D Material Heterostructures with Excellent Control Over Filament Growth and Volatility

Abstract This report demonstrates that atomic‐level controlled formation/rupture of conductive filaments using all 2D heterostructure of hBN‐graphene is a feasible way to achieve excellent switching characteristics for ideal atomic switches. At a threshold voltage, graphene with stable ion migration routes forms a few atom comprising Ag filaments in hBN, which subsequently spontaneously break as the applied voltage lowers, resulting in optimal threshold switching behavior in an hBN atomic switch. The hBN‐graphene atomic threshold switch maintains volatile threshold switching behavior in a wide range of operating currents (10 nA – 100 µA), has an extremely high on/off ratio > 10⁸, ultralow leakage current < 1 pA and exceptionally rapid switching (≈70 ns). Ionic transport of Ag⁺ through graphene can avoid the migration of excessive Ag atoms into single layer hBN during operations. As a result, the growth of conductive filaments is stable and protected from atomic defects widening in hBN. The novel findings of this study show that the scaling layer thickness can reach the physical limit of vertical thickness scaling to accommodate the single‐atom volume of silver (≈0.257 nm) when using hBN, and a single‐atom‐thick ionic barrier made of graphene can be used to control switching.