Resistive Switching Observation in a Gallium-Based Liquid Metal/Graphene Junction

Resistive switching effect is observed for a gallium–indium/gallium oxide/graphene junction. The use of a gallium-based liquid metal (LM) alloy, in this case, the eutectic gallium–indium with its native gallium oxide skin, directly provides the metal top contact and the oxide layer needed to fabricate a memory. Graphene is used as the bottom electrode due to its electrical properties and, importantly, because it prevents the formation of alloys, leading to a stable simple junction. With this structure, the ON/OFF ratio at 0.5 V between the high resistance state (HRS) and low resistance state (LRS) reached is ∼104 under ambient conditions. Deposition of an additional switching layer is not needed compared to other resistive random access memories [RRAMs], which makes this system less complex to fabricate. The migration of the oxygen atoms of the oxide layer would be intuitively considered the main reason for the modulation of the tunneling junction resistance, but we suggest that this is not the case and instead of that, charge trapping/detrapping at the very interface may dominate the switching function.