Probing the Mechanism for Bipolar Resistive Switching in Annealed Graphene Oxide Thin Films.

The bipolar resistive switching (BRS) between a metallic low resistance state (LRS) and an insulating high resistance state (HRS) is demonstrated for annealed graphene oxide (GO) thin film-based device structures with aluminum (Al) as one of the contact electrodes. An optimal switching of ∼104 order is recorded for Al/GO (200 °C)/indium tin oxide (ITO) among the device structures in metal (M2)/GO (T)/metal (M1) configurations (M1 = Al, Au, or ITO and M2 = Au or Al), fabricated using GO (T)/metal (M1), annealed at different temperatures, T = 100, 200, 300, and 400 °C. The initial Ohmic conduction for electronic transport and the presence of metal contents through GO thin films in the X-ray photoelectron spectroscopy support the physical evidence of Al filament formation between the two electrodes as imaged by the high-resolution transmission electron microscopy. The speculated mechanism for BRS in repeated voltage sweep cycles is attributed to the current triggered breaking of metal filaments because of the combined effect of Joule's heating and Peltier heat generation at LRS → HRS transition, and electric field induced migration of metal atoms, leading to the formation of metal filaments through the GO film at the HRS → LRS transition. The higher switching ratio exhibited in the current study could be translated to engineer simple and low-cost resistive memory devices.