Ar ion plasma surface modification on the heterostructured TaOx/InGaZnO thin films for flexible memristor synapse

The enhanced resistive switching (RS) characteristics of the flexible TaOx/InGaZnO (IGZO)-based bilayer memristor deposited on the polyethylene terephthalate (PET) substrate are demonstrated in the Ti/TaOx/IGZO/Pt heterostructure. The Ar ion (Ar+) plasma treatment was intentionally induced on the surface of TaOx/IGZO thin films to improve RS filament consistency and results displayed the improved uniform RS behavior of the plasma-treated device. Further, this device is investigated as an artificial electronic synapse and important synaptic functions such as long term potentiation (LTP), long term depression (LTD), paired-pulse facilitation (PPF), post-tetanic potential (PTP) and spike-timing dependent plasticity (STDP) characteristics are well emulated and analogues to the biological synapse behavior. The bending test to assess influence of stress/strain induction on the RS properties is also demonstrated. Further, bulk and angle-resolved x-ray photoelectron spectroscopy (XPS) is utilized to shed a light on the influence of Ar+ plasma on the surface of TaOx/IGZO thin films, as well as AFM analysis, and this insight is argued in the elaborated RS mechanism discussion.