Fig. 3: Analog memristor behaviors.
From: Enhanced analog synaptic behavior of SiNx/a-Si bilayer memristors through Ge implantation

Memristor currents under five consecutive DC voltage sweeps of a SiNx/a-Si memristor device a without implantation and b with implantation. Voltage and current curves of a, b in temporal space for c the unimplanted and d implanted devices (V–I–t curves).