Versatile GeS-based CBRAM with compliance-current-controlled threshold and bipolar resistive switching for electronic synapses

•A CBRAM device with a structure stacking sequence of Ag/GeS/Pt/Ti/SiO2 is fabricated.•GeS-based CBRAM device exhibits the reversible CC-controlled transition between threshold resistive switching (T-RS) and bipolar resistive switching (B-RS).•The device exhibits B-RS behavior with excellent retention and highly reproducible endurance characteristics, illustrated by a very high ION/IOFF ratio of almost ∼2 × 108.•GeS-based CBRAM device in T-RS mode is investigated to perform important biological synaptic functions.