A circuit model for defective bilayer graphene transistors

•Consistent bombardment the graphene channel with low radiation of Helium ions shows a degrade in the device characteristics.•Development of a SPICE compatible model and parameter extractions.•Investigation of the resulting current ratio against the number of exposures to Helium ions.

This paper investigates the behaviour of a defective single-gate bilayer graphene transistor. Point defects were introduced into pristine graphene crystal structure using a tightly focused helium ion beam. The transfer characteristics of the exposed transistors were measured ex-situ for different defect concentrations. The channel peak resistance increased with increasing defect concentration whilst the on–off ratio showed a decreasing trend for both electrons and holes. To understand the electrical behaviour of the transistors, a circuit model for bilayer graphene is developed which shows a very good agreement when validated against experimental data. The model allowed parameter extraction of bilayer transistor and can be implemented in circuit level simulators.