Charge transfer and trapping as origin of a double dip in the transfer characteristics of graphene based field-effect transistors

TL;DR

This paper investigates the origin of a double dip in graphene FET transfer characteristics, attributing it to charge transfer and trapping effects at the contacts and interface, and proposes a comprehensive model.

Contribution

It introduces a model explaining the double dip phenomenon in graphene FETs based on charge transfer, trapping, and partial charge pinning effects.

Findings

Double dip arises from charge transfer between graphene and metal electrodes.

Charge trapping at the graphene/SiO2 interface enhances the double dip.

The proposed model explains all features observed in gate voltage loops.

Abstract

We discuss the origin of an additional dip other than the charge neutrality point observed in transfer characteristics of graphene-based field-effect transistors. The double-dip is proved to arise from charge transfer between graphene and metal electrodes, while charge storage at the graphene/SiO2 interface enhances it. Considering different Fermi energy from the neutrality point along the channel and partial charge pinning at the contacts, we propose a model which explains all features in gate voltage loops.