Observation of the Ambient Effect in BTI Characteristics of Back-Gated Single Layer Graphene Field Effect Transistors

In this paper, the ambient doping effect on negative/positive bias temperature instability (NBTI/PBTI) of single layer graphene field effect transistors (FETs) is investigated. In ambient air, the ΔV th of NBTI is comparable with that of PBTI under the same stress voltage at room temperature. The ΔV th of NBTI appears insensitive to temperature, while the ΔV th of PBTI increases significantly with rising temperatures, due to the thermally activated charging of ambient doped defects at the graphene/SiO 2 interface. This effect also results in an abnormal recovery of NBTI. In an ambient vacuum, the ΔV th is much less than that in ambient air. In addition, the ΔV th of both NBTI and PBTI decreases substantially for higher temperatures in the vacuum. The adsorbed molecules are mainly responsible for the ΔV th under BTI stress and the back-gated graphene FETs in the air.