Observation of the ambient effect in BTI characteristics of back-gated single layer graphene field effect transistors

Abstract

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 ΔVth of NBTI is comparable with that of PBTI under the same stress voltage at room temperature. The ΔVth of NBTI appears insensitive to temperature, while the ΔVth of PBTI increases significantly with rising temperatures, due to the thermally activated charging of ambient doped defects at the graphene/SiO2 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 ΔVth of both NBTI and PBTI decreases substantially for higher temperatures in the vacuum. The adsorbed molecules are mainly responsible for the ΔVth under BTI stress and the back-gated graphene FETs in the air. © 1963-2012 IEEE.