Detangling Extrinsic and Intrinsic Hysteresis for Detecting Dynamic Switch of Electric Dipoles using Graphene Field-Effect Transistors on Ferroelectric Gates

摘要

A transition in source-drain current vs back gate voltage ID - VBGcharacteristics from extrinsic polar molecule dominant hysteresis toanti-hysteresis induced by an oxygen deficient surface layer that is intrinsicto the ferroelectric thin films has been observed on graphene field-effecttransistors on Pb0.92La0.08Zr0.52Ti0.48O3 gates GFET/PLZT-Gate during a vacuumannealing process developed to systematically remove the polar moleculesadsorbed on the GFET channel surface. This allows detangle of the extrinsic andintrinsic hysteresis on GFET/PLZT-gate devices and detection of the dynamicswitch of electric dipoles using GFETs, taking advantage of their high gatingefficiency on ferroelectric gate. A model of the charge trapping and pinningmechanism is proposed to successfully explain the transition. In response topulsed VBG trains of positive, negative, as well as alternating polarities,respectively, the source-drain current ID variation is instantaneous with theresponse amplitude following the ID - VBG loops measured by DC VBG withconsideration of the remnant polarization after a given VBG pulse when the gateelectric field exceeds the coercive field of the PLZT. A detection sensitivityof around 212 dipole/um2 has been demonstrated at room temperature, suggestingthe GFET/ferroelectric-gate devices provide a promising high-sensitivity schemefor uncooled detection of electrical dipole dynamic switch.