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

TL;DR

This paper distinguishes between extrinsic and intrinsic hysteresis in graphene FETs on ferroelectric gates, enabling detection of electric dipole switching with high sensitivity through vacuum annealing and a proposed charge trapping model.

Contribution

It introduces a method to separate extrinsic and intrinsic hysteresis in GFETs on ferroelectric gates, revealing the dynamic electric dipole switch detection capability.

Findings

Hysteresis transition observed during vacuum annealing.

Detection sensitivity of around 212 dipoles/μm² at room temperature.

Successful modeling of charge trapping and pinning mechanisms.

Abstract

A transition in source-drain current vs back gate voltage ID - VBG characteristics from extrinsic polar molecule dominant hysteresis to anti-hysteresis induced by an oxygen deficient surface layer that is intrinsic to the ferroelectric thin films has been observed on graphene field-effect transistors on Pb0.92La0.08Zr0.52Ti0.48O3 gates GFET/PLZT-Gate during a vacuum annealing process developed to systematically remove the polar molecules adsorbed on the GFET channel surface. This allows detangle of the extrinsic and intrinsic hysteresis on GFET/PLZT-gate devices and detection of the dynamic switch of electric dipoles using GFETs, taking advantage of their high gating efficiency on ferroelectric gate. A model of the charge trapping and pinning mechanism is proposed to successfully explain the transition. In response to pulsed VBG trains of positive, negative, as well as alternating polarities, respectively, the source-drain current ID variation is instantaneous with the response amplitude following the ID - VBG loops measured by DC VBG with consideration of the remnant polarization after a given VBG pulse when the gate electric field exceeds the coercive field of the PLZT. A detection sensitivity of around 212 dipole/um2 has been demonstrated at room temperature, suggesting the GFET/ferroelectric-gate devices provide a promising high-sensitivity scheme for uncooled detection of electrical dipole dynamic switch.