High-Mobility Few-Layer Graphene Field Effect Transistors Fabricated on Epitaxial Ferroelectric Gate Oxides

TL;DR

Replacing SiO2 with epitaxial PZT substrates significantly enhances the carrier mobility in few-layer graphene transistors, approaching the intrinsic phonon-limited limit and demonstrating the impact of ferroelectric gate oxides on device performance.

Contribution

This work demonstrates a ten-fold increase in graphene mobility using epitaxial ferroelectric PZT substrates, approaching the phonon-limited transport regime.

Findings

Mobility reaches 7x10^4 cm^2/Vs at room temperature

Mobility increases to 1.4x10^5 cm^2/Vs at low temperature

LA phonon scattering signature observed in resistivity data

Abstract

The carrier mobility \mu of few-layer graphene (FLG) field-effect transistors increases ten-fold when the SiO_2 substrate is replaced by single-crystal epitaxial Pb(Zr_0.2Ti_0.8)O_3 (PZT). In the electron-only regime of the FLG, \mu reaches 7x10^4 cm^2/Vs at 300K for n = 2.4x10^12/cm^2, 70% of the intrinsic limit set by longitudinal acoustic (LA) phonons; it increases to 1.4x10^5 cm^2/Vs at low temperature. The temperature-dependent resistivity \rho(T) reveals a clear signature of LA phonon scattering, yielding a deformation potential D = 7.8+/-0.5 eV.