Remote Surface Optical Phonon Scattering in Ferroelectric Ba$_{0.6}$Sr$_{0.4}$TiO$_{3}$ Gated Graphene

TL;DR

This study investigates how remote surface optical phonon scattering affects carrier mobility in ferroelectric-gated graphene, revealing a fundamental mobility limit at room temperature due to RSO phonons.

Contribution

It provides the first detailed analysis of RSO phonon modes in Ba0.6Sr0.4TiO3 and their impact on graphene mobility, combining fabrication, spectroscopy, and transport measurements.

Findings

Achieved high mobility of 23,000 cm^2V^{-1}s^{-1} in graphene transistors

Identified RSO phonon mode at 35.8 meV as dominant scattering source

Established RSO phonon scattering as the fundamental mobility limit at room temperature

Abstract

We report the effect of remote surface optical (RSO) phonon scattering on carrier mobility in monolayer graphene gated by ferroelectric oxide. We fabricate monolayer graphene transistors back-gated by epitaxial (001) Ba$_{0.6}$Sr$_{0.4}$TiO$_{3}$ films, with field effect mobility up to 23,000 cm$^{2}$V$^{-1}$s$^{-1}$ achieved. Switching the ferroelectric polarization induces nonvolatile modulation of resistance and quantum Hall effect in graphene at low temperatures. Ellipsometry spectroscopy studies reveal four pairs of optical phonon modes in Ba$_{0.6}$Sr$_{0.4}$TiO$_{3}$, from which we extract the RSO phonon frequencies. The temperature dependence of resistivity in graphene can be well accounted for by considering the scattering from the intrinsic longitudinal acoustic phonon and the RSO phonon, with the latter dominated by the mode at 35.8 meV. Our study reveals the room temperature mobility limit of ferroelectric-gated graphene transistors imposed by RSO phonon scattering.