Ferroelectrically driven spatial carrier density modulation in graphene.

Christoph Baeumer,Diomedes Saldana-Greco,John Mark P Martirez,Moonsub Shim,Lane W Martin,Andrew M Rappe

doi:10.1038/ncomms7136

Abstract

The next technological leap forward will be enabled by new materials and inventive means of manipulating them. Among the array of candidate materials, graphene has garnered much attention; however, due to the absence of a semiconducting gap, the realization of graphene-based devices often requires complex processing and design. Spatially controlled local potentials, for example, achieved through lithographically defined split-gate configurations, present a possible route to take advantage of this exciting two-dimensional material. Here we demonstrate carrier density modulation in graphene through coupling to an adjacent ferroelectric polarization to create spatially defined potential steps at 180°-domain walls rather than fabrication of local gate electrodes. Periodic arrays of p-i junctions are demonstrated in air (gate tunable to p-n junctions) and density functional theory reveals that the origin of the potential steps is a complex interplay between polarization, chemistry, and defect structures in the graphene/ferroelectric couple.

Highlights

The technological leap forward will be enabled by new materials and inventive means of manipulating them
Experimental observations of charge density modulation in graphene/LiNbO3 couples qualitatively match the intuitive picture of compensation of the ferroelectric polarization that should lead to n- or p-doping for ferroelectric polarization pointing towards or away from graphene, respectively
To simulate the experimental observations, we include in the model all the intrinsic influences on the interfacial chemistry, including the polar stacking, ferroelectric polarization, surface reconstruction, and sample history, yielding an upper limit for the expected carrier density modulation

Summary

Introduction

The technological leap forward will be enabled by new materials and inventive means of manipulating them. To simulate the experimental observations, we include in the model all the intrinsic influences on the interfacial chemistry, including the polar stacking, ferroelectric polarization, surface reconstruction, and sample history, yielding an upper limit for the expected carrier density modulation.

Results

Conclusion