Global strain-induced scalar potential in graphene devices

Takashi Taniguchi,Lujun Wang,David I. Indolese,Kenji Watanabe,Blesson Sam Varghese,Simon Zihlmann,Andreas Baumgartner,Christian Schönenberger,Péter Makk

doi:10.1038/s42005-021-00651-y

Abstract

By mechanically distorting a crystal lattice it is possible to engineer the electronic and optical properties of a material. In graphene, one of the major effects of such a distortion is an energy shift of the Dirac point, often described as a scalar potential. We demonstrate how such a scalar potential can be generated systematically over an entire electronic device and how the resulting changes in the graphene work function can be detected in transport experiments. Combined with Raman spectroscopy, we obtain a characteristic scalar potential consistent with recent theoretical estimates. This direct evidence for a scalar potential on a macroscopic scale due to deterministically generated strain in graphene paves the way for engineering the optical and electronic properties of graphene and similar materials by using external strain.

Highlights

By mechanically distorting a crystal lattice it is possible to engineer the electronic and optical properties of a material
The predicted strain effects in the low-energy band structure of graphene can be summarized as changes in the magnitude and isotropy of the Fermi velocity and in the density of states[5,6,7,8], shifts in the energy of the Dirac point, which is typically incorporated as a scalar potential[6,8,9], and changes in the position of the Dirac cone in the twodimensional Brillouin zone, often described by a pseudo-vector potential acting on the valley degree of freedom[9,10,11,12,13,14]
We find that all investigated transport characteristics are shifted systematically in gate voltage, qualitatively and quantitatively consistent with the expectations for the scalar potential generated by the applied strain, where the strain values are confirmed by separate Raman spectroscopy experiments

Summary

Introduction

By mechanically distorting a crystal lattice it is possible to engineer the electronic and optical properties of a material. One of the major effects of such a distortion is an energy shift of the Dirac point, often described as a scalar potential We demonstrate how such a scalar potential can be generated systematically over an entire electronic device and how the resulting changes in the graphene work function can be detected in transport experiments. Combined with Raman spectroscopy, we obtain a characteristic scalar potential consistent with recent theoretical estimates This direct evidence for a scalar potential on a macroscopic scale due to deterministically generated strain in graphene paves the way for engineering the optical and electronic properties of graphene and similar materials by using external strain. We find that all investigated transport characteristics are shifted systematically in gate voltage, qualitatively and quantitatively consistent with the expectations for the scalar potential generated by the applied strain, where the strain values are confirmed by separate Raman spectroscopy experiments

Methods

Results

Conclusion