Affordable Access

deepdyve-link
Publisher Website

Gating electron-hole asymmetry in twisted bilayer graphene.

Authors
  • Yeh, Chao-Hui
  • Lin, Yung-Chang
  • Chen, Yu-Chen
  • Lu, Chun-Chieh
  • Liu, Zheng
  • Suenaga, Kazu
  • Chiu, Po-Wen
Type
Published Article
Journal
ACS Nano
Publisher
American Chemical Society
Publication Date
Jul 22, 2014
Volume
8
Issue
7
Pages
6962–6969
Identifiers
DOI: 10.1021/nn501775h
PMID: 24999754
Source
Medline
License
Unknown

Abstract

Electron-hole symmetry is one of the unique properties of graphene that is generally absent in most semiconductors because of the different conduction and valence band structures. Here we report on the manipulation of electron-hole symmetry in the low-energy band structure of twisted bilayer graphene, where symmetric saddle points form in the conduction and valence bands as a result of interlayer coupling. By applying a gate voltage to a twisted bilayer with a critical rotation angle, enhanced electron resonance between the two saddle points can be turned on or off, depending on the electron-hole symmetry near the saddle points. The appearance of a 2D(+) peak, a gate-tunable Raman feature found near the critical angle, indicates a reduction of Fermi velocity in the vicinity of the saddle point to/from which electrons are inelastically scattered by phonons in the round trip of the double-resonance process.

Report this publication

Statistics

Seen <100 times