Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Strong asymmetric charge carrier dependence in inelastic electron tunneling spectroscopy of graphene phonons

Published

Author(s)

Donat F. Natterer, Yue Y. Zhao, Jonathan E. Wyrick, Yang-Hao Chan, Wen-Ying Ruan, Mei-Yin Chou, Kenji Watanabe, Takashi Taniguchi, Nikolai B. Zhitenev, Joseph A. Stroscio

Abstract

The observation of phonons in graphene by inelastic electron tunneling spectroscopy has been met with limited success in previous measurements arising from weak signals and other spectral features which inhibit a clear distinction between phonons and miscellaneous excitations. Utilizing a back-gated graphene device that allows adjusting the global charge carrier density, we introduce an averaging method where individual tunneling spectra at varying charge carrier density are combined into one representative spectrum. This method improves the signal for inelastic transitions while it suppresses dispersive spectral features. We thereby map the total graphene phonon density of states, in good agreement with density functional calculations. Unexpectedly, an abrupt change in the phonon intensity is observed when the graphene charge carrier type is switched through a variation of the back-gate electrode potential. This sudden variation in phonon intensity is asymmetric in the carrier type, depending on the sign of the tunneling bias.
Citation
Physical Review Letters
Volume
114
Issue
24

Keywords

graphene, phonons, scanning tunneling microscopy, scanning tunneling spectroscopy

Citation

Natterer, D. , Zhao, Y. , Wyrick, J. , Chan, Y. , Ruan, W. , Chou, M. , Watanabe, K. , Taniguchi, T. , Zhitenev, N. and Stroscio, J. (2015), Strong asymmetric charge carrier dependence in inelastic electron tunneling spectroscopy of graphene phonons, Physical Review Letters, [online], https://doi.org/10.1103/PhysRevLett.114.245502 (Accessed May 22, 2022)
Created June 16, 2015, Updated November 10, 2018