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Visualizing electrostatic gating effects in two-dimensional heterostructures.

Authors :
Nguyen PV
Teutsch NC
Wilson NP
Kahn J
Xia X
Graham AJ
Kandyba V
Giampietri A
Barinov A
Constantinescu GC
Yeung N
Hine NDM
Xu X
Cobden DH
Wilson NR
Source :
Nature [Nature] 2019 Aug; Vol. 572 (7768), pp. 220-223. Date of Electronic Publication: 2019 Jul 17.
Publication Year :
2019

Abstract

The ability to directly monitor the states of electrons in modern field-effect devices-for example, imaging local changes in the electrical potential, Fermi level and band structure as a gate voltage is applied-could transform our understanding of the physics and function of a device. Here we show that micrometre-scale, angle-resolved photoemission spectroscopy <superscript>1-3</superscript> (microARPES) applied to two-dimensional van der Waals heterostructures <superscript>4</superscript> affords this ability. In two-terminal graphene devices, we observe a shift of the Fermi level across the Dirac point, with no detectable change in the dispersion, as a gate voltage is applied. In two-dimensional semiconductor devices, we see the conduction-band edge appear as electrons accumulate, thereby firmly establishing the energy and momentum of the edge. In the case of monolayer tungsten diselenide, we observe that the bandgap is renormalized downwards by several hundreds of millielectronvolts-approaching the exciton energy-as the electrostatic doping increases. Both optical spectroscopy and microARPES can be carried out on a single device, allowing definitive studies of the relationship between gate-controlled electronic and optical properties. The technique provides a powerful way to study not only fundamental semiconductor physics, but also intriguing phenomena such as topological transitions <superscript>5</superscript> and many-body spectral reconstructions under electrical control.

Details

Language :
English
ISSN :
1476-4687
Volume :
572
Issue :
7768
Database :
MEDLINE
Journal :
Nature
Publication Type :
Academic Journal
Accession number :
31316202
Full Text :
https://doi.org/10.1038/s41586-019-1402-1