Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session L57: 2D Electron Devices and Transport
8:00 AM–11:00 AM,
Wednesday, March 4, 2020
Room: Mile High Ballroom 3A
Sponsoring
Unit:
APS
Abstract: L57.00008 : Controlling optoelectronic properties of 2D semiconductors: band engineering and moiré superlattices.
Presenter:
Roman Gorbachev
(University of Manchester)
Author:
Roman Gorbachev
(University of Manchester)
the possibility of manipulating their physical properties via controlled composition, order
and relative rotation of adjacent atomic planes. In this talk I will review our recent progress
working with semiconducting 2D materials. I will start with discussing InSe, 2D material with high
electronic quality and interesting optoelectronic properties. When placed on graphene, its valence
band hybridize with graphene bands producing avoided crossing. This effect occurs in the second
Brillouin zone, however significant reconstruction of the electronic spectrum is observed in the first
Brillouin zone, where no actual band crossing happens though Umklapp reflection.
In the second topic covered, I will discuss how direct Gamma-Gamma optical transitions can be
engineered by combining indirect materials, such as few-layer TMDs with InSe. This can boost the
efficiency of light emission and opens a pathway for high tuneability of emission wavelength,
reaching down to 0.8 eV telecommunication range.
Lastly, I will report our latest work on twisted TMDs, describing atomic reconstruction with TEM
measurements. For 3R stacking, a tessellated pattern of mirror reflected triangular 3R
domains merges, separated by a network of partial dislocations for the twist angles < 2o. The
electronic properties of these 3R domains appear qualitatively different from 2H TMDs,
featuring layer-polarized conduction band states caused by lack of both inversion and mirror
symmetry. In contrast, for 2H stacking, stable 2H domains dominate, with nuclei of a second
metastable phase. This appears as a kagome-like pattern at, transitioning at to a hexagonal
array of screw dislocations separating large-area 2H domains. The tunnelling measurements
show that such reconstruction creates strong piezoelectric textures, opening a new avenue
for engineering of 2D material properties.
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