Chalcogen

Nanotechnology

Organic chemistry

Scanning transmission electron microscopy

Scanning tunneling microscope

Crystallography

Transition metal

Semiconductor

Epitaxy

Density functional theory

Catalysis

Transmission electron microscopy

Computational chemistry

Band gap

Chemical physics

Composite material

Crystallographic defect

Chemistry

Materials science

Annealing (glass)

Ab initio

Layer (electronics)

Molecular beam epitaxy

Monolayer

Optoelectronics

Biochemistry

Nature Communications

Chalcogen vacancies are generally considered to be the most common point defects in transition metal dichalcogenide (TMD) semiconductors because of their low formation energy in vacuum and their frequent observation in transmission electron microscopy studies. Consequently, unexpected optical, transport, and catalytic properties in 2D-TMDs have been attributed to in-gap states associated with chalcogen vacancies, even in the absence of direct experimental evidence. Here, we combine low-temperature non-contact atomic force microscopy, scanning tunneling microscopy and spectroscopy, and state-of-the-art ab initio density functional theory and GW calculations to determine both the atomic structure and electronic properties of an abundant chalcogen-site point defect common to MoSe

Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides