Abstract

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 MoSe2 and WS2 monolayers grown by molecular beam epitaxy and chemical vapor deposition, respectively. Surprisingly, we observe no in-gap states. Our results strongly suggest that the common chalcogen defects in the described 2D-TMD semiconductors, measured in vacuum environment after gentle annealing, are oxygen substitutional defects, rather than vacancies.

Details

Title
Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides
Author
Barja, Sara 1 ; Refaely-Abramson, Sivan 2 ; Schuler, Bruno 3   VIAFID ORCID Logo  ; Qiu, Diana Y 4 ; Pulkin, Artem 5 ; Wickenburg, Sebastian 3 ; Ryu, Hyejin 6 ; Ugeda, Miguel M 7 ; Kastl, Christoph 3 ; Chen, Christopher 3 ; Hwang, Choongyu 8 ; Schwartzberg, Adam 3 ; Aloni, Shaul 3 ; Sung-Kwan, Mo 9   VIAFID ORCID Logo  ; Ogletree, D Frank 3   VIAFID ORCID Logo  ; Crommie, Michael F 10   VIAFID ORCID Logo  ; Yazyev, Oleg V 5   VIAFID ORCID Logo  ; Louie, Steven G 4   VIAFID ORCID Logo  ; Neaton, Jeffrey B 11 ; Weber-Bargioni, Alexander 3 

 Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain; Donostia International Physics Center, Donostia-San Sebastián, Spain 
 Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, USA; Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel 
 Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA 
 Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA 
 Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland 
 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; Center for Spintronics, Korea Institute of Science and Technology, Seoul, Korea 
 Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain; Donostia International Physics Center, Donostia-San Sebastián, Spain 
 Department of Physics, Pusan National University, Busan, Korea 
 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA 
10  Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, USA; Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA, USA 
11  Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; Department of Physics, University of California at Berkeley, Berkeley, Berkeley, CA, USA; Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA, USA 
Pages
1-8
Publication year
2019
Publication date
Jul 2019
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2266312257
Copyright
© 2019. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.