Optical properties of atomically thin transition metal dichalcogenides: observations and puzzles

• Published in: Nanophotonics (Berlin, Germany) Vol. 6; no. 6; pp. 1289 - 1308
• Main Authors: Koperski, Maciej, Molas, Maciej R., Arora, Ashish, Nogajewski, Karol, Slobodeniuk, Artur O., Faugeras, Clement, Potemski, Marek
• Format: Journal Article
• Language: English
• Published: Berlin De Gruyter 01.11.2017; Walter de Gruyter GmbH
• Subjects: atomically-thin transition metal dicalcogenides; Band structure of solids; Boron nitride; Chalcogenides; electronic bands and optical properties; Emitters; Layered materials; optical orientation; Optical properties; Optical pumping; single photon emitters; Zeeman spectroscopy
• ISSN: 2192-8614; 2192-8606; 2192-8614
• DOI: 10.1515/nanoph-2016-0165

Recent results on the optical properties of monolayer and few layers of semiconducting transition metal dichalcogenides are reviewed. Experimental observations are presented and discussed in the frame of existing models, highlighting the limits of our understanding in this emerging field of research. We first introduce the representative band structure of these systems and their interband optical transitions. The effect of an external magnetic field is then considered to discuss Zeeman spectroscopy and optical pumping experiments, both revealing phenomena related to the valley degree of freedom. Finally, we discuss the observation of single photon emitters in different types of layered materials, including wide band gap hexagonal boron nitride. While going through these topics, we try to focus on open questions and on experimental observations, which do not yet have a clear explanation.