EXPERIMENTAL AND THEORETICAL COMPARATIVE STUDY OF MONOLAYER AND BULK MOS2 UNDER COMPRESSION

1 DEL CORRO Elena
Co-authors:
2 MORALES-GARCIA Ángel 1,3 Peña-ALVAREZ Miriam 1 KAVAN Ladislav 1 KALBAC Martin 1 FRANK Otakar
Institutions:
1 J.Heyrovsky Institute of Physical Chemistry of the AS CR, v.v.i., Prague, Czech Republic, elena.delcorro@jh-inst.cas.cz
2 Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, Czech Republic
3 Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Spain
Conference:
7th International Conference on Nanomaterials - Research & Application, Hotel Voronez I, Brno, Czech Republic, EU, October 14th - 16th 2015
Proceedings:
Proceedings 7th International Conference on Nanomaterials - Research & Application
Pages:
45-50
ISBN:
978-80-87294-59-8
ISSN:
2694-930X
Published:
11th January 2016
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
20 views / 6 downloads
Abstract

Recently, a new family of 2D materials with exceptional optoelectronic properties has stormed into the scene of nanotechnology, the transition metal dichalcogenides (e.g., MoS2). In contrast with graphene, which is a zero band gap semiconductor, many of the single layered materials from this family show a direct band-gap in the visible range. This band-gap can be tuned by several factors, including the thickness of the sample; the transition from a direct to indirect semiconductor state takes place in MoS2 when increasing the number of layers from 1 towards the bulk. Applying strain/stress has been revealed as another tool for promoting changes in the electronic structure of these materials; however, only a few experimental works exist for MoS2. In this work we present a comparative study of single layered and bulk MoS2 subjected to direct out-of-plane compression, using high pressure anvil cells and monitoring with non-resonant Raman spectroscopy; accompanying the results with theoretical DFT studies. In the case of monolayer MoS2 we observe transitions from direct to indirect band-gap semiconductor and to semimetal, analogous to the transitions observed under hydrostatic pressure, but promoted at more accessible pressure ranges (~25 times lower pressure). For bulk MoS2, both regimes, hydrostatic and uniaxial, lead to the semimetallization at similar pressure values, around 30 GPa. Our calculations reveal different driving forces for the metallization in bulk and monolayer samples.

Keywords: Keywords: MoS2, High Pressure, Raman Spectroscopy, DFT Calculations, Optoelectronic Properties
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