Abstract
Transition Metal Dichalcogenides TMDs MoX2 (X=S, Se, Te) are an emergent class of layered materials displaying exciting optoelectronic properties which can be modified by varying the number of layers, by intercalation, or by applying an external strain/compression. In particular, these semiconducting materials can get a band gap closure under pressure and enter in a metallic phase. Here, we investigate the optical properties of MoSe2 under high pressure by means of Raman spectroscopy over a wide pressure range (0-30 GPa). No anomaly has been observed in the pressure dependence of the frequencies of the vibrational modes A1g, E12g (Raman first order) and E1g - E22g (Raman second-order), in agreement with the absence previously reported of any pressure induced structural transition. Interestingly, our detailed line-shape analysis show a clear anomaly in the pressure behavior of the linewidth of the A1g and E12g phonons at the insurgent metallization process which was observed in previous infrared and transport experiments. Our results indicate that the linewidths of Raman phonons peaks can be sensitive to even subtle pressure-induced electronic rearrangements and can thus be used to monitor the insurgence of a pressure-induced semiconductor-metal transition.
Highlights
Graphene-like two-dimensional (2D) materials such as layered Transition Metal Dichalcogenides (TMD) attract a lot of interest because of their extraordinary physical and chemical properties, tunable in particular by varying number of layers, thermodynamic conditions (P,T) and doping [1]
No anomaly has been observed in the pressure dependence of the frequencies of the vibrational modes A1g, E12g (Raman first order) and E1g - E22g (Raman second-order), in agreement with the absence previously reported of any pressure induced structural transition
Our detailed line-shape analysis show a clear anomaly in the pressure behavior of the linewidth of the A1g and E12g phonons at the insurgent metallization process which was observed in previous infrared and transport experiments
Summary
Graphene-like two-dimensional (2D) materials such as layered Transition Metal Dichalcogenides (TMD) attract a lot of interest because of their extraordinary physical and chemical properties, tunable in particular by varying number of layers, thermodynamic conditions (P,T) and doping [1]. Semiconducting TMDs belonging to the family of the MoX2 compounds (X=S, Se, Te) are layered materials built up of a stacking of X-Mo-X layers [2], consisting of three hexagonal planes, two made by X atoms and one of Mo atoms in between. Within this three-layers structure, Mo is coordinated through covalent interactions with the X atoms in a trigonal prismatic arrangement (symmetry group: P63/mmc).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
