Temperature Dependence of Optical Properties of MoS<sub>2</sub> and WS<sub>2</sub> Heterostructures Assessed by Spectroscopic Ellipsometry

Temperature Dependence of Optical Properties of MoS<sub>2</sub> and WS<sub>2</sub> Heterostructures Assessed by Spectroscopic Ellipsometry

We report the complex dielectric function <i>ε</i> = <i>ε</i><sub>1</sub> + <i>iε</i><sub>2</sub> of MoS<sub>2</sub>/WS<sub>2</sub> and WS<sub>2</sub>/MoS<sub>2</sub> heterostructures and thei...

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Bibliographic Details
Main Authors:	Hoang Tung Nguyen, Van Long Le, Thi Mai Nguyen, Xuan Khuyen Bui, Thi Giang Nguyen, Nhat Linh Nguyen, Xuan Au Nguyen, Tae Jung Kim
Format:	Article
Language:	English
Published:	MDPI AG 2025-01-01
Series:	Nanomaterials
Subjects:	MoS<sub>2</sub> and WS<sub>2</sub> heterostructures spectroscopic ellipsometry dielectric function temperature dependence critical point exciton
Online Access:	https://www.mdpi.com/2079-4991/15/1/76
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Summary:	We report the complex dielectric function <i>ε</i> = <i>ε</i><sub>1</sub> + <i>iε</i><sub>2</sub> of MoS<sub>2</sub>/WS<sub>2</sub> and WS<sub>2</sub>/MoS<sub>2</sub> heterostructures and their constituent monolayers MoS<sub>2</sub> and WS<sub>2</sub> for an energy range from 1.5 to 6.0 eV and temperatures from 39 to 300 K. Comparisons between the optical properties of the heterostructures and their monolayers were conducted. Critical-point (CP) energies of the heterostructures were traced back to their origins in the monolayers. Low-temperature measurements confirmed the existence of only three excitonic CPs from 1.5 to 2.5 eV due to the overlap of trion <i>B</i><sup>−</sup> of the MoS<sub>2</sub> monolayer and exciton <i>A</i><sup>0</sup> of the WS<sub>2</sub> monolayer. Due to the dielectric screening effect, most CPs exhibit red shifts in the heterostructures compared to their monolayer counterparts.
ISSN:	2079-4991