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Substrate impact on the thickness dependence of vibrational and optical properties of large area MoS2 produced by gold-assisted exfoliation.
- Source :
- Applied Physics Letters; 2021, Vol. 119 Issue 9, p1-6, 6p
- Publication Year :
- 2021
-
Abstract
- The gold-assisted exfoliation is a very effective method to produce large-area (cm<superscript>2</superscript>-scale) membranes of molybdenum disulfide (MoS<subscript>2</subscript>) for electronics. However, the strong MoS<subscript>2</subscript>/Au interaction, beneficial for the exfoliation process, has a strong impact on the vibrational and light emission properties of MoS<subscript>2</subscript>. Here, we report an atomic force microscopy, micro-Raman, and micro-photoluminescence (μ-PL) investigation of 2H-MoS<subscript>2</subscript> with variable thickness exfoliated on Au and subsequently transferred on an Al<subscript>2</subscript>O<subscript>3</subscript>/Si substrate. The E<subscript>2g</subscript>–A<subscript>1g</subscript> vibrational mode separation Δω (typically used to estimate MoS<subscript>2</subscript> thickness) exhibits an anomalous large value (Δω ≈ 21.2 cm<superscript>−1</superscript>) for monolayer (1L) MoS<subscript>2</subscript> on Au as compared to the typical one (Δω ≈ 18.5 cm<superscript>−1</superscript>) measured on 1L MoS<subscript>2</subscript> on Al<subscript>2</subscript>O<subscript>3</subscript>. Such substrate-related differences, explained in terms of tensile strain and p-type doping arising from the MoS<subscript>2</subscript>/Au interaction, were found to gradually decrease while increasing the number of MoS<subscript>2</subscript> layers. Furthermore, μ-PL spectra for 1L MoS<subscript>2</subscript> on Au exhibit a strong quenching and an overall redshift of the main emission peak at 1.79 eV, compared to the 1.84 eV peak for 1L MoS<subscript>2</subscript> on Al<subscript>2</subscript>O<subscript>3</subscript>. After PL spectra deconvolution, such redshift was explained in terms of a higher trion/exciton intensity ratio, probably due to the higher polarizability of the metal substrate, as well as to the smaller equilibrium distance at the MoS<subscript>2</subscript>/Au interface. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00036951
- Volume :
- 119
- Issue :
- 9
- Database :
- Complementary Index
- Journal :
- Applied Physics Letters
- Publication Type :
- Academic Journal
- Accession number :
- 152271385
- Full Text :
- https://doi.org/10.1063/5.0062106