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Ripples and layers in ultrathin MoS2 membranes
Jacopo Brivio1, Duncan T L Alexander, Andras Kis
1Electrical Engineering Institute and Interdisciplinary Center for Electron Microscopy (CIME), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Nano Letters
|October 21, 2011
Summary
Single-layer molybdenum disulfide (MoS2) shows long-range crystalline order but has ripples, similar to graphene. These ripples may affect MoS2
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Single-layer molybdenum disulfide (MoS2) is a promising 2D semiconductor for nanoelectronics and energy harvesting.
- Its properties are highly dependent on its crystalline structure and order at the ultrathin limit.
Purpose of the Study:
- To investigate the structural and morphological properties of suspended single- and few-layer MoS2 membranes using transmission electron microscopy (TEM).
- To explore the influence of layer number on MoS2's electronic properties and identify methods for distinguishing single layers.
Main Methods:
- Suspended single- and few-layer MoS2 membranes were prepared and characterized.
- Transmission electron microscopy (TEM) was employed to study their structure and morphology.
- Optical identification and atomic force microscopy (AFM) were used for thickness determination.
Main Results:
- Monolayer MoS2 exhibits long-range crystalline order with surface ripples up to 1 nm in height, akin to graphene.
- These ripples may contribute to reduced charge carrier mobility in exfoliated MoS2.
- Distinctive electron diffraction patterns arise from symmetry breaking in single- and multilayer MoS2, enabling layer identification.
Conclusions:
- TEM analysis reveals the crystalline nature and surface morphology of suspended MoS2 membranes.
- The findings provide insights into the stability of 2D materials and the relationship between structure and properties.
- Electron diffraction offers a potential method for identifying single-layer MoS2.
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