Rapid and reliable thickness identification of two-dimensional nanosheets using optical microscopy

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• The physical and electronic properties of ultrathin two-dimensional (2D) nanomaterials are intrinsically linked to their layer thickness.
• Accurate characterization of single-layer and few-layer (multilayer) nanosheets is critical for both fundamental research and practical applications of 2D materials.

Purpose of the Study:

• To develop a universal, simple, rapid, and reliable optical method for identifying the layer number of 2D nanosheets.
• To establish a standard reference for layer number determination without complex calculations or expensive equipment.

Main Methods:

• Developed a universal optical method for identifying 2D nanosheets on silicon substrates with SiO2 coatings (90 or 300 nm).
• Collected and tabulated optical contrast differences between substrates and 2D nanosheets (graphene, MoS2, WSe2, TaS2) of varying layer numbers (1L-15L).

Main Results:

• Successfully demonstrated a method for reliable identification of 2D nanosheet layers from 1 to 15 layers.
• The optical contrast data serves as a readily accessible standard reference for layer number determination.
• The method is applicable to various 2D materials including graphene, MoS2, WSe2, and TaS2.

Conclusions:

• The developed optical method provides a facile and accurate way to determine the layer number of 2D nanosheets.
• This technique will significantly aid in thickness-dependent studies of diverse 2D nanomaterials.
• The method is expected to accelerate the research and development of 2D materials for practical applications.