Nanoscale Raman Characterization of a 2D Semiconductor Lateral Heterostructure Interface

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Lateral heterostructures of 2D semiconductors are crucial for advanced optoelectronics.
• The interface's properties (composition, size, heterogeneity) dictate device functionality.
• Understanding these interfaces at the nanoscale is essential for material development.

Purpose of the Study:

• To characterize the interface in single-layer MoS2/WS2 lateral heterostructures using nanoscale techniques.
• To determine the composition, size, and heterogeneity of the interfacial region.
• To correlate interfacial properties with the functionalities of 2D systems.

Main Methods:

• Tip-enhanced Raman scattering (TERS) spectroscopy with 50 nm spatial resolution.
• Utilizing both resonant and nonresonant TERS modes.
• Nanoscale imaging of continuous interfacial evolution.

Main Results:

• The interface is alloyed, with domain sizes ranging from 50 to 600 nm within a single crystal.
• TERS enabled deconvolution of defect activation, resonant enhancement, and material composition (MoS2, MoWS2, WS2).
• Detailed nanoscale mapping of vibrational modes across the heterostructure.

Conclusions:

• Nanoscale TERS is effective for elucidating structure-property relationships in 2D materials.
• Characterization of lateral interfaces at imperative length scales is demonstrated.
• The findings are vital for designing next-generation 2D optoelectronic devices.