Breaking Inversion Symmetry in 2D Semiconductors by Built-In Electric Fields across the van der Waals...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Multilayer and bulk 2D layered semiconductors are crucial for optoelectronics but often possess out-of-plane inversion symmetry.
• This inherent symmetry limits their potential for diverse multifunctional applications in integrated devices.

Purpose of the Study:

• To propose and demonstrate a method for breaking inversion symmetry in 2D semiconductors.
• To explore the use of semiconductor-metal van der Waals heterostructures for advanced optoelectronic applications.

Main Methods:

• Interfacial engineering using built-in electric fields at semiconductor-metal interfaces.
• Fabrication of bulk tungsten disulfide (WS₂)/gold (Au) heterostructures.
• Experimental characterization using second harmonic generation (SHG), atomic force microscopy (AFM), and surface potential mapping.
• Theoretical validation through density functional theory (DFT) simulations.

Main Results:

• Successfully broke the out-of-plane inversion symmetry of 2H WS₂ layers.
• Experimentally confirmed broken symmetry via strong SHG signals in WS₂/Au heterostructures.
• DFT simulations and correlated measurements unambiguously validated the proposed physical mechanism.

Conclusions:

• The proposed interfacial engineering approach effectively breaks inversion symmetry in 2D semiconductors.
• 2D semiconductor/metal heterostructures offer a promising platform for developing multifunctional integrated optoelectronic chips.
• This work expands the design possibilities for next-generation optoelectronic devices.