Band-Gap Landscape Engineering in Large-Scale 2D Semiconductor van der Waals Heterostructures

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Van der Waals heterostructures are crucial for next-generation electronics.
• Current fabrication methods like exfoliation and transfer have limitations in scalability and complexity.
• Achieving large-scale, high-quality heterostructures remains a significant challenge.

Purpose of the Study:

• To present a scalable growth process for complex van der Waals heterostructures using pulsed laser deposition.
• To demonstrate the fabrication of encapsulated WSe2/WS2 quantum wells.
• To validate the structural integrity and homogeneity of the synthesized heterostructures.

Main Methods:

• Pulsed laser deposition (PLD) for *in situ* growth of multilayer heterostructures.
• Raman spectroscopy and transmission electron microscopy (TEM) for structural characterization.
• Macro- and microscale Raman mapping for homogeneity assessment.
• *Ab initio* calculations to support electronic transport analysis.

Main Results:

• Successful large-scale fabrication of WSe2 encapsulated in WS2 quantum wells at 400 °C (CMOS-compatible).
• Confirmation of structural integrity and high homogeneity across the 2D heterostructures.
• Demonstration of a vertical tunneling device exhibiting quantum well-controlled electronic transport.
• Preservation of fragile 2D layers through encapsulation.

Conclusions:

• Pulsed laser deposition offers a flexible and scalable approach for fabricating complex van der Waals heterostructures.
• This *in situ* growth method overcomes limitations of traditional techniques, enabling novel device designs.
• The process unlocks vast possibilities for combining different 2D materials, similar to III-V semiconductor advancements.