Arrayed van der Waals Vertical Heterostructures Based on 2D GaSe Grown by Molecular Beam Epitaxy

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Vertically stacking 2D materials offers pathways to novel electronic and optoelectronic devices.
• Fabricating wafer-scale heterostructures with atomic precision remains a significant challenge.

Purpose of the Study:

• To develop a controllable method for producing wafer-scale 2D Gallium Selenide (GaSe) thin films.
• To fabricate and characterize high-performance photodetectors based on these GaSe films.

Main Methods:

• Wafer-scale 2D GaSe thin films were grown using molecular beam epitaxy.
• In situ reflection high-energy electron diffraction oscillations and Raman spectroscopy were employed to analyze growth modes.
• Photodiodes were fabricated using few-layer GaSe on silicon substrates.

Main Results:

• A layer-by-layer van der Waals epitaxial growth mode was confirmed.
• Photodiodes exhibited steady rectifying characteristics and a high external quantum efficiency of 23.6%.
• Devices demonstrated a super-fast response time of 60 μs and exceptional operational stability over 1 million cycles.

Conclusions:

• The study presents a novel, controllable approach for large-area 2D heterostructure fabrication.
• The developed GaSe films are suitable for robust, high-performance photodetector applications.
• This work is a significant step towards the practical application of 2D material-based heterostructures.