Scalable Large-Area 2D-MoS₂/Silicon-Nanowire Heterostructures for Enhancing Energy Storage Applications

Area of Science:

• Materials Science and Engineering
• Nanotechnology
• Energy Storage and Conversion

Background:

• Two-dimensional (2D) transition-metal dichalcogenides, like molybdenum disulfide (MoS2), offer potential for energy storage due to their unique properties.
• Vertical silicon nanowires (SiNWs) serve as ideal substrates for growing 2D materials, creating high-surface-area heterostructures.
• Scalable fabrication methods are crucial for commercializing next-generation energy storage devices based on these materials.

Purpose of the Study:

• To demonstrate the large-scale, commercially viable fabrication of hybrid MoS2/SiNW heterostructures.
• To investigate the tunability of MoS2 layer thickness, down to the monolayer scale, on SiNW substrates.
• To explore the impact of an alumina (Al2O3) interface on MoS2 quality and its suitability for energy applications.

Main Methods:

• Utilized a two-step atomic layer deposition (ALD) process for conformal growth of MoS2 directly onto vertical SiNWs.
• Employed Raman spectroscopy to confirm the formation and quality of MoS2/SiNW heterostructures.
• Used transmission electron microscopy (TEM) to verify conformal MoS2 growth parallel to the SiNWs.
• Investigated the effect of ALD alumina interface on MoS2 quality using photoluminescence (PL) spectroscopy.

Main Results:

• Successfully fabricated large-surface-area, commercially scalable MoS2/SiNW heterostructures with tunable MoS2 layer thickness (monolayer to bulk) via ALD cycle control.
• Achieved conformal MoS2 growth on SiNWs without substrate damage, confirmed by TEM.
• Demonstrated enhanced MoS2 quality and uniformity with an ALD alumina interface, evidenced by a significant reduction in the B/A exciton PL intensity ratio.
• Identified alumina-free heterostructures as suitable for direct electrical contact applications, such as high-capacity ion battery electrodes.

Conclusions:

• The developed ALD method provides a scalable route to high-quality MoS2/SiNW heterostructures with precise layer control.
• The integration of an alumina interface improves MoS2 quality, making heterostructures suitable for interfacial layers in batteries or photocathodes.
• Alumina-free heterostructures are promising for direct electrical contact applications, benefiting from multiple MoS2 layers in high-capacity ion batteries.