Direct Characterization of Buried Interfaces in 2D/3D Heterostructures Enabled by GeO₂ Release Layer

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Inconsistent interface control in two-dimensional materials (2DMs) hinders device development.
• Variability in 2D/three-dimensional (2D/3D) interface properties is poorly understood due to limited direct investigation of buried interfaces.

Purpose of the Study:

• To develop a novel process for fabricating and isolating 2D/3D heterostructures for buried interface characterization.
• To compare interface properties of monolayer MoS2 heterostructures fabricated by direct deposition versus transfer techniques.

Main Methods:

• Utilized a water-soluble germanium dioxide (GeO2) substrate for heterostructure assembly.
• Released heterostructures by dissolving the GeO2 substrate, enabling direct characterization of buried interfaces.
• Investigated the effects of direct deposition versus transfer fabrication on MoS2 chemistry, doping, and strain.

Main Results:

• Direct deposition of Ni and Ti films caused significant reactions, converting 50% of MoS2 into intermetallic species.
• Transfer-fabricated heterostructures showed 0% MoS2 conversion, contrasting with previous reports.
• Direct deposition of Au, Ni, and Al2O3 films increased MoS2 hole concentration by over 10^12 cm^-2 compared to transfer methods.

Conclusions:

• Demonstrated a universal method for fabricating 2D/3D heterostructures and exposing buried interfaces.
• Highlighted the critical impact of fabrication methods on 2D/3D interface properties and device performance.
• Provided insights into controlling interface chemistry and doping in 2DM devices.