2D Indium Oxide at the Epitaxial Graphene/SIC Interface: Synthesis, Structure, Properties, and Devices

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• High-quality insulators are essential for 2D/3D hybrid vertical electronic devices.
• Fabrication of these devices is limited by the availability of bulk layered wide bandgap semiconductors.

Purpose of the Study:

• To synthesize a novel 2D insulator, monolayer indium oxide (InO2), with a different stoichiometry than its bulk form.
• To investigate the properties and potential applications of monolayer InO2 in vertical electronic devices.

Main Methods:

• Large-area synthesis of monolayer InO2 via intercalation at the epitaxial graphene (EG)/SiC interface.
• Tuning InO2 thickness using optical lithography to control graphene lateral size.
• Utilizing molecular dynamics and density functional theory (DFT) for theoretical analysis.
• Fabricating and measuring metal-oxide-semiconductor (MOS) based Schottky diodes.

Main Results:

• Achieved large-area (>300 µm²) synthesis of monolayer InO2, with 85% monolayer thickness achieved by controlling graphene size.
• Calculated a bandgap of 4.1 eV for monolayer InO2, significantly different from its bulk form (2.7 eV).
• Demonstrated transformation of the ohmic EG/n-SiC junction to a Schottky junction with a barrier height of 0.87 eV and rectification ratio of ~10⁵ upon InO2 intercalation.

Conclusions:

• Introduced monolayer InO2 as a new 2D insulator material.
• Established the utility of monolayer InO2 as an effective barrier in vertical electronic devices.
• Highlighted the potential for advanced electronic device fabrication using this novel 2D material.