A back-to-back diode model applied to van der Waals Schottky diodes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Van der Waals (vdW) contacts are crucial for optimizing 2D semiconducting devices.
• Compared to traditional methods, vdW contacts reduce Fermi level pinning, leading to lower contact resistance and higher carrier mobility.
• These contacts exhibit Schottky barriers that adhere to the Schottky-Mott rule, enabling prediction from material properties.

Purpose of the Study:

• To present a double Schottky barrier model for analyzing vdW transistors.
• To apply this model to a barrier-tunable, all-vdW transistor based on molybdenum disulfide (MoS2).
• To demonstrate the extraction of Schottky barrier heights and their tunability.

Main Methods:

• Development and application of a double Schottky barrier model.
• Fabrication of a molybdenum disulfide (MoS2) transistor utilizing graphene and few-layer graphene vdW contacts.
• Room-temperature, two-terminal current-voltage (I-V) measurements.
• In-situ tuning of the Schottky barrier using a regional contact gate.

Main Results:

• The double Schottky barrier model successfully extracted Schottky barrier heights from I-V measurements.
• Extracted barrier heights align with predictions from the Schottky-Mott rule.
• Demonstrated in-situ tunability of the Schottky barrier height via a contact gate.
• Validated the model for characterizing all-vdW transistors.

Conclusions:

• The double Schottky barrier model is effective for characterizing all-vdW transistors.
• vdW contacts in MoS2 transistors allow for barrier height extraction and in-situ tuning.
• This approach simplifies device analysis and highlights the potential of vdW heterostructures.