A more reliable measurement method for metal/graphene contact resistance

Area of Science:

• Materials Science
• Electrical Engineering
• Condensed Matter Physics

Background:

• Contact resistance is a critical limitation in graphene device performance.
• The standard transmission line model (TLM) for contact resistance measurement often suffers from inaccuracy and instability.
• Accurate characterization of metal/graphene interfaces is essential for advancing graphene electronics.

Purpose of the Study:

• To develop a more reliable and accurate method for measuring contact resistance in graphene devices.
• To introduce a modified transmission line measurement (mTLM) structure incorporating a cross-bridge.
• To simultaneously extract multiple contact-related parameters, including specific contact resistivity and transfer length.

Main Methods:

• Implementation of a modified transmission line measurement (mTLM) structure with an added cross-bridge.
• Comparison of contact resistance values obtained from the standard TLM and the new mTLM approach.
• Simultaneous extraction of specific contact resistivity, transfer length, and graphene sheet resistance.

Main Results:

• The mTLM structure provides more reliable contact resistance values compared to the standard TLM.
• Specific contact resistivity was measured in the range of 2.0-3.0 × 10⁻⁶ Ω·cm² at room temperature.
• Transfer length remained stable around 1.7 μm as temperature decreased from 290 K to 60 K, with specific contact resistivity dropping below 2.0 × 10⁻⁶ Ω·cm².

Conclusions:

• The novel cross-bridge mTLM structure significantly improves the accuracy and stability of contact resistance measurements in graphene devices.
• This method enables comprehensive characterization of metal/graphene contact properties, including specific contact resistivity and transfer length.
• The findings are crucial for optimizing graphene-based electronic device design and fabrication.