Titanium contacts to graphene: process-induced variability in electronic and thermal transport

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Contact resistance (R_C) significantly limits graphene device performance.
• R_C is influenced by interface quality and contact material composition, which are affected by fabrication processes like graphene transfer and contact deposition.
• Understanding and controlling these factors are crucial for advancing graphene electronics.

Purpose of the Study:

• To investigate the relationship between titanium (Ti) contact composition and Ti/graphene contact resistance.
• To explore the tunability of contact composition through deposition parameters.
• To analyze the effect of contact deposition conditions on thermal transport properties at the interface.

Main Methods:

• X-ray photoelectron spectroscopy (XPS) for characterizing Ti contact composition.
• Transfer length method (TLM) for measuring Ti/graphene contact resistance.
• Time-domain thermoreflectance (TDR) for evaluating thermal transport.

Main Results:

• A linear correlation was observed between Ti contact composition and measured contact resistance.
• Contact composition was successfully tuned by altering deposition rate and base pressure.
• Reactor base pressure was identified as a key factor influencing contact resistance.
• Interfaces with higher oxide composition exhibited lower thermal boundary conductance.

Conclusions:

• Contact resistance in Ti/graphene systems is directly tunable by controlling contact composition through deposition parameters.
• Base pressure during deposition is a critical factor for managing contact resistance.
• Interface oxide composition plays a role in modulating thermal boundary conductance, suggesting potential for thermal management applications.