Strong doping reduction on wafer-scale CVD graphene devices via Al₂O₃ALD encapsulation

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Graphene's unique electronic properties make it promising for advanced electronic devices.
• Integrating graphene into existing semiconductor fabrication flows, particularly CMOS, presents significant challenges.
• Reliable electrical characteristics and stability are crucial for practical graphene device applications.

Purpose of the Study:

• To present the electrical characterization of wafer-scale graphene devices.
• To evaluate an industrially-relevant, contact-first integration scheme with Al2O3 encapsulation.
• To assess the impact of this fabrication process on graphene's electrical properties, specifically the Dirac point and mobility.

Main Methods:

• Fabrication of wafer-scale graphene devices using a contact-first integration approach.
• Application of aluminum oxide (Al2O3) encapsulation via atomic layer deposition (ALD).
• Electrical characterization, including measurement of the Dirac point position (Vcnp) and carrier mobility.

Main Results:

• A statistically significant reduction in the Dirac point position (Vcnp) was observed, shifting from approximately +47 V to a range of -5 V to +5 V on 285 nm SiO2.
• Carrier mobility values were maintained after the encapsulation process.
• The results demonstrate improved electrical stability of the graphene devices.

Conclusions:

• The presented contact-first integration and Al2O3 encapsulation method enhances the electrical stability of graphene devices.
• This approach is compatible with standard CMOS back-end-of-line processes.
• The findings pave the way for the integration of graphene-based sensors and other devices in mainstream semiconductor manufacturing.