Wafer-Level Fabrication of Radiofrequency Devices Featuring 2D Materials Integration.

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Two-dimensional (2D) materials, like graphene, offer potential for innovative devices but face fabrication challenges.
• Wafer-level scale fabrication is crucial for reproducible manufacturing of 2D material-based devices.
• Current methods struggle with integrating 2D materials reliably for complex applications.

Purpose of the Study:

• To develop and present fabrication processes for on-wafer manufacturing of active and passive radiofrequency (RF) devices using graphene.
• To demonstrate the versatility and potential of graphene in RF applications through fabricated devices.
• To enable the development of complex circuits and sensors utilizing 2D materials.

Main Methods:

• Two distinct graphene transfer processes were developed: one using critical point drying and another employing ion milling for surface planarization.
• A damascene-like fabrication process was utilized to ensure a flat surface and preserve graphene lattice quality.
• Fabrication included RF transistors, passive RF components, and antennas for backscatter applications.

Main Results:

• High-quality, flat graphene was achieved, enabling the fabrication of RF active devices (graphene transistors) with high performance (fT of 14 GHz, fmax of 80 GHz).
• Demonstrated graphene's capability as a passive device in an antenna for wireless sensor development, showing tunable backscatter response.
• Achieved excellent yield and reproducibility in fabricated devices.

Conclusions:

• The presented fabrication processes facilitate wafer-level integration of graphene for advanced RF devices.
• The methods are versatile and can potentially be extended to other 2D materials grown by Chemical Vapor Deposition (CVD).
• This work paves the way for scalable manufacturing of 2D material-based RF electronics and sensors.