A GaN Schottky Barrier Diode-Based Terahertz Metasurface for High-Precision Phase Control and High-Speed Beam...

Area of Science:

• Terahertz (THz) technology
• Metamaterials and Nanophotonics
• Semiconductor device physics

Background:

• Effective wavefront control is crucial for terahertz (THz) applications like high-directionality beamforming and wireless communication.
• Existing THz phase modulation technologies face limitations in loss, precision, and speed due to material constraints and device trade-offs.
• Gallium nitride (GaN) based devices offer potential for high-performance THz applications.

Purpose of the Study:

• To develop a programmable THz metasurface (GaNMS) that overcomes limitations in low-loss, precise, and rapid phase modulation.
• To design and fabricate a GaNMS array for dynamic THz phase shifting.
• To demonstrate robust beam scanning and integrated system functionality using the GaNMS.

Main Methods:

• Design and fabrication of a 32 × 25-element GaNMS array utilizing gallium nitride Schottky barrier diodes with high-mobility 2D electron gas.
• Characterization of unit cell performance, including continuous phase modulation range (0°–210°), phase error (1.8°), modulation speed (>200 MHz), and insertion loss (≈5 dB) at 0.32 THz.
• Implementation of a differential evolution optimization algorithm for mitigating array nonuniformities and enabling beam scanning.

Main Results:

• The fabricated GaNMS achieved continuous phase modulation from 0° to 210° with low average phase error.
• Demonstrated high modulation speed exceeding 200 MHz and low average insertion loss of approximately 5 dB.
• Achieved robust ±45° beam scanning in both analog and digital modes with significant main lobe gains (18.5 dBi and 16 dBi, respectively).

Conclusions:

• The developed GaNMS effectively addresses the need for low-loss, fast, and precise THz phase modulation.
• The integrated optimization algorithm enables robust beam steering, crucial for practical system implementation.
• The GaNMS technology shows significant promise for next-generation THz sensing and communication systems.