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

Abstract

Effective wavefront control in the terahertz (THz) regime is essential for achieving high-directionality beamforming, spatial multiplexing, and real-time wireless communication. However, low-loss, precise, and rapid THz phase modulation remains fundamentally constrained by material limitations and inherent device-level trade-offs. A programmable THz metasurface (GaNMS) is presented, employing a gallium nitride Schottky barrier diode with a high-mobility 2D electron gas, specifically designed to overcome these limitations by leveraging its low insertion loss, fast response, and continuously tunable junction capacitance. A 32 × 25-element array is designed and fabricated. Each unit cell functions as a direct THz phase shifter, dynamically tuning the junction capacitance to enable continuous phase modulation from 0° to 210° at 0.32 THz, with a 1.8° average phase error, modulation speed exceeding 200 MHz, and ≈5 dB average insertion loss. To mitigate array-level nonuniformities, a differential evolution-based optimization algorithm is introduced, enabling robust ±45° beam scanning in both analog and digital modes, with main lobe gains of 18.5 and 16 dBi, respectively. An integrated GaNMS-based sensing and communication system is also demonstrated, validating its potential in next-generation THz applications. The proposed GaNMS bridges device-level phase tunability and system-level functionality, enabling practical THz technologies.