| Keywords [eng] |
TeraFET, SENSORS BASED ON FIELD-EFFECT TRANSISTORS, Terahertz, THz, FIELD-EFFECT TRANSISTORS, THz SENSORS, THz FETs, Angular dependence |
| Abstract [eng] |
To bridge the terahertz gap, room-temperature patch-antenna-coupled TeraFET detectors were developed using a 65-nm CMOS process optimized for 2.52 THz operation. The methodology progressed from ADS numerical antenna modelling and LTspice electrical simulation. A highly stable OPA858/OPA211 multi-stage amplifier was implemented to minimise room-temperature 1/f noise. After custom PCB soldering, precise microscopic chip alignment and wire bonding, the sensors were integrated into a 30 mm cage measurement system. Spatial and angular characterisation of single-pixel, 3×3 and 4×4 array THz antennas utilised a CO₂-pumped FIR laser, an optical chopper and a DSP lock-in amplifier. To map profiles, an automated X-Y translation stage was used. Experimental characterisation yielded vital performance metrics that verified the design. IV analysis revealed typical gate-modulated resistance, peaking in responsivity at 0.6 V (1,000 Ω). The single-pixel detector significantly outperformed the simulations, achieving a directivity of 6.2 dBi and an effective area of 4.69×10⁻⁹ m² – five times larger than predicted. Spatial mapping revealed that a 0.5 mm aperture was necessary to transform an unfiltered, doughnut-shaped beam profile (0.3410 V) into a focused, elliptical shape (0.1060 V) and eliminate background reflections effectively. Multi-pixel arrays drastically improved signal uniformity by eliminating the irregular E-plane double peaks of the single pixel. Performance scaled efficiently with array size, establishing the 4×4 configuration as the optimal design through maximising energy collection with elevated 11.7 dBi directivity, an expanded 1.67×10⁻⁸ m² effective area. |
