Ultrabroadband Terahertz Detectors Based on CMOS Field-Effect Transistors with Integrated Antennas

We report on the modeling, implementation and characterization of optimized, ultrabroadband antenna-coupled field-effect transistors for the detection of terahertz (THz) radiation. The detectors were fabricated in 90-nm silicon CMOS technology with integrated bow-tie and log-spiral antennas. We also investigated a third design with a narrowband dipole antenna. In the frequency range from 0.5 to 1.5 THz, the detector with the bow-tie antenna design exhibited a nearly flat frequency response at an optical responsivity of ~100 V/W. We found minimum optical noise equivalent powers (NEPs) as low as 48 pW/√Hz at 0.6 THz and 70 pW/√Hz at 1.5 THz. The dipole-design detector achieved an optical NEP of 17 pW/√Hz at resonance frequency of 490 GHz. Our detectors were optimized with the help of a self-developed circuit model based on device parameters such as transistor geometry, antenna impedance matching and the peculiarities of the employed fabrication technology.