In this work we review the most important results concerning the physics and applications of FETs as Terahertz
detectors. We present two experiments showing: i) Terahertz detection based on low cost 130 nm silicon
technology Field Effect Transistors in the sub-THz range (0.2 THz up to 1.1 THz) and ii) first results on
detection by FETs of emission from 3.1 THz Quantum Cascade Lasers.