Broadband Terahertz Detection With Zero-Bias Field-Effect Transistors Between 100 GHz and 11.8 THz With a Noise Equivalent Power of 250 pW/$\sqrt{\text{Hz}}$ at 0.6 THz

We demonstrate UV contact lithographically fabricated III-V field-effect transistors (FETs) examined over a bandwidth of 100 GHz-11.8 THz. The zero-bias device reaches a noise √ equivalent power as low as 250 pW/√Hz at 0.6 THz, which then increases as f4 at higher frequencies. The responsivity is modeled by a simple equivalent circuit, showing good agreement over the frequency range of two decades. The FETs have been characterized using a photomixer, a quantum cascade laser, and a free-electron laser, proving the versatility and large applicability of the detection concept.