Record-High Performance Trantenna based on Asymmetric Nano-Ring FET for Polarization-Independent Large-Scale/Real-Time THz Imaging

Abstract

We demonstrate a record-high performance monolithic trantenna (transistor-antenna) using 65-nm CMOS foundry in the field of a plasmonic terahertz (THz) detector. By applying ultimate structural asymmetry between source and drain on a ring FET with source diameter $(d_{\text{S}})$ scaling from 30 to $0.37\mu \text{m}$, we obtained 180 times more enhanced photoresponse $(\Delta u)$ in on-chip THz measurement. Through free-space THz imaging experiments, the conductive drain region of ring FET itself showed a frequency sensitivity with resonance frequency at 0.12 THz in $0.09\sim 0.2$ THz range and polarization-independent imaging results as an isotropic circular antenna. Highly-scalable and feeding line-free monolithic trantenna enables a high-performance THz detector with responsivity of 8.8 kV/$W$ and NEP of $3.36\text{pW}/\text{Hz}^{05}$ at the target frequency.