A Broadband Antenna-Coupled Terahertz Direct Detector in a 0.13-μm SiGe HBT Technology

This paper presents an integrated silicon-lens coupled THz direct detector. It comprises a pair of differentially driven antenna-coupled HBT transistors in common-base configuration implemented in an advanced $0.13-\mu m$ SiGe HBT technology with $f_{T}/f_{\max}$ of 350/550 GHz. Based on the antenna detector co-design approach, a broadband operation with an optical noise equivalent power (NEP) lower than 40 $pW/\sqrt{Hz}$ in the measured 220 GHz to 1 THz band is achieved. The detector operates in a voltage mode readout with an external resistance of 1.83 $k\Omega$. Two device regions have been investigated. In the forward-active mode the detector achieves its minimum NEP of 1.9 $pW/\sqrt{Hz}$ at 292 GHz and values less than 4.3 $pW/\sqrt{Hz}$ from 275 to 525 GHz at 100 kHz chopping frequency. The maximum voltage responsivities $(R_{v})$ are 9 $kV/W$ and around 7.5 $kV/W$ respectively. In the saturation region the minimum measured NEP from 220 GHz to 1 THz is 5.1 $pW/\sqrt{Hz}$.