THz Direct Detector and Heterodyne Receiver Arrays in Silicon Nanoscale Technologies

Abstract

The main scope of this paper is to address various implementation aspects of THz detector arrays in the nanoscale silicon technologies operating at room temperatures. This includes the operation of single detectors, detectors operated in parallel (arrays), and arrays of detectors operated in a video-camera mode with an internal reset to support continuous-wave illumination without the need to synchronize the source with the camera (no lock-in receiver required). A systematic overview of the main advantages and limitations in using silicon technologies for THz applications is given. The on-chip antenna design challenges and co-design aspects with the active circuitry are thoroughly analyzed for broadband detector/receiver operation. A summary of the state-of-the-art arrays of broadband THz direct detectors based on two different operation principles is presented. The first is based on the non-quasistatic resistive mixing process in a MOSFET channel, whereas the other relies on the THz signal rectification by nonlinearity of the base-emitter junction in a high-speed SiGe heterojunction bipolar transistor (HBT) . For the MOSFET detector arrays implemented in a 65 nm bulk CMOS technology, a state-of-the-art optical noise equivalent power (NEP) of 14 pW/ √ H z at 720 GHz was measured, whereas for the HBT detector arrays in a 0.25 μm SiGe process technology, an optical NEP of 47 pW/ √ H z at 700 GHz was found. Based on the implemented 1k-pixel CMOS camera with an average power consumption of 2.5μW/pixel, various design aspects specific to video-mode operation are outlined and co-integration issues with the readout circuitry are analyzed. Furthermore, a single-chip 2 × 2 array of heterodyne receivers for multi-color active imaging in a 160-1000 GHz band is presented with a Janusz Grzyb J Infrared Milli Terahz Waves well-balanced NEP across the operation bandwidth ranging from 0.1 to 0.24 fW/Hz (44.1-47.8 dB single-sideband NF) and an instantaneous IF bandwidth of 10 GHz. In its present implementation, the receiver RF bandwidth is not continuously covered but divided into six bands centered around 165, 330, 495, 660, 820, and 990 GHz.

Terahertz Imaging and Sensing Applications With Silicon-Based Technologies

“…At present, the low speed of silicon transistors and the issues related to efficient THz signal escape [31] constitute an ongoing research challenge for both technology development and IC design. Over time, silicon technology has undergone a steady scaling and an improvement of device parasitics, recently achieving an f max of 500 GHz in commercially available 0.13-μm SiGe BiCMOS technology [32].…”

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

“…Further details on the rectification effect can be found elsewhere [10], [11]. To date, FET rectifiers reach NEPs in the range of 14 to 20 pW/ √ Hz at 720 and 590 GHz [12], [13] with narrow band designs. While this is still higher than the NEPs of Schottky diodes, the NEP of THz-tailored FETs has improved by 4 to 5 orders of magnitude within the last 10 years.…”

Technology trend in real-time, uncooled image sensors for sub-THz and THz wave detection

“…pixel pitch of 50 μm, which was incorporated into THz camera shown in Fig.6(b) [34,35] . For references, CMOS THz camera shown in Fig.6(c) was developed, which contained antenna-coupled 32x32 CMOS FPA (pixel pitch: 80 μm) and covered the spectral frequency range of 0.3-1.3 THz [12,17,36] . Sub-THz camera shown in Fig.6(d) was also developed, which contained 64x64 sub-THz FPA (pixel pitch: 1.5 mm) made of GaAs high-mobility heterostructure, and covered the spectral frequency range of 0.05-0.7 THz [25] .…”

“…In this section, the MDP values per pixel for the MB-THz-FPAs [26,31,32,34] are compared with those of other THz detectors, such as antenna-coupled CMOS-THz-FPAs [12,13,15,16,36,44] and antenna-coupled detectors based on III-V compound semiconductor technologies [18][19][20][22][23][24] . Table 2 summarizes the parameters of these THz detectors.…”

“…[32] 290, 450 GHz 1.39, 2.5, 4.25 THz 384x288 35 μm LETI (CMOS) [26] 270, 600 GHz 31x31 240 μm Wuppertal Univ. (CMOS) [12,36] 856 GHz 32x32 80 μm Goethe Univ. (CMOS) [13,44] 600 GHz 24x24 195 μm Tower Jazz (SiGe BiCMOS) [15] 315 GHz 4x4 ca.…”