Improving terahertz-detection sensitivity of 8x8 FET arrays through liquid-nitrogen cooling in a compact low-noise cryostat
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866911441618993152 |
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| author | Holstein, Jakob North, Nicholas K. Hof, Arne Kondawar, Sanchit But, Dmytro B. Salih, Mohammed Li, Lianhe Linfield, Edmund H. Davies, A. Giles Freeman, Joshua R. Valavanis, Alexander Lisauskas, Alvydas Roskos, Hartmut G. |
| author_facet | Holstein, Jakob North, Nicholas K. Hof, Arne Kondawar, Sanchit But, Dmytro B. Salih, Mohammed Li, Lianhe Linfield, Edmund H. Davies, A. Giles Freeman, Joshua R. Valavanis, Alexander Lisauskas, Alvydas Roskos, Hartmut G. |
| contents | We show that the sensitivity of antenna-coupled field-effect transistors (FETs) to terahertz (THz) radiation improves continuously with decreasing temperature. The noise-equivalent power (NEP) of 540 GHz patch-antenna-coupled FETs decreases as temperature reduces to 20 K. We project NEP values approaching 1 to 2 pW/sqrt(Hz) under efficient power coupling conditions (e.g., using a superstrate Si-lens), which is comparable to superconducting niobium transition-edge sensors (TESs) at 4 K. Building on these findings, a compact, low-noise, liquid-nitrogen-cooled (77 K) FET-based direct (incoherent) THz-power sensing system} for spectroscopy applications was realized. Here, an 8x8 pixel-binned detector array fabricated in a commercial 65-nm Si-CMOS process, was optimized for operation in the 2.85 to 3.4 THz band. Characterization was performed in the focal plane of a 2.85-THz quantum-cascade laser delivering approx. 2~mW of THz power. A linear dynamic range exceeding 67 dB was achieved without saturation (for 1~Hz-detection bandwidth). The system provides a -3 dB readout bandwidth of 5 MHz, exceeding that of conventional thermal detectors (typically 1 kHz). Combined with its broad temperature operability 20 K to 300 K and compact design, the system is particularly well suited for space- and payload-constrained platforms such as balloon- and satellite-based missions, where deep cryogenic cooling is impractical. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_15323 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Improving terahertz-detection sensitivity of 8x8 FET arrays through liquid-nitrogen cooling in a compact low-noise cryostat Holstein, Jakob North, Nicholas K. Hof, Arne Kondawar, Sanchit But, Dmytro B. Salih, Mohammed Li, Lianhe Linfield, Edmund H. Davies, A. Giles Freeman, Joshua R. Valavanis, Alexander Lisauskas, Alvydas Roskos, Hartmut G. Applied Physics Instrumentation and Detectors We show that the sensitivity of antenna-coupled field-effect transistors (FETs) to terahertz (THz) radiation improves continuously with decreasing temperature. The noise-equivalent power (NEP) of 540 GHz patch-antenna-coupled FETs decreases as temperature reduces to 20 K. We project NEP values approaching 1 to 2 pW/sqrt(Hz) under efficient power coupling conditions (e.g., using a superstrate Si-lens), which is comparable to superconducting niobium transition-edge sensors (TESs) at 4 K. Building on these findings, a compact, low-noise, liquid-nitrogen-cooled (77 K) FET-based direct (incoherent) THz-power sensing system} for spectroscopy applications was realized. Here, an 8x8 pixel-binned detector array fabricated in a commercial 65-nm Si-CMOS process, was optimized for operation in the 2.85 to 3.4 THz band. Characterization was performed in the focal plane of a 2.85-THz quantum-cascade laser delivering approx. 2~mW of THz power. A linear dynamic range exceeding 67 dB was achieved without saturation (for 1~Hz-detection bandwidth). The system provides a -3 dB readout bandwidth of 5 MHz, exceeding that of conventional thermal detectors (typically 1 kHz). Combined with its broad temperature operability 20 K to 300 K and compact design, the system is particularly well suited for space- and payload-constrained platforms such as balloon- and satellite-based missions, where deep cryogenic cooling is impractical. |
| title | Improving terahertz-detection sensitivity of 8x8 FET arrays through liquid-nitrogen cooling in a compact low-noise cryostat |
| topic | Applied Physics Instrumentation and Detectors |
| url | https://arxiv.org/abs/2507.15323 |