Fundamental Limits of Few-Layer NbSe₂ Microbolometers at Terahertz Frequencies

The rapid development of infrared spectroscopy, observational astronomy, and scanning near-field microscopy has been enabled by the emergence of sensitive mid- and far-infrared photodetectors. Superconducting hot-electron bolometers (HEBs), known for their exceptional signal-to-noise ratio and fast photoresponse, play a crucial role in these applications. While superconducting HEBs are traditionally crafted from sputtered thin films such as NbN, the potential of layered van der Waals (vdW) superconductors is untapped at THz frequencies. Here, we introduce superconducting HEBs made from few-layer NbSe2 microwires. By improving the interface between NbSe2 and metal leads, we overcome impedance mismatch with RF readout, enabling large responsivity THz detection (0.13 to 2.5 THz) with a minimal noise equivalent power of 7 pW/ root Hz and nanosecond-range response time. Our work highlights NbSe2 as a promising platform for HEB technology and presents a reliable vdW assembly protocol for custom bolometer production.