A niobium nitride superconducting hot electron bolometer direct terahertz detector working at 9 K

Increasing the bath temperature of the hot electron bolometer (HEB) while ensuring sensitivity could expand the application field and reduce the system complexity and cost. This study proposed and prepared a suspended NbN/Nb5N6 HEB with doubled bath temperature and undegraded sensitivity compared to NbN HEB. Under the bath temperature of 9 K, the optical noise equivalent power of the system was still of the order of pW/Hz1/2. Moreover, the influence of thermal relaxation on the device sensitivity was simulated. The results would provide a pathway for improving the bath temperature and detector sensitivity through fine adjustments of the thermal boundaries.