Investigation of superconducting NbN hot-electron bolometers for terahertz direct detection

In this paper, we report on the terahertz (THz) direct detection performance of two superconducting niobium nitride (NbN) hot-electron bolometers (HEBs) of different micro-bridge sizes. At the optimum bias point, the two HEB devices show similar thermal conductance (~80nW/K). The measured responsivity coincides well with the electrical responsivity calculated from the measured current-voltage (IV) curves at different bath temperatures. The noise equivalent power (NEP) of the two HEB devices is found to be about 10
^-12
W/√Hz.