Quantum response of a bolometer based on the SINIS structure with a suspended absorber

Bolometers based on the superconductor–insulator–normal–metal–insulator–superconductor (SINIS) structure with an absorber suspended above the substrate are developed, fabricated, and experimentally studied in the terahertz frequency range. In contrast to the previously studied bolometers with an absorber located directly on the substrate, the real bolometric mode of operation is achieved, i.e., there is more than one excited electron per quantum of electromagnetic radiation (the quantum efficiency is larger than 1). A quantum efficiency of fifteen electrons per quantum of radiation with a frequency of 350 GHz was achieved in the studied bolometers.