Normal-metal hot-electron bolometer with Andreev reflection from superconductor boundaries

This paper describes the design and experimental testing of a high-sensitiv ity hot-electron bolometer based a film of normal metal, exploiting the And reev reflection from superconductor boundaries, and cooled with the help of a superconductor-insulator-normal metal junction. At the measured thermal conductivity, G approximate to 6 x 10(-12) W/K, and a time constant of tau = 0.2 mu s, and a temperature of 300 mK, the estimated noise-equivalent pow er NEP = 5 x 10(-18) W/Hz(1/2), assuming that temperature fluctuations are the major source of noise. At a temperature of 100 mK, the thermal conducti vity drops to G approximate to 7 x 10(-14) W/K, which yields NEP = 2 x 10(- 19) W/Hz(1/2) at a time constant of tau = 5 mu s. The microbolometer has be en designed to serve as a detector of millimeter and FIR waves in space-bas ed radio telescopes. (C) 1999 American Institute of Physics. [S1063-7761(99 )02303-3].