Superconductive bolometers for submillimeter wavelengths

Journal Article · Thu Dec 01 00:00:00 EST 1977 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.323612· OSTI ID:5438784

Clarke, J; Hoffer, G I; Richards, P L; Yeh, N h

Three types of composite superconductive bolometers are described in which the temperature-sensitive element is a superconducting film at the transition temperature, a superconductor--normal metal--superconductor Josephson junction, or a superconductor--insulator--normal metal quasiparticle tunneling junction. The temperature-sensitive element is evaporated onto a sapphire substrate on the reverse side of which is a bismuth film to absorb the submillimeter radiation. The noise limitations of each type of bolometer are calculated. The fabrication and measured performance of the transition-edge bolometer and the Josephson-junction bolometer are described. The best electrical (noise-equivalent power) NEP obtained with a transition-edge bolometer fabricated on a 4 x 4 x 0.005-mm sapphire substrate is (1.7 +- 0.1) x 10/sup -15/ W Hz/sup -1/2/ at 2 Hz at an operating temperature of 1.27 K. This NEP is within a factor of 2 of the thermal noise limit. The effective absorptivity of the bismuth film is measured to be 0.47 +- 0.05, and the corresponding detectivity D* is calculated to be (1.1 +- 0.1) x 10/sup 14/ cm W/sup -1/ Hz/sup 1/2/. Suggestions are made for further improvements in sensitivity.

• Research Organization: Univ. of California, Berkeley, CA (United States). Dept. of Physics
• OSTI ID: 5438784
• Journal Information: J. Appl. Phys.; (United States), Vol. 48:12
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
BOLOMETERS
SUPERCONDUCTING DEVICES
BISMUTH
JOSEPHSON JUNCTIONS
PERFORMANCE
SENSITIVITY
SUPERCONDUCTING FILMS
ELEMENTS
FILMS
MEASURING INSTRUMENTS
METALS
SUPERCONDUCTING JUNCTIONS
420201* - Engineering- Cryogenic Equipment & Devices
440101 - Radiation Instrumentation- General Detectors or Monitors & Radiometric Instruments