Passivation, Transition Width, and Noise for YBCO Bolometers on Silicon

Published

June 1, 1999

Author(s)

Donald G. McDonald, Robert J. Phelan, Leila R. Vale, Ronald H. Ono, David A. Rudman

Abstract

We are developing Yba₂Cu₃O_7-x (YBCO) thermometers for large area bolometers that include a heater for calibration by the electrical substitution of power. Because YBCO on buffered Si is under mechanical stress and must be very thin to avoid cracking, we find it is electrically sensitive to its passivation layer. For example, passivation by SrTiO₃ raised the noise in our films by about a factor of 100. An alternative is to first cap the insulator for electrical isolation. Such devices have a narrower transition width, with by a factor of 3.9. A model with a shunt resistor across the superconductor predicts a narrowing of the transition, but by less than the observed amount. The noise equivalent temperatures of our thermometers, about 4 nK Hz^-1/2, are not degraded by the normal metal shunt, although the resistance is decreased. The resistance can be raised using AgAu alloy in place of Au, with equivalent noise performance.

Citation

IEEE Trans. on Appl. Supercond.

Volume

9

Issue

2

Pub Type

Journals

Keywords

bolometers, YBCO on Si

Citation

McDonald, D. , Phelan, R. , Vale, L. , Ono, R. and Rudman, D. (1999), Passivation, Transition Width, and Noise for YBCO Bolometers on Silicon, IEEE Trans. on Appl. Supercond. (Accessed September 26, 2025)