ELECTRONIC NOISE PROPERTIES OF BARIUM POTASSIUM BISMUTH OXIDE (BKBO) THIN FILMS

We have measured the low frequency electrical "noise fluctuations in superconducting barium potassium bismuth oxide (BKBO) thin films deposited by magnetron sputtering and by laser ablation. The excess noise in the presence of a bias current was 1/f noise. The magnitudes of the room temperature 1/f noise were somewhat higher than observed in the best cuprate high temperature superconducting thin films. The noise magnitude did not scale as expected with film geometry, and the noisier BKBO film also had the highest superconducting transition temperature. We suggest that etch pits observed on the patterned films contributed to the total 1/f noise measured. Both films exhibit a peak in the noise voltage at the foot of the superconducting transition which cannot be explained from a model of 1/f noise resulting from temperature fluctuations.