  We report that annealing Al-AlOx-Al tunnel junctions in a vacuum chamber at
temperature of 400C reduces the characteristic 1/f noise in the junctions, in
some cases by an order of magnitude. Both ultra high vacuum and high vacuum
fabricated samples demonstrated a significant reduction in the 1/f noise level.
Temperature dependence of the noise was studied between 4.2 and 340 Kelvin,
with a linear dependence below 100 K, but a faster increase above. The results
are consistent with a model where the density of charge trapping two
level-systems within the tunneling barrier is reduced by the annealing process.
