We have studied the low-frequency conductance fluctuations of very small-area metalinsulator-metal tunnel junctions. We find that the spectral power density at high temperature is typical of $\frac{1}{f}$ noise, but is resolved into a small number of Lorentzian spectra for $T\lesssim 80$ K. The thermally activated Lorentzians are described by a two-rate kinetics and a broad distribution of activation energies and attempt rates.

• Received 16 July 1984

DOI:https://doi.org/10.1103/PhysRevLett.53.1272