1/f noise in the tunneling current of thin gate oxides

We have observed fluctuations in the tunneling current through 3.5 nm gate oxides with a 1/f power spectrum where f is the frequency. For voltages in the direct tunneling regime we find an anomalous current dependence of the noise relative to previous observations of noise in thin oxides. We present a simplified model for the current noise in terms of fluctuations in a trap assisted tunneling current that exists in the oxide in addition to the direct tunneling current. Current noise appears to be a very sensitive probe of trap assisted tunneling and degradation in oxides.