Temperature Dependence of the 2D Electronic Density of States in Disordered Metal Films.

We present measurements of the temperature dependence of the conductance of a tunnel junction of the form Al/oxide/disordered granular Ag film at low temperatures. From these measurements we deduce that the logarithmic corrections to the two dimensional density of states due to disorder enhanced Coulomb interactions depend on temperature. Specifically, for sheet resistances 1.35k Omega/square6.12k Omega/square and temperatures 0.07K6.0K the logarithmic singularity in the density of states centered on the Fermi energy is sharp at low temperatures and smears out as the temperature increases. Our data is consistent with a model which attributes the temperature dependence of the density of states to a redistribution of the zero temperature energies of the quasiparticle states over an energy range of the order of k sub B T.