Electron-electron interaction with decreasing conductance

The contribution of the electron-electron interaction to conductivity is analyzed step by step starting from the high conductivity in gated GaAs/InxGa1-xAs/GaAs heterostructures with different starting disorders. We demonstrate that the diffusion theory works down to k(F)lsimilar or equal to1.5-2, where k(F) is the Fermi quasimomentum and l is the mean free path. It is shown that the e-e interaction gives smaller contribution to the conductivity than the interference independent of the starting disorder, and its role rapidly decreases with decreasing k(F)l.