Electron-electron interaction and tunnel density of states at the Fermi level in high-density two- dimensional electron system

The zero bias anomaly (ZBA) of the tunnel conductivity are investigated in the Al/δ−GaAs tunnel structure with 2D electron concentration in δ-layer to be equal to 3.6∗10 cm−2. We find that the dip (ZBA) in the tunnel density of states near the Fermi level EF reveals logarithmic dependence on the energy ε in the range kT < ε< h̄/τ . Here ε is the energy relative to EF and τ is the elastic relaxation time of 2D electrons. The depth of the ZBA is proportional to ln(T/T0) in the range T = 0.1 − 20 K. These results are in agreement with Aronov-Altshuler theory in which the correction to the 2D density of states is due to the effects of the electron-electron interaction in diffusion channel. The unusual behavior of the tunnel magnetoconductivity is observed.