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

Abstract

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*1012 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 e in the range kT < ϵ< ℏ/r. Here ϵ is the energy relative to Ef and r 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.