Tunneling Between Parallel Two-Dimensional Electron Gases

TL;DR

This paper investigates tunneling between parallel two-dimensional electron gases, analyzing effects of temperature, carrier density, and magnetic field, revealing electron lifetime, scattering mechanisms, and tunneling density of states behavior.

Contribution

It provides new measurements of electron lifetime, tunneling density of states, and models conductance in strong magnetic fields, advancing understanding of 2DEG tunneling phenomena.

Findings

Lorentzian lineshape of tunneling resonance at zero magnetic field

Electron lifetime varies with density and temperature

Magnetic field suppresses tunneling and reveals a tunneling gap

Abstract

The tunneling between two parallel two-dimensional electron gases has been investigated as a function of temperature $T$, carrier density $n$, and the applied perpendicular magnetic field $B$. In zero magnetic field the equilibrium resonant lineshape is Lorentzian, reflecting the Lorentzian form of the spectral functions within each layer. From the width of the tunneling resonance the lifetime of the electrons within a 2DEG has been measured as a function of $n$ and $T$, giving information about the density dependence of the electron-impurity scattering and the temperature dependence of the electron-electron scattering. In a magnetic field there is a general suppression of equilibrium tunneling for fields above $B=0.6$ T. A gap in the tunneling density of states has been measured over a wide range of magnetic fields and filling factors, and various theoretical predictions have been examined. In a strong magnetic field, when there is only one partially filled Landau level in each layer, the temperature dependence of the conductance characteristics has been modeled with a double-Gaussian spectral density.