TUNNELING CONDUCTANCE BETWEEN PARALLEL 2-DIMENSIONAL ELECTRON-SYSTEMS

We derive and evaluate expressions for the low-temperature dc equilibrium tunneling conductance between parallel two-dimensional electron systems. Our theory is based on a linear-response formalism and on impurity-averaged perturbation theory. The disorder broadening of features in the dependence of tunneling conductance on sheet densities and in-plane magnetic-field strengths is influenced both by the finite lifetime of electrons within the wells and by momentum-nonconserving tunneling events. Disorder vertex corrections are important only for weak in-plane magnetic fields and strong interwell impurity-potential correlations. We comment, on the basis of our results, on the possibility of using tunneling measurements to determine the lifetime of electrons in the quantum wells.