Electron–hole superlattices in GaAs/Al_xGa_1−xAs multiple quantum wells

Abstract

A GaAs/Al _x Ga_{1− x} As semiconductor structure is proposed, which is predicted to superconduct at T _c ≈ 2 K. Formation of an alternating sequence of electron- and hole-populated quantum wells (an electron–hole superlattice) in a modulation-doped GaAs/Al _x Ga_{1− x} As superlattice is considered. This superlattice may be analogous to the layered electronic structure of high-T _c superconductors. In the structures of interest, the mean spacing between nearest electron (or hole) wells is the same as the mean distance between the electrons (or holes) in any given well. This geometrical relationship mimics a prominent property of optimally doped high-T _c superconductors. Band bending by built-in electric fields from ionized donors and acceptors induces electron and heavy-hole bound states in alternate GaAs quantum wells. A proposed superlattice structure meeting this criterion for superconductivity is studied by self-consistent numerical simulation.

Acknowledgements

This work was supported in part by US Army Energetics, the US Army Research Office (W911NF-05-1-0346 ARO), the US Air Force Office of Scientific Research, Physikon Research Corporation (PL-206) and New Jersey Institute of Technology. The authors are most grateful for this support.