Energy Transfer of Excitons Between Quantum Wells Separated by a Wide Barrier

We present a microscopic theory of the excitonic Stokes and anti-Stokes energy transfer mechanisms between two widely separated unequal quantum wells with a large energy mismatch (Δ) at low temperatures (T). Exciton transfer through dipolar coupling, photon-exchange coupling and over-barrier ionization of the excitons through exciton-exciton Auger processes are examined. The energy transfer rate is calculated as a function of T and the center-to-center distance d between the two wells. The rates depend sensitively on T for plane-wave excitons. For located excitons, the rates depend on T only through the T-dependence of the localization radius