Temperature dependent effects on luminescence polarization and recombination lifetime in serpentine superlattice quantum wire arrays

We have measured photoluminescence excitation (PLE) spectra and radiative lifetimes as functions of temperature for serpentine superlattice quantum-wire arrays. The (Al, Ga)As arrays have lateral periods near 10 nm, and lateral confining potentials of 120 meV in the conduction band. At low temperature the excitons are strongly localized within potential fluctuations along the wires. The radiative lifetime of these localized states is 340 ps at 2 K. The degree of exciton localization decreases with increasing temperature, from which we estimate the strongly-localizing potential fluctuations to be approximately 10 meV deep. Above 80 K the excitons have sufficient thermal energy for motion along the wires. The radiative lifetimes increase with temperature, to 20 ns for free carriers at 325 K. The lateral potential barriers inhibit diffusion to non-radiative recombination sites.