TEMPERATURE-DEPENDENT EFFECTS ON LUMINESCENCE POLARIZATION AND RECOMBINATION LIFETIME IN SERPENTINE SUPERLATTICE QUANTUM-WIRE ARRAYS

We have measured photoluminescence excitation (PLE) spectra and radiat ive lifetimes as functions of temperature for serpentine superlattice quantum-wire arrays. The (Al, Ga)As arrays have lateral periods near 1 0 nm, and lateral confining potentials of 120 meV in the conduction ba nd. At law temperature the excitons are strongly localized within pote ntial fluctuations along the wires. The radiative lifetime of these lo calized states is 340 ps at 2 K. The degree of exciton localization de creases with increasing temperature, from which we estimate the srrong ly-localizing potential fluctuations to be approximately 10 meV deep. Above 80 K the excitons have sufficient thermal energy for motion alon g 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.