One-dimensional excitonic states and lasing in highly uniform quantum wires formed by cleaved-edge overgrowth with growth-interrupt annealing

High quality T-shaped quantum wire lasers are fabricated by cleaved-edge overgrowth with molecular beam epitaxy on an interface improved by a growth-interrupt high temperature annealing. Microphotoluminescence and photoluminescence (PL) excitation spectroscopy at low temperatures reveals the formation of quantum wires with unprecedentedly high quality, and intrinsic structures of one-dimensional (1D) free excitons, exciton excited states, and 1D continuum states. At high pumping levels, the PL evolves from showing a sharp free exciton peak via exhibiting a biexciton peak to a Coulomb correlated electron-hole plasma PL band. Lasing has been achieved with a low lasing threshold, and its emission patterns are measured in imaging experiments. The lasing energy is in the plasma PL band and is about 5 meV below the free exciton level. The observed shift excludes the possibility of free excitons in the lasing, and suggests a contribution from the electron-hole plasma. Single T-wire samples such as a single-quantum-wire laser and a field-effect-transistor-type doped single quantum wire are fabricated and studied optically.