SATURATION OF ELECTRON PHASE BREAKING TIME IN GAAS ALGAAS QUANTUM WIRES/

We have systematically studied an electron phase breaking time in AlGa As/GaAs quantum wires by measuring the weak-localization effect. The p hase breaking time does not saturate down to 0.5 K for quantum wires w hose undoped AlGaAs spacers are not thinner than 30 nm, while it satur ates below 1 K for quantum wires whose spacers are not thicker than 15 nm. The saturated magnetoconductance shows no antilocalization featur es characteristic of a spin-orbit interaction. A spin-flip scattering by paramagnetic electron-trapped donors is discussed as one of the pos sible origins of the saturation. (C) 1996 American Institute of Physic s.