The low-temperature conductivity of etched quantum wires
Low-temperature transport measurements made on nearly depleted n+ GaAs quantum wires fabricated by molecular beam epitaxy and reactive ion etching are described. In such wires, damage generated by the etching process introduces traps at the wire edges and increases the effective depletion regions there. Exposure of the wires to low-level visible light at low temperatures causes conductance increases whereas the application of a high electric field to the wires causes a subsequent reduction in low-field conductance. Both nonequilibrium states decay slowly and logarithmically with time and can be annealed away by raising the temperature to around 150 K. It is postulated that the traps resulting from damage induced in the wire surfaces during preparation are responsible for the nonequilibrium low-temperature effects and suggest microscopic models for the mechanisms concerned.