Investigation of size fluctuations in quantum wires by micro-luminescence

Disorder and spectral broadening of vertically-stacked InGaAs/GaAs V-grooved quantum wires have been investigated by means of micro-probe luminescence. We show that the main spectral broadening mechanism originates from monolayer fluctuations at the bottom of the wire. A direct evidence of monolayer height islands of area 40^*40 nm formed at the bottom of the grooves is provided by atomic force microscopy. Lateral and vertical wire-to-wire fluctuations are found to be negligible on the micron-scale