Recombination in InGaAs/GaAs quantum wire lasers

We have studied the recombination mechanism of InGaAs/GaAs V-shaped quantum wire lasers under electrical injection and in high magnetic field, from well below to above lasing threshold. The emission originates from free-carrier recombination independent of temperature and injection density. No excitonic contribution is found, indicating that excitons are weakly bound in these wires due to the internal piezoelectric field causing a strong Stark effect. A quantitative analysis of the piezoelectric field is performed by measuring the screening induced blue-shift of the electroluminescence at different densities and comparing it with the piezoelectric potential calculated from the quantum wire cross-sections observed by transmission electron microscopy. (C) 1999 Elsevier Science Ltd. All rights reserved.