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 we ll below to above lasing threshold. The emission originates from free-carri er recombination independent of temperature and injection density. No excit onic contribution is found, indicating that excitons are weakly bound in th ese wires due to the internal piezoelectric field causing a strong Stark ef fect. A quantitative analysis of the piezoelectric field is performed by me asuring the screening induced blue-shift of the electroluminescence at diff erent densities and comparing it with the piezoelectric potential calculate d from the quantum wire cross-sections observed by transmission electron mi croscopy. (C) 1999 Elsevier Science Ltd. All rights reserved.