To improve the performance of metalorganic chemical vapor deposition (MOCVD)-grown long wavelength InGaAsN quantum well (QW) diode lasers emitting beyond 1.3 mum, a detailed examination of the growth parameters was performed, including DMHy/V ratio, QW growth temperature, choice of barrier material and thermal annealing temperature. This study reveals that a growth temperature in the 530-540 degreesC range is preferred in order to improve nitrogen incorporation and prevent degradation of the material luminescence. Increasing the DMHy/V ratio is found to be the preferred method to achieve wavelength extension. Utilization of GaAsN barrier layers, instead of GaAs barriers, Suppresses the spectral blue-shift of the quantum well luminescence after thermal annealing treatment. Under optimized growth conditions, InGaAsN diode lasers emitting at 1.378 mum are realized with a threshold current density of 661 A/cm(2) and external differential quantum efficiency of 34%. Lasing wavelengths as long as 1.41 mum with a threshold current density of 1.93 kA/cm(2) are also demonstrated, representing the longest wavelength InGaAsN QW lasers realized by MOCVD. (C) 2004 Elsevier B.V. All rights reserved.