Physica E 40 (2008) 489–493 Nitrogen effect on optical gain and radiative current density for mid-infrared InAs(N)/GaSb/InAs(N) quantum-well laser M. Debbichi a,1 , A. Ben Fredj a , M. Saı¨d a , J.-L. Lazzari b , Y. Cuminal c , P. Christol c,Ã a Unite´de Recherche de Physique des Solides, De´partement de Physique, Faculte´des Sciences de Monastir, 5019 Monastir, Tunisia b Centrede Rechercheen Matie`re Condense´e et Nanosciences, CRMC-N 2 , UPR-CNRS 7251, Case 913, Campus de Luminy, 13288 Marseille cedex 9, France c Institut d’Electronique du Sud (IES) UMR CNRS 5507, Case 067, Universite´Montpellier 2, 34095 Montpellier cedex 05, France Received 6 March 2007; accepted 4 July 2007 Available online 8 August 2007 Abstract Dilute-nitride InAsN/GaSb/InAsN ‘‘W’’ laser structure is theoretically investigated and compared with similar nitride-free InAs/GaSb/InAs ‘‘W’’ structure. The two laser diodes, to be grown on (0 0 1) InAs substrate, are designed to operate at 3.3 mm at room temperature. Their performances are evaluated in terms of modal gain and radiative efficiency characteristics deduced from optical gain calculation. We find that the inclusion of nitrogen in the laser active region improves optical gain performances leading to peak gain values of the order of 1000 cm 1 for typical injected carrier concentration of 1.5  10 18 cm 3 . Modal gain value equal to 70 cm 1 can be achieved and radiative current density inferior to 100 A/cm 2 is predicted. These results demonstrate that the dilute-nitride InAsN/GaSb/ InAsN laser structure is very attractive for room temperature operation in the midwave infrared domain. r 2007 Elsevier B.V. All rights reserved. PACS: 73.21.Fg; 73.61.Ey; 42.55.Px Keywords: Mid-infrared lasers; Dilute nitride; W lasers; Optical gain 1. Introduction Mid-wave infrared (MWIR) semiconductor laser diodes emitting in the 3–5 mm wavelength domain have a wide range of applications such as high-resolution gas spectro- scopy, environmental monitoring, medicine diagnostics and military countermeasure systems. For such applica- tions, high performance laser structures operating at room temperature (RT) in continuous wave (CW) regime are required with single optical mode emission. In the mid- infrared region, an impressive progress has been made recently by using highly sophisticated interband [1] and intraband [2] quantum-cascade lasers. But more conven- tional Sb-based lasers using type-I [3], type II ‘‘W’’-like [4] and dilute-nitride [5] multi-quantum well (MQW) struc- tures are also very promising to reach high performance device operation. Recently, dilute nitride III–V compounds have been the subject of important research interest as they exhibit new properties that are potentially useful for narrow band gap devices [6]. In particular, these compounds have been proposed as a new class of material for the realization of semiconductor quantum well (QW) laser diodes emitting at 1.3 and 1.55 mm [7–10]. It has been found that replacing a small amount (o5%) of the group V element by nitrogen in III–V compounds reduces the energy gap and changes the electronic structure, such as InAsN alloy due to its large bowing factor [11], thus offering new perspectives for band structure engineering in order to improve optoelec- tronic properties. Among the effects induced by nitrogen incorporation in III–V compounds, we can precise that the presence of nitrogen in the active quantum well is responsible of non-radiative recombination centres and an enlargement of the spectral linewidth [7]. Because the N ARTICLE IN PRESS www.elsevier.com/locate/physe 1386-9477/$ - see front matter r 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.physe.2007.07.003 Ã Corresponding author. E-mail address: philippe.christol@ies.univ-montp2.fr (P. Christol). 1 Also for correspondence. 2 Laboratory associated with the Universite´ de la Me´diterrane´e and the Universite´ Paul Ce´zanne.