In this work, the structural properties of Ga(1-x)Tn(x)N(y)As(1-y) (GINA) quantum wells (QW) are investigated in terms of interface roughness and chemical composition variations by using conventional and high-resolution transmission electron microscopy (HRTEM). The structural behaviors of these heterostructures are systematically compared with the optical properties investigated by photoluminescence (PL). Our results demonstrate that high PL efficiency of GINA material, irrespective of composition, can be obtained only when the epitaxy is performed under conditions preserving a 2D growth mode. Moreover, composition variations are shown at a local scale using HRTEM and strain mapping. (C) 2002 Elsevier Science B.V. All rights reserved.