Magnetophotoluminescence studies of (InGa)(AsN)/GaAs heterostructures

Photoluminescence (PL) measurements under a magnetic field (B=0--12T) have been performed on InₓGa_1-xAs_1-yNy/GaAs heterostructures for a wide range of N concentration $(0<~y<~0.052).$ We find that the value of the diamagnetic shift depends on temperature as long as localized carrier recombination contributes sizably to the PL spectra. Consequently, magneto-PL data have been taken at sufficiently high temperature so as to eliminate such contribution. The diamagnetic shift of the free exciton energy has been analyzed using a theoretical model developed in two dimensions for arbitrary strengths of the magnetic field. From this analysis we derive values of the electron effective mass, which are in good agreement with those reported in the literature from different experimental techniques and measuring different physical quantities. Finally, our work suggests that the concept of effective mass based on the envelope-function approximation holds also in the InₓGa_1-xAs_1-yNy/GaAs system, although the crystal translational symmetry is strongly perturbed by the nitrogen atoms.