Interaction between conduction band edge and nitrogen states probed by carrier effective-mass measurements in Ga As1-x Nx

The electron effective mass, me, has been determined by magnetophotoluminescence in as-grown and hydrogenated Ga As1-x Nx samples for a wide range of nitrogen concentrations (from x<0.01% to x=1.78%). A modified kp model, which takes into account hybridization effects between N cluster states and the conduction band edge, reproduces quantitatively the experimental me values up to x≤0.6%. Experimental and theoretical evidence is provided for the N complexes responsible for the nonmonotonic and initially puzzling compositional dependence of the electron mass.