Photoreflectance evidence on the N-induced increase of the exciton binding energy in a InGaAsN alloy

The binding energy of the heavy-hole ground-state exciton in In0.25Ga0.75As(1-y)Ny /GaAs single quantum wells (y= 0 , 0.011) was experimentally derived by photoreflectance measurements. We measured a binding energy of 6.6 and 8.5 meV for the N-free and the N-containing sample, respectively. The observed increase of the exciton binding energy can be accounted for by an increase of the exciton reduced mass of about 30% upon N introduction into the InxGa(1-x)As lattice, consistently with recent experimental results and in agreement with earlier theoretical predictions.