Effect of nitrogen in the electronic structure of GaAsN and GaAsSb(N) compounds

Bandgap energy of GaAs1−xNx strained layers and of GaAs0.83Sb0.17/GaAs, GaAs0.74Sb0.25N0.01/GaAs quantum wells grown on (001) GaAs substrates by molecular beam epitaxy (MBE) were studied by absorption measurements. We have investigated the red-shift bandgap effect by the incorporation of low percentage of nitrogen in GaAs1−xNx strained layers with 0.1%<x<1.5%. At T=15 K, we have observed a red-shift of the band edge of about 250 meV for 1% of nitrogen. This effect has been explained by the band anticrossing (BAC) model in which the localized nitrogen states interact with the extended states of the conduction band of GaAs. We have also performed by absorption measurements the optical transitions of GaAsSb/GaAs and GaAsSbN/GaAs quantum well structures. To interpret the measurement results, we have used the envelope function approximation.