Influence of the valenceband offset on absorption and gain in GaAs/GaNAs quantum wells

Summary form only given. In recent years, the unusually strong bandgap reduction of GaAs through the replacement of a few percent of arsenic atoms by nitrogen has been successfully explained for bulk semiconductors. It is modeled by anticrossing between the conduction band of GaAs and a degenerate and almost dispersionless nitrogen band. According to this model, the existence of the nitrogen band only influences the conduction band states. Therefore, it would seem reasonable to assume that the whole gap mismatch between well and barrier material in a GaAs/GaNAs heterostructures shows up in the conduction bandedge, the valenceband offset being zero. Usually it is not easy to determine valenceband offsets. As we show, the gain spectra could serve an unequivocal measure for the existence of a nonzero valenceband offset in GaAs/GaNAs quantum well structures.