E₊ transition in GaAs_1-xN_x and GaAs_1-xBi_x due to isoelectronic-impurity-induced perturbation of the conduction band, B. Fluegel, A. Mascarenhas, A. J. Ptak, S. Tixier, E. C. Young, T. Tiedje, Phys. Rev. B 76, 155209 (2007)

An above-band-gap transition E+ is experimentally observed in the dilute GaAs_1-xBi_x alloy. Precise measurements at very low dilutions are made of the above-band-gap transition E₊ that is observed in GaAs_1-xN_x, making it possible to compare the behavior of the different isoelectronic traps Bi and N in the common host GaAs with respect to their perturbation to the host electronic structure. We suggest that the origin of the E₊ level observed in GaAs is not the isolated isoelectronic impurity level N_x, as is presumed in the band-anticrossing model, but rather the isoelectronic-impurity-induced perturbation of the conduction band L E₆ E^c.