Auger $KLL$ and $1s$ photoelectron spectra of silicon have been studied from samples of Si delta doped layers in GaAs with very thin capping layers. By tuning the exciting photon energy through the Si K edge resonant Auger spectra were obtained. A comparison of the $x$-ray absorption spectra (XAS) in the vicinity of the Si K edges with the energy dependence of the resonant Auger spectra indicates that in each material the resonant process involves a narrow state in the GaAs band gap localized at the Si sites. The energy dispersion of the resonant peak sheds light on the nature of these localized states and XAS data around the Si K edge indicates that they are located in the GaAs band gap. The results yield information on the positions and widths of the localized states.

• Received 16 July 2004

DOI:https://doi.org/10.1103/PhysRevB.71.075313