The dependence of the optical properties on the 57Fe doping concentration in GaAs epilayers

Photoluminescence PL.and photoreflectance PR.measurements were performed to investigate the dependence of the optical properties on the 57Fe doping concentration in GaAs epilayers grown on GaAs substrates by molecular beam epitaxy. The results of the PL spectra for the undoped and the 57Fe-doped GaAs epilayers grown on GaAs substrates show that the peaks corresponding to the free exciton and the neutral donor bound exciton increasingly overlap with increasing Fe mole fraction. The PR spectra show that the surface electric field increases with increasing 57Fe doping concentration. These results indicate that the optical properties of the 57Fe-doped GaAs epilayers grown on GaAs substrates are strongly dependent on the 57Fe doping concentration and that 57Fe-doped GaAs epilayers hold promise for applications as semi-insulating substrate layers for the growth of active layers. q1999 Elsevier Science B.V. All rights reserved