HALL-EFFECT AND LOW-TEMPERATURE PHOTOLUMINESCENCE MEASUREMENTS OF RARE-EARTH ERBIUM (ER) IMPLANTED GAAS

Hall-effect and laser-excited low-temperature photoluminescence (PL) t echniques were used to investigate the effect of rare-earth (RE) eleme nt Er-doped GaAs. Hall-effect measurements show that the introduction of Er and rapid thermal-annealing (RTA) treatment of undoped semi-insu lating and p-type GaAs substrates tend to make the substrates more con ducting, however, in general, leave the substrate semi-insulating. For the Er-implanted n-type GaAs, the Er-doping reduces the electron conc entration in the implant region. PL measurements show that the maximum intensity of the Er3+ intra-4f transitions occurs at a 750 degrees C anneal for undoped semi-insulating and n-type GaAs, and at 725 degrees C for p-type GaAs, These Er3+ intra-4f emissions may originate from E r ions at the interstitial sites rather than substitutional sites in t he GaAs lattice. The PL spectra of Er-implanted GaAs for identical Er- doping and annealing conditions show that the Er-4f luminescence is mo re intense in p-type compared to semi-insulating and n-type GaAs. The annealing study also shows that the Er is forming at least two differe nt luminescence centers upon annealing.