Effects of thermal annealing on the optical properties of Er-ion-implanted Al Ga As layers grown on GaAs substrates

Thermal annealing effects on the optical properties of erbium Er.-ion-implanted Al Ga As layers grown on GaAs by x 1yx metalorganic chemical vapor deposition were investigated by photoluminescence PL., photoreflectance PR., and Raman scattering measurements. The results of the Hall effect measurements showed that the carrier concentration of the Erq-implanted n-type Al Ga As layer decreases as the magnitude of the Er dose decreases. The results of the PL spectra x 1yx for the as-grown Al Ga As layers showed two peaks related to the bound exciton B, X.and to the recombination x 1yx between the carbon acceptor impurities and the electrons in the conduction band e, A8.c. As the magnitude of the Er-ion dose increased, the e, A8.c and B, X.peaks shifted to their higher energy sides. The results of the PR spectra showed that the broadening parameter decreased as the Er dose increased. This behavior originates from the passivation of the mobile carriers. The results of the Raman scattering measurements for the as-grown Al Ga As layers showed that a peak x 1yx appeared at 290 cmy1 corresponding to the GaAs-like longitudinal optical LO.phonon. When the Er-ion implantation in Al Ga As was accomplished at 1 MeV with a dose of 5=1013 cmy2, the GaAs LO phonon peak disappeared. After x 1yx thermal treatment, the results of the PL and PR spectra indicate that the number of donors decreases due to the formation of the donor–acceptor pairs. Those of the PL, PR and the Raman spectra show that the damaged crystallinity of the Er-doped Al Ga As layers is improved by thermal treatment. This result indicates that mobile carriers in the Al Ga As layers x 1yx x 1yx are passivated by the Er-ion injection and that the passivated Al Ga As layers are recovered by thermal treatment. x 1yx q2000 Published by Elsevier Science B.V.