Abstract :
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.
