Lattice disorder and radiation enhanced annealing in La-implanted TiO2 single crystals

Rutherford backscattering spectrometry and channeling were used to characterize the disorder produced by implantation of La ions into TiO2 (rutile) single crystals at substrate temperatures T-i between 77 and 1100 K. Complete amorphization was observed at T-i of 77 and 300 K for La fluences of 1 x 10(15) cm(-2) and 2 x 10(15) cm(-2), respectively. At T-i equal to 300 K acid fluences of 1 x 10(15) cm(-2), radiation-enhanced annealing starts to affect the disorder profile. The recovery occurs preferentially in the near-surface region. With increasing T-i, two recovery stages of the lattice disorder, between 300 and 500 EC and above 700 K, have been observed. These stages are about 200 K lower than those observed for subsequent isochronal annealing of an amorphous TiO2 layer. At T-i equal to 1100 K recovery of the lattice disorder was nearly complete. A minimum yield of 2.5% was reached, similar to that of the virgin crystal. Radiation-enhanced diffusion of La into TiO2 leads to an estimated substitutional component of 35%.