Oxygen-activated epitaxial recrystallization of Li-implanted alpha-SiO2

A very strong exchange of oxygen between alpha-quartz (O-16) and annealing atmosphere (O-18) observed during solid-phase epitaxial growth of Li+- and Cs+-ion-beam-amorphized single-crystal alpha-quartz is reported. Epitaxial regrowth was observed in Li-irradiated samples after 700 degrees C annealing and in Cs-irradiated samples after 870 degrees C annealing, by means of Rutherford backscattering spectrometry in channeling geometry. The O-18/O-16 exchange and the outdiffusion of Li were investigated by the use of time-of-flight elastic recoil detection analysis. Our experiments show that alkali-ion implantation strongly enhances the exchange of O-16 in SiO2 with O-18 of the annealing atmosphere. The exchange accompanies the loss of alkali atoms, thus favoring the recrystallization of the lattice. Mechanisms of epitaxial regrowth in Li- and Cs-implanted alpha-quartz are discussed.