Thermally induced epitaxial crystallization of thin a-SiO2 films represents a promising procedure for removing the ion-beam damage induced during the fabrication of integrated optical devices. In this paper we report on the crystallization of a-SiO2 films deposited on single crystalline α-quartz substrates, investigated by means of Rutherford backscattering spectrometry in channeling geometry (RBS-C). The epitaxial crystallization was achieved by means of a novel three-step procedure which uses high-fluence Cs+-ion doping of the films and subsequent annealing in air at 800-900°C. Similarly, amorphous SiO2 layers, created by the ion irradiation of α-quartz samples, were epitaxially regrown after alkali post-implantation and annealing, thus demonstrating that the regrowth is independent of the production history of the amorphous film. Optical spectroscopy in the range 300-1100 nm showed the good optical properties of the regrown layer. © 2001 Elsevier Science B.V.