Influences of ion species (Ge +, Sb +, Au 2+) on crystallization of amorphous Ge films induced by high energy ion irradiation

Abstract

Amorphous Ge films deposited on CaF 2 substrates were irradiated with Ge, Sb and Au ions and their structural changes were examined. Samples during irradiations were kept at a constant temperature about 380°C since a formation of randomly oriented crystals in amorphous matrix was closely related to temperature. It was found that the crystal quality of the epitaxial Ge films became good and the formation of randomly oriented crystals was retarded with increasing ion mass. These results presumably suggested that the crystal quality was correlated with the amount of randomly oriented crystals. Furthermore, it was assumed that the formation of randomly oriented crystals were affected by the single collision cascade whose size was increased with ion mass. From these results, it was concluded that heavy ion irradiation was effective for the enhancement of the epitaxial crystallization and the suppression of the formation of randomly oriented crystals.