A study on the crystallization behavior of Sn-doped amorphous Ge_2Sb_2Te_5 by ultraviolet laser radiation

摘要

In this paper, the influence of Sn doping (0%, 8% and 14%) on the crystallization of Ge_2Sb_2Te_5 was studied with the aid of an ultraviolet laser. The XRD analyses revealed that the addition of Sn maintained the Nad-type structure of Ge_2Sb_2Te_5 after crystallization but expanded the lattice parameter due to the smaller atomic radii of Ge replaced by Sn. Raman peaks (123,150 and 110 cm~(-1)) moved towards lower wavenumbers (118,137 and 104 cm~(-1)), which can be explained by the remarkable decrease of the binding energy from Ge-Te to Sn-Te. A remarkable increase in optical contrast from 15% to 40% was observed in the Sn-doped Ge_2Sb_2Te_5 film after crystallization with both the isothermal annealing and laser radiance. While the optical contrast changed little for a fixed volume fraction of Sn-doped sample with the variation of laser fluence which is attributed to the crystallization mechanism induced by laser under different fluences is the same.