Structural Transformation of Thin Ge2Sb2Te5<Ag> Films Produced by Ion-Plasma Co-Sputtering Under Laser Irradiation

Structural transformation under laser irradiation in nanosized amorphous Ge2Sb2Te5 films modified with silver (Ge2Sb2Te5<Ag>) is investigated herein. Films with thickness of ~ 100 nm were obtained by ion-plasma radio-frequency magnetron sputtering of a Ge2Sb2Te5-Ag combined polycrystalline target in an argon atmosphere. The silver concentration in the films was varied up to 12.3 at.%. The structure of amorphous films under laser irradiation was assessed in situ by Raman spectroscopy. The results showed that in the Ge2Sb2Te5 and Ge2Sb2Te5<Ag> films, under the action of laser irradiation, a phase transition occurred from an amorphous to a crystalline state. A phenomenon was observed in the phase transition in the Ge2Sb2Te5<Ag> films featuring the absence of an intermediate phase with a cubic structure (fcc) under the transition from the amorphous phase to the final phase with a stable hexagonal structure (hcp) at a certain concentration of Ag (5.5 and 12.3 at.%) and irradiation energy (1.6 mW). The discovery of this feature of the phase transition in Ge2Sb2Te5<Ag> films, which is controlled by the Ag concentration and irradiation power, is important for both the implementation of multilevel information recording and increased recording speed.