Local structure and optical property of GeTe@Cu composite thin film

Nano particle embedded thin film has great potential application in tuning the optical properties of phase change material. In this paper, we prepared GeTe nano particle embedded Cu composite thin film (GeTe@Cu) by magnetic co-sputtering GeTe and Cu targets. High-resolution transmission electron microscopy (HR-TEM) was used to characterize the local structure of the composite thin film and the GeTe nano particles. It was found that the composite thin film was constituted of net-like Cu-Cu bonds, Ge (Te)-Cu bonds as well as GeTe nano particles. Optical reflectivity of the composite thin film was also measured. Ab initio molecular dynamics (AIMD) simulations was employed to investigate the forming mechanism of GeTe nano particles and the local features in detail. Simulation results revealed that Ge-Te-Ge-Te four-fold ring promote the formation of GeTe atom cluster and large amount of free electrons from Cu atoms make the Ge-Te bonds stronger, in further leading to the formation of GeTe nano particles. These results in this paper paved the way for further research about multi-level optical storage of nano particles embedded phase change composite thin film.

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