Layer thickness dependence of the phase separation and phase change properties of Ge2Sb2Te5/TiN superlattice-like thin films

Highlights: • The phase separation is observed in Ge₂Sb₂Te₅/TiN superlattice-like (SLL) films. • Phase change properties can be greatly improved by increasing the layer thickness. • The SLL film may have potential in high-speed phase change memory applications. - Abstract: The dependence on the layer thickness of the structural and phase change properties of Ge₂Sb₂Te₅/TiN superlattice-like thin films are investigated. The phase separation of binary Sb₂Te₃ and GeTe phases is investigated using X-ray diffraction and Raman spectral analysis. The Ge₂Sb₂Te₅/TiN interface is believed lead to phase separation, as well as the interface effects that facilitate the phase separation process in the superlattice-like films. In this investigation of the phase change properties, the critical temperature, 10-year lifetime temperature, phase change speed, and optical band gap are measured. We found that the phase change properties of Ge₂Sb₂Te₅ are greatly improved by increasing the layer thickness as a result of the phase separation suppression in the structure. This superlattice-like thin film may have potential in high-speed phase change memory applications.