Uncovering the physical properties, structural characteristics, and electronic application of superlattice-like Ti/Sb phase-change thin films

Abstract

Superlattice-like (SLL) Ti/Sb thin films were proposed and investigated from the viewpoint of physical properties, structural characteristics, and electronic application. Magnetron sputtering was employed to deposit the SLL Ti/Sb thin films with different thickness ratios. In-situ resistance–temperature measurement indicates that the crystallization temperature, crystallization-activation energy, and data-retention capacity increase significantly and the resistance drift index reduces with an increment in thickness ratio of the Ti to Sb layer, meaning higher amorphous thermal stability and reliability of SLL Ti/Sb thin films. X-ray diffraction and Raman spectra reveal that the inserted Ti layer can inhibit grain growth and refine the grain size, causing remarkable improvement of thermal stability and crystalline resistance. Analyses of x-ray reflectivity and atomic force microscopy demonstrate that the thickness fluctuation of SLL Ti/Sb thin films becomes smaller and the surface topography becomes smoother, respectively. The Avrami exponent of the SLL (Ti3Sb7)5 thin film reflects the growth-dominated crystallization mechanism, implying a rapid phase transition speed. Phase-change memory cells based on the SLL (Ti3Sb7)5 thin film can realize a reversible SET/RESET operation under an electrical pulse with a width of 100 ns. The RESET power consumption was estimated to be much lower than that of traditional Ge2Sb2Te5 material. The above results strongly prove that the suitable SLL structure of Ti/Sb thin films have tremendous potential in the area of high-temperature and low-power electronic storage.