Tailorable Fragile-to-Strong Kinetics Features of Phase-Change Antimony Films by Metallic Oxides Doping

A fragile-to-strong (F-S) kinetics feature is desirable in phase-change supercooled liquids, for decoupling the contradictory relation between good thermal stability nearby glass transition temperature and fast crystallization speed around melting temperature. We designed three metallic oxides (MOs), i.e., the fragile TiO2, the moderate ZnO, and the strong GeO2, doping into a very fragile Sb matrix, which is an ideal elementary phase-change materials (PCMs) for overcoming the composition segregation in fatigued device, to tailor the F-S transition behavior in their supercooled liquids. Depending on the crystallization kinetics analyses of three representative films, which all exhibit the similar thermal stability with crystallization temperature of 200 ± 6 ºC, crystallization activation energy of 2.83 ± 0.09 eV, and the temperature for ten years data retention of 101 ± 7 ºC, we found no F-S behavior in the Sb62.1(TiO2)37.9 film, but weak and strong F-S behavior in Sb82.7(ZnO)17.3 and Sb73.6(GeO2)26.4 film, respectively. It seems likely that, doping the MOs with different fragility in Sb matrix can bring tailorable F-S kinetics features. Nevertheless, although the metal elementaries of Ti, Zn, Ge, have been confirmed could not bond with the Sb atoms, the Sb2O3 phase are detected more or less in Sb62.1 (TiO2)37.9 and Sb82.717.3 but not found in Sb73.6(GeO2)26.4 film. It is thus believed the formation of Sb2O3 would impede the F-S behavior in the supercooled liquids. The Sb73.6(GeO2)26.4 film that has large F-S transition magnitude of 2.3 and high F-S transition temperature of 536 K, is suggested to be a candidate for potential phase-change memory application. Such distinct F-S behavior in nano-size confined Sb73.6(GeO2)26.4 matrix, which consists of phase-changeable Sb and non-phase-changeable GeO2, stems from the competition between short-range ordering cluster that with abundant Peierls-like distortions in fragile Sb phase and medium-range ordering cluster that with energetical favorable networks in strong GeO2 phase.