Controllable phase separation and improved grain growth mode of Mg-doped Sb7Te3 films

The effects of Mg on the structure and phase-change kinetics of Sb7Te3 were investigated for phase change memory application. The results revealed that the addition of Mg increased the crystallization temperature, and crystalline activation energy, while hindering grain growth and suppressing phase separation from Sb+Sb2Te, Sb2Te, to Sb phases. Laser-induced phase-change behavior showed four regions in the Mg-Sb7Te3 films: crystallization, transition toward stability, amorphization and ablation. A reversible switching between crystallization and amorphization occurred more rapidly in Mg-doped Sb7Te3 films than in conventional Ge2Sb2Te5. Evaluation of Johnson-Mehl-Avrami plots indicated that the crystallization mode changed from three, two to one-dimensional grain growth as the Mg-doping level increased. This phenomenon contributed to the rapid phase change of Mg-doped Sb7Te3 films.