In situ transmission electron microscopy investigation of Si _x Sb _100-x phase-change materials

The crystallization processes of Si-Sb thin films containing different amounts of Si were investigated by in situ transmission electron microscopy (thermal annealing and electron beam irradiation). It was found that increase in the Si content significantly improve the thermal stability of Si _xSb _100-x thin films and changes the crystallization behaviour from growth-dominated to nucleation-dominated, thus leading to the refinement of the grain size. Further analysis shows that phase separation occurs if the Si content increases by more than 18.1%, resulting in the coexistence of high-Si amorphous regions and low-Si crystalline regions. Our results suggest a critical Si content, below which phase separations can be prevented.