Improved Mechanical and Electrical Properties of Phase-Change-Memory Ga-Sb Thin Films.

In this study, we focus on the mechanical and electrical properties of Ga-Sb thin films with different Sb contents; the corresponding improvement mechanism is also discussed. The phase-identification results prove that cubic GaSb phase and rhombohedral Sb phase exist in crystalline Ga-Sb thin films. Moreover, elemental Ga formed in small sizes around the boundary was observed. The resistance-temperature curves prove that the crystallization temperature (T) of Ga-Sb is 40 °C higher than that of Ge₂Sb₂Te (GST), and that T increased with increasing Ga content, while the resistance contrasts decreased. Consequently, the amorphous thermal stability of Ga-Sb is superior. Nanoindentation results prove that the hardness and elasticity modulus of Ga-Sb increases with increasing Ga content and is higher than that of GST thin films. In addition, structural investigation demonstrated that with different Ga contents, the hardness improvement of Ga-Sb thin films benefits from grain-size effects and the precipitation of elemental Ga in grain boundaries. Therefore, the ratio of Ga and Sb content has a different influence on the properties of both constituents. These findings indicate that binary Ga-Sb compositions are promising candidates for phase-change-memory applications.