Study on the Crystallization Behavior of Sb2Te Thin Films for Phase-Change Memory Applications

Sb2Te thin films were deposited on SiO2/Si (100) substrates by magnetron sputtering. We investigated the crystallization behavior of Sb2Te thin films for phase-change memory applications. The experimental results show that the optical reflectivity is increased by more than 30% before and after crystallization. The resistance is decreased at least 102 orders of magnitude in the crystallization process, which suggests the application potential of Sb2Te thin film as optoelectronic storage material. The computational results show that the local crystallization activation energy is 1.72 eV and the crystal growth velocity is 4.96 m s−1, confirming the strong crystallization tendency of Sb2Te thin film. We examined the features of amorphous local bonding and found that the local octahedral geometry is the structural origin of optoelectronic contrast and crystallization tendency. Furthermore, the presence of weak Sb-Sb, Sb-Te, and Te-Te bonds and high mobility of Sb atoms facilitate the high-speed and low-activation-energy crystallization. Hence, we suggested that reducing the number of octahedrons and introducing the strong chemical bonds could promote stable optoelectronic memory applications of Sb2Te thin film.