Crystallization behavior and electrical characteristics of Ga–Sb thin films for phase change memory

Abstract

In this work, we investigated the structural and conductivity stability of Ga-Sb thin films for phase change memory (PCM). The mass density and thickness change are significant for stability and reliability of PCM. The Ga-Sb thin films were deposited on SiO₂/Si (100) wafer using magnetron co-sputtering method. Phase identification revealed that nanoscale face center cubic structure GaSb and rhombohedral structure Sb formed in Ga-Sb thin films, the formation of phase Sb was more obvious in Ga₂₀Sb₈₀. Ga-Sb film exhibits an unusual behavior upon crystallization with less mass density and thickness change. The microstructure of Ga₄₅Sb₅₅ thin films improved their structural (density and film thickness) characteristics: the crystal growth of {111} and {110} oriented grains in Ga-Sb thin films is obvious, the grains growth in Ga₄₅Sb₅₅ thin films was more even and the bonding states in Ga-Sb thin films were more stable. In addition, the conductivity activation energy of Ga-Sb decreased with increasing Sb contents, thus the temperature stability of conductivity was improved. The structure transformation and conductivity activation energy of Ga-Sb phase change materials are in favor of mechanical stresses reduction and reliability enhancement of PCM. This study introduces the influence mechanism of structural and conductivity stability in Ga-Sb thin films and may provide reference for further testing in higher endurance performance phase change materials.