Crystallization kinetics of Ga–Sb–Te films for phase change memory

Ga–Sb–Te ternary thin films were prepared by co-sputtering using targets GaSb and Sb8Te2. Crystallization processes of these films were studied by measuring the temperature-dependent electrical resistance during non-isothermal heating. The activation energy (Ea), rate factor (Ko), and kinetics exponent (n) were deduced from Kissinger and Ozawa's plots, respectively. The crystallization temperatures (Tx = 108∼319°C) increase with increasing GaSb contents. The activation energy (1.82∼7.52 eV) increases with increasing Ga content until 31.6 at.% then it decreases. The crystallization mechanisms of compositions A∼D (Ga17∼32Sb71∼62Te12∼6), as evidenced from n values, are nuclei formation and subsequent crystal growth; the nucleation rate decreases with grain growth. While composition E (Ga38.2Sb57.7Te4.1) reveals an n value lower than 1.5, it implies the one-dimensional crystal growth from the nuclei. The crystallization time of each composition was evaluated using JMA equation using all derived kinetics parameters. Composition C (Ga26.4Sb65.2Te8.4), showing the shortest crystallization time, is suggested for phase change RAM applications.