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

Abstract

Ga–Sb–Te ternary thin films were prepared by co-sputtering using targets GaSb and Sb 8Te 2. Crystallization processes of these films were studied by measuring the temperature-dependent electrical resistance during non-isothermal heating. The activation energy ( E a), rate factor ( K o), and kinetics exponent ( n) were deduced from Kissinger and Ozawa's plots, respectively. The crystallization temperatures ( T x = 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 (Ga 17∼32Sb 71∼62Te 12∼6), as evidenced from n values, are nuclei formation and subsequent crystal growth; the nucleation rate decreases with grain growth. While composition E (Ga 38.2Sb 57.7Te 4.1) 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 (Ga 26.4Sb 65.2Te 8.4), showing the shortest crystallization time, is suggested for phase change RAM applications.