GeTe₄ as a Candidate for Phase Change Memory Application

GeTe₄ films are deposited by using a dc magnetron sputtering technique, and its structural, thermal and electrical properties are investigated systematically. The prototypical phase-change memory cells are fabricated by using a focused ion beam and magnetron sputtering techniques. Compared with Ge₂Sb₂Te₅, the GeTe₄ film exhibits a higher crystallization temperature (235°C), better data retention of ten years at 129°C, and larger activation energy (2.94 eV). GeTe₄ phase change memory cells with an effective diameter of 1 μm show proper switching speed, low power consumption, and good resistance contrast. The Set and Reset operations are achieved by using a 200-ns 2.0-V pulse and a 30-ns 3.0-V pulse, respectively. The dynamic switching ratio between the OFF and ON states is larger than 1×10⁴.