LETTER
Applied Physics Express 12, 015504 (2019) https://doi.org/10.7567/1882-0786/aaed9d
Re-amorphization of GeSbTe alloys not through a melt-quenching process Junji Tominaga* and Leonid Bolotov* Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, 305-8565, Japan *
E-mail:
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Received August 10, 2018; accepted November 1, 2018; published online November 26, 2018 Ge–Sb–Te (GST) alloys are one of the most successful chalcogenides used in rewritable optical discs and electric non-volatile memories. In these materials the structural phase transition between amorphous and crystalline states is used for recording. Here, we report that a melt-quenching method is not necessarily the only way to form a high-resistance phase. We found that amorphous-like grains with high resistance are formed in the GST crystal film by holding it at above the crystallization temperature under an external magnetic field, followed by cooling accompanied with pulse current injection. The treatment may open new route for ultra-low current switching phase change memory. © 2018 The Japan Society of Applied Physics
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halcogenides, especially, Ge–Sb–Te (GST) alloys are widely used materials in rewritable phase-change optical discs and electric non-volatile memory. Since the discovery in the late 1960s, these alloys have been studied for nearly 40 years.1–4) Now, the alloys are used as recording films in digital versatile disc random access memory and blu-ray discs, and also are used as a recording materials in phase-change non-volatile memory (PRAM).5–7) The recording principle relies on the phase transition (change) between an amorphous state and a crystalline state, which is accompanied by a large change in refractive index and electric resistance.8–14) To form an amorphous mark in optical discs or bit in PRAM, a recording area is heated to the melting point (∼900 K), followed by rapid cooling down to below the crystallization temperature (∼430 K).15) When the cooling rate is slow (
