Chalcogenides and their applications to advanced phase-change-devices toward future IoT era

In this talk, chalcogenides and their applications to advanced high-performance devices such as nonvolatile memories and artificial synapses, which will play a great role in future IoT era, will be discussed from reliability, storage density, power consumption, and so on. To improve reliability, doping N or O into conventional chalcogenides with a fast operation speed was investigated with the aim of reducing the volume change upon crystallization. For ultrahigh-storage density, the multilevel storage was investigated using GeSbTe chalcogenide devices. More than 20 resistance levels with good stability were demonstrated, which resulted mainly from the gradual enlargement of crystalline region between electrodes by Joule heating. For ultralow power consumption, the phase-change device incorporated with nanostructures and a high-resistivity chalcogenide layer was systematically investigated and its heating efficiency was proved to be much higher than that of the conventional device. Finally, the chalcogenides and their applications to artificial synapses will be specially discussed.