Ultrahigh drive current and large selectivity in GeS selector

• Published in: Nature communications 2020-09, Vol.11 (1), p.4636-9, Article 4636
• Main Authors: Jia, Shujing, Li, Huanglong, Gotoh, Tamihiro, Longeaud, Christophe, Zhang, Bin, Lyu, Juan, Lv, Shilong, Zhu, Min, Song, Zhitang, Liu, Qi, Robertson, John, Liu, Ming
• Format: Article
• Language: English
• Subjects: 119/118; 140/133; 140/146; 147/137; 147/143; 639/301/1005/1007; 639/925/927; Alloys; Arrays; Crystallization; Current density; Electric fields; First principles; Germanium sulfide; Humanities and Social Sciences; Hybridization; Information technology; Internet of Things; Laboratories; Materials selection; Memory devices; multidisciplinary; Nonlinear systems; Nonlinearity; Phase transitions; Physics; Random access memory; Science; Science (multidisciplinary); Selectivity; Semiconductor devices; Silicon transistors; Stoichiometry; Sulfides; Switching; Valence band
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-18382-z

Selector devices are indispensable components of large-scale nonvolatile memory and neuromorphic array systems. Besides the conventional silicon transistor, two-terminal ovonic threshold switching device with much higher scalability is currently the most industrially favored selector technology. However, current ovonic threshold switching devices rely heavily on intricate control of material stoichiometry and generally suffer from toxic and complex dopants. Here, we report on a selector with a large drive current density of 34 MA cm −2 and a ~10 6 high nonlinearity, realized in an environment-friendly and earth-abundant sulfide binary semiconductor, GeS. Both experiments and first-principles calculations reveal Ge pyramid-dominated network and high density of near-valence band trap states in amorphous GeS. The high-drive current capacity is associated with the strong Ge-S covalency and the high nonlinearity could arise from the synergy of the mid-gap traps assisted electronic transition and local Ge-Ge chain growth as well as locally enhanced bond alignment under high electric field. Designing efficient selector devices for large-scale nonvolatile memory and neuromorphic array systems remains a challenge. Here, the authors propose a two-terminal ovonic threshold switching selector device with a large drive current density and a high nonlinearity, capable emulating stochastic integrate-and-fire neuron behavior.