Jia Shujing, Li Huanglong, Gotoh Tamihiro, Longeaud Christophe, Zhang Bin, Lyu Juan, Lv Shilong, Zhu Min, Song Zhitang, Liu Qi, Robertson John, Liu Ming
State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China.
Key Laboratory of Microelectronic Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China.
Nat Commun. 2020 Sep 15;11(1):4636. 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 and a ~10 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.
选择器器件是大规模非易失性存储器和神经形态阵列系统中不可或缺的组件。除了传统的硅晶体管外，具有更高可扩展性的两终端硫系阈值开关器件是目前工业上最青睐的选择器技术。然而，目前的硫系阈值开关器件严重依赖于对材料化学计量的复杂控制，并且通常使用有毒且复杂的掺杂剂。在此，我们报道了一种在环境友好且储量丰富的硫化物二元半导体GeS中实现的选择器，其驱动电流密度高达34 MA/cm²，非线性约为10。实验和第一性原理计算均表明，非晶态GeS中存在以Ge金字塔为主的网络结构以及高密度的近价带陷阱态。高驱动电流能力与强Ge-S共价性相关，而高非线性可能源于带隙中陷阱辅助电子跃迁、局部Ge-Ge链生长以及高电场下局部增强的键排列协同作用。
