(Invited) 0D Defects in 2D Materials for Memory Effect

Abstract

Two-dimensional (2D) materials are intrinsically heterogeneous and host a variety of defects. Among them, zero-dimensional defects such as vacancies and dopants modify the energy landscape at the atomic scale and lead to fascinating local electronic properties different from the ‘‘ideal” 2D sheets. Controlling and exploiting these defects can provide novel functionalities and electron devices with unprecedented spatial densities. Recently, by using monolayer MoS2 as a model material, we actualized the smallest memristor device. This atomic-scale memory unit utilizes a singular defect for non-volatile resistive switching. Atomistic imaging, spectroscopy and transport measurements with scanning tunneling microscope reveal that metal substitution into sulfur vacancy is responsible for the non-volatile resistance change. Experimental observations are supported by computational studies of defects and their electronic states. These findings do not only provide an atomistic understanding of the non-volatile switching observed in a large set of monolayer transitional metal dichalcogenide (TMD) sandwich structures but also open new avenues for precision defect engineering in 2D materials for ultra-dense memory and brain-inspired or neuromorphic computing applications.