Controlled Layer-by-Layer Etching of MoS2

Two-dimensional (2D) metal dichalcogenides like molybdenum disulfide (MoS2) may provide a pathway to high-mobility channel materials that are needed for beyond-complementary metal-oxide-semiconductor (CMOS) devices. Controlling the thickness of these materials at the atomic level will be a key factor in the future development of MoS2 devices. In this study, we propose a layer-by-layer removal of MoS2 using the atomic layer etching (ALET) that is composed of the cyclic processing of chlorine (Cl)-radical adsorption and argon (Ar)+ ion-beam desorption. MoS2 etching was not observed with only the Cl-radical adsorption or low-energy (<20 eV) Ar+ ion-beam desorption steps; however, the use of sequential etching that is composed of the Cl-radical adsorption step and a subsequent Ar+ ion-beam desorption step resulted in the complete etching of one monolayer of MoS2. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) indicated the removal of one monolayer of MoS2 with ea...