title: Controlled Layer-by-Layer Etching of MoS₂.
abstract: 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 each ALET cycle; therefore, the number of MoS2 layers could be precisely controlled by using this cyclical etch method. In addition, no noticeable damage or etch residue was observed on the exposed MoS2.
authors.affiliation: †Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Korea.|∥Department of Physics, Jilin University, Changchun, Province of Jilin China.
authors.forename: TaiZhe
authors.initials: T
authors.lastname: Lin
authors.affiliation: ⊥Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: BaoTao
authors.initials: B
authors.lastname: Kang
authors.affiliation: ‡SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: MinHwan
authors.initials: M
authors.lastname: Jeon
authors.affiliation: §SEMATECH, 257 Fuller Road, Suite 2200, Albany, New York 12203, United States.
authors.forename: Craig
authors.initials: C
authors.lastname: Huffman
authors.affiliation: ‡SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: JeaHoo
authors.initials: J
authors.lastname: Jeon
authors.affiliation: ‡SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: SungJoo
authors.initials: S
authors.lastname: Lee
authors.affiliation: ∥Department of Physics, Jilin University, Changchun, Province of Jilin China.
authors.forename: Wei
authors.initials: W
authors.lastname: Han
authors.affiliation: ⊥Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: JinYong
authors.initials: J
authors.lastname: Lee
authors.affiliation: ‡SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: SeHan
authors.initials: S
authors.lastname: Lee
authors.affiliation: †Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Korea.|‡SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: GeunYoung
authors.initials: G
authors.lastname: Yeom
authors.affiliation: †Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: KyongNam
authors.initials: K
authors.lastname: Kim
keywords: MoS2; adsorption; atomic layer etching; desorption; layer by layer etching; plasma; two-dimensional (2D) material