Low‐Damaged Layer‐by‐Layer Etching of Large‐Area Molybdenum Disulfide Films via Mild Plasma Treatment

Abstract Controlling the number of layers of 2D transition metal dichalcogenide (TMDC) film is indispensable for optoelectronic applications because of their layer‐dependent optical features. However, most of methodologies on controlling TMDC layers induce undesirable defect formation and are performed on TMDC flakes, obtained from mechanical exfoliation. These limitations make practical TMDC‐based optoelectronic applications more difficult. Herein, layer‐by‐layer etching methodology of molybdenum disulfide (MoS₂) films is developed using mild sulfur hexafluoride (SF₆) plasma treatment. It is confirmed that the number of layers is successfully controlled from trilayer to monolayer by increasing plasma treatment time, while preserving overall film quality. Such low‐damaged layer‐by‐layer etching is attributed to this mild plasma etching system to only introduce the chemical reaction between ionized fluorine and MoS₂, without physical damage to MoS₂. Electrical properties of layer‐controlled MoS₂ devices are also investigated, achieving comparatively high field‐effect mobilities of 16.2, 8.84, and 2.87 cm² V⁻¹ s⁻¹ for tri‐, bi‐, and monolayer MoS₂, respectively. This finding provides the possibility of realizing layer‐by‐layer engineering of 2D TMDCs.