Atomic Layer Deposition of Large-Area Polycrystalline Transition Metal Dichalcogenides from 100 °c through Control of Plasma Chemistry

Two-dimensional transition metal dichalcogenides, such as MoS₂, are intensely studied for applications in electronics. However, the difficulty of depositing large-area films of sufficient quality under application-relevant conditions remains a major challenge. Herein, we demonstrate deposition of polycrystalline, wafer-scale MoS₂, TiS₂, and WS₂films of controlled thickness at record-low temperatures down to 100 °C using plasma-enhanced atomic layer deposition. We show that preventing excess sulfur incorporation from H₂S-based plasma is the key to deposition of crystalline films, which can be achieved by adding H₂to the plasma feed gas. Film composition, crystallinity, growth, morphology, and electrical properties of MoS_xfilms prepared within a broad range of deposition conditions have been systematically characterized. Film characteristics are correlated with results of field-effect transistors based on MoS₂films deposited at 100 °C. The capability to deposit MoS₂on poly(ethylene terephthalate) substrates showcases the potential of our process for flexible devices. Furthermore, the composition control achieved by tailoring plasma chemistry is relevant for all low-temperature plasma-enhanced deposition processes of metal chalcogenides.