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

摘要

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 WS2 films of controlled thickness at record-low temperatures down to 100 ℃ 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 H2 to the plasma feed gas.Film composition,crystallinity,growth,morphology,and electrical properties of MoSx films prepared within a broad range of deposition conditions have been systematically characterized.Film characteristics are correlated with results of field-effect transistors based on MoS2 films deposited at 100 ℃.The capability to deposit MoS2 on 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.