Adsorption of aluminum precursors on MoS2 toward nucleation of atomic layer deposition

Two-dimensional (2D) materials, such as molybdenum disulfide (MoS 2 ), have gained considerable attention for future electronic applications because of their exceptional characteristics with atomic-scale thickness. However, uniform deposition of dielectric materials such as aluminum oxide (Al 2 O 3 ) on 2D materials remains challenging because of the chemically inert nature of these surfaces. In this study, the adsorption behaviors of aluminum ALD precursors on MoS 2 substrates were investigated using density functional theory (DFT) calculations. The results show that the physisorption of the popular trimethylaluminum (TMA) precursor shows low thermodynamic stability, whereas larger molecules such as aluminum triisopropoxide (ATIP) and triisobutylaluminum (TIBA) display greater stability for physisorption, suggesting better nucleation in ALD. While physisorption of these precursors is more stable on the basal plane than on the edge sites of MoS 2 , edge sites may be preferred for dissociative chemisorption. • Uniform nucleation of ALD on TMDCs requires physisorption of precursors. • DFT calculations on physisorption and chemisorption of Al precursors on MoS 2 . • Aluminum triisopropoxide (ATIP), triisobutylaluminum (TIBA), and trimethylaluminum (TMA) are compared. • ATIP and TIBA show greater physisorption stability than TMA • Basal planes are preferred for physisorption, while edge sites show reactivity toward chemisorption.