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

Abstract

Two-dimensional (2D) materials, such as molybdenum disulfide (MoS₂), 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 (Al₂O₃) 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 MoS₂ 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 MoS₂, edge sites may be preferred for dissociative chemisorption.