Modeling Atomic Layer Deposition of Alumina as an Ultra-thin Tunnel Barrier using Reactive Molecular Dynamics*

In this study, we utilized the reactive molecular dynamics (MD) to simulate the Atomic Layer Deposition (ALD) process to form an ultra-thin tunnel barrier made of alumina. We chose reactive MD over the ab-initio molecular dynamics simulation for to its lower computational cost, its ability to model over a relatively longer period and its capability to assess atomistic-based dynamics for a larger substrate. We systematically evaluated the role of the various ALD precursors including the thrimethylaluminum (TMA) and Bis(2-ethyl-1,3-cyclopentadien-1-yl)magnesium (C14H18Mg) and the water pulse toward the chemical reactions that take place on the surface during ALD. We additionally evaluated the role of experimentally- observable parameters including the operating temperature and precursor concentrations for the internal structure of the amorphous alumina/magnesium as the final deposition products. Lastly, we assessed the role of wetting layers as the means to improve the quality and performance of the tunnel barrier.