The use of AlN as a nucleation layer has been critical to the development of III-nitride on silicon devices. AlN acts as a barrier, preventing gallium precursors from etching the substrate. It also induces compressive strain in overgrown GaN layers which compensates the tensile stress that arises during cooling. Many studies have investigated the influence of AlN growth parameters on the crystal quality and morphology of subsequent GaN layers; however there is a limited understanding of the growth mechanisms of single AlN films in the literature. This work investigates the morphology and structure of AlN grown on silicon (111) with the use of an aluminum interlayer. Atomic force microscopy (AFM) and transmission electron microscopy are utilized to understand the thermodynamics and kinetics of AlN grown below the melting point of aluminum, at 800OC and near 1100OC. The morphological evolution of a two temperature (low temperature to high temperature) nucleation layer is studied with AFM. Finally, molecular dynamics simulations are employed to better understand interdiffusion between the substrate and the initial Al and AlN layers.