Molecular dynamics simulation of nanoconfinement induced organization of n-decane

Molecular dynamics (MD) simulations are used to study the behavior of n-decane under sub-10 nm confinement between two gold {111} surfaces. This confinement and dielectric medium are characteristic of those used in nanoscale electromachining (nano-EM) processes; thus, it is important that the behavior of the nanoconfined dielectric medium be investigated for better process understanding. Results obtained via MD simulations indicate that, when confined down to a thickness less than 1 nm, the mechanical boundary conditions trigger organization in the n-decane medium, resulting in two distinct molecular layers. The n-decane chains lie flat on the {111} gold surfaces and show preferred orientation in the close-packed 110 crystallographic directions. A 4-fold increase in the maximum local density as compared with the experimental bulk (liquid) density is observed at the interface between the molecular medium and the gold {111} surfaces, regardless of confinement spacing. Radial distribution function curves are used to quantitatively examine organization of the medium into molecular layers. The deliberate introduction of ledges (atomic steps) on the gold surface triggers a preferred alignment of the n-decane chains toward the boundaries of the ledges.