Kinetic Roughening of Organic Energetic Material Thin Films by Atomic Force Microscopy

Morphology evolution of pentaerythritol tetranitrate (PETN) films formed on 16-mercaptohexadecanoic acid (MHA) self-assembly monolayer (SAM) has been investigated using tapping mode atomic force microscopy (AFM). The PETN films with thicknesses ranging from 30 nm to 1000 nm are thermally deposited on MHA SAM surface at room temperature. The dynamic exponents of the surface fluctuation are calculated in terms of dynamic scaling theory using AFM images. The roughness exponent α, the growth exponent β and the dynamic exponent 1/z are about 0.84, 0.52 and 0.14, respectively. The morphologies show mound-like features and crevices between mounds features formed as the thickness is increased. The effect of shadowing effect, surface diffusion, and Ehrlich- Schwoebel barrier (ESB) effect on the variations of scaling exponents and morphology formation has been discussed.