Controlling the microstructure of vapor-deposited pentaerythritol tetranitrate films

We have demonstrated that the microstructure of thick pentaerythritol tetranitrate (PETN) films can be controlled using physical vapor deposition by varying the film/substrate interface. PETN films were deposited on silicon and fused silica with and without a thin layer of sputtered aluminum to demonstrate the effects of the interface on subsequent film growth. Evolution of surface morphology, average density, and surface roughness as a function of film thickness were characterized using surface profilometry, scanning electron microscopy, and atomic force microscopy. Significant variations in density, pore size, and surface morphology were observed in films deposited on the different substrates. In addition, x-ray diffraction experiments showed that while films deposited on bare fused silica or silicon had only weak texturing, films deposited on a sputtered aluminum layer were highly oriented, with a strong (110) out-of-plane texture.