Morphological, elemental, and optical characterization of plasma polymerized n-butyl methacrylate thin films

Abstract

Plasma polymerized n-butyl methacrylate (PPnBMA) thin films of varying thicknesses were prepared at room temperature by AC plasma polymerization system using a capacitively coupled parallel plate reactor. Field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), energy-dispersive X-ray (EDX) analysis, and ultraviolet–visible (UV–Vis) spectroscopic investigation have been performed to study the morphological, elemental, and optical properties of the PPnBMA thin films, respectively. The flat and defect-free nature of thin films were confirmed by FESEM and AFM images. With declining plasma power, average roughness and root mean square roughness increase. Allowed direct transition (Egd) and indirect transition (Egi) energy gaps were found to be 3.64–3.80 and 3.38–3.45 eV, respectively, for PPnBMA thin films of different thicknesses. Values of Egd as well as Egi increase with the increase of thickness. The extinction coefficient, Urbach energy, and steepness parameter were also determined for these thin films.