Microstructural, compositional, topological and optical properties of plasma polymerized cyclohexane amorphous thin films

Abstract

Synthesis of plasma polymerized cyclohexane (PPCHex) thin films on to glass substrates has been done using a capacitively coupled parallel plate low-pressure glow discharge technique from cyclohexane at room temperature. From scanning electron microscopy, smooth and homogeneous surface of PPCHex thin films is observed and atomic force microscopic micrographs show the roughness of 0.815 to 0.364 nm which also confirm the smooth, homogenous, pinhole free and uniform surface of the PPCHex thin films. The presence of 73.1 and 74.7 percentage of carbon in PPCHex thin films of thicknesses 220 and 350 nm with a small percentage of oxygen is confirmed by the energy dispersive x-ray analysis. The PPCHex thin film is thermally stable up to about 510 K. The structure of PPCHex thin films is observed to vary with film’s thickness by forming new chemical bonds such as O-H stretching, C=C stretching, C≡C stretching, C-O stretching compared to that of the monomer. Allowed direct band gaps of PPCHex thin films are found between 2.97 and 3.61 eV for different thicknesses and allowed indirect band gaps are found to be 1.83 to 2.31 eV. Therefore, the PPCHex could be used in different type of optoelectronic devices.