Investigations of the ac electrical properties of the thin films of 2-furaldehyde synthesized by plasma polymerization technique

Abstract

Plasma polymerized 2-Furaldehyde (PPFDH) thin films of different thicknesses were synthesized onto glass substrates by using a capacitively coupled plasma polymerization reactor at line frequency. The thicknesses of the samples were measured by interferometric method and was found within the range of 250-980 nm. Smooth, aw-less and pinhole free surfaces of the PPFDH thin films were observed through Field Emission Scanning Electron Microscopy. The topological information was analyzed by the Atomic Force Microscopy and the surface roughness was found considerably low ( 1 nm). The chemical composition found by Energy Dispersive X-ray analyses, revealing that carbon is the omnipresent (around 81%) element, and oxygen was found in minimum proportion (around 19%) in the PPFDH thin films. Types of different chemical bonding of the synthesized thin films were studied by Attenuated Total Reactance Fourier Transform Infrared analyses, and then compared to that of the 2-Furaldehyde (FDH) monomer. Differential Thermal Analyzer (DTA) and Thermo gravimetric Analyzer (TGA) were used for thermal analysis in oxygen and nitrogen environments. The DTA curve for oxygen environment showed that two-stage degradation occurred, whereas in nitrogen it was single stage. From TGA analysis of PPFDH, weight losses were found 50% and 70% in nitrogen and oxygen environments respectively. PPFDH was found thermally stable up to around 500K in both environment. Optical analyses were carried out by UV-Vis. spectroscopy and direct and indirect band gaps were found in the range of 3.0-3.4 eV and 1.75-2.13 eV, respectively. Alternating current electrical conductivity was measured and the aver-age index value (n ≤1) indicated Debye type conduction mechanism. The dielectric constants and the loss factors were calculated. The Cole-Cole graphs referred the Debye type relaxation process.