Fabrication and Characterization of Camphor-based Amorphous Carbon Thin Films

Abstract

Pure amorphous carbon (a-C) and nitrogen doped amorphous carbon (a-C: N) thin films were prepared using Thermal Chemical Vapor Deposition (CVD) with deposition temperature ranging from 5000C to 6500C using camphor (C10H16O) as a precursor from natural source. The physical and optical properties of deposited a-C and a-C: N thin films were characterized by UV-Vis-NIR spectroscope and Raman spectroscope. The presence of 2 peaks known as Raman D peaks and Raman G peaks ensure the amorphous structure of carbon (C). Raman ID/IG ratio for both pure and nitrogen doped a-C as deposition temperature increase indicates more graphitic structure in high temperature of a-C and a-C: N. Highest transmittance indicated at thin film with lowest deposition temperature (500oC) and vice versa. At visible range (390nm to 790nm) the transmittance exhibit high transmittance of above 80% at low temperature (500 and 550). However, at high temperature (600 and 650) transmittance is low (30% - 70%). The absorption coefficient, for both a-C and a-C: N is reported to be ∼x105cm-1. From Tauc's plot, optical band gap (Eg) was determined and Eg found to decrease as deposition temperature increased from 0.2 to 0.9eV for pure a-C and 0.2 to 0.75eV for nitrogen doped a-C.