The individual effect of coating thicknesses and deposition temperatures on Raman spectra of carbon films deposited on silica glass fibers by thermal chemical vapor deposition

Abstract

Carbon films are deposited on silica glass fibers by thermal chemical vapor deposition using pure methane as the precursor gas, and the individual effect of coating thicknesses and deposition temperatures on Raman spectra of carbon films is investigated. The results show that if the temperature is fixed at 950°C, the D peak position, the full‐width‐at‐half maximum of D band, and the integrated intensity ratio of the D band to the G band increase with increasing the coating thickness. This is because the size and number of particles grown on the carbon film surface increase with increasing the coating thickness and the carbon film becomes more disordered. Alternatively, if the coating thickness is fixed at 1200 nm, the D peak position, the full‐width‐at‐half maximum of D band, and the integrated intensity ratio of the D band to the G band decrease with increasing the deposition temperature. This indicates that the carbon film becomes more ordered and its nano‐grain size increases as the deposition temperature increases from 925 to 1025°C.