Optical properties and electrical transport in intercalated amorphous carbon

Iodine and sulfur incorporated amorphous carbon (a-C) films are prepared by vapor phase pyrolysis of carbon rich organic precursor, maleic anhydride. Transmission electron microscopy (TEM) analysis depicts the intercalation induced local structural ordering and evolution of nano-graphitic phases in the sample. An X-ray photoelectron spectroscopy (XPS) study on these samples confirms the presence of intercalates. The study of optical properties of the samples by UV-vis absorption spectrometry accounts for a decrease in optical bandgap and Urbach energy with impurity incorporation and increase in pyrolysis temperature. This refers to induced structural ordering, decrease in disorder and increase in sp2 or π-sites in the sample. Electrical conductivity measurement on a-C samples reveals increase in conductivity with pyrolysis temperature induced by iodine and sulfur incorporation.