Effects of ethylene gas flow rate on optoelectrical properties of nitrogenated thin amorphous carbon films grown by microwave surface wave plasma CVD

Abstract

We report on the effects of ethylene gas (C 2H 4) on the electrical and optical properties of amorphous carbon (a-C) thin films grown on silicon, indium tin oxide (ITO) and quartz substrates by microwave surface wave plasma chemical vapor deposition (MW SWP CVD) at low temperature (< 100 °C). For film deposition, we used argon gas with ethylene composition as plasma source. The influence of the nitrogen incorporation on the optical and structural properties of the carbon films were investigated using different spectroscopic techniques. The nitrogen has been incorporated into a-C: N films which was confirmed by the x-ray photoelectron spectroscopy (XPS) measurement. The results indicate that the increasing flow of source (C 2H 4) has microstructure consisting of atomic sp 2/C phase, cross linked by sp 3/C which is very similar to the properties of a-C: N. It was found that the optical gap was shifted from 2.1 to 2.6 eV with increasing flow of source.