Correlation study of structural, optical, and hydrophobicity properties of diamond-like carbon films prepared by an anode layer source

Diamond- like carbon (DLC) thin films were deposited using anode layer source system on glass substrate at substrate temperature ranging from room temperature (RT) to 375 degrees C. An anode layer source is a specific ion gun, which can be fed with carbon precursors like propane to deposit hard and highly defect-free hydrogenated DLC thin films. The morphological, structural, optical, and hydrophobicity properties of DLC thin films were characterized by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, UV- Vis spectrophotometer, and water contact angle (CA) measurement. The surface roughness was found to increase with substrate temperature. Disorder (D) and graphite (G) peak positions have been observed to respectively move toward 1400 cm(-1) and 1546 cm(-1), with substrate temperature, indicating a graphitization of DLC thin films, which may probably be ascribed to the sp(2) cluster sites growth. The full width at half maximum (FWHM) of G peak increased upon increasing the substrate temperature. From the FWHM values of G peak, the clusters became more ordered with increasing the substrate temperature of DLC thin films. The G peak position changed by increasing the substrate temperature that in turn led to increment in the I-D/I-G ratio from 0.71 to 0.85, and also the graphite cluster size increased from 1.07 to 1.24 nm. Optical transmittance in UV and near infrared regions of the prepared DLC thin films found to decrease with the increase of substrate temperature. The refractive index (n) and extinction coefficient (k) of the films have been found to increase with substrate temperature. The CA of DLC thin films slightly increased with increasing substrate temperature from 80 degrees at RT to 94 degrees at 300 degrees C.