Characterization of carbon-doped ZnO thin films: case study on doping concentration and substrate

Carbon-doped zinc oxide thin films (C:ZnO) were deposited via RF magnetron sputtering onto glass and Si substrates to investigate their viability as transparent and conductive oxide thin films. Incorporating highly inert carbon atoms into the ZnO thin films modulated the inherent defect sites, with the dopant concentration controlled by varying the number of graphite serving as carbon sources. The C:ZnO thin film with a nominal carbon concentration of 16% exhibited a sheet resistance of 224 Ω/□ and transparency in the visible regions. Moreover, an increasing trend in the photo-luminescence peak intensity was observed by carbon doping. The optical band gap values of the C:ZnO thin films decreased from 3.22 to 2.98 eV with increasing carbon concentration. Furthermore, a linear relationship was discerned between the band gap energy and tail width. The results of this study suggest that the C:ZnO thin film holds considerable promise as a transparent and conductive phosphor screen for implementation in solar cells and field emission displays.