Investigation of fractal behavior, optical properties and electronic environments of carbon-doped of ZnO Thin Films

The undoped zinc oxide (ZnO) and carbon-doped zinc oxide (C:ZnO) thin films were synthesized with different process temperatures by using a chemical vapor deposition technique. The fractal dimension of AFM images was evaluated by power spectral density function, spatial function distribution, cube counting, and triangular counting by Gwyddion software. AFM results reveal undoped and C:ZnO indicated a larger particle size (~ 1.5 µm) and 200–50 nm, respectively, with increase in process temperature from 650 to 750 °C. The estimated lattice strain varied from 0.0033 to 0.0008 and 0.0038 to 0.0078 corresponding to the process temperature 650–750 °C for ZnO and C:ZnO thin films, respectively. The oxygen and zinc contents varied from 43.65 to 47.16 at.% and 47.13 to 33.83 at.%, respectively. The optical bandgap varied from 3.17 to 3.19 eV and 3.14 to 3.06 eV for undoped ZnO and C:ZnO thin films, respectively, and ID/IG varied 1.97–2.22 as the carbon content increased from 9.21 to 19 at.%. Photoluminescence of C:ZnO indicated deep level defect shifted from 481.56 to 515.1 nm with increase in process temperature from 650 to 750 °C. The possible bonding network of core orbital of Zn(2p), C(1s), and O(1s) in the C:ZnO thin films has been discussed by deconvolution with the Origin 2018.