Effect of main gas and carrier gas on ZnO thin films deposited by atmospheric pressure plasma jet

The effect of main gas flow rate and gas type of carrier gas on the electrical and optical properties of Ga-doped ZnO films deposited by atmospheric pressure plasma jet was investigated. Adding Ar and H2 in the carrier gas reduces the sheet resistance of the films from 230 to 90 Ω/□ and increases the deposition rate by 38% due to the incorporation of hydrogen as a shallow donor and the lower breakdown potential of Ar, respectively. The effect of the main gas flow rate is less significant compared with the gas type of the carrier gas, but a proper flow rate is required to produce the film with lower resistivity. The lowest resistivity of 1.25 × 10− 3 Ω cm was achieved with a carrier gas mixture percentage of 75% and a main gas flow rate of 30 slm at a substrate temperature of 180 °C in open air. All the samples presented in this study exhibit average transmittance above 80% in the visible region and low haze below 5.5%.