High conductivity along with high visible light transparency in Al implanted sol-gel ZnO thin film with an elevated figure of merit value as a transparent conducting layer.

In this work, sol–gel ZnO thin films were implanted with Al ions of various fluences to study their electrical transport properties as transparent conducting oxide (TCO) layers. Additionally, formation of structural defects and modifications of the optical emission properties due to implantation have been investigated extensively to correlate the resultant electrical properties. By varying the ion fluence over two orders of magnitude from 1 × 1013 to 6 × 1015 ions/cm2, interestingly the electrical transport properties have been seen to be degraded in an unexpected manner as soon as Al is implanted and beyond a certain fluence (5 × 1013 ions/cm2), the electrical properties begin to improve. For the highest fluence (6 × 1015 ions/cm2), the sheet resistance is found to be 156 Ω/sq with an average visible transmission of 82%. The figure of merit value of our Al implanted ZnO film for an Al fluence of 5 × 1015 ions/cm2 is the highest till date, which may be prospective as a TCO layer. Detailed investigation on the evolution of the electrical and photoluminescence properties with an increase in the Al ion fluence reveals that zinc vacancy type defects are formed in large number which on healing produces further higher conductivity in the films. Image 1 • Sol-gel ZnO thin films were implanted with Al ions followed by annealing at 450 °C. • Film with 156 Ω/sq sheet resistance and >80% visible transmittance is produced. • Maximum FOM value of 9.57 × 10 −4 Ω −1 has been achieved. • Zinc vacancy plays a vital role in controlling the observed electrical properties. • The study is useful for understanding implantation effect and utilization of films as TCO. [ABSTRACT FROM AUTHOR]