Electrical percolation threshold evaluation of silver thin films for multilayer WO₃/Ag/WO₃ transparent conductive oxide

In this work, we developed an algorithm capable of identifying the electrical percolation threshold from AFM images of silver (Ag) thin films with different thickness. The percolation threshold was first determined experimentally using electrical measurements. Subsequently, the AFM images, film thicknesses, and conductivity values were fed to the algorithm to correlate the morphology from the AFM images and determine the existence of electrical conductivity. Then, the algorithm was calibrated using the threshold values found experimentally. Finally, the minimum thickness necessary for electrical percolation of silver thin films was determined to be around 7 nm. This methodology eliminates the urgency to carry out electrical measurements once the morphological ones are available, providing a criterion that allows to decide whether a film is suitable for its use as an intermediate layer in multilayer TCOs. To validate these results, indium free room temperature TCOs multilayer WO3/Ag/WO3 were grown and the Haacke figure of merit (FOM) were calculated. A good quality WO3-based TCO was obtained with a FOM value of 1.11 x 10(-2) Omega(-1) for WO3 (10 nm)/Ag(7 nm)/WO3 (20 nm). (C) 2019 Elsevier B.V. All rights reserved.