Fabrication of a novel low-cost triple layer system (TaZO/Ag/TaZO) with an enhanced quality factor for transparent electrode applications

Abstract

A triple layer system (TaZO/Ag/TaZO), consisting of tantalum doped zinc oxide (TaZO) as the top and bottom layers and metallic silver (Ag) as the intermediate layer, was deposited onto glass substrates. The top and bottom layers were deposited using an inexpensive home-made automated jet nebulizer spray technique (AJNSP) and the intermediate Ag layer was deposited using a thermal evaporation technique. Three different sets of samples with top and bottom layers having thickness values of around 50, 75 and 100 nm, respectively, were prepared, keeping the thickness of the middle layer constant (15 nm). The influence of thickness on structural, electrical, optical and photoluminescence properties along with surface morphology of the deposited triple layer systems was studied. A structural study revealed that the deposited films have the hexagonal wurtzite structure of ZnO, and an X-ray photoelectron spectroscopic study confirmed the presence of the expected elements in the system. Optical studies showed that the overall thickness of the films influences only marginally the transmittance of the films. The decrease in sheet resistance with the increase in thickness is explained on the basis of a grain boundary scattering mechanism. Among all the films examined, the multilayer film with the 75 + 15 + 75 nm thickness exhibited the best quality factor (8.98 × 10⁻³ (Ω sq⁻¹)⁻¹), and may be considered as a potential candidate for transparent electrode applications. To the best of our knowledge, this is the first report in which a low-cost chemical technique has been employed to fabricate a triple layer system.