Fabrication and Characterization of Transparent Conductive ZnO:Al Thin Films Deposited on Polyethylene Terephthalate Substrates

Abstract

This article deals with the optimization of the process parameters, with regard to multiple performance characteristics, involved in the preparation of transparent conducting Al 2 O 3doped (2 wt.%) zinc oxide (AZO) thin films deposited onto flexible polyethylene terephthalate (PET) substrates, using radio frequency (RF) magnetron sputtering. Experiments based on the Grey-Taguchi method were conducted to examine the influence of deposition parameters (RF power, sputtering pressure, substrate-to-target distance, and coating time) on the deposition rate, electrical resistivity and structural, morphological and optical transmittance. Experimental results indicate that using the optimal parameter set selected by Grey theory prediction, it is possible to achieve an improvement of 3.8% in deposition rate, of 45.6% in resistivity, and to maintain the transmittance over 80%, compared to that achieved by using the Taguchi method. For the Grey theory prediction, films were deposited using substrate-to-target distance of 80, 85, and 90 mm, while maintaining constant values for the other conditions. A clear decrease in resistivity was observed, as substrate-totarget distance decreased, with the lowest resistivity being obtained at 80 mm, although a better optical transmittance was achieved at a distance of 85 mm. It is evident that the resistivity decreases as the Al buffer thickness increases, with the lowest resistivity 7.0 3 10 À4 Ω-cm, being found for a 15 nm thickness of Al buffer. The transmittance decreases, as the Al buffer thickness increases; transmittance values of 84.5%, 81.8%, and 79.4% correspond to an Al buffer thickness of 5, 10, and 15 nm, respectively. From the results of pulloff testing, the adhesive strength of the AZO film on a PET substrate increases, as the buffer thickness is increased.

ZnO‐Based Transparent Conductive Thin Films: Doping, Performance, and Processing

“…This relationship does not mean all hope for low-temperature growth lost. In recent years, the growth of high quality films at low temperature on flexible substrates has attracted extensive attention owing to the rather low cost with many unique applications [51,52]. Clatot et al successfully deposited Si-doped zinc oxide (SZO, Si 3%) thin films at a relatively low temperature (≤150 ∘ C) by pulsed laser deposition (PLD).…”

Effect of Ga-modified layer on flexible hydrogen sensor using ZnO nanorods decorated by Pd catalysts

“…Several groups developed ZnO nanorods (NRs) on flexible substrates via a seed layer such as ITO-coated PET [18,20] and ZnO-seeded PET [17,19]. Further, the effects of processing conditions such as concentration of the precursors [18], deposition time [16,17], sputtering conditions [13], as well as structural [17,18,20] and optical properties [17,20] were also investigated. Among all the approaches, the aqueous solution method has the advantages of simplicity, low cost, low growth temperature, and easy coating of large surfaces.…”

“…Many approaches have been proposed and developed for the deposition of ZnO films on polymer substrates, such as radio-frequency (RF) magnetron sputtering [3,13], pulsed laser deposition (PLD) [14], dual plasma-enhanced metal-organic chemical vapor deposition (DPEMOCVD) [15], ion-exchange techniques [11], solution-based methods [16][17][18], and chemical bath deposition (CBD) [19]. Several groups developed ZnO nanorods (NRs) on flexible substrates via a seed layer such as ITO-coated PET [18,20] and ZnO-seeded PET [17,19].…”

Influence of Thickness on the Structural, Electrical and Optical Properties of Al-Doped ZnO Films Deposited by RF Magnetron Sputtering

“…Transparent conducting oxides (TCOs) are being considered for manufacturing transparent electrodes in flat panel displays, solar cells and organic light emitting diodes. At present, as good alternatives to ITO, many research groups have studied ZnO based materials such as Al doped ZnO (AZO) which are non-toxic, inexpensive source materials and abundant for thin-film transparent electrode applications [1][2][3]. Although the properties of AZO films prepared by magnetron sputtering are greatly influenced by processing parameters, such as sputtering power, working pressure, substrate temperature and so on, some studies have considered the changes of electrical, optical and structural properties of AZO films with thickness change and explained their mechanisms [3][4][5].…”