Al-Doped ZnO Thin Films with 80% Average Transmittance and 32 Ohms per Square Sheet Resistance: A Genuine Alternative to Commercial High-Performance Indium Tin Oxide

Abstract

In this study, a low-sophistication low-cost spray pyrolysis system built by undergraduate students is used to grow aluminum-doped zinc oxide thin films (ZnO:Al). The pyrolysis system was able to grow polycrystalline ZnO:Al with a hexagonal wurtzite structure preferentially oriented on the c-axis, corresponding to a hexagonal wurtzite structure, and exceptional reproducibility. The ZnO:Al films were studied as transparent conductive oxides (TCOs). Our best ZnO:Al TCO are found to exhibit an 80% average transmittance in the visible range of the electromagnetic spectrum, a sheet resistance of 32 Ω/□, and an optical bandgap of 3.38 eV. After an extensive optical and nanostructural characterization, we determined that the TCOs used are only 4% less efficient than the best ZnO:Al TCOs reported in the literature. This latter, without neglecting that literature-ZnO:Al TCOs, have been grown by sophisticated deposition techniques such as magnetron sputtering. Consequently, we estimate that our ZnO:Al TCOs can be considered an authentic alternative to high-performance aluminum-doped zinc oxide or indium tin oxide TCOs grown through more sophisticated equipment.