Nanocolumnar growth of sputtered ZnO thin films

Sequential sputtering technology was developed for the formation of transparent and conductive very thin films of ZnO doped by Al (AZO) with a nanocolumnar polycrystalline structure. The characterization of their properties, including structural (scanning electron microscopy, X-ray diffractometry), electrical (Hall measurements) and optical (visible spectrometry, ellipsometry), was performed. AZO thin films with thicknesses of approximately 100nm were prepared with a pronounced nanocolumnar and (002) textured crystalline structure, sufficient low resistivity (≈10−1Ωcm), satisfactory optical transparency (≈90%) and adequate refractive index (≈2.0) for future applications in biochemical sensors. •Development of sequential sputtering of very thin ZnO films doped by Al•Substrate temperature (200°C) increased the preferential (002) columnar texture.•Sequential sputtering at a substrate temperature of 200°C enlarged crystallite sizes.•Sequential deposition mode increased the optical transparency in the visible region.