Structural and Electrical Properties of Sputtered Aluminum Doped Zinc Oxide Thin Films

Aluminium-doped zinc oxide (ZnO: Al) thin films were grown by RF sputtering method using a ZnO target containing 2wt.% Al₂O₃. The ZnO: Al thin films were grown on glass substrates at room temperature, 200°C substrate temperatures, at 60W and 40W RF-powers. The samples were characterized using XRD, SEM and EDX. The XRD study reveals that the thin films were polycrystalline with hexagonal wurtzite structure with preferred orientations (002) along the c-axis. The SEM analysis indicates that the films have smooth grain size, spherical in shape and the particle size distribution closely packed. The results reveal that the average grain size from XRD ranged from 22.03–25.14μm and SEM from 21–25μm. The results from both XRD and SEM were in agreement. It is evident from energy dispersive X-ray microanalysis (EDX) analysis that the films contains Zn, O₂, Al and other elements due to impurity the glass used as substrates. Resistivities of the films were ranging from 2.14x10⁻³Ω.cm to 3.09x10⁻³Ω.cm which shows that deposition parameters have noticeable effects on the electrical resistivity of the films. It was concluded that ZnO: Al thin films grown using RF sputtering have good structural and electrical properties that is suitable for manufacturing transparent conducting oxide films semiconductor materials.