Abstract:
The bilayer ZnO(Al) thin films were grown on 5x6 cm[superscript 2] soda lime glass substrates. In case 1, the Zn target and ZnO(Al[subscirpt 2]O[subscript 3] 2.5 wt%) target were co-sputtered, then followed by rf-magnetron sputtering of ZnO(Al[subscirpt 2]O[subscript 3] 2.5 wt%) target (Zn-added-ZnO(Al)/ZnO(Al)). In case 2, the first layer started by rf-magnetron sputtering of ZnO(Al[subscirpt 2]O[subscript 3] 2.5wt%) followed by co-sputtering of Zn target and ZnO(Al[subscirpt 2]O[subscript 3] 2.5wt%) target (ZnO(Al)/Zn-added-ZnO(Al)). The growth conditions of the ZnO(Al) bilayer films with the best electrical, optical and structural properties were chosen for the growth of sequentially layered ZnO(Al) thin films. The total thickness of the sequentially layered ZnO(Al) films were kept at 3000 Å, while varying the thickness of the Zn-added-ZnO(Al) layer from 0-100% with a step of 20% increment. The obtained sequentially layered ZnO(Al) films were characterized by Hall measurement, optical transmission measurement and X-ray diffraction for its electrical, optical and structural properties, respectively. It was found that the films with 9 sequential layers yielded the minimum resistivity of about 5.60x10[superscript -4] omega-cm and maximum transmission higher than 90% in the 400-1000 nm range, accordingly. The XRD pattern also showed a c-axis prefered orientation compared to the bulk ZnO.