Electrical and optical properties of Al-doped ZnO and ZnAl(2)O(4) films prepared by atomic layer deposition

ZnO/Al(2)O(3) multilayers were prepared by alternating atomic layer deposition (ALD) at 150°C using diethylzinc, trimethylaluminum, and water. The growth process, crystallinity, and electrical and optical properties of the multilayers were studied with a variety of the cycle ratios of ZnO and Al(2)O(3) sublayers. Transparent conductive Al-doped ZnO films were prepared with the minimum resistivity of 2.4 × 10(−3) Ω·cm at a low Al doping concentration of 2.26%. Photoluminescence spectroscopy in conjunction with X-ray diffraction analysis revealed that the thickness of ZnO sublayers plays an important role on the priority for selective crystallization of ZnAl(2)O(4) and ZnO phases during high-temperature annealing ZnO/Al(2)O(3) multilayers. It was found that pure ZnAl(2)O(4) film was synthesized by annealing the specific composite film containing alternative monocycle of ZnO and Al(2)O(3) sublayers, which could only be deposited precisely by utilizing ALD technology.