All authors read and approved the final manuscript.”
“Background In the ZnO-Al2O3 composite material system, Al-doped zinc oxide (AZO) and zinc aluminate (ZnAl2O4) spinels are well known for their applications in optoelectronic devices and chemical industry. AZO was considered as an alternative low-cost transparent conductive oxide material instead of indium tin oxide in photovoltaic cells and displays [1, 2]. ZnAl2O4 material

has been used in many catalytic reactions, such as cracking, dehydration, hydrogenation, and dehydrogenation reactions [3, 4]. As a wide-bandgap semiconductor material, ZnAl2O4 was also used as host of phosphors doping with Mn and rare earth ions [5, 6]. AZO and ZnAl2O4 thin films have been deposited ubiquitin-Proteasome degradation by different buy BMN 673 techniques [7], such as sol–gel coating [8], pulsed laser deposition [9], chemical vapor deposition [10], radio-frequency sputtering [11], and atomic layer deposition (ALD) [12,

13]. Recently, ALD technology has been employed to grow transparent conductive AZO films with low resistivity in the order of 10−3 Ω·cm [14, 15]. However, the correlation between the optical and the electrical properties in the ALD of AZO films has not yet been understood very well. Meanwhile, ZnAl2O4 film deposited on porous or nanostructure supporting materials by ALD technology may have large surface area and potential applications in catalysts and phosphors. However, since the ZnAl2O4 films need to be synthesized by annealing ZnO/Al2O3 composite films at elevated temperatures, the preferable crystallization of ZnO in the ALD of ZnO/Al2O3 composite films may strongly influence the purity of the synthesized

ZnAl2O4 films. A detailed study on the correlation between the ZnO/Al2O3 cycle ratios in the multilayers and the formation of ZnO and ZnAl2O4 crystal phases during the subsequent thermal annealing would be crucial for synthesizing high purity ZnAl2O4 films. In this paper, the ALD processes of the Al2O3 and ZnO thin films were studied using diethylzinc (DEZn), trimethylaluminum (TMA), and water with a variety of substrate temperatures. The growth temperature of the ZnO/Al2O3 composite films was determined by optimizing the growth Tobramycin temperature of ZnO layer according to the photoluminescence (PL) spectroscopy analysis. Then AZO films were prepared by adding a small fraction of Al2O3 doping cycles in the ALD process of ZnO films. The dependences of the crystalline structure, resistivity, and optical band gap of the AZO films on the Al doping concentration were studied in detail. Afterwards, multiple crystalline ZnAl2O4 films were synthesized by annealing the ALD ZnO/Al2O3 multilayers with a high fraction of Al2O3 layers. The influences of the ALD cycle ratio of the ZnO/Al2O3 sublayers and the annealing temperature on the formation of ZnO and ZnAl2O4 phases were studied by X-ray diffraction analysis.