Navegando por Autor "Azevedo Filho, João Batista"
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Artigo Synthesis and characterization of ZnO/ZnAl2O4/ Zn2TiO4 composite films by AreO2 mixture hollow cathode glow discharge(Elsevier, 2021) Feitor, Michelle Cequeira; Queiroz, José César Augusto de; Naeem, Muhammad; Azevedo Filho, João Batista; Libório, Maxwell Santana; Queiroz, M. G. O.; Sousa, R. R. M.; Melo, E. B.; Costa, Thércio Henrique de CarvalhoIn this study, ZnO/ZnAl2O4/Zn2TiO4 composite nanostructured thin films are deposited assisted with hollow-cathode glow discharge (HCD). The films are deposited using various argon-oxygen gases mixture (0e50% O2), and its effect on film quality, optical and electrical properties is examined. Remarkably, instead of metallic targets, ZnO, TiO2, and Al2O3 powders filled in hollow-cathode are used for deposition, and thus no specific metallic targets are required in this technique. The deposited films consist of hexagonal wurtzite ZnO structure, ZnAl2O4, and Zn2TiO4 phases, and the crystalline size of films increases for higher oxygen contents. The thickness of films reduced by increasing oxygen contents, and all deposited films exhibit transmittance higher than 82%. The carrier concentration and mobility increase, whereas resistivity decreases when a higher amount of oxygen is added. This study shows that HCD can effectively synthesize the composite film with good optical and electrical properties. Additionally, the film’s properties and elemental composition can be tuned by changing the gas composition, and thus, no separate target metallic materials with the specific composition are requiredArtigo Synthesis of Al-Doped ZnO films assisted with hollow-cathode glow discharge and their characterization(Journal of Electronic Materials, 2021-02-19) Feitor, Michelle Cequeira; Queiroz, José César Augusto de; Naeem, Muhammad; Azevedo Filho, João Batista; Liborio, Maxwell Santana; Santos, E. J. C.; Sousa, R. R. M.; Costa, Thércio Henrique de Carvalho; Khan, Naveed H.Transparent conductive oxides, such as aluminum-doped zinc oxide (AZO), are of substantial importance for use in a broad range of applications because of their excellent optical and electrical properties. AZO film can be deposited by using several conventional techniques, although they suffer from limitations such as long deposition time, high cost, and the requirement for complex deposition equipment. Here, we used hollow-cathode glow discharge, which produces a high-density plasma and achieves high deposition efficiency. Remarkably, instead of metallic target materials, we used Al2O3 and ZnO powders filled in the hollow cathode as a target, thus avoiding the need for specifically designed targets in this technique. The films were deposited using mixtures of argon and oxygen at various ratios (0% to 50% oxygen), to improve the film characteristics. The films deposited under all conditions exhibited hexagonal wurtzite ZnO structure, while the grain size increased with increasing oxygen content. The film was thick and porous when using low oxygen content, but became thin and dense with increasing oxygen content. The optical transmittance was found to be strongly dependent on the processing gases used, with the highest transmittance of 84% being attained when using 25% oxygen gas. The bandgap of the films lay between 3.27 eV and 3.33 eV. The highest carrier concentration and mobility were attained when using 25% oxygen, and the Hall resistivity decreased with increasing oxygen content. Besides the excellent transmittance and electrical properties of the deposited films, it is expected that the results of this study will be useful for solar cells and optoelectronic applications due to the relatively low cost of this technique and the lack of specific target requirements