Preparation And Performance Study Of Al-doped ZnO Transparent And Conductive Thin Films On Flexible Substrate

Al-doped zinc oxide (ZAO) transparent conducting films have been prepared firstly by RF magnetron sputtering method flexible TPT substrates. The dependence of structural, optical and electrical properties of the films on critical process parameters, such as the Al2O3 content in the ZnO target, RF power, Ar pressure and so on has been studied. At the same time, ZAO films were also prepared for the purpose of comparison and simulation analysis. The simulation analysis and experimental validation have been done for the e electrical properties of ZAO thin films and the optical properties of ZAO films have been analyzed. Textured ZAO films have been etched by acetic acid successfully. The main research results were as follows:All the prepared ZAO thin films were hexagonal structure and a c-axis preferred orientation perpendicular to the structure. The ZAO films prepared from ZnO target with 2 wt% Al2O3 content had better crystallinity and lowest resistivity; The obtained films deposited at low Ar pressure were more compact, the impact factor of ZAO films arrived at 10254.1Ω-1cm-1 when Ar pressure was maintained at 1Pa. The grain size of ZAO films increased with increasing RF power. The resistivity of films on glass decreased and then increased with power increasing. The lowest resistivity was 2.3×10-3Ω·cm at the RF power of 120W. The transmittance in visible light region was over 80% for the films on glass prepared below 180W. The resistivity of films on TPT decreased with the increase of RF power, the lowest was 3.15×10-2Ω·cm at 200W. The crystallinity was improved in Ar+H2 sputtering atmosphere. The introduction of Hydrogen made O 1s peak of the films move to lower binding energy, which indicated that the films were oxygen-deficient. The resistivity decreased and then increased with the increase of H2 flux. For the ZAO films deposited on glass substrates, the lowest resistivity of 5.32×10-4Ω·cm was achieved at H2 flux of 1sccm with a carrier concentration of 6.85×1020 cm-3 and Hall mobility of 10.5 cm2/Vs. For the ZAO films deposited on TPT substrates, the lowest resistivity of 6.5×10-3Ω·cm was achieved at H2 flux of 0.5sccm with a carrier concentration of 2.45×1020cm-3 and Hall mobility of 2.36cm2/Vs.The crystal quality of ZAO films were enhanced by introducing proper oxygen with lattice distortion and internal stress reducing. There has a emission band near the wavelength of 590nm.The intensity of emission band reduced with introduction of oxygen in the sputtering atmosphere, which maybe related to defect energy level resulting from stoichiometric imbalance between Zn and O elements.The carrier resulted mainly from Aluminum substituting Zinc atoms. When the carrier concentration was below the magnitude of 1018cm-3, the grain boundary scattering was the dominant factor to influence the electrical properties of ZAO films. When the carrier concentration reached to the magnitude of 1020cm-3, the ionized impurity scattering was the dominant factor to influence the electrical properties of ZAO films, and the carrier mobility had a linear relationship with -2.14/3 power of corresponding carrier concentration. When the carrier concentration was between 1018cm-3 and 1020cm-3, there existed many scattering mechanism to affect the electrical properties of ZAO films.The optical band gap of the obtained ZAO samples had a linear relationship with 2/3 power of corresponding carrier concentration. The transmittance in visible light was influenced by grain size and surface roughness. The optical properties were improved as increasing grain sizes or decreasing roughness.ZAO films on TPT were etched by acetic acid liquid. It was found that the surface of etched ZAO films in 1% acetic acid had a pyramid structure, and light scattering ability was enhanced. At the same time, the transmittance in the visible region and sheet resistance were over 60% and about 260Ω/(?) separately.