Abstract
Highly Ti-doped ZnO films have been produced by a spin-casting sol-gel process. The spin-casted films show high in plane homogeneity and optical quality. However, when inspected in depth, the surface composition is Ti rich. We show that two possible annealing processes can be considered depending on the properties to exploit. To promote in-depth homogenization, thermal annealing processes have been applied. Meanwhile, the gradients can be exacerbated, thanks to a non-negligible surface sputtering, by applying microwave (MW) plasma treatments with Ar discharges at different pressures. The microstructural properties of the differently processed films have been obtained prior to a study by grazing incidence X-ray fluorescence (GI-XRF) spectroscopy, which reveals the in-depth composition trends induced by the two alternative annealing procedures. The final wetting, electrical and optical properties of the films are described in accordance with the Ti distribution pattern revealed by GI-XRF. The study underlines for the first time how MW plasma annealing processes can be used to exacerbate self-induced atomic gradients in sol-gel films with potential implications in catalytic and biomedical applications.
Highlights
The applications of advanced materials have increasingly implied their deposition in the form of thin films in conjunction with their micro-nanostructuring
The analysis of Ti-doped ZnO thin films was performed after sequential deposition of 5 layers
1b and filmsafter treated by microwave plasma annealing (MwPA) at plasma
Summary
The applications of advanced materials have increasingly implied their deposition in the form of thin films in conjunction with their micro-nanostructuring. ZnO has been exposed to this trend in a wide range of applications, such as in photovoltaics [1], light-emitting devices [2], biosensors [3] or photocatalysis [4], which exploit the tunable light absorption and charge transfer properties of ZnO. From the point of view of processing, ZnO is an extremely flexible material with adapted protocols described for physical and chemical deposition techniques. As examples of doped ZnO deposition by physical techniques, Al-doped ZnO film synthesis has been achieved by using magnetron sputtering [5], while blue-emitting Er-doped ZnO films have been deposited by electron beam evaporation [6] or magnetic Co-rich ZnO was obtained by pulsed laser deposition [7]. For the chemical techniques, Li- [8] and Ga- [9] doped ZnO deposition was described by the sol-gel process leading to highly oriented structures. Additional examples can be found of deposition of B-doped (n-type) ZnO by metal organic chemical vapor deposition [10] or Zr-doped ZnO by atomic layer deposition (ALD) [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
