A Revised Growth Model for Transparent Conducting Ga Doped ZnO Films: Improving Crystallinity by Means of Buffer Layers

Abstract

Ga-doped ZnO (GZO) thin films are recently raising both scientific and industrial interests, due to the lack of natural resources. Indium is a crucial raw material, due to ITO modern touchscreen market. By doping ZnO with Ga conductive transparent thin films with various concentrations of dopant are prepared by DC magnetron sputtering from ceramic targets. It is shown how the Ga content plays an important role on the growth kinetics on an initial stage of the film formation and hence on the morphologies, microstructure and electrical properties of as-grown GZO films. A mechanism explaining the role of Ga content on the nucleation process and the structure of growing films is proposed. Based on this mechanism, it is successfully demonstrated that the crystalline quality and hence the conductivity of GZO thin films can be improved by using a GZO buffer layer.

Influence of polarity inversion on the electrical properties of Ga‐doped ZnO thin films

“…Ogino et al reported that GZO tends to nucleate Zn‐polar grains, and so heavy doping tends to produce Zn‐polar films, whereas light doping produces O‐polar films through abnormal grain growth . However, Abduev et al have suggested that GZO causes the nucleation of both Zn‐polar and O‐polar grains, but that O‐polar grains become dominant in lightly doped GZO at some point after film growth . As heavy doping was used in the present study, the results are consistent with previous reports of Zn‐polarity in thick films.…”

“…A flipping of polarity during the growth of doped ZnO films has been previously reported and discussed in relation to the film growth mechanism . Ogino et al reported that GZO tends to nucleate Zn‐polar grains, and so heavy doping tends to produce Zn‐polar films, whereas light doping produces O‐polar films through abnormal grain growth .…”

Structural and Optical Properties of Mg Doped ZnO Thin Films Deposited by DC Magnetron Sputtering

“…The thicknesses of undoped ZnO, ZnO:1 at% Mg and ZnO:5 at% Mg thin films were 1050, 730 and 540 nm, respectively. It is known for ZnO-based films that the roughness tends to increase with rise the film thickness [15]. The roughness of the film affects the transparency due to scattering of incident light.…”

UAVs You Can't See or Hear - A Survey of Key Technologies

“…This explains why a good electronic conductor has a metallic appearance: the first intrinsically conductive polymer ever discovered (70s), polyacetylene, was silvery [13]. A possible solution to this problem comes from ionic conductors belonging to the group of Transparent Conductive Oxides (TCOs), such as Indium Tin Oxide (ITO), Fluorinated Tin Oxide (FTO) and the most promising AZO (Aluminum-doped Zinc Oxide) and GZO (Gallium-doped Zinc Oxide), currently used in all the applications where flat / touch screens are necessary [14]. However, the typical resistivity of such materials is three orders of magnitude lower than that of metal.…”