Effects of cobalt doping concentration on the structural, electrical, and optical properties of titanium dioxide thin films

Abstract

Cobalt-doped titanium dioxide thin films have been successfully deposited using sol-gel spin coating technique. The doping process has been done by mixing cobalt source into TiO 2 sol-gel. The doping concentration has been varied and its effects to the structural, electrical, and optical properties of the thin films have been studied. Reduction in electrical resistivity is observed with the increase of cobalt doping concentration. Higher cobalt doping concentration sample also shows a shift of absorption edge to longer wavelength which is a desired characteristic for application in optoelectronic devices.

Properties of Metallic and Oxide Thin Films Based on Ti and Co Prepared by Magnetron Sputtering from Sintered Targets with Different Co-Content

“…Such effect was also reported in other works. For example, Subramanian et al [ 18 ] or Musa et al [ 20 ] in transparent TiO 2 :Co films also obtained a shift of λ cutoff towards longer wavelengths due to a large amount of cobalt. It should be noted that the position of the optical absorption edge is mostly determined by the manufacturing technique and the process parameters.…”

“…In the case of the structures with (Ti,Co)Ox thin films containing lower Co concentration, a unipolar memristive-like effect can be observed, which is manifested by the memory loop with forward bias polarization ( Figure 13 a) [ 38 , 39 ]. The occurrence of such effects has not been reported so far in the case of TiO 2 coatings with the addition of Co. Usually, for these types of thin-film materials, a linear relationship between current and voltage is usually observed [ 15 , 20 ]. This means that materials based on titanium and cobalt oxides may be prospective for electronics, not only because of their spintronic application but also because of their memristive-like behavior.…”

“…Materials based on titanium and cobalt constitute a “new group” of materials whose properties have not been fully understood and used so far. Doping titanium dioxide with cobalt allows to modify a number of its properties, primarily: structural [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], optical [ 14 , 15 , 16 , 17 , 18 , 20 , 21 ], electrical [ 15 , 16 , 20 , 21 ] and magnetic [ 20 ]. These coatings have been of great interest due to the formation of dilute magnetic semiconductors (DMS), which is promising for the manufacturing of spintronic and magneto-optic devices [ 22 , 23 , 24 ].…”

Surface and Electrical Characterization of Non-Stoichiometric Semiconducting Thin-Film Coatings Based on Ti-Co Mixed Oxides Obtained by Gas Impulse Magnetron Sputtering

“…It is important to note that the majority of research focuses mainly on characterizing cobalt oxides in the form of Co3O4 rather than cobalt oxides in the form of CoO, which is attributed to significant challenges in obtaining the latter form [22]. However, it should be noted that in the case of oxide materials containing both of these elements, only single publications are available that discuss the issue of their resistivity [23,24]. Coatings 2023, 13, x FOR PEER REVIEW 2 of 18 materials that have not undergone such treatment (Figure 2) [6][7][8][9][10][11]20,21].…”

“…A review of the current state of knowledge reveals a lack of comprehensive research on titanium and cobalt oxide materials (especially in non-stoichiometric form), which restricts the full utilization of the potential their combination can offer. Currently, only two reports exist on the electrical properties of oxide materials concerning mixtures of these two elements (Ti,Co)O x [23,24], while research on materials based solely on titanium or cobalt oxides predominates (Figure 3). Therefore, the objective of this study was to fabricate films based on Ti and Co with varying material compositions, while reducing the oxygen content and achieving lower resistivity.…”