The influences of doping amounts of TiO2 on the structure and electrical properties of In2O3 films were experimentally studied. In this study, titanium-doped indium oxide (ITiO) conductions were deposited on glass substrate by the dual-target-type radio frequency magnetron sputtering (RFS) system under different conditions of Ti-doped In2O3 targets, from Ti-0.5 wt% to Ti-5.0 wt%, along with 10 mTorr and 300 W pressure of RF power control that was used as a cost-effective transparent electrochemiluminescence (ECL) cell. From this process, the correlation between structural, optical, and electrical properties is reported. It was found that the best
The transparent conducting oxide (TCO) films have become of interest in the study of light-emitting materials because they have a high electrical conductivity and good transparency in the visible region. The potential application of TCO materials includes flat panel displays, electrooptical devices, and solar cells [
In this study, we focus on the use of titanium-doped indium oxide (ITiO) that was deposited on glass substrate by using the RF magnetron sputtering method. The influence of doping concentration on the optical and electrical properties of conductive ITiO thin films was experimented in relation to their structural characterization. A further ECL cell was synthesized and applied with ITiO electrode to improve the efficiency of the ECL cells.
The preparation of titanium-doped indium oxide (ITiO) films was the same as in previous research [
The radio frequency magnetron sputtering (13.56 MHz) process was used for ITiO deposition in a 2
Schematic diagram of dual-target type by the radio frequency magnetron sputtering systems.
The chamber was pumped down to a base pressure (vacuum-exhausted) of
The microstructure information of the film deposition on the glass substrate was studied by using an X-ray diffractometer (XRD) (Rigaku Co., D/max 2100H) under Cu Ka irradiation (
In order to perform a systematic study, the detailed analysis of ITiO films deposited on the glass substrate was controlled with the different variation of Ti-doped In2O3 target from 0.5 wt% to 5.0 wt% and 10 mTorr and 300 W of RF power working pressure. This process forms the scope of this study. In the first stage, the roughness parameter was carefully considered for an optical surface. Typically, surface roughness provides a light scattering and characterization surface. The roughness quality can be analyzed by reference [
The average roughness (
Ti (wt%) | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 | 4.5 | 5.0 |
---|---|---|---|---|---|---|---|---|---|---|
15.915 | 13.889 | 11.730 | 10.872 | 5.676 | 11.264 | 11.370 | 15.248 | 18.926 | 19.287 |
Figure
The XRD spectra of the ITiO films with various doping concentrations, deposited at 300 W of RF power.
The surface morphology of the ITiO films deposited on the glass substrate was investigated by the AFM analysis as shown in Figure
The surface morphology of ITiO films of different doping concentrations from Ti-0.5 wt% to Ti-5.0 wt%.
In Figure
The SEM images of physical characteristics of ITiO films of different doping concentrations from Ti-0.5 wt% to Ti-5.0 wt%.
As mentioned earlier, in Figure
Overall variation in the electrical properties of the deposited films of different Ti doping concentrations: (a) resistivity; (b) carrier concentration; (c) Hall mobility.
Table
Comparison the electrical properties of the ITiO obtained from study to those of the films deposited by other processes.
Deposited methods of ITiO films | Substrate temperature (°C) | Resistivity ( | Mobility (cm2/V·s) | Carrier concentration (cm-3) | References |
---|---|---|---|---|---|
Without oxygen atmosphere | 300 | — | 27.5 | [ | |
RF magnetron sputtering (influence of RF power conditions) | 400 | 45.5 | [ | ||
Pulsed DC magnetron sputtering | 450 | 64 | [ | ||
Oxygen plasma treatment (PET substrate) | 130 | — | — | [ | |
RF magnetron sputtering (influence of Ti doping concentration) | 300 | 1.14 × 10-4 | 46.03 | 1.15 × 1021 | This study |
Additionally, we investigated the optical transmittance spectra of ITiO films at various Ti doping concentrations as shown in Figure
Optical transmittance of the deposited ITiO films of different doping concentrations from Ti-0.5 wt% to Ti-5.0 wt%.
In addition, the relationship between the photo energy (
The
Energy gap (
Ti (wt%) | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 | 4.5 | 5.0 |
---|---|---|---|---|---|---|---|---|---|---|
2.73 | 2.79 | 2.85 | 2.97 | 3.18 | 3.22 | 3.29 | 3.35 | 3.42 | 3.57 |
Moreover, we investigated the luminance properties of the ITiO films under different conditions of doping concentration from 0.5 wt% to 5.0 wt%. As presented in Figure
The luminance and ECL efficiency of the deposited ITiO films’ different doping concentrations from Ti-0.5 wt% to Ti-5.0 wt%.
In this study, we have investigated the characteristic film properties of the ITiO films with the different doping concentrations deposited by using the RF magnetron sputtering method. The experimental results have shown that the average roughness (RMS) of ITiO films is sensitive to the doping concentration. As a result, the results show a great influence on the structural, morphological, electrical, and optical properties together with ECL efficiency on the ITiO films. The lowest resistivity of
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that there is no conflict of interest regarding the publication of this paper.
This work was supported by the Petchra Pra Jom Klao Master’s Degree Scholarship from King Mongkut’s University of Technology Thonburi (KMUTT), Thailand (grant number 11, 2019), and under the project of the Research, Innovation, and Partnerships Office (RIPO) and National Research University Project of Thailand’s Office of the Higher Education.