The Journal of the Korea institute of electronic communication sciences (한국전자통신학회논문지)

Korea Institute of Electronic Communication Science (한국전자통신학회)
권호 표지
DOI QR코드

DOI QR Code

Electrical and Optical Properties of ITO Thin Films with Various Thicknesses of SiO2 Buffer Layer for Capacitive Touch Screen Panel

정전용량식 터치스크린 패널을 위한 SiO2 버퍼층 두께에 따른 ITO 박막의 전기적 및 광학적 특성

  • 정윤근 (전남대학교 기계설계공학과) ;
  • 정양희 (전남대학교 전기 및 반도체공학과) ;
  • 강성준 (전남대학교 전기 및 반도체공학과)
  • Received : 2022.09.21
  • Accepted : 2022.12.17
  • Published : 2022.12.31
Download PDF
⟨ Previous Next ⟩

Abstract

In this study, we prepared ITO thin films on the Nb2O5/SiO2 double buffer layer and investigated electrical and optical properties according to the change of SiO2 buffer layer thickness (40~50nm). The ITO thin film fabricated on the Nb2O5/SiO2 double buffer layer exhibited a broad surface roughness with a small value ranging of 0.815 to 1.181nm, and the sheet resistance was 99.3 to 134.0Ω/sq. It seems that there is no problem in applying the ITO thin film to a capacitive touch screen panel. In particular, the average transmittance in the short-wavelength (400~500nm) region and the chromaticity (b*) of the ITO thin film deposited on the Nb2O5(10nm)/SiO2(40nm) double buffer layer showed significantly improved results as 83.58% and 0.05, respectively, compared to 74.46% and 4.28 of ITO thin film without double buffer layer. As a result, it was confirmed that optical properties such as transmittance in the short-wavelength region and chromaticity were remarkably improved due to the index matching effect in the ITO thin film with the Nb2O5/SiO2 double buffer layer.

본 연구에서는 Nb2O5/SiO2 이중 버퍼층위에 ITO박막을 증착하여, SiO2버퍼층 두께 변화 (40~50 nm)에 따른 전기적 및 광학적 특성을 조사하였다. Nb2O5/SiO2 이중 버퍼층을 도입한 ITO박막의 표면 거칠기는 0.815에서 1.181 nm 범위의 작은 값을 가지는 매끄러운 형상을 보였고, 면저항은 99.3~134.0 Ω/sq. 범위로 정전용량식 터치스크린 패널에 적용하는데 문제가 없는 것으로 나타났다. 특히 Nb2O5 (10 nm) / SiO2 (40 nm) 이중 버퍼층을 삽입한 ITO박막의 단파장(400~500 nm) 영역에서의 평균 투과도와 색도(b*)는 83.58 % 와 0.05로 이중버퍼층이 삽입되지 않은 ITO박막의 74.46 % 와 4.28에 비해 상당히 향상된 결과를 나타내었다. 이를 통해 Nb2O5/SiO2 이중 버퍼층을 도입한 ITO박막에서 인덱스 매칭 효과로 인해 단파장 영역의 투과도 및 색도와 같은 광학적 특성이 현저히 향상되었음을 확인할 수 있었다.

Keywords

References

  1. X. Zhou, J. Xu, L. Yang, G. Zhu, and Z. Yu, "Effects of Tin Content on Structure, Properties Electrical Repeatability, Uniformity and Stability of High Sheet Resistance ITO Thin Films for Touch Panels," J. Materials Science : Materials in Electronics, vol. 26, issue 9, June 2015, pp. 6954-6960. https://doi.org/10.1007/s10854-015-3314-7
  2. S. Kim, W. Choi, W. Rim, Y. Chun, H. Shim, H. Kwon, J. Kim, I, Kee, S. Kim, S. Lee, and J. Park, "A Highly Sensitive Capacitive Touch Sensor Integrated on a Thin-Film-Encapsulated Active-Matrix OLED for Ultrathin Displays," IEEE Trans. Electron. Dev., vol. 58, no. 10, Oct. 2011, pp. 3609-3615. https://doi.org/10.1109/TED.2011.2162844
  3. C. Wu, "Ultra-high Transparent Sandwich Structure with a Silicon Dioxide Passivation Layer Prepared on a Colorless Polyimide Substrate for a Flexible Capacitive Touch Screen Panel," Sol. Energy Mater Sol. Cells, vol. 207, Apr. 2020, pp. 1-8.
  4. T. Hwang, W. Cui, I. Yang, and O. Kwon, "A Highly Area-Efficient Controller for Capacitive Touch Screen Panel Systems," IEEE Trans. Consumer Electron., vol. 56, issue 2, May 2010, pp. 1115-1122. https://doi.org/10.1109/TCE.2010.5506047
  5. L. Cao, T. Wang, K. Ma, Z. Zhang, F. Luo, H. Zhou, D. Liu, M. Miao, B. Luo, and Y. Xu, "A Leaf-like Structured ITO Conductive Transparent Thin Film from Visible to Near-infrared Region with Enhanced Stability," J. Eur. Ceram. Soc., vol. 42, issue 6, June 2022, pp. 2836-2843. https://doi.org/10.1016/j.jeurceramsoc.2022.01.056
  6. C. Torasa and I. Srithanachai, "Optimization of Electrical and Optical Properties of ITO Thin Films by Annealing in Air and Nitrogen," Mater. Today : Proc., vol. 65, part 4, June 2022, pp. 2439-2441. https://doi.org/10.1016/j.matpr.2022.06.073
  7. C. Hong, J. Shin, B. Ju, K. Kim, N. Park, B. Kim, and W. Cheong, "Index-Matched Indium Tin Oxide Electrodes for Capacitive Touch Screen Panel Applications," J. Nanosci. Nanotechnol., vol. 13, no. 11, Nov. 2013, pp. 7756-7759. https://doi.org/10.1166/jnn.2013.7814
  8. C. Kim, W. Choi, S. K. Cho, G. Daiji, D. Ham, K. Kim, J. Jeong, J. Lee, and S. Lee, "Fabrication of Structurally Simple Index-Matched ITO Films Using Roll-to-Roll Sputtering for Touch Screen Panel Devices," Plasma Processes & Polymers, vol. 12, issue 11, Nov. 2015, pp. 1322-1327. https://doi.org/10.1002/ppap.201500057
  9. H. Joung and J. Kang, "Influence of DC Power on the Electrical and Optical Properties of ITO Thin Films Deopsited on Nb2O5/SiO2 Buffer Layer," J. of the Korea Institute of Electronic Communication Sciences, vol. 14, no. 2, Apr. 2019, pp. 297-302. https://doi.org/10.13067/JKIECS.2019.14.2.297
  10. M. Park, B. Kang, J. Kim, H. Kim, H. Kim, W. Lim, and S. Choi, "Chromaticity (b*), Sheet Resistance and Transmittance of SiO2-ITO Thin Films Deposited on PET Film by Using Roll-to-Roll Sputter System," Korean J. Materials Research, vol. 21, no. 5, May 2011, pp. 255-262. https://doi.org/10.3740/MRSK.2011.21.5.255
  11. Y. Kwon and G. Jang, "Effect of SiO2 and Nb2O5 Buffer Layer on Optical Characteristics of ITO Thin Film," Trans. Electr. Electron. Mater., vol. 16, no. 1, Feb. 2015, pp. 29-33. https://doi.org/10.4313/TEEM.2015.16.1.29
  12. J. Seok, "Touch screen panel development trend," Vacuum Magazine, vol. 4, issue 3, Sept. 2017, pp. 29-31.
  13. G. Haacke, "New Figure of merit for Transparent Conductors," J. Applied Physics, vol. 47, issue 9, Oct. 1976, pp. 4086-4089. https://doi.org/10.1063/1.323240