The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films

Ahmad Ajjaq

doi:10.54287/gujsa.1979919

The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films

Abstract

The influence of electrode positioning on the gas-sensing and charge-transport properties of ZnO thin films remains insufficiently explored despite its importance in resistive sensor design. Here, ZnO thin-film NH₃ sensors incorporating top-, bottom-, and hybrid-interdigitated electrode configurations (T-IDT, B-IDT, and H-IDT) were systematically compared under identical synthesis, device geometry, and measurement conditions. Sol–gel spin-coated ZnO films exhibited a polycrystalline hexagonal wurtzite structure, homogeneous elemental distribution, and continuous morphology. Electrical measurements revealed approximately linear I–V characteristics, while equivalent-circuit analysis of the impedance spectra demonstrated configuration-dependent resistive and relaxation behavior, with B-IDT exhibiting the most complex electrical response. Gas-sensing measurements toward 50 ppm NH₃ showed a strong dependence on electrode position, with responses at 230°C reaching 163%, 147%, and 106% for B-IDT, H-IDT, and T-IDT, respectively. Quantitative t₉₀ analysis further revealed that the response/recovery dynamics depend on both electrode configuration and operating temperature, indicating that no single electrode configuration consistently provides the fastest dynamic response under all conditions. Repeated exposure–recovery measurements demonstrated stabilization of the sensing response after initial cycling, while concentration-dependent measurements over 5–200 ppm NH₃ produced systematic response increases for all configurations. These findings demonstrate that electrode positioning governs how gas-induced conductivity changes are electrically sampled within the same ZnO sensing layer, producing a practical trade-off between response magnitude, resistance, and dynamic behavior. Electrode positioning therefore represents a simple device-level design parameter for tailoring the performance of resistive metal-oxide gas sensors.

Keywords

Project Number

+90 (505) 474 31 33

Thanks

The author gratefully acknowledges Prof. Dr. Selim Acar for providing access to the chemical synthesis and gas-sensing measurement facilities at Gazi University.

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Details

Primary Language

English

Subjects

Condensed Matter Physics (Other)

Journal Section

Research Article

Authors

Ahmad Ajjaq ^*
0000-0002-2136-3965
Türkiye

Early Pub Date

September 28, 2026

Publication Date

September 30, 2026

Submission Date

June 26, 2026

Acceptance Date

September 1, 2026

Published in Issue

Year 2026 Volume: 13 Number: 3

DOI

https://doi.org/10.54287/gujsa.1979919

IZ

https://izlik.org/JA44BM62DD

Cite

RIS / Bibtex

APA

Ajjaq, A. (2026). The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films. Gazi University Journal of Science Part A: Engineering and Innovation, 13(3), 1239-1257. https://doi.org/10.54287/gujsa.1979919

AMA

1.Ajjaq A. The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films. GU J Sci, Part A. 2026;13(3):1239-1257. doi:10.54287/gujsa.1979919

Chicago

Ajjaq, Ahmad. 2026. “The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films”. Gazi University Journal of Science Part A: Engineering and Innovation 13 (3): 1239-57. https://doi.org/10.54287/gujsa.1979919.

EndNote

Ajjaq A (September 1, 2026) The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films. Gazi University Journal of Science Part A: Engineering and Innovation 13 3 1239–1257.

IEEE

[1]A. Ajjaq, “The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films”, GU J Sci, Part A, vol. 13, no. 3, pp. 1239–1257, Sept. 2026, doi: 10.54287/gujsa.1979919.

ISNAD

Ajjaq, Ahmad. “The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films”. Gazi University Journal of Science Part A: Engineering and Innovation 13/3 (September 1, 2026): 1239-1257. https://doi.org/10.54287/gujsa.1979919.

JAMA

1.Ajjaq A. The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films. GU J Sci, Part A. 2026;13:1239–1257.

MLA

Ajjaq, Ahmad. “The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films”. Gazi University Journal of Science Part A: Engineering and Innovation, vol. 13, no. 3, Sept. 2026, pp. 1239-57, doi:10.54287/gujsa.1979919.

Vancouver

1.Ahmad Ajjaq. The Role of Electrode Position in Gas Sensing and Charge Transport in ZnO Thin Films. GU J Sci, Part A. 2026 Sep. 1;13(3):1239-57. doi:10.54287/gujsa.1979919