Fabrication and Characterization of Self-Assembled Low Voltage Operated OTFT for H2S Gas Sensor for Oil and Gas Industry

• Published in: IEEE transactions on electron devices 2024-01, Vol.71 (1), p.769-776
• Main Authors: Mehrolia, Mukuljeet Singh, Kumar, Dharmendra, Verma, Ankit, Singh, Abhishek Kumar
• Format: Article
• Language: English
• Subjects: Dielectric films; Dielectrics; Emission; Floating film transfer method (FTM); gas sensor; Gas sensors; Hydrogen sulfide; hydrogen sulfide (H₂S) sensor; Leakage current; Low voltage; Nanoparticles; organic semiconductor (OSC); organic sensor; organic thin film transistor (OTFT); Organic thin film transistors; Pinholes; Room temperature; Self-assembly; Semiconductor devices; Sensors; Silver; Spin coating; Substrates; Surface roughness; Thin film transistors; Threshold voltage
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2023.3336301

The article examines the low-voltage organic thin film transistor's (OTFTs) manufacturing and characterization process for hydrogen sulfide ( \text{H}_{{2}}\text{S} ) gas sensing at room temperature and could be helpful at various emanating sites. The fabrication methodology utilizes a cost-efficient solution processed spin coating method for high- {k} dielectric (SrZrOx) as a gate oxide and floating film transfer method (FTM) for silver nanoparticles doped PBTTT-C14 film for the active semiconductor layer. The developed spin-coated dielectric film offers a high capacitance of 433 nF/cm2 with a high band gap of 4.95 eV. and also offers 0.1 nA/cm2 leakage current density, which clarifies that the dielectric film has very less numbers of pin holes suitable for good-performing OTFT. The surface morphology of the dielectric film shows a very smooth dielectric film (rms roughness 0.245 nm), which demonstrates a high-quality dielectric/semiconductor interface offered by the dielectric film for the high performance of the device. On the other hand, the low-cost FTM deposited silver nanoparticles doped PBTTT-C14 active layer film is quite uniform (30 ± 3 nm thickness) and free from any anisotropic effect, which further improves the device performance for sensing applications. The developed sensor is deliberately characterized for \text{H}_{{2}}\text{S} gas sensor shows a sensing response of 80% at 5 ppm. The sensor passes with a low detection limit of 15.17 ppb and exhibits a relative shift of 47.7% over 5 ppm \text{H}_{{2}}\text{S} gas in threshold voltage. The developed device can be used in various gas emanating sites and oil industries.