Structural, Optical, and Sensing Properties of Nb-Doped ITO Thin Films Deposited by the Sol–Gel Method

Abstract

The aim of the present study was the development of Nb-doped ITO thin films for carbon monoxide (CO) sensing applications. The detection of CO is imperious because of its high toxicity, with long-term exposure having a negative impact on human health. Using a feasible sol–gel method, the doped ITO thin films were prepared at room temperature and deposited onto various substrates (Si, SiO2/glass, and glass). The structural, morphological, and optical characterization was performed by the following techniques: X-ray diffractometry (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV/Vis/NIR spectroscopic ellipsometry (SE). The analysis revealed a crystalline structure and a low surface roughness of the doped ITO-based thin films. XTEM analysis (cross-sectional transmission electron microscopy) showed that the film has crystallites of the order of 5–10 nm and relatively large pores (around 3–5 nm in diameter). A transmittance value of 80% in the visible region and an optical band-gap energy of around 3.7 eV were found for dip-coated ITO/Nb films on SiO2/glass and glass supports. The EDX measurements proved the presence of Nb in the ITO film in a molar ratio of 3.7%, close to the intended one (4%). Gas testing measurements were carried out on the ITO undoped and doped thin films deposited on glass substrate. The presence of Nb in the ITO matrix increases the electrical signal and the sensitivity to CO detection, leading to the highest response for 2000 ppm CO concentration at working temperature of 300 °C.

ITO Thin Films for Low-Resistance Gas Sensors

“…Energy-dispersive X-ray (EDX) spectroscopy of ITO films was carried out using a Phenom ProX scanning electron microscope (Thermo Fisher Scientific, Shanghai, China) with special detectors at an accelerating voltage of 15 kV. This EDX mode with an accelerating voltage of 15 kV is adequate for the study of ITO films with a thickness of 180 nm [32][33][34][35]. X-ray diffraction analysis (XRD) was performed to determine the phase composition of the thin films.…”

Numerical Simulation of Highly Efficient Cs2TiI6 based Pb Free Perovskites Solar Cell with the Help of Optimized ETL and HTL Using SCAPS-1D Software

“…ITO sheet resistance, however, will rise with heating, resulting in a higher series resistance in the finished product. It is demonstrated that FTO has a number of advantages over ITO, including cost [12]. There are many compound materials for example 𝐶𝑠 2 𝑇𝑖𝐵𝑟 6 , 𝐶𝑠 2 𝑇𝑖𝐼 1 𝐵𝑟 5 , 𝐶𝑠 2 𝑇𝑖𝐼 2 𝐵𝑟 4 , 𝐶𝑠 2 𝑇𝑖𝐼 3 𝐵𝑟 3 , 𝐶𝑠 2 𝑇𝑖𝐼 4 𝐵𝑟 2 , 𝐶𝑠 2 𝑇𝑖𝐼 5 𝐵𝑟 1 , and 𝐶𝑠 2 𝑇𝑖𝐼 6 which are used in perovskite solar cell currently [13].…”

Optical and electrical properties of Al-doped ZnO thin films deposited by sol-gel method

“…[1][2][3][4][5][6][7] ZnO thin films are processed using methods such as chemical vapor deposition, 8 spray pyrolysis, 9 thermal evaporation, 10 r.f. magnetron sputtering, 11,12 and sol-gel method. [13][14][15] The sol-gel is a low cost deposition method which offers the possibility to obtain oxide films with thickness of nanometric scale, with controlled stoichiometry, good reproducibility, uniformity and doping.…”