研究目的
To fabricate high-quality nanocrystalline SnO2 thin film gas sensors using sol-gel spin coating method on SiO2/Si and Al2O3 substrates for detecting hydrogen gas at different concentrations and operating temperatures, aiming to achieve high sensitivity and performance.
研究成果
High-quality nanocrystalline SnO2 thin films were successfully fabricated on SiO2/Si and Al2O3 substrates, with Al2O3-based sensors showing superior performance. The high porosity from glycerin addition enabled efficient gas adsorption/desorption, leading to high sensitivities (up to 9200% at 125°C) and potential for cost-effective hydrogen sensing applications in various environments.
研究不足
The sensitivity drifts from zero during repeated gas cycling, with poor recovery and decreased repeatability at room temperature due to incomplete H2 removal and inefficient O2 adsorption. Optimization is needed for better stability and recovery.
1：Experimental Design and Method Selection:
The study uses sol-gel spin coating to prepare nanocrystalline SnO2 thin films, with glycerin added to the sol solution to increase porosity. Structural and morphological characterizations are performed using XRD and FESEM, and gas sensing measurements are conducted using MSM devices with Pd contacts.
2：Sample Selection and Data Sources:
p-type Si (100) substrates with SiO2 layer and Al2O3 substrates are used. Hydrogen gas concentrations range from 150 ppm to 1000 ppm.
3：List of Experimental Equipment and Materials:
Equipment includes a tube furnace for annealing, XRD (PANalytical X'pert Pro MRD), FESEM (Leo-Supra 50VP), RF sputtering system for Pd deposition, and Keithley 2400 source meter for electrical measurements. Materials include SnO2 sol-gel precursors, glycerin, Pd, Si and Al2O3 substrates, H2O2, H2SO
4：Experimental Procedures and Operational Workflow:
Substrates are cleaned using RCA and Piranha methods. SnO2 thin films are deposited by spin coating, annealed at 400-600°C, characterized by XRD and FESEM. Pd electrodes are sputtered, and gas sensing is measured at bias voltages of 0.2V or 0.5V with H2 gas exposure at room temperature, 75°C, and 125°C for up to 50 minutes.
5：2V or 5V with H2 gas exposure at room temperature, 75°C, and 125°C for up to 50 minutes.
Data Analysis Methods:
5. Data Analysis Methods: Sensitivity is calculated from electrical current changes. XRD patterns are compared to standard SnO2 structures, and FESEM images analyze surface morphology.
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