研究目的
To study the effect of temperature on optical, structural and NH3 gas sensing properties of TeO2 thin films.
研究成果
Increasing deposition temperature improves crystalline structure, decreases grain size, reduces optical energy gap from 3.95 eV to 3.80 eV, enhances NH3 gas sensitivity, and shortens response and recovery times due to reduced defect density and increased grain boundaries, making TeO2 films suitable for sensor applications.
研究不足
The study is limited to specific temperature ranges (400-500°C) and uses only thermal evaporation method; other deposition techniques or temperatures were not explored. Gas sensing was tested only for NH3 at room temperature, and long-term stability was assessed over 60 days but may require longer periods for comprehensive evaluation.
1：Experimental Design and Method Selection:
TeO2 thin films were synthesized on glass substrates by thermal evaporation of tellurium powder in air without any catalyst, using a horizontal quartz tube furnace heated to 400°C, 450°C, and 500°C. The aim was to investigate temperature effects on properties.
2：Sample Selection and Data Sources:
Glass substrates were used, with tellurium powder (99.99%) as the source. Samples were prepared at different temperatures for analysis.
3：99%) as the source. Samples were prepared at different temperatures for analysis.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment includes a horizontal quartz tube furnace, alumina boat, mechanical profilometer (DECTAK 3) for thickness measurement, X-ray diffractometer (Philips-PW 1800 with Cu(Kα) radiation), scanning electron microscope (Hitachi 4160), UV-VIS spectrometer for optical measurements, Raman spectrometer with Ar+ laser excitation (785 nm line), and a gas flow system with a multimeter for resistance measurement. Materials include tellurium powder, glass substrates, gold electrodes, copper wires, and silver paste.
4：Experimental Procedures and Operational Workflow:
Tellurium powder was placed in an alumina boat inside the furnace, heated to specified temperatures, and evaporated onto glass substrates. After cooling, films were characterized for thickness, microstructure (XRD), morphology (SEM), optical properties (UV-VIS), Raman spectra, and gas sensing response to NH3 at room temperature using a container and flow system.
5：Data Analysis Methods:
XRD patterns were analyzed for crystallinity, SEM images for grain size, optical energy gap was calculated from transmittance and reflectance using the Tauc plot method, and gas sensitivity was computed using the formula S = (Rg - Ra)/Ra * 100, with response and recovery times measured from resistance curves.
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