A Study on the Properties of Pure SnO2 Gas Sensors

1. Introduction – SnO2 have been commonly used in its potential applications such as gas sensors, solar cells, display devices. It has also noteworthy characteristics such as high transmittance in the ultraviolet-visible... [ view full abstract ]

1. Introduction – SnO2 have been commonly used in its potential applications such as gas sensors, solar cells, display devices. It has also noteworthy characteristics such as high transmittance in the ultraviolet-visible region and high reflectance in infrared region, easy doping and easy tailoring.

In this study, the structural, optical and electrical properties the SnO2 gas sensors have been investigated with changing SnO2 target power, butane gas concentration, applied voltage, and operating temperature.

2. Experimental – SnO2 thin films were deposited on n-Si (100) and glass substrates with 50W and 100W SnO2 target power by using RF sputtering technique at room temperature. The other deposition parameters were kept constant at whole depositions. They were called as SnO2-1 (50W) and SnO2-2 (100W). After the deposition processes, the thicknesses of the thin films were confirmed by a stylus type profilometer. The structural and optical properties of the thin films were analyzed by the X-Ray diffractometer and UV-Visible spectrometer. Then, the fabrication processes were completed with the formation of the heaters and interdigital electrodes by the deposition of Pt metals with the thickness of 1000 nm and 500 nm, respectively. The gas sensors were tested with the different butane gas concentrations (0-750 ppm), applied voltages (0-5.0 V) and operating temperatures (100°C and 300 °C).

3. Results and Discussion – The X-Ray diffraction measurements showed that the SnO2 thin films have SnO2 diffraction peaks at different peak positions. That means, the deposited SnO2 thin films have polycrystalline with tetragonal structure. It was obtained from the analyzing UV-Visible results that; the bandgap values were found around 3.8 eV. As can be seen from the Sensitivity - Gas Concentration graph that, the SnO2-2 gas sensor with 300 °C operating temperature has the best sensitivities at all butane concentrations.

4. Conclusions – The results showed that the best gas sensors properties were obtained at 300 °C operating temperature for the SnO2-2 gas sensor which is deposited by using 100W target power.

5. Acknowledgments – This work is supported by the MD and MSIT of Turkey with Project No: 2011K120290 and 0633.STZ.2014, respectively.