Fabrications of volatile organic compound detector systems based on semiconductor materials SnO2 nanostructure

Volatile organic compounds (VOCs) could be categorized as the one of air pollution source. They are hazardous to human´s health if they were exposed to human above the allowed threshold level value (TLV). Some of them are odorless and colorless so they were difficult to be detected by human senses. Therefore, the presence of VOCs gas sensor device is required. One of semiconductor materials that usually utilized in sensor applications is SnO₂ due to some reasons, i.e. reactive, ease to adsorb gas, and relatively low-cost. SnO₂ based VOCs gas sensor could be synthesized with Chemical Bath Deposition (CBD) method that is cost effective, low process temperature and simple. This work would study the sensing performance of SnO₂ based VOCs sensor which the kind of VOCs used in this work are ethanol, isopropyl alcohol (IPA) and acetone. The synthesis of SnO₂ via CBD method conducted using stannous chloride (SnCl₂ · 2H₂O) as precursor and deionized water as solvent. Precursor solutions were prepared with concentration of 0.15 M, ratio of catalyst (urea) and solvent was 1:15. Substrate used in this work was alumina (Al₂O₃) and it was immersed in precursor solution as long as 48 hours at 60°C. Furthermore, substrate was calcined at 575°C. Synthesized SnO₂ thin films were characterized using X-Ray Diffractometer (XRD), Energy Dispersive Spectroscope (EDS) and Scanning Electron Microscope (SEM). Characterization results show that SnO₂ thin film successfully formed with morphology in the form of small grains with 90-120 nm in size. From testing result data, optimum performance of sensor has been obtained at operating temperature of 300°C for 500 ppm ethanol with sensitivity level of 99.57%. The sensor is more selective to isopropyl alcohol among others, with highest sensitivity level of 99.94%, response time of 0.15 minutes and recovery - ime of 7.3 minutes.