Synthesis and characterization of SnO2 nanowires

Abstract

In this study, tin dioxide (SnO2) nanowires (NWs) have been synthesized using a Chemical Vapor Deposition (CVD) furnace. The optimal growth conditions were 900 °C, with 1 g of Sn as the precursor and 100 Standard Cubic Centimeters per Minute (sccm) of 1000 parts per million (ppm) of oxygen (O2) diluted in argon (Ar) as the carrier gas. Their characterization has been done using Scanning Electron Microscopy (SEM) and gas sensing properties under controlled UV light intensity have been studied in a gas chamber. Regarding gas measurements, the sensor's behaviour was studied with and without the influence of UV light in different atmospheres using a 360 nm LED. In dry air, the I(V) characteristics of the sensor were analysed. It was observed that the sensor exhibited Schottky behaviour (metal-semiconductor-metal junction) when the LED intensity was below 3 mA, and ohmic behaviour for intensities equal or above 3 mA. Subsequently, the sensor's response was examined in the presence of wet air, at different fixed levels of relative humidity (RH), and the response and response time were studied under increasing UV illumination. It was found that both the response time and the relative change in electrical resistance decreased as the LED intensity or humidity increased. Finally, the sensor's behaviour in dry air with humidity pulses (varying RH) was investigated. It was observed that the sensor exhibited n-type behaviour when not illuminated and p-type behaviour when illuminated. In addition, the sensor was exposed to methane (CH4) pulses, showing no response