Effect of indium-doped SnO2 nanoparticles on NO2 gas sensing properties

Undoped and indium-doped SnO2 thin films with different doping concentrations have been prepared by sol–gel spin coating process on float glass substrates. XRD, TEM and AFM studies are carried out to investigate the effect of indium in SnO2 thin films. TEM studies reveal the dispersed nanoparticles of around 3 nm size (∼Debye length). In addition we have observed that indium doping improves the sensor response and selectivity towards NO2 gas at a low operating temperature and also resolves the problem of agglomeration of particles that is responsible for the lowering of sensor response and stability in the above mentioned particle size range. A very high sensor response of around 7200% has been observed in 10 wt% indium-doped SnO2 films to 500 ppm of NO2 gas at an operating temperature of 150 °C.