Plasma-assisted chemical vapor synthesis of indium tin oxide (ITO) nanopowder and hydrogen-sensing property of ITO thin film

Transparent conducting indium tin oxide (ITO) nanoparticles were synthesized by plasma-assisted chemical vapor synthesis route using indium nitrate and tin nitrate as the precursors. The injected precursors were vaporized in the plasma flame followed by vapor-phase reaction and subsequent quenching of the vaporized precursors produced nanosized ITO. The amount of tin nitrate was varied to obtain 5, 10 and 15 atomic percent Sn designated as ITO1, ITO2 and ITO3, respectively. The grain size of the produced ITO powder increased with increasing plasma torch power. On the other hand, it decreased with increasing plasma gas flow rate. The electrical and optical properties of ITO films prepared by spin-coating a dispersion of synthesized nanoparticles on a glass substrate vary as a function of tin content. Hall effect measurements showed that the minimum resistivity of 6.65 x 10(-4) Omega cm was obtained for ITO2 film. ITO1 and ITO2 film exhibited an average transmission of 85% indicating their suitability in optoelectronic applications. The ITO gas sensor was exposed to different concentrations of H-2 gas and temperatures to evaluate its gas sensitivity. The optimum operating temperature and gas concentration of H-2 showing the highest sensitivity was determined to be 350 degrees C and 400 ppm, respectively. The linear relation between sensitivity and concentration up to 400 ppm of H-2 can benefit the actuator to detect the concentration of H-2 and thus making it suitable for high-performance hydrogen gas sensing applications.