Determination of free carrier density and space charge layer variation in nanocrystalline In3+ doped tin oxides using Fourier transforminfrared spectroscopy

A correlation between the surface reactions and the electrical response of doped nano-metal-oxide-semiconductors exposed to reducing gas is established using Fourier transform infrared (FTIR) spectroscopy. The effect of processing temperature on the microstructure evolution and the electronic conduction of the nanocrystalline In–SnO2 is presented. Variation in the charge carrier density is correlated to the solid/gas reaction of In–SnO2 in the nanodomain using the Drude-Zener theory including Spitzer and Fan’s [Phys. Rev. 99, 1893 (1955)] correction to accommodate for the quantum effects. Higher gas sensitivity for nanocrystalline size less than twice the space charge layer thickness is observed using in situ FTIR.