Determination of free carrier density and space charge layer variation in nanocrystalline In3+ doped tin oxides using Fourier transform infrared 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\u27s [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